Update and fix staticcheck

vendor/honnef.co/go/tools/ir/LICENSE

@@ -0,0 +1,28 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+Copyright (c) 2016 Dominik Honnef. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/honnef.co/go/tools/ir/blockopt.go

@@ -0,0 +1,209 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// Simple block optimizations to simplify the control flow graph.
+
+// TODO(adonovan): opt: instead of creating several "unreachable" blocks
+// per function in the Builder, reuse a single one (e.g. at Blocks[1])
+// to reduce garbage.
+
+import (
+	"fmt"
+	"os"
+)
+
+// If true, perform sanity checking and show progress at each
+// successive iteration of optimizeBlocks.  Very verbose.
+const debugBlockOpt = false
+
+// markReachable sets Index=-1 for all blocks reachable from b.
+func markReachable(b *BasicBlock) {
+	b.gaps = -1
+	for _, succ := range b.Succs {
+		if succ.gaps == 0 {
+			markReachable(succ)
+		}
+	}
+}
+
+// deleteUnreachableBlocks marks all reachable blocks of f and
+// eliminates (nils) all others, including possibly cyclic subgraphs.
+//
+func deleteUnreachableBlocks(f *Function) {
+	const white, black = 0, -1
+	// We borrow b.gaps temporarily as the mark bit.
+	for _, b := range f.Blocks {
+		b.gaps = white
+	}
+	markReachable(f.Blocks[0])
+	// In SSI form, we need the exit to be reachable for correct
+	// post-dominance information. In original form, however, we
+	// cannot unconditionally mark it reachable because we won't
+	// be adding fake edges, and this breaks the calculation of
+	// dominance information.
+	markReachable(f.Exit)
+	for i, b := range f.Blocks {
+		if b.gaps == white {
+			for _, c := range b.Succs {
+				if c.gaps == black {
+					c.removePred(b) // delete white->black edge
+				}
+			}
+			if debugBlockOpt {
+				fmt.Fprintln(os.Stderr, "unreachable", b)
+			}
+			f.Blocks[i] = nil // delete b
+		}
+	}
+	f.removeNilBlocks()
+}
+
+// jumpThreading attempts to apply simple jump-threading to block b,
+// in which a->b->c become a->c if b is just a Jump.
+// The result is true if the optimization was applied.
+//
+func jumpThreading(f *Function, b *BasicBlock) bool {
+	if b.Index == 0 {
+		return false // don't apply to entry block
+	}
+	if b.Instrs == nil {
+		return false
+	}
+	for _, pred := range b.Preds {
+		switch pred.Control().(type) {
+		case *ConstantSwitch:
+			// don't optimize away the head blocks of switch statements
+			return false
+		}
+	}
+	if _, ok := b.Instrs[0].(*Jump); !ok {
+		return false // not just a jump
+	}
+	c := b.Succs[0]
+	if c == b {
+		return false // don't apply to degenerate jump-to-self.
+	}
+	if c.hasPhi() {
+		return false // not sound without more effort
+	}
+	for j, a := range b.Preds {
+		a.replaceSucc(b, c)
+
+		// If a now has two edges to c, replace its degenerate If by Jump.
+		if len(a.Succs) == 2 && a.Succs[0] == c && a.Succs[1] == c {
+			jump := new(Jump)
+			jump.setBlock(a)
+			a.Instrs[len(a.Instrs)-1] = jump
+			a.Succs = a.Succs[:1]
+			c.removePred(b)
+		} else {
+			if j == 0 {
+				c.replacePred(b, a)
+			} else {
+				c.Preds = append(c.Preds, a)
+			}
+		}
+
+		if debugBlockOpt {
+			fmt.Fprintln(os.Stderr, "jumpThreading", a, b, c)
+		}
+	}
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+// fuseBlocks attempts to apply the block fusion optimization to block
+// a, in which a->b becomes ab if len(a.Succs)==len(b.Preds)==1.
+// The result is true if the optimization was applied.
+//
+func fuseBlocks(f *Function, a *BasicBlock) bool {
+	if len(a.Succs) != 1 {
+		return false
+	}
+	if a.Succs[0] == f.Exit {
+		return false
+	}
+	b := a.Succs[0]
+	if len(b.Preds) != 1 {
+		return false
+	}
+	if _, ok := a.Instrs[len(a.Instrs)-1].(*Panic); ok {
+		// panics aren't simple jumps, they have side effects.
+		return false
+	}
+
+	// Degenerate &&/|| ops may result in a straight-line CFG
+	// containing φ-nodes. (Ideally we'd replace such them with
+	// their sole operand but that requires Referrers, built later.)
+	if b.hasPhi() {
+		return false // not sound without further effort
+	}
+
+	// Eliminate jump at end of A, then copy all of B across.
+	a.Instrs = append(a.Instrs[:len(a.Instrs)-1], b.Instrs...)
+	for _, instr := range b.Instrs {
+		instr.setBlock(a)
+	}
+
+	// A inherits B's successors
+	a.Succs = append(a.succs2[:0], b.Succs...)
+
+	// Fix up Preds links of all successors of B.
+	for _, c := range b.Succs {
+		c.replacePred(b, a)
+	}
+
+	if debugBlockOpt {
+		fmt.Fprintln(os.Stderr, "fuseBlocks", a, b)
+	}
+
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+// optimizeBlocks() performs some simple block optimizations on a
+// completed function: dead block elimination, block fusion, jump
+// threading.
+//
+func optimizeBlocks(f *Function) {
+	if debugBlockOpt {
+		f.WriteTo(os.Stderr)
+		mustSanityCheck(f, nil)
+	}
+
+	deleteUnreachableBlocks(f)
+
+	// Loop until no further progress.
+	changed := true
+	for changed {
+		changed = false
+
+		if debugBlockOpt {
+			f.WriteTo(os.Stderr)
+			mustSanityCheck(f, nil)
+		}
+
+		for _, b := range f.Blocks {
+			// f.Blocks will temporarily contain nils to indicate
+			// deleted blocks; we remove them at the end.
+			if b == nil {
+				continue
+			}
+
+			// Fuse blocks.  b->c becomes bc.
+			if fuseBlocks(f, b) {
+				changed = true
+			}
+
+			// a->b->c becomes a->c if b contains only a Jump.
+			if jumpThreading(f, b) {
+				changed = true
+				continue // (b was disconnected)
+			}
+		}
+	}
+	f.removeNilBlocks()
+}

vendor/honnef.co/go/tools/ir/const.go

@@ -0,0 +1,153 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines the Const SSA value type.
+
+import (
+	"fmt"
+	"go/constant"
+	"go/types"
+	"strconv"
+)
+
+// NewConst returns a new constant of the specified value and type.
+// val must be valid according to the specification of Const.Value.
+//
+func NewConst(val constant.Value, typ types.Type) *Const {
+	return &Const{
+		register: register{
+			typ: typ,
+		},
+		Value: val,
+	}
+}
+
+// intConst returns an 'int' constant that evaluates to i.
+// (i is an int64 in case the host is narrower than the target.)
+func intConst(i int64) *Const {
+	return NewConst(constant.MakeInt64(i), tInt)
+}
+
+// nilConst returns a nil constant of the specified type, which may
+// be any reference type, including interfaces.
+//
+func nilConst(typ types.Type) *Const {
+	return NewConst(nil, typ)
+}
+
+// stringConst returns a 'string' constant that evaluates to s.
+func stringConst(s string) *Const {
+	return NewConst(constant.MakeString(s), tString)
+}
+
+// zeroConst returns a new "zero" constant of the specified type,
+// which must not be an array or struct type: the zero values of
+// aggregates are well-defined but cannot be represented by Const.
+//
+func zeroConst(t types.Type) *Const {
+	switch t := t.(type) {
+	case *types.Basic:
+		switch {
+		case t.Info()&types.IsBoolean != 0:
+			return NewConst(constant.MakeBool(false), t)
+		case t.Info()&types.IsNumeric != 0:
+			return NewConst(constant.MakeInt64(0), t)
+		case t.Info()&types.IsString != 0:
+			return NewConst(constant.MakeString(""), t)
+		case t.Kind() == types.UnsafePointer:
+			fallthrough
+		case t.Kind() == types.UntypedNil:
+			return nilConst(t)
+		default:
+			panic(fmt.Sprint("zeroConst for unexpected type:", t))
+		}
+	case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature:
+		return nilConst(t)
+	case *types.Named:
+		return NewConst(zeroConst(t.Underlying()).Value, t)
+	case *types.Array, *types.Struct, *types.Tuple:
+		panic(fmt.Sprint("zeroConst applied to aggregate:", t))
+	}
+	panic(fmt.Sprint("zeroConst: unexpected ", t))
+}
+
+func (c *Const) RelString(from *types.Package) string {
+	var p string
+	if c.Value == nil {
+		p = "nil"
+	} else if c.Value.Kind() == constant.String {
+		v := constant.StringVal(c.Value)
+		const max = 20
+		// TODO(adonovan): don't cut a rune in half.
+		if len(v) > max {
+			v = v[:max-3] + "..." // abbreviate
+		}
+		p = strconv.Quote(v)
+	} else {
+		p = c.Value.String()
+	}
+	return fmt.Sprintf("Const <%s> {%s}", relType(c.Type(), from), p)
+}
+
+func (c *Const) String() string {
+	return c.RelString(c.Parent().pkg())
+}
+
+// IsNil returns true if this constant represents a typed or untyped nil value.
+func (c *Const) IsNil() bool {
+	return c.Value == nil
+}
+
+// Int64 returns the numeric value of this constant truncated to fit
+// a signed 64-bit integer.
+//
+func (c *Const) Int64() int64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if i, ok := constant.Int64Val(x); ok {
+			return i
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return int64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Uint64 returns the numeric value of this constant truncated to fit
+// an unsigned 64-bit integer.
+//
+func (c *Const) Uint64() uint64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if u, ok := constant.Uint64Val(x); ok {
+			return u
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return uint64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Float64 returns the numeric value of this constant truncated to fit
+// a float64.
+//
+func (c *Const) Float64() float64 {
+	f, _ := constant.Float64Val(c.Value)
+	return f
+}
+
+// Complex128 returns the complex value of this constant truncated to
+// fit a complex128.
+//
+func (c *Const) Complex128() complex128 {
+	re, _ := constant.Float64Val(constant.Real(c.Value))
+	im, _ := constant.Float64Val(constant.Imag(c.Value))
+	return complex(re, im)
+}

vendor/honnef.co/go/tools/ir/create.go

@@ -0,0 +1,275 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file implements the CREATE phase of IR construction.
+// See builder.go for explanation.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"sync"
+
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// NewProgram returns a new IR Program.
+//
+// mode controls diagnostics and checking during IR construction.
+//
+func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
+	prog := &Program{
+		Fset:     fset,
+		imported: make(map[string]*Package),
+		packages: make(map[*types.Package]*Package),
+		thunks:   make(map[selectionKey]*Function),
+		bounds:   make(map[*types.Func]*Function),
+		mode:     mode,
+	}
+
+	h := typeutil.MakeHasher() // protected by methodsMu, in effect
+	prog.methodSets.SetHasher(h)
+	prog.canon.SetHasher(h)
+
+	return prog
+}
+
+// memberFromObject populates package pkg with a member for the
+// typechecker object obj.
+//
+// For objects from Go source code, syntax is the associated syntax
+// tree (for funcs and vars only); it will be used during the build
+// phase.
+//
+func memberFromObject(pkg *Package, obj types.Object, syntax ast.Node) {
+	name := obj.Name()
+	switch obj := obj.(type) {
+	case *types.Builtin:
+		if pkg.Pkg != types.Unsafe {
+			panic("unexpected builtin object: " + obj.String())
+		}
+
+	case *types.TypeName:
+		pkg.Members[name] = &Type{
+			object: obj,
+			pkg:    pkg,
+		}
+
+	case *types.Const:
+		c := &NamedConst{
+			object: obj,
+			Value:  NewConst(obj.Val(), obj.Type()),
+			pkg:    pkg,
+		}
+		pkg.values[obj] = c.Value
+		pkg.Members[name] = c
+
+	case *types.Var:
+		g := &Global{
+			Pkg:    pkg,
+			name:   name,
+			object: obj,
+			typ:    types.NewPointer(obj.Type()), // address
+		}
+		pkg.values[obj] = g
+		pkg.Members[name] = g
+
+	case *types.Func:
+		sig := obj.Type().(*types.Signature)
+		if sig.Recv() == nil && name == "init" {
+			pkg.ninit++
+			name = fmt.Sprintf("init#%d", pkg.ninit)
+		}
+		fn := &Function{
+			name:      name,
+			object:    obj,
+			Signature: sig,
+			Pkg:       pkg,
+			Prog:      pkg.Prog,
+		}
+
+		fn.source = syntax
+		fn.initHTML(pkg.printFunc)
+		if syntax == nil {
+			fn.Synthetic = "loaded from gc object file"
+		} else {
+			fn.functionBody = new(functionBody)
+		}
+
+		pkg.values[obj] = fn
+		pkg.Functions = append(pkg.Functions, fn)
+		if sig.Recv() == nil {
+			pkg.Members[name] = fn // package-level function
+		}
+
+	default: // (incl. *types.Package)
+		panic("unexpected Object type: " + obj.String())
+	}
+}
+
+// membersFromDecl populates package pkg with members for each
+// typechecker object (var, func, const or type) associated with the
+// specified decl.
+//
+func membersFromDecl(pkg *Package, decl ast.Decl) {
+	switch decl := decl.(type) {
+	case *ast.GenDecl: // import, const, type or var
+		switch decl.Tok {
+		case token.CONST:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], nil)
+					}
+				}
+			}
+
+		case token.VAR:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], spec)
+					}
+				}
+			}
+
+		case token.TYPE:
+			for _, spec := range decl.Specs {
+				id := spec.(*ast.TypeSpec).Name
+				if !isBlankIdent(id) {
+					memberFromObject(pkg, pkg.info.Defs[id], nil)
+				}
+			}
+		}
+
+	case *ast.FuncDecl:
+		id := decl.Name
+		if !isBlankIdent(id) {
+			memberFromObject(pkg, pkg.info.Defs[id], decl)
+		}
+	}
+}
+
+// CreatePackage constructs and returns an IR Package from the
+// specified type-checked, error-free file ASTs, and populates its
+// Members mapping.
+//
+// importable determines whether this package should be returned by a
+// subsequent call to ImportedPackage(pkg.Path()).
+//
+// The real work of building IR form for each function is not done
+// until a subsequent call to Package.Build().
+//
+func (prog *Program) CreatePackage(pkg *types.Package, files []*ast.File, info *types.Info, importable bool) *Package {
+	p := &Package{
+		Prog:      prog,
+		Members:   make(map[string]Member),
+		values:    make(map[types.Object]Value),
+		Pkg:       pkg,
+		info:      info,  // transient (CREATE and BUILD phases)
+		files:     files, // transient (CREATE and BUILD phases)
+		printFunc: prog.PrintFunc,
+	}
+
+	// Add init() function.
+	p.init = &Function{
+		name:         "init",
+		Signature:    new(types.Signature),
+		Synthetic:    "package initializer",
+		Pkg:          p,
+		Prog:         prog,
+		functionBody: new(functionBody),
+	}
+	p.init.initHTML(prog.PrintFunc)
+	p.Members[p.init.name] = p.init
+	p.Functions = append(p.Functions, p.init)
+
+	// CREATE phase.
+	// Allocate all package members: vars, funcs, consts and types.
+	if len(files) > 0 {
+		// Go source package.
+		for _, file := range files {
+			for _, decl := range file.Decls {
+				membersFromDecl(p, decl)
+			}
+		}
+	} else {
+		// GC-compiled binary package (or "unsafe")
+		// No code.
+		// No position information.
+		scope := p.Pkg.Scope()
+		for _, name := range scope.Names() {
+			obj := scope.Lookup(name)
+			memberFromObject(p, obj, nil)
+			if obj, ok := obj.(*types.TypeName); ok {
+				if named, ok := obj.Type().(*types.Named); ok {
+					for i, n := 0, named.NumMethods(); i < n; i++ {
+						memberFromObject(p, named.Method(i), nil)
+					}
+				}
+			}
+		}
+	}
+
+	// Add initializer guard variable.
+	initguard := &Global{
+		Pkg:  p,
+		name: "init$guard",
+		typ:  types.NewPointer(tBool),
+	}
+	p.Members[initguard.Name()] = initguard
+
+	if prog.mode&GlobalDebug != 0 {
+		p.SetDebugMode(true)
+	}
+
+	if prog.mode&PrintPackages != 0 {
+		printMu.Lock()
+		p.WriteTo(os.Stdout)
+		printMu.Unlock()
+	}
+
+	if importable {
+		prog.imported[p.Pkg.Path()] = p
+	}
+	prog.packages[p.Pkg] = p
+
+	return p
+}
+
+// printMu serializes printing of Packages/Functions to stdout.
+var printMu sync.Mutex
+
+// AllPackages returns a new slice containing all packages in the
+// program prog in unspecified order.
+//
+func (prog *Program) AllPackages() []*Package {
+	pkgs := make([]*Package, 0, len(prog.packages))
+	for _, pkg := range prog.packages {
+		pkgs = append(pkgs, pkg)
+	}
+	return pkgs
+}
+
+// ImportedPackage returns the importable Package whose PkgPath
+// is path, or nil if no such Package has been created.
+//
+// A parameter to CreatePackage determines whether a package should be
+// considered importable. For example, no import declaration can resolve
+// to the ad-hoc main package created by 'go build foo.go'.
+//
+// TODO(adonovan): rethink this function and the "importable" concept;
+// most packages are importable. This function assumes that all
+// types.Package.Path values are unique within the ir.Program, which is
+// false---yet this function remains very convenient.
+// Clients should use (*Program).Package instead where possible.
+// IR doesn't really need a string-keyed map of packages.
+//
+func (prog *Program) ImportedPackage(path string) *Package {
+	return prog.imported[path]
+}

vendor/honnef.co/go/tools/ir/doc.go

@@ -0,0 +1,129 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ir defines a representation of the elements of Go programs
+// (packages, types, functions, variables and constants) using a
+// static single-information (SSI) form intermediate representation
+// (IR) for the bodies of functions.
+//
+// THIS INTERFACE IS EXPERIMENTAL AND IS LIKELY TO CHANGE.
+//
+// For an introduction to SSA form, upon which SSI builds, see
+// http://en.wikipedia.org/wiki/Static_single_assignment_form.
+// This page provides a broader reading list:
+// http://www.dcs.gla.ac.uk/~jsinger/ssa.html.
+//
+// For an introduction to SSI form, see The static single information
+// form by C. Scott Ananian.
+//
+// The level of abstraction of the IR form is intentionally close to
+// the source language to facilitate construction of source analysis
+// tools.  It is not intended for machine code generation.
+//
+// The simplest way to create the IR of a package is
+// to load typed syntax trees using golang.org/x/tools/go/packages, then
+// invoke the irutil.Packages helper function. See ExampleLoadPackages
+// and ExampleWholeProgram for examples.
+// The resulting ir.Program contains all the packages and their
+// members, but IR code is not created for function bodies until a
+// subsequent call to (*Package).Build or (*Program).Build.
+//
+// The builder initially builds a naive IR form in which all local
+// variables are addresses of stack locations with explicit loads and
+// stores.  Registerisation of eligible locals and φ-node insertion
+// using dominance and dataflow are then performed as a second pass
+// called "lifting" to improve the accuracy and performance of
+// subsequent analyses; this pass can be skipped by setting the
+// NaiveForm builder flag.
+//
+// The primary interfaces of this package are:
+//
+//    - Member: a named member of a Go package.
+//    - Value: an expression that yields a value.
+//    - Instruction: a statement that consumes values and performs computation.
+//    - Node: a Value or Instruction (emphasizing its membership in the IR value graph)
+//
+// A computation that yields a result implements both the Value and
+// Instruction interfaces.  The following table shows for each
+// concrete type which of these interfaces it implements.
+//
+//                      Value?          Instruction?    Member?
+//   *Alloc             ✔               ✔
+//   *BinOp             ✔               ✔
+//   *BlankStore                        ✔
+//   *Builtin           ✔
+//   *Call              ✔               ✔
+//   *ChangeInterface   ✔               ✔
+//   *ChangeType        ✔               ✔
+//   *Const             ✔               ✔
+//   *Convert           ✔               ✔
+//   *DebugRef                          ✔
+//   *Defer             ✔               ✔
+//   *Extract           ✔               ✔
+//   *Field             ✔               ✔
+//   *FieldAddr         ✔               ✔
+//   *FreeVar           ✔
+//   *Function          ✔                               ✔ (func)
+//   *Global            ✔                               ✔ (var)
+//   *Go                ✔               ✔
+//   *If                                ✔
+//   *Index             ✔               ✔
+//   *IndexAddr         ✔               ✔
+//   *Jump                              ✔
+//   *Load              ✔               ✔
+//   *MakeChan          ✔               ✔
+//   *MakeClosure       ✔               ✔
+//   *MakeInterface     ✔               ✔
+//   *MakeMap           ✔               ✔
+//   *MakeSlice         ✔               ✔
+//   *MapLookup         ✔               ✔
+//   *MapUpdate         ✔               ✔
+//   *NamedConst                                        ✔ (const)
+//   *Next              ✔               ✔
+//   *Panic                             ✔
+//   *Parameter         ✔               ✔
+//   *Phi               ✔               ✔
+//   *Range             ✔               ✔
+//   *Recv              ✔               ✔
+//   *Return                            ✔
+//   *RunDefers                         ✔
+//   *Select            ✔               ✔
+//   *Send              ✔               ✔
+//   *Sigma             ✔               ✔
+//   *Slice             ✔               ✔
+//   *Store             ✔               ✔
+//   *StringLookup      ✔               ✔
+//   *Type                                              ✔ (type)
+//   *TypeAssert        ✔               ✔
+//   *UnOp              ✔               ✔
+//   *Unreachable                       ✔
+//
+// Other key types in this package include: Program, Package, Function
+// and BasicBlock.
+//
+// The program representation constructed by this package is fully
+// resolved internally, i.e. it does not rely on the names of Values,
+// Packages, Functions, Types or BasicBlocks for the correct
+// interpretation of the program.  Only the identities of objects and
+// the topology of the IR and type graphs are semantically
+// significant.  (There is one exception: Ids, used to identify field
+// and method names, contain strings.)  Avoidance of name-based
+// operations simplifies the implementation of subsequent passes and
+// can make them very efficient.  Many objects are nonetheless named
+// to aid in debugging, but it is not essential that the names be
+// either accurate or unambiguous.  The public API exposes a number of
+// name-based maps for client convenience.
+//
+// The ir/irutil package provides various utilities that depend only
+// on the public API of this package.
+//
+// TODO(adonovan): Consider the exceptional control-flow implications
+// of defer and recover().
+//
+// TODO(adonovan): write a how-to document for all the various cases
+// of trying to determine corresponding elements across the four
+// domains of source locations, ast.Nodes, types.Objects,
+// ir.Values/Instructions.
+//
+package ir // import "honnef.co/go/tools/ir"

vendor/honnef.co/go/tools/ir/dom.go

@@ -0,0 +1,461 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines algorithms related to dominance.
+
+// Dominator tree construction ----------------------------------------
+//
+// We use the algorithm described in Lengauer & Tarjan. 1979.  A fast
+// algorithm for finding dominators in a flowgraph.
+// http://doi.acm.org/10.1145/357062.357071
+//
+// We also apply the optimizations to SLT described in Georgiadis et
+// al, Finding Dominators in Practice, JGAA 2006,
+// http://jgaa.info/accepted/2006/GeorgiadisTarjanWerneck2006.10.1.pdf
+// to avoid the need for buckets of size > 1.
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"math/big"
+	"os"
+	"sort"
+)
+
+// Idom returns the block that immediately dominates b:
+// its parent in the dominator tree, if any.
+// The entry node (b.Index==0) does not have a parent.
+//
+func (b *BasicBlock) Idom() *BasicBlock { return b.dom.idom }
+
+// Dominees returns the list of blocks that b immediately dominates:
+// its children in the dominator tree.
+//
+func (b *BasicBlock) Dominees() []*BasicBlock { return b.dom.children }
+
+// Dominates reports whether b dominates c.
+func (b *BasicBlock) Dominates(c *BasicBlock) bool {
+	return b.dom.pre <= c.dom.pre && c.dom.post <= b.dom.post
+}
+
+type byDomPreorder []*BasicBlock
+
+func (a byDomPreorder) Len() int           { return len(a) }
+func (a byDomPreorder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byDomPreorder) Less(i, j int) bool { return a[i].dom.pre < a[j].dom.pre }
+
+// DomPreorder returns a new slice containing the blocks of f in
+// dominator tree preorder.
+//
+func (f *Function) DomPreorder() []*BasicBlock {
+	n := len(f.Blocks)
+	order := make(byDomPreorder, n)
+	copy(order, f.Blocks)
+	sort.Sort(order)
+	return order
+}
+
+// domInfo contains a BasicBlock's dominance information.
+type domInfo struct {
+	idom      *BasicBlock   // immediate dominator (parent in domtree)
+	children  []*BasicBlock // nodes immediately dominated by this one
+	pre, post int32         // pre- and post-order numbering within domtree
+}
+
+// buildDomTree computes the dominator tree of f using the LT algorithm.
+// Precondition: all blocks are reachable (e.g. optimizeBlocks has been run).
+//
+func buildDomTree(fn *Function) {
+	// The step numbers refer to the original LT paper; the
+	// reordering is due to Georgiadis.
+
+	// Clear any previous domInfo.
+	for _, b := range fn.Blocks {
+		b.dom = domInfo{}
+	}
+
+	idoms := make([]*BasicBlock, len(fn.Blocks))
+
+	order := make([]*BasicBlock, 0, len(fn.Blocks))
+	seen := fn.blockset(0)
+	var dfs func(b *BasicBlock)
+	dfs = func(b *BasicBlock) {
+		if !seen.Add(b) {
+			return
+		}
+		for _, succ := range b.Succs {
+			dfs(succ)
+		}
+		if fn.fakeExits.Has(b) {
+			dfs(fn.Exit)
+		}
+		order = append(order, b)
+		b.post = len(order) - 1
+	}
+	dfs(fn.Blocks[0])
+
+	for i := 0; i < len(order)/2; i++ {
+		o := len(order) - i - 1
+		order[i], order[o] = order[o], order[i]
+	}
+
+	idoms[fn.Blocks[0].Index] = fn.Blocks[0]
+	changed := true
+	for changed {
+		changed = false
+		// iterate over all nodes in reverse postorder, except for the
+		// entry node
+		for _, b := range order[1:] {
+			var newIdom *BasicBlock
+			do := func(p *BasicBlock) {
+				if idoms[p.Index] == nil {
+					return
+				}
+				if newIdom == nil {
+					newIdom = p
+				} else {
+					finger1 := p
+					finger2 := newIdom
+					for finger1 != finger2 {
+						for finger1.post < finger2.post {
+							finger1 = idoms[finger1.Index]
+						}
+						for finger2.post < finger1.post {
+							finger2 = idoms[finger2.Index]
+						}
+					}
+					newIdom = finger1
+				}
+			}
+			for _, p := range b.Preds {
+				do(p)
+			}
+			if b == fn.Exit {
+				for _, p := range fn.Blocks {
+					if fn.fakeExits.Has(p) {
+						do(p)
+					}
+				}
+			}
+
+			if idoms[b.Index] != newIdom {
+				idoms[b.Index] = newIdom
+				changed = true
+			}
+		}
+	}
+
+	for i, b := range idoms {
+		fn.Blocks[i].dom.idom = b
+		if b == nil {
+			// malformed CFG
+			continue
+		}
+		if i == b.Index {
+			continue
+		}
+		b.dom.children = append(b.dom.children, fn.Blocks[i])
+	}
+
+	numberDomTree(fn.Blocks[0], 0, 0)
+
+	// printDomTreeDot(os.Stderr, fn) // debugging
+	// printDomTreeText(os.Stderr, root, 0) // debugging
+
+	if fn.Prog.mode&SanityCheckFunctions != 0 {
+		sanityCheckDomTree(fn)
+	}
+}
+
+// buildPostDomTree is like buildDomTree, but builds the post-dominator tree instead.
+func buildPostDomTree(fn *Function) {
+	// The step numbers refer to the original LT paper; the
+	// reordering is due to Georgiadis.
+
+	// Clear any previous domInfo.
+	for _, b := range fn.Blocks {
+		b.pdom = domInfo{}
+	}
+
+	idoms := make([]*BasicBlock, len(fn.Blocks))
+
+	order := make([]*BasicBlock, 0, len(fn.Blocks))
+	seen := fn.blockset(0)
+	var dfs func(b *BasicBlock)
+	dfs = func(b *BasicBlock) {
+		if !seen.Add(b) {
+			return
+		}
+		for _, pred := range b.Preds {
+			dfs(pred)
+		}
+		if b == fn.Exit {
+			for _, p := range fn.Blocks {
+				if fn.fakeExits.Has(p) {
+					dfs(p)
+				}
+			}
+		}
+		order = append(order, b)
+		b.post = len(order) - 1
+	}
+	dfs(fn.Exit)
+
+	for i := 0; i < len(order)/2; i++ {
+		o := len(order) - i - 1
+		order[i], order[o] = order[o], order[i]
+	}
+
+	idoms[fn.Exit.Index] = fn.Exit
+	changed := true
+	for changed {
+		changed = false
+		// iterate over all nodes in reverse postorder, except for the
+		// exit node
+		for _, b := range order[1:] {
+			var newIdom *BasicBlock
+			do := func(p *BasicBlock) {
+				if idoms[p.Index] == nil {
+					return
+				}
+				if newIdom == nil {
+					newIdom = p
+				} else {
+					finger1 := p
+					finger2 := newIdom
+					for finger1 != finger2 {
+						for finger1.post < finger2.post {
+							finger1 = idoms[finger1.Index]
+						}
+						for finger2.post < finger1.post {
+							finger2 = idoms[finger2.Index]
+						}
+					}
+					newIdom = finger1
+				}
+			}
+			for _, p := range b.Succs {
+				do(p)
+			}
+			if fn.fakeExits.Has(b) {
+				do(fn.Exit)
+			}
+
+			if idoms[b.Index] != newIdom {
+				idoms[b.Index] = newIdom
+				changed = true
+			}
+		}
+	}
+
+	for i, b := range idoms {
+		fn.Blocks[i].pdom.idom = b
+		if b == nil {
+			// malformed CFG
+			continue
+		}
+		if i == b.Index {
+			continue
+		}
+		b.pdom.children = append(b.pdom.children, fn.Blocks[i])
+	}
+
+	numberPostDomTree(fn.Exit, 0, 0)
+
+	// printPostDomTreeDot(os.Stderr, fn) // debugging
+	// printPostDomTreeText(os.Stderr, fn.Exit, 0) // debugging
+
+	if fn.Prog.mode&SanityCheckFunctions != 0 { // XXX
+		sanityCheckDomTree(fn) // XXX
+	}
+}
+
+// numberDomTree sets the pre- and post-order numbers of a depth-first
+// traversal of the dominator tree rooted at v.  These are used to
+// answer dominance queries in constant time.
+//
+func numberDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
+	v.dom.pre = pre
+	pre++
+	for _, child := range v.dom.children {
+		pre, post = numberDomTree(child, pre, post)
+	}
+	v.dom.post = post
+	post++
+	return pre, post
+}
+
+// numberPostDomTree sets the pre- and post-order numbers of a depth-first
+// traversal of the post-dominator tree rooted at v.  These are used to
+// answer post-dominance queries in constant time.
+//
+func numberPostDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
+	v.pdom.pre = pre
+	pre++
+	for _, child := range v.pdom.children {
+		pre, post = numberPostDomTree(child, pre, post)
+	}
+	v.pdom.post = post
+	post++
+	return pre, post
+}
+
+// Testing utilities ----------------------------------------
+
+// sanityCheckDomTree checks the correctness of the dominator tree
+// computed by the LT algorithm by comparing against the dominance
+// relation computed by a naive Kildall-style forward dataflow
+// analysis (Algorithm 10.16 from the "Dragon" book).
+//
+func sanityCheckDomTree(f *Function) {
+	n := len(f.Blocks)
+
+	// D[i] is the set of blocks that dominate f.Blocks[i],
+	// represented as a bit-set of block indices.
+	D := make([]big.Int, n)
+
+	one := big.NewInt(1)
+
+	// all is the set of all blocks; constant.
+	var all big.Int
+	all.Set(one).Lsh(&all, uint(n)).Sub(&all, one)
+
+	// Initialization.
+	for i := range f.Blocks {
+		if i == 0 {
+			// A root is dominated only by itself.
+			D[i].SetBit(&D[0], 0, 1)
+		} else {
+			// All other blocks are (initially) dominated
+			// by every block.
+			D[i].Set(&all)
+		}
+	}
+
+	// Iteration until fixed point.
+	for changed := true; changed; {
+		changed = false
+		for i, b := range f.Blocks {
+			if i == 0 {
+				continue
+			}
+			// Compute intersection across predecessors.
+			var x big.Int
+			x.Set(&all)
+			for _, pred := range b.Preds {
+				x.And(&x, &D[pred.Index])
+			}
+			if b == f.Exit {
+				for _, p := range f.Blocks {
+					if f.fakeExits.Has(p) {
+						x.And(&x, &D[p.Index])
+					}
+				}
+			}
+			x.SetBit(&x, i, 1) // a block always dominates itself.
+			if D[i].Cmp(&x) != 0 {
+				D[i].Set(&x)
+				changed = true
+			}
+		}
+	}
+
+	// Check the entire relation.  O(n^2).
+	ok := true
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			b, c := f.Blocks[i], f.Blocks[j]
+			actual := b.Dominates(c)
+			expected := D[j].Bit(i) == 1
+			if actual != expected {
+				fmt.Fprintf(os.Stderr, "dominates(%s, %s)==%t, want %t\n", b, c, actual, expected)
+				ok = false
+			}
+		}
+	}
+
+	preorder := f.DomPreorder()
+	for _, b := range f.Blocks {
+		if got := preorder[b.dom.pre]; got != b {
+			fmt.Fprintf(os.Stderr, "preorder[%d]==%s, want %s\n", b.dom.pre, got, b)
+			ok = false
+		}
+	}
+
+	if !ok {
+		panic("sanityCheckDomTree failed for " + f.String())
+	}
+
+}
+
+// Printing functions ----------------------------------------
+
+// printDomTree prints the dominator tree as text, using indentation.
+//lint:ignore U1000 used during debugging
+func printDomTreeText(buf *bytes.Buffer, v *BasicBlock, indent int) {
+	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
+	for _, child := range v.dom.children {
+		printDomTreeText(buf, child, indent+1)
+	}
+}
+
+// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
+// (.dot) format.
+//lint:ignore U1000 used during debugging
+func printDomTreeDot(buf io.Writer, f *Function) {
+	fmt.Fprintln(buf, "//", f)
+	fmt.Fprintln(buf, "digraph domtree {")
+	for i, b := range f.Blocks {
+		v := b.dom
+		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
+		// TODO(adonovan): improve appearance of edges
+		// belonging to both dominator tree and CFG.
+
+		// Dominator tree edge.
+		if i != 0 {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.dom.pre, v.pre)
+		}
+		// CFG edges.
+		for _, pred := range b.Preds {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.dom.pre, v.pre)
+		}
+	}
+	fmt.Fprintln(buf, "}")
+}
+
+// printDomTree prints the dominator tree as text, using indentation.
+//lint:ignore U1000 used during debugging
+func printPostDomTreeText(buf io.Writer, v *BasicBlock, indent int) {
+	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
+	for _, child := range v.pdom.children {
+		printPostDomTreeText(buf, child, indent+1)
+	}
+}
+
+// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
+// (.dot) format.
+//lint:ignore U1000 used during debugging
+func printPostDomTreeDot(buf io.Writer, f *Function) {
+	fmt.Fprintln(buf, "//", f)
+	fmt.Fprintln(buf, "digraph pdomtree {")
+	for _, b := range f.Blocks {
+		v := b.pdom
+		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
+		// TODO(adonovan): improve appearance of edges
+		// belonging to both dominator tree and CFG.
+
+		// Dominator tree edge.
+		if b != f.Exit {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.pdom.pre, v.pre)
+		}
+		// CFG edges.
+		for _, pred := range b.Preds {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.pdom.pre, v.pre)
+		}
+	}
+	fmt.Fprintln(buf, "}")
+}

vendor/honnef.co/go/tools/ir/emit.go

@@ -0,0 +1,450 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// Helpers for emitting IR instructions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+)
+
+// emitNew emits to f a new (heap Alloc) instruction allocating an
+// object of type typ.  pos is the optional source location.
+//
+func emitNew(f *Function, typ types.Type, source ast.Node) *Alloc {
+	v := &Alloc{Heap: true}
+	v.setType(types.NewPointer(typ))
+	f.emit(v, source)
+	return v
+}
+
+// emitLoad emits to f an instruction to load the address addr into a
+// new temporary, and returns the value so defined.
+//
+func emitLoad(f *Function, addr Value, source ast.Node) *Load {
+	v := &Load{X: addr}
+	v.setType(deref(addr.Type()))
+	f.emit(v, source)
+	return v
+}
+
+func emitRecv(f *Function, ch Value, commaOk bool, typ types.Type, source ast.Node) Value {
+	recv := &Recv{
+		Chan:    ch,
+		CommaOk: commaOk,
+	}
+	recv.setType(typ)
+	return f.emit(recv, source)
+}
+
+// emitDebugRef emits to f a DebugRef pseudo-instruction associating
+// expression e with value v.
+//
+func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
+	if !f.debugInfo() {
+		return // debugging not enabled
+	}
+	if v == nil || e == nil {
+		panic("nil")
+	}
+	var obj types.Object
+	e = unparen(e)
+	if id, ok := e.(*ast.Ident); ok {
+		if isBlankIdent(id) {
+			return
+		}
+		obj = f.Pkg.objectOf(id)
+		switch obj.(type) {
+		case *types.Nil, *types.Const, *types.Builtin:
+			return
+		}
+	}
+	f.emit(&DebugRef{
+		X:      v,
+		Expr:   e,
+		IsAddr: isAddr,
+		object: obj,
+	}, nil)
+}
+
+// emitArith emits to f code to compute the binary operation op(x, y)
+// where op is an eager shift, logical or arithmetic operation.
+// (Use emitCompare() for comparisons and Builder.logicalBinop() for
+// non-eager operations.)
+//
+func emitArith(f *Function, op token.Token, x, y Value, t types.Type, source ast.Node) Value {
+	switch op {
+	case token.SHL, token.SHR:
+		x = emitConv(f, x, t, source)
+		// y may be signed or an 'untyped' constant.
+		// TODO(adonovan): whence signed values?
+		if b, ok := y.Type().Underlying().(*types.Basic); ok && b.Info()&types.IsUnsigned == 0 {
+			y = emitConv(f, y, types.Typ[types.Uint64], source)
+		}
+
+	case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
+		x = emitConv(f, x, t, source)
+		y = emitConv(f, y, t, source)
+
+	default:
+		panic("illegal op in emitArith: " + op.String())
+
+	}
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setType(t)
+	return f.emit(v, source)
+}
+
+// emitCompare emits to f code compute the boolean result of
+// comparison comparison 'x op y'.
+//
+func emitCompare(f *Function, op token.Token, x, y Value, source ast.Node) Value {
+	xt := x.Type().Underlying()
+	yt := y.Type().Underlying()
+
+	// Special case to optimise a tagless SwitchStmt so that
+	// these are equivalent
+	//   switch { case e: ...}
+	//   switch true { case e: ... }
+	//   if e==true { ... }
+	// even in the case when e's type is an interface.
+	// TODO(adonovan): opt: generalise to x==true, false!=y, etc.
+	if x, ok := x.(*Const); ok && op == token.EQL && x.Value != nil && x.Value.Kind() == constant.Bool && constant.BoolVal(x.Value) {
+		if yt, ok := yt.(*types.Basic); ok && yt.Info()&types.IsBoolean != 0 {
+			return y
+		}
+	}
+
+	if types.Identical(xt, yt) {
+		// no conversion necessary
+	} else if _, ok := xt.(*types.Interface); ok {
+		y = emitConv(f, y, x.Type(), source)
+	} else if _, ok := yt.(*types.Interface); ok {
+		x = emitConv(f, x, y.Type(), source)
+	} else if _, ok := x.(*Const); ok {
+		x = emitConv(f, x, y.Type(), source)
+	} else if _, ok := y.(*Const); ok {
+		y = emitConv(f, y, x.Type(), source)
+		//lint:ignore SA9003 no-op
+	} else {
+		// other cases, e.g. channels.  No-op.
+	}
+
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setType(tBool)
+	return f.emit(v, source)
+}
+
+// isValuePreserving returns true if a conversion from ut_src to
+// ut_dst is value-preserving, i.e. just a change of type.
+// Precondition: neither argument is a named type.
+//
+func isValuePreserving(ut_src, ut_dst types.Type) bool {
+	// Identical underlying types?
+	if structTypesIdentical(ut_dst, ut_src) {
+		return true
+	}
+
+	switch ut_dst.(type) {
+	case *types.Chan:
+		// Conversion between channel types?
+		_, ok := ut_src.(*types.Chan)
+		return ok
+
+	case *types.Pointer:
+		// Conversion between pointers with identical base types?
+		_, ok := ut_src.(*types.Pointer)
+		return ok
+	}
+	return false
+}
+
+// emitConv emits to f code to convert Value val to exactly type typ,
+// and returns the converted value.  Implicit conversions are required
+// by language assignability rules in assignments, parameter passing,
+// etc.  Conversions cannot fail dynamically.
+//
+func emitConv(f *Function, val Value, typ types.Type, source ast.Node) Value {
+	t_src := val.Type()
+
+	// Identical types?  Conversion is a no-op.
+	if types.Identical(t_src, typ) {
+		return val
+	}
+
+	ut_dst := typ.Underlying()
+	ut_src := t_src.Underlying()
+
+	// Just a change of type, but not value or representation?
+	if isValuePreserving(ut_src, ut_dst) {
+		c := &ChangeType{X: val}
+		c.setType(typ)
+		return f.emit(c, source)
+	}
+
+	// Conversion to, or construction of a value of, an interface type?
+	if _, ok := ut_dst.(*types.Interface); ok {
+		// Assignment from one interface type to another?
+		if _, ok := ut_src.(*types.Interface); ok {
+			c := &ChangeInterface{X: val}
+			c.setType(typ)
+			return f.emit(c, source)
+		}
+
+		// Untyped nil constant?  Return interface-typed nil constant.
+		if ut_src == tUntypedNil {
+			return emitConst(f, nilConst(typ))
+		}
+
+		// Convert (non-nil) "untyped" literals to their default type.
+		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
+			val = emitConv(f, val, types.Default(ut_src), source)
+		}
+
+		f.Pkg.Prog.needMethodsOf(val.Type())
+		mi := &MakeInterface{X: val}
+		mi.setType(typ)
+		return f.emit(mi, source)
+	}
+
+	// Conversion of a compile-time constant value?
+	if c, ok := val.(*Const); ok {
+		if _, ok := ut_dst.(*types.Basic); ok || c.IsNil() {
+			// Conversion of a compile-time constant to
+			// another constant type results in a new
+			// constant of the destination type and
+			// (initially) the same abstract value.
+			// We don't truncate the value yet.
+			return emitConst(f, NewConst(c.Value, typ))
+		}
+
+		// We're converting from constant to non-constant type,
+		// e.g. string -> []byte/[]rune.
+	}
+
+	// A representation-changing conversion?
+	// At least one of {ut_src,ut_dst} must be *Basic.
+	// (The other may be []byte or []rune.)
+	_, ok1 := ut_src.(*types.Basic)
+	_, ok2 := ut_dst.(*types.Basic)
+	if ok1 || ok2 {
+		c := &Convert{X: val}
+		c.setType(typ)
+		return f.emit(c, source)
+	}
+
+	panic(fmt.Sprintf("in %s: cannot convert %s (%s) to %s", f, val, val.Type(), typ))
+}
+
+// emitStore emits to f an instruction to store value val at location
+// addr, applying implicit conversions as required by assignability rules.
+//
+func emitStore(f *Function, addr, val Value, source ast.Node) *Store {
+	s := &Store{
+		Addr: addr,
+		Val:  emitConv(f, val, deref(addr.Type()), source),
+	}
+	// make sure we call getMem after the call to emitConv, which may
+	// itself update the memory state
+	f.emit(s, source)
+	return s
+}
+
+// emitJump emits to f a jump to target, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitJump(f *Function, target *BasicBlock, source ast.Node) *Jump {
+	b := f.currentBlock
+	j := new(Jump)
+	b.emit(j, source)
+	addEdge(b, target)
+	f.currentBlock = nil
+	return j
+}
+
+// emitIf emits to f a conditional jump to tblock or fblock based on
+// cond, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitIf(f *Function, cond Value, tblock, fblock *BasicBlock, source ast.Node) *If {
+	b := f.currentBlock
+	stmt := &If{Cond: cond}
+	b.emit(stmt, source)
+	addEdge(b, tblock)
+	addEdge(b, fblock)
+	f.currentBlock = nil
+	return stmt
+}
+
+// emitExtract emits to f an instruction to extract the index'th
+// component of tuple.  It returns the extracted value.
+//
+func emitExtract(f *Function, tuple Value, index int, source ast.Node) Value {
+	e := &Extract{Tuple: tuple, Index: index}
+	e.setType(tuple.Type().(*types.Tuple).At(index).Type())
+	return f.emit(e, source)
+}
+
+// emitTypeAssert emits to f a type assertion value := x.(t) and
+// returns the value.  x.Type() must be an interface.
+//
+func emitTypeAssert(f *Function, x Value, t types.Type, source ast.Node) Value {
+	a := &TypeAssert{X: x, AssertedType: t}
+	a.setType(t)
+	return f.emit(a, source)
+}
+
+// emitTypeTest emits to f a type test value,ok := x.(t) and returns
+// a (value, ok) tuple.  x.Type() must be an interface.
+//
+func emitTypeTest(f *Function, x Value, t types.Type, source ast.Node) Value {
+	a := &TypeAssert{
+		X:            x,
+		AssertedType: t,
+		CommaOk:      true,
+	}
+	a.setType(types.NewTuple(
+		newVar("value", t),
+		varOk,
+	))
+	return f.emit(a, source)
+}
+
+// emitTailCall emits to f a function call in tail position.  The
+// caller is responsible for all fields of 'call' except its type.
+// Intended for wrapper methods.
+// Precondition: f does/will not use deferred procedure calls.
+// Postcondition: f.currentBlock is nil.
+//
+func emitTailCall(f *Function, call *Call, source ast.Node) {
+	tresults := f.Signature.Results()
+	nr := tresults.Len()
+	if nr == 1 {
+		call.typ = tresults.At(0).Type()
+	} else {
+		call.typ = tresults
+	}
+	tuple := f.emit(call, source)
+	var ret Return
+	switch nr {
+	case 0:
+		// no-op
+	case 1:
+		ret.Results = []Value{tuple}
+	default:
+		for i := 0; i < nr; i++ {
+			v := emitExtract(f, tuple, i, source)
+			// TODO(adonovan): in principle, this is required:
+			//   v = emitConv(f, o.Type, f.Signature.Results[i].Type)
+			// but in practice emitTailCall is only used when
+			// the types exactly match.
+			ret.Results = append(ret.Results, v)
+		}
+	}
+
+	f.Exit = f.newBasicBlock("exit")
+	emitJump(f, f.Exit, source)
+	f.currentBlock = f.Exit
+	f.emit(&ret, source)
+	f.currentBlock = nil
+}
+
+// emitImplicitSelections emits to f code to apply the sequence of
+// implicit field selections specified by indices to base value v, and
+// returns the selected value.
+//
+// If v is the address of a struct, the result will be the address of
+// a field; if it is the value of a struct, the result will be the
+// value of a field.
+//
+func emitImplicitSelections(f *Function, v Value, indices []int, source ast.Node) Value {
+	for _, index := range indices {
+		fld := deref(v.Type()).Underlying().(*types.Struct).Field(index)
+
+		if isPointer(v.Type()) {
+			instr := &FieldAddr{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(types.NewPointer(fld.Type()))
+			v = f.emit(instr, source)
+			// Load the field's value iff indirectly embedded.
+			if isPointer(fld.Type()) {
+				v = emitLoad(f, v, source)
+			}
+		} else {
+			instr := &Field{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(fld.Type())
+			v = f.emit(instr, source)
+		}
+	}
+	return v
+}
+
+// emitFieldSelection emits to f code to select the index'th field of v.
+//
+// If wantAddr, the input must be a pointer-to-struct and the result
+// will be the field's address; otherwise the result will be the
+// field's value.
+// Ident id is used for position and debug info.
+//
+func emitFieldSelection(f *Function, v Value, index int, wantAddr bool, id *ast.Ident) Value {
+	fld := deref(v.Type()).Underlying().(*types.Struct).Field(index)
+	if isPointer(v.Type()) {
+		instr := &FieldAddr{
+			X:     v,
+			Field: index,
+		}
+		instr.setSource(id)
+		instr.setType(types.NewPointer(fld.Type()))
+		v = f.emit(instr, id)
+		// Load the field's value iff we don't want its address.
+		if !wantAddr {
+			v = emitLoad(f, v, id)
+		}
+	} else {
+		instr := &Field{
+			X:     v,
+			Field: index,
+		}
+		instr.setSource(id)
+		instr.setType(fld.Type())
+		v = f.emit(instr, id)
+	}
+	emitDebugRef(f, id, v, wantAddr)
+	return v
+}
+
+// zeroValue emits to f code to produce a zero value of type t,
+// and returns it.
+//
+func zeroValue(f *Function, t types.Type, source ast.Node) Value {
+	switch t.Underlying().(type) {
+	case *types.Struct, *types.Array:
+		return emitLoad(f, f.addLocal(t, source), source)
+	default:
+		return emitConst(f, zeroConst(t))
+	}
+}
+
+func emitConst(f *Function, c *Const) *Const {
+	f.consts = append(f.consts, c)
+	return c
+}

vendor/honnef.co/go/tools/ir/exits.go

@@ -0,0 +1,271 @@
+package ir
+
+import (
+	"go/types"
+)
+
+func (b *builder) buildExits(fn *Function) {
+	if obj := fn.Object(); obj != nil {
+		switch obj.Pkg().Path() {
+		case "runtime":
+			switch obj.Name() {
+			case "exit":
+				fn.WillExit = true
+				return
+			case "throw":
+				fn.WillExit = true
+				return
+			case "Goexit":
+				fn.WillUnwind = true
+				return
+			}
+		case "github.com/sirupsen/logrus":
+			switch obj.(*types.Func).FullName() {
+			case "(*github.com/sirupsen/logrus.Logger).Exit":
+				// Technically, this method does not unconditionally exit
+				// the process. It dynamically calls a function stored in
+				// the logger. If the function is nil, it defaults to
+				// os.Exit.
+				//
+				// The main intent of this method is to terminate the
+				// process, and that's what the vast majority of people
+				// will use it for. We'll happily accept some false
+				// negatives to avoid a lot of false positives.
+				fn.WillExit = true
+				return
+			case "(*github.com/sirupsen/logrus.Logger).Panic",
+				"(*github.com/sirupsen/logrus.Logger).Panicf",
+				"(*github.com/sirupsen/logrus.Logger).Panicln":
+
+				// These methods will always panic, but that's not
+				// statically known from the code alone, because they
+				// take a detour through the generic Log methods.
+				fn.WillUnwind = true
+				return
+			case "(*github.com/sirupsen/logrus.Entry).Panicf",
+				"(*github.com/sirupsen/logrus.Entry).Panicln":
+
+				// Entry.Panic has an explicit panic, but Panicf and
+				// Panicln do not, relying fully on the generic Log
+				// method.
+				fn.WillUnwind = true
+				return
+			case "(*github.com/sirupsen/logrus.Logger).Log",
+				"(*github.com/sirupsen/logrus.Logger).Logf",
+				"(*github.com/sirupsen/logrus.Logger).Logln":
+				// TODO(dh): we cannot handle these case. Whether they
+				// exit or unwind depends on the level, which is set
+				// via the first argument. We don't currently support
+				// call-site-specific exit information.
+			}
+		}
+	}
+
+	buildDomTree(fn)
+
+	isRecoverCall := func(instr Instruction) bool {
+		if instr, ok := instr.(*Call); ok {
+			if builtin, ok := instr.Call.Value.(*Builtin); ok {
+				if builtin.Name() == "recover" {
+					return true
+				}
+			}
+		}
+		return false
+	}
+
+	// All panics branch to the exit block, which means that if every
+	// possible path through the function panics, then all
+	// predecessors of the exit block must panic.
+	willPanic := true
+	for _, pred := range fn.Exit.Preds {
+		if _, ok := pred.Control().(*Panic); !ok {
+			willPanic = false
+		}
+	}
+	if willPanic {
+		recovers := false
+	recoverLoop:
+		for _, u := range fn.Blocks {
+			for _, instr := range u.Instrs {
+				if instr, ok := instr.(*Defer); ok {
+					call := instr.Call.StaticCallee()
+					if call == nil {
+						// not a static call, so we can't be sure the
+						// deferred call isn't calling recover
+						recovers = true
+						break recoverLoop
+					}
+					if len(call.Blocks) == 0 {
+						// external function, we don't know what's
+						// happening inside it
+						//
+						// TODO(dh): this includes functions from
+						// imported packages, due to how go/analysis
+						// works. We could introduce another fact,
+						// like we've done for exiting and unwinding,
+						// but it doesn't seem worth it. Virtually all
+						// uses of recover will be in closures.
+						recovers = true
+						break recoverLoop
+					}
+					for _, y := range call.Blocks {
+						for _, instr2 := range y.Instrs {
+							if isRecoverCall(instr2) {
+								recovers = true
+								break recoverLoop
+							}
+						}
+					}
+				}
+			}
+		}
+		if !recovers {
+			fn.WillUnwind = true
+			return
+		}
+	}
+
+	// TODO(dh): don't check that any specific call dominates the exit
+	// block. instead, check that all calls combined cover every
+	// possible path through the function.
+	exits := NewBlockSet(len(fn.Blocks))
+	unwinds := NewBlockSet(len(fn.Blocks))
+	for _, u := range fn.Blocks {
+		for _, instr := range u.Instrs {
+			if instr, ok := instr.(CallInstruction); ok {
+				switch instr.(type) {
+				case *Defer, *Call:
+				default:
+					continue
+				}
+				if instr.Common().IsInvoke() {
+					// give up
+					return
+				}
+				var call *Function
+				switch instr.Common().Value.(type) {
+				case *Function, *MakeClosure:
+					call = instr.Common().StaticCallee()
+				case *Builtin:
+					// the only builtins that affect control flow are
+					// panic and recover, and we've already handled
+					// those
+					continue
+				default:
+					// dynamic dispatch
+					return
+				}
+				// buildFunction is idempotent. if we're part of a
+				// (mutually) recursive call chain, then buildFunction
+				// will immediately return, and fn.WillExit will be false.
+				if call.Package() == fn.Package() {
+					b.buildFunction(call)
+				}
+				dom := u.Dominates(fn.Exit)
+				if call.WillExit {
+					if dom {
+						fn.WillExit = true
+						return
+					}
+					exits.Add(u)
+				} else if call.WillUnwind {
+					if dom {
+						fn.WillUnwind = true
+						return
+					}
+					unwinds.Add(u)
+				}
+			}
+		}
+	}
+
+	// depth-first search trying to find a path to the exit block that
+	// doesn't cross any of the blacklisted blocks
+	seen := NewBlockSet(len(fn.Blocks))
+	var findPath func(root *BasicBlock, bl *BlockSet) bool
+	findPath = func(root *BasicBlock, bl *BlockSet) bool {
+		if root == fn.Exit {
+			return true
+		}
+		if seen.Has(root) {
+			return false
+		}
+		if bl.Has(root) {
+			return false
+		}
+		seen.Add(root)
+		for _, succ := range root.Succs {
+			if findPath(succ, bl) {
+				return true
+			}
+		}
+		return false
+	}
+
+	if exits.Num() > 0 {
+		if !findPath(fn.Blocks[0], exits) {
+			fn.WillExit = true
+			return
+		}
+	}
+	if unwinds.Num() > 0 {
+		seen.Clear()
+		if !findPath(fn.Blocks[0], unwinds) {
+			fn.WillUnwind = true
+			return
+		}
+	}
+}
+
+func (b *builder) addUnreachables(fn *Function) {
+	for _, bb := range fn.Blocks {
+		for i, instr := range bb.Instrs {
+			if instr, ok := instr.(*Call); ok {
+				var call *Function
+				switch v := instr.Common().Value.(type) {
+				case *Function:
+					call = v
+				case *MakeClosure:
+					call = v.Fn.(*Function)
+				}
+				if call == nil {
+					continue
+				}
+				if call.Package() == fn.Package() {
+					// make sure we have information on all functions in this package
+					b.buildFunction(call)
+				}
+				if call.WillExit {
+					// This call will cause the process to terminate.
+					// Remove remaining instructions in the block and
+					// replace any control flow with Unreachable.
+					for _, succ := range bb.Succs {
+						succ.removePred(bb)
+					}
+					bb.Succs = bb.Succs[:0]
+
+					bb.Instrs = bb.Instrs[:i+1]
+					bb.emit(new(Unreachable), instr.Source())
+					addEdge(bb, fn.Exit)
+					break
+				} else if call.WillUnwind {
+					// This call will cause the goroutine to terminate
+					// and defers to run (i.e. a panic or
+					// runtime.Goexit). Remove remaining instructions
+					// in the block and replace any control flow with
+					// an unconditional jump to the exit block.
+					for _, succ := range bb.Succs {
+						succ.removePred(bb)
+					}
+					bb.Succs = bb.Succs[:0]
+
+					bb.Instrs = bb.Instrs[:i+1]
+					bb.emit(new(Jump), instr.Source())
+					addEdge(bb, fn.Exit)
+					break
+				}
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/ir/func.go

@@ -0,0 +1,961 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file implements the Function and BasicBlock types.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/format"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+	"strings"
+)
+
+// addEdge adds a control-flow graph edge from from to to.
+func addEdge(from, to *BasicBlock) {
+	from.Succs = append(from.Succs, to)
+	to.Preds = append(to.Preds, from)
+}
+
+// Control returns the last instruction in the block.
+func (b *BasicBlock) Control() Instruction {
+	if len(b.Instrs) == 0 {
+		return nil
+	}
+	return b.Instrs[len(b.Instrs)-1]
+}
+
+// SIgmaFor returns the sigma node for v coming from pred.
+func (b *BasicBlock) SigmaFor(v Value, pred *BasicBlock) *Sigma {
+	for _, instr := range b.Instrs {
+		sigma, ok := instr.(*Sigma)
+		if !ok {
+			// no more sigmas
+			return nil
+		}
+		if sigma.From == pred && sigma.X == v {
+			return sigma
+		}
+	}
+	return nil
+}
+
+// Parent returns the function that contains block b.
+func (b *BasicBlock) Parent() *Function { return b.parent }
+
+// String returns a human-readable label of this block.
+// It is not guaranteed unique within the function.
+//
+func (b *BasicBlock) String() string {
+	return fmt.Sprintf("%d", b.Index)
+}
+
+// emit appends an instruction to the current basic block.
+// If the instruction defines a Value, it is returned.
+//
+func (b *BasicBlock) emit(i Instruction, source ast.Node) Value {
+	i.setSource(source)
+	i.setBlock(b)
+	b.Instrs = append(b.Instrs, i)
+	v, _ := i.(Value)
+	return v
+}
+
+// predIndex returns the i such that b.Preds[i] == c or panics if
+// there is none.
+func (b *BasicBlock) predIndex(c *BasicBlock) int {
+	for i, pred := range b.Preds {
+		if pred == c {
+			return i
+		}
+	}
+	panic(fmt.Sprintf("no edge %s -> %s", c, b))
+}
+
+// succIndex returns the i such that b.Succs[i] == c or -1 if there is none.
+func (b *BasicBlock) succIndex(c *BasicBlock) int {
+	for i, succ := range b.Succs {
+		if succ == c {
+			return i
+		}
+	}
+	return -1
+}
+
+// hasPhi returns true if b.Instrs contains φ-nodes.
+func (b *BasicBlock) hasPhi() bool {
+	_, ok := b.Instrs[0].(*Phi)
+	return ok
+}
+
+func (b *BasicBlock) Phis() []Instruction {
+	return b.phis()
+}
+
+// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
+func (b *BasicBlock) phis() []Instruction {
+	for i, instr := range b.Instrs {
+		if _, ok := instr.(*Phi); !ok {
+			return b.Instrs[:i]
+		}
+	}
+	return nil // unreachable in well-formed blocks
+}
+
+// replacePred replaces all occurrences of p in b's predecessor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replacePred(p, q *BasicBlock) {
+	for i, pred := range b.Preds {
+		if pred == p {
+			b.Preds[i] = q
+		}
+	}
+}
+
+// replaceSucc replaces all occurrences of p in b's successor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
+	for i, succ := range b.Succs {
+		if succ == p {
+			b.Succs[i] = q
+		}
+	}
+}
+
+// removePred removes all occurrences of p in b's
+// predecessor list and φ-nodes.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) removePred(p *BasicBlock) {
+	phis := b.phis()
+
+	// We must preserve edge order for φ-nodes.
+	j := 0
+	for i, pred := range b.Preds {
+		if pred != p {
+			b.Preds[j] = b.Preds[i]
+			// Strike out φ-edge too.
+			for _, instr := range phis {
+				phi := instr.(*Phi)
+				phi.Edges[j] = phi.Edges[i]
+			}
+			j++
+		}
+	}
+	// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
+	for i := j; i < len(b.Preds); i++ {
+		b.Preds[i] = nil
+		for _, instr := range phis {
+			instr.(*Phi).Edges[i] = nil
+		}
+	}
+	b.Preds = b.Preds[:j]
+	for _, instr := range phis {
+		phi := instr.(*Phi)
+		phi.Edges = phi.Edges[:j]
+	}
+}
+
+// Destinations associated with unlabelled for/switch/select stmts.
+// We push/pop one of these as we enter/leave each construct and for
+// each BranchStmt we scan for the innermost target of the right type.
+//
+type targets struct {
+	tail         *targets // rest of stack
+	_break       *BasicBlock
+	_continue    *BasicBlock
+	_fallthrough *BasicBlock
+}
+
+// Destinations associated with a labelled block.
+// We populate these as labels are encountered in forward gotos or
+// labelled statements.
+//
+type lblock struct {
+	_goto     *BasicBlock
+	_break    *BasicBlock
+	_continue *BasicBlock
+}
+
+// labelledBlock returns the branch target associated with the
+// specified label, creating it if needed.
+//
+func (f *Function) labelledBlock(label *ast.Ident) *lblock {
+	lb := f.lblocks[label.Obj]
+	if lb == nil {
+		lb = &lblock{_goto: f.newBasicBlock(label.Name)}
+		if f.lblocks == nil {
+			f.lblocks = make(map[*ast.Object]*lblock)
+		}
+		f.lblocks[label.Obj] = lb
+	}
+	return lb
+}
+
+// addParam adds a (non-escaping) parameter to f.Params of the
+// specified name, type and source position.
+//
+func (f *Function) addParam(name string, typ types.Type, source ast.Node) *Parameter {
+	var b *BasicBlock
+	if len(f.Blocks) > 0 {
+		b = f.Blocks[0]
+	}
+	v := &Parameter{
+		name: name,
+	}
+	v.setBlock(b)
+	v.setType(typ)
+	v.setSource(source)
+	f.Params = append(f.Params, v)
+	if b != nil {
+		// There may be no blocks if this function has no body. We
+		// still create params, but aren't interested in the
+		// instruction.
+		f.Blocks[0].Instrs = append(f.Blocks[0].Instrs, v)
+	}
+	return v
+}
+
+func (f *Function) addParamObj(obj types.Object, source ast.Node) *Parameter {
+	name := obj.Name()
+	if name == "" {
+		name = fmt.Sprintf("arg%d", len(f.Params))
+	}
+	param := f.addParam(name, obj.Type(), source)
+	param.object = obj
+	return param
+}
+
+// addSpilledParam declares a parameter that is pre-spilled to the
+// stack; the function body will load/store the spilled location.
+// Subsequent lifting will eliminate spills where possible.
+//
+func (f *Function) addSpilledParam(obj types.Object, source ast.Node) {
+	param := f.addParamObj(obj, source)
+	spill := &Alloc{}
+	spill.setType(types.NewPointer(obj.Type()))
+	spill.source = source
+	f.objects[obj] = spill
+	f.Locals = append(f.Locals, spill)
+	f.emit(spill, source)
+	emitStore(f, spill, param, source)
+	// f.emit(&Store{Addr: spill, Val: param})
+}
+
+// startBody initializes the function prior to generating IR code for its body.
+// Precondition: f.Type() already set.
+//
+func (f *Function) startBody() {
+	entry := f.newBasicBlock("entry")
+	f.currentBlock = entry
+	f.objects = make(map[types.Object]Value) // needed for some synthetics, e.g. init
+}
+
+func (f *Function) blockset(i int) *BlockSet {
+	bs := &f.blocksets[i]
+	if len(bs.values) != len(f.Blocks) {
+		if cap(bs.values) >= len(f.Blocks) {
+			bs.values = bs.values[:len(f.Blocks)]
+			bs.Clear()
+		} else {
+			bs.values = make([]bool, len(f.Blocks))
+		}
+	} else {
+		bs.Clear()
+	}
+	return bs
+}
+
+func (f *Function) exitBlock() {
+	old := f.currentBlock
+
+	f.Exit = f.newBasicBlock("exit")
+	f.currentBlock = f.Exit
+
+	ret := f.results()
+	results := make([]Value, len(ret))
+	// Run function calls deferred in this
+	// function when explicitly returning from it.
+	f.emit(new(RunDefers), nil)
+	for i, r := range ret {
+		results[i] = emitLoad(f, r, nil)
+	}
+
+	f.emit(&Return{Results: results}, nil)
+	f.currentBlock = old
+}
+
+// createSyntacticParams populates f.Params and generates code (spills
+// and named result locals) for all the parameters declared in the
+// syntax.  In addition it populates the f.objects mapping.
+//
+// Preconditions:
+// f.startBody() was called.
+// Postcondition:
+// len(f.Params) == len(f.Signature.Params) + (f.Signature.Recv() ? 1 : 0)
+//
+func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.FuncType) {
+	// Receiver (at most one inner iteration).
+	if recv != nil {
+		for _, field := range recv.List {
+			for _, n := range field.Names {
+				f.addSpilledParam(f.Pkg.info.Defs[n], n)
+			}
+			// Anonymous receiver?  No need to spill.
+			if field.Names == nil {
+				f.addParamObj(f.Signature.Recv(), field)
+			}
+		}
+	}
+
+	// Parameters.
+	if functype.Params != nil {
+		n := len(f.Params) // 1 if has recv, 0 otherwise
+		for _, field := range functype.Params.List {
+			for _, n := range field.Names {
+				f.addSpilledParam(f.Pkg.info.Defs[n], n)
+			}
+			// Anonymous parameter?  No need to spill.
+			if field.Names == nil {
+				f.addParamObj(f.Signature.Params().At(len(f.Params)-n), field)
+			}
+		}
+	}
+
+	// Named results.
+	if functype.Results != nil {
+		for _, field := range functype.Results.List {
+			// Implicit "var" decl of locals for named results.
+			for _, n := range field.Names {
+				f.namedResults = append(f.namedResults, f.addLocalForIdent(n))
+			}
+		}
+
+		if len(f.namedResults) == 0 {
+			sig := f.Signature.Results()
+			for i := 0; i < sig.Len(); i++ {
+				// XXX position information
+				v := f.addLocal(sig.At(i).Type(), nil)
+				f.implicitResults = append(f.implicitResults, v)
+			}
+		}
+	}
+}
+
+func numberNodes(f *Function) {
+	var base ID
+	for _, b := range f.Blocks {
+		for _, instr := range b.Instrs {
+			if instr == nil {
+				continue
+			}
+			base++
+			instr.setID(base)
+		}
+	}
+}
+
+// buildReferrers populates the def/use information in all non-nil
+// Value.Referrers slice.
+// Precondition: all such slices are initially empty.
+func buildReferrers(f *Function) {
+	var rands []*Value
+	for _, b := range f.Blocks {
+		for _, instr := range b.Instrs {
+			rands = instr.Operands(rands[:0]) // recycle storage
+			for _, rand := range rands {
+				if r := *rand; r != nil {
+					if ref := r.Referrers(); ref != nil {
+						*ref = append(*ref, instr)
+					}
+				}
+			}
+		}
+	}
+}
+
+func (f *Function) emitConsts() {
+	if len(f.Blocks) == 0 {
+		f.consts = nil
+		return
+	}
+
+	// TODO(dh): our deduplication only works on booleans and
+	// integers. other constants are represented as pointers to
+	// things.
+	if len(f.consts) == 0 {
+		return
+	} else if len(f.consts) <= 32 {
+		f.emitConstsFew()
+	} else {
+		f.emitConstsMany()
+	}
+}
+
+func (f *Function) emitConstsFew() {
+	dedup := make([]*Const, 0, 32)
+	for _, c := range f.consts {
+		if len(*c.Referrers()) == 0 {
+			continue
+		}
+		found := false
+		for _, d := range dedup {
+			if c.typ == d.typ && c.Value == d.Value {
+				replaceAll(c, d)
+				found = true
+				break
+			}
+		}
+		if !found {
+			dedup = append(dedup, c)
+		}
+	}
+
+	instrs := make([]Instruction, len(f.Blocks[0].Instrs)+len(dedup))
+	for i, c := range dedup {
+		instrs[i] = c
+		c.setBlock(f.Blocks[0])
+	}
+	copy(instrs[len(dedup):], f.Blocks[0].Instrs)
+	f.Blocks[0].Instrs = instrs
+	f.consts = nil
+}
+
+func (f *Function) emitConstsMany() {
+	type constKey struct {
+		typ   types.Type
+		value constant.Value
+	}
+
+	m := make(map[constKey]Value, len(f.consts))
+	areNil := 0
+	for i, c := range f.consts {
+		if len(*c.Referrers()) == 0 {
+			f.consts[i] = nil
+			areNil++
+			continue
+		}
+
+		k := constKey{
+			typ:   c.typ,
+			value: c.Value,
+		}
+		if dup, ok := m[k]; !ok {
+			m[k] = c
+		} else {
+			f.consts[i] = nil
+			areNil++
+			replaceAll(c, dup)
+		}
+	}
+
+	instrs := make([]Instruction, len(f.Blocks[0].Instrs)+len(f.consts)-areNil)
+	i := 0
+	for _, c := range f.consts {
+		if c != nil {
+			instrs[i] = c
+			c.setBlock(f.Blocks[0])
+			i++
+		}
+	}
+	copy(instrs[i:], f.Blocks[0].Instrs)
+	f.Blocks[0].Instrs = instrs
+	f.consts = nil
+}
+
+// buildFakeExits ensures that every block in the function is
+// reachable in reverse from the Exit block. This is required to build
+// a full post-dominator tree, and to ensure the exit block's
+// inclusion in the dominator tree.
+func buildFakeExits(fn *Function) {
+	// Find back-edges via forward DFS
+	fn.fakeExits = BlockSet{values: make([]bool, len(fn.Blocks))}
+	seen := fn.blockset(0)
+	backEdges := fn.blockset(1)
+
+	var dfs func(b *BasicBlock)
+	dfs = func(b *BasicBlock) {
+		if !seen.Add(b) {
+			backEdges.Add(b)
+			return
+		}
+		for _, pred := range b.Succs {
+			dfs(pred)
+		}
+	}
+	dfs(fn.Blocks[0])
+buildLoop:
+	for {
+		seen := fn.blockset(2)
+		var dfs func(b *BasicBlock)
+		dfs = func(b *BasicBlock) {
+			if !seen.Add(b) {
+				return
+			}
+			for _, pred := range b.Preds {
+				dfs(pred)
+			}
+			if b == fn.Exit {
+				for _, b := range fn.Blocks {
+					if fn.fakeExits.Has(b) {
+						dfs(b)
+					}
+				}
+			}
+		}
+		dfs(fn.Exit)
+
+		for _, b := range fn.Blocks {
+			if !seen.Has(b) && backEdges.Has(b) {
+				// Block b is not reachable from the exit block. Add a
+				// fake jump from b to exit, then try again. Note that we
+				// only add one fake edge at a time, as it may make
+				// multiple blocks reachable.
+				//
+				// We only consider those blocks that have back edges.
+				// Any unreachable block that doesn't have a back edge
+				// must flow into a loop, which by definition has a
+				// back edge. Thus, by looking for loops, we should
+				// need fewer fake edges overall.
+				fn.fakeExits.Add(b)
+				continue buildLoop
+			}
+		}
+
+		break
+	}
+}
+
+// finishBody() finalizes the function after IR code generation of its body.
+func (f *Function) finishBody() {
+	f.objects = nil
+	f.currentBlock = nil
+	f.lblocks = nil
+
+	// Remove from f.Locals any Allocs that escape to the heap.
+	j := 0
+	for _, l := range f.Locals {
+		if !l.Heap {
+			f.Locals[j] = l
+			j++
+		}
+	}
+	// Nil out f.Locals[j:] to aid GC.
+	for i := j; i < len(f.Locals); i++ {
+		f.Locals[i] = nil
+	}
+	f.Locals = f.Locals[:j]
+
+	optimizeBlocks(f)
+	buildReferrers(f)
+	buildDomTree(f)
+	buildPostDomTree(f)
+
+	if f.Prog.mode&NaiveForm == 0 {
+		lift(f)
+	}
+
+	// emit constants after lifting, because lifting may produce new constants.
+	f.emitConsts()
+
+	f.namedResults = nil // (used by lifting)
+	f.implicitResults = nil
+
+	numberNodes(f)
+
+	defer f.wr.Close()
+	f.wr.WriteFunc("start", "start", f)
+
+	if f.Prog.mode&PrintFunctions != 0 {
+		printMu.Lock()
+		f.WriteTo(os.Stdout)
+		printMu.Unlock()
+	}
+
+	if f.Prog.mode&SanityCheckFunctions != 0 {
+		mustSanityCheck(f, nil)
+	}
+}
+
+func isUselessPhi(phi *Phi) (Value, bool) {
+	var v0 Value
+	for _, e := range phi.Edges {
+		if e == phi {
+			continue
+		}
+		if v0 == nil {
+			v0 = e
+		}
+		if v0 != e {
+			if v0, ok := v0.(*Const); ok {
+				if e, ok := e.(*Const); ok {
+					if v0.typ == e.typ && v0.Value == e.Value {
+						continue
+					}
+				}
+			}
+			return nil, false
+		}
+	}
+	return v0, true
+}
+
+func (f *Function) RemoveNilBlocks() {
+	f.removeNilBlocks()
+}
+
+// removeNilBlocks eliminates nils from f.Blocks and updates each
+// BasicBlock.Index.  Use this after any pass that may delete blocks.
+//
+func (f *Function) removeNilBlocks() {
+	j := 0
+	for _, b := range f.Blocks {
+		if b != nil {
+			b.Index = j
+			f.Blocks[j] = b
+			j++
+		}
+	}
+	// Nil out f.Blocks[j:] to aid GC.
+	for i := j; i < len(f.Blocks); i++ {
+		f.Blocks[i] = nil
+	}
+	f.Blocks = f.Blocks[:j]
+}
+
+// SetDebugMode sets the debug mode for package pkg.  If true, all its
+// functions will include full debug info.  This greatly increases the
+// size of the instruction stream, and causes Functions to depend upon
+// the ASTs, potentially keeping them live in memory for longer.
+//
+func (pkg *Package) SetDebugMode(debug bool) {
+	// TODO(adonovan): do we want ast.File granularity?
+	pkg.debug = debug
+}
+
+// debugInfo reports whether debug info is wanted for this function.
+func (f *Function) debugInfo() bool {
+	return f.Pkg != nil && f.Pkg.debug
+}
+
+// addNamedLocal creates a local variable, adds it to function f and
+// returns it.  Its name and type are taken from obj.  Subsequent
+// calls to f.lookup(obj) will return the same local.
+//
+func (f *Function) addNamedLocal(obj types.Object, source ast.Node) *Alloc {
+	l := f.addLocal(obj.Type(), source)
+	f.objects[obj] = l
+	return l
+}
+
+func (f *Function) addLocalForIdent(id *ast.Ident) *Alloc {
+	return f.addNamedLocal(f.Pkg.info.Defs[id], id)
+}
+
+// addLocal creates an anonymous local variable of type typ, adds it
+// to function f and returns it.  pos is the optional source location.
+//
+func (f *Function) addLocal(typ types.Type, source ast.Node) *Alloc {
+	v := &Alloc{}
+	v.setType(types.NewPointer(typ))
+	f.Locals = append(f.Locals, v)
+	f.emit(v, source)
+	return v
+}
+
+// lookup returns the address of the named variable identified by obj
+// that is local to function f or one of its enclosing functions.
+// If escaping, the reference comes from a potentially escaping pointer
+// expression and the referent must be heap-allocated.
+//
+func (f *Function) lookup(obj types.Object, escaping bool) Value {
+	if v, ok := f.objects[obj]; ok {
+		if alloc, ok := v.(*Alloc); ok && escaping {
+			alloc.Heap = true
+		}
+		return v // function-local var (address)
+	}
+
+	// Definition must be in an enclosing function;
+	// plumb it through intervening closures.
+	if f.parent == nil {
+		panic("no ir.Value for " + obj.String())
+	}
+	outer := f.parent.lookup(obj, true) // escaping
+	v := &FreeVar{
+		name:   obj.Name(),
+		typ:    outer.Type(),
+		outer:  outer,
+		parent: f,
+	}
+	f.objects[obj] = v
+	f.FreeVars = append(f.FreeVars, v)
+	return v
+}
+
+// emit emits the specified instruction to function f.
+func (f *Function) emit(instr Instruction, source ast.Node) Value {
+	return f.currentBlock.emit(instr, source)
+}
+
+// RelString returns the full name of this function, qualified by
+// package name, receiver type, etc.
+//
+// The specific formatting rules are not guaranteed and may change.
+//
+// Examples:
+//      "math.IsNaN"                  // a package-level function
+//      "(*bytes.Buffer).Bytes"       // a declared method or a wrapper
+//      "(*bytes.Buffer).Bytes$thunk" // thunk (func wrapping method; receiver is param 0)
+//      "(*bytes.Buffer).Bytes$bound" // bound (func wrapping method; receiver supplied by closure)
+//      "main.main$1"                 // an anonymous function in main
+//      "main.init#1"                 // a declared init function
+//      "main.init"                   // the synthesized package initializer
+//
+// When these functions are referred to from within the same package
+// (i.e. from == f.Pkg.Object), they are rendered without the package path.
+// For example: "IsNaN", "(*Buffer).Bytes", etc.
+//
+// All non-synthetic functions have distinct package-qualified names.
+// (But two methods may have the same name "(T).f" if one is a synthetic
+// wrapper promoting a non-exported method "f" from another package; in
+// that case, the strings are equal but the identifiers "f" are distinct.)
+//
+func (f *Function) RelString(from *types.Package) string {
+	// Anonymous?
+	if f.parent != nil {
+		// An anonymous function's Name() looks like "parentName$1",
+		// but its String() should include the type/package/etc.
+		parent := f.parent.RelString(from)
+		for i, anon := range f.parent.AnonFuncs {
+			if anon == f {
+				return fmt.Sprintf("%s$%d", parent, 1+i)
+			}
+		}
+
+		return f.name // should never happen
+	}
+
+	// Method (declared or wrapper)?
+	if recv := f.Signature.Recv(); recv != nil {
+		return f.relMethod(from, recv.Type())
+	}
+
+	// Thunk?
+	if f.method != nil {
+		return f.relMethod(from, f.method.Recv())
+	}
+
+	// Bound?
+	if len(f.FreeVars) == 1 && strings.HasSuffix(f.name, "$bound") {
+		return f.relMethod(from, f.FreeVars[0].Type())
+	}
+
+	// Package-level function?
+	// Prefix with package name for cross-package references only.
+	if p := f.pkg(); p != nil && p != from {
+		return fmt.Sprintf("%s.%s", p.Path(), f.name)
+	}
+
+	// Unknown.
+	return f.name
+}
+
+func (f *Function) relMethod(from *types.Package, recv types.Type) string {
+	return fmt.Sprintf("(%s).%s", relType(recv, from), f.name)
+}
+
+// writeSignature writes to buf the signature sig in declaration syntax.
+func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature, params []*Parameter) {
+	buf.WriteString("func ")
+	if recv := sig.Recv(); recv != nil {
+		buf.WriteString("(")
+		if n := params[0].Name(); n != "" {
+			buf.WriteString(n)
+			buf.WriteString(" ")
+		}
+		types.WriteType(buf, params[0].Type(), types.RelativeTo(from))
+		buf.WriteString(") ")
+	}
+	buf.WriteString(name)
+	types.WriteSignature(buf, sig, types.RelativeTo(from))
+}
+
+func (f *Function) pkg() *types.Package {
+	if f.Pkg != nil {
+		return f.Pkg.Pkg
+	}
+	return nil
+}
+
+var _ io.WriterTo = (*Function)(nil) // *Function implements io.Writer
+
+func (f *Function) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+	WriteFunction(&buf, f)
+	n, err := w.Write(buf.Bytes())
+	return int64(n), err
+}
+
+// WriteFunction writes to buf a human-readable "disassembly" of f.
+func WriteFunction(buf *bytes.Buffer, f *Function) {
+	fmt.Fprintf(buf, "# Name: %s\n", f.String())
+	if f.Pkg != nil {
+		fmt.Fprintf(buf, "# Package: %s\n", f.Pkg.Pkg.Path())
+	}
+	if syn := f.Synthetic; syn != "" {
+		fmt.Fprintln(buf, "# Synthetic:", syn)
+	}
+	if pos := f.Pos(); pos.IsValid() {
+		fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos))
+	}
+
+	if f.parent != nil {
+		fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name())
+	}
+
+	from := f.pkg()
+
+	if f.FreeVars != nil {
+		buf.WriteString("# Free variables:\n")
+		for i, fv := range f.FreeVars {
+			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, fv.Name(), relType(fv.Type(), from))
+		}
+	}
+
+	if len(f.Locals) > 0 {
+		buf.WriteString("# Locals:\n")
+		for i, l := range f.Locals {
+			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, l.Name(), relType(deref(l.Type()), from))
+		}
+	}
+	writeSignature(buf, from, f.Name(), f.Signature, f.Params)
+	buf.WriteString(":\n")
+
+	if f.Blocks == nil {
+		buf.WriteString("\t(external)\n")
+	}
+
+	for _, b := range f.Blocks {
+		if b == nil {
+			// Corrupt CFG.
+			fmt.Fprintf(buf, ".nil:\n")
+			continue
+		}
+		fmt.Fprintf(buf, "b%d:", b.Index)
+		if len(b.Preds) > 0 {
+			fmt.Fprint(buf, " ←")
+			for _, pred := range b.Preds {
+				fmt.Fprintf(buf, " b%d", pred.Index)
+			}
+		}
+		if b.Comment != "" {
+			fmt.Fprintf(buf, " # %s", b.Comment)
+		}
+		buf.WriteByte('\n')
+
+		if false { // CFG debugging
+			fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs)
+		}
+
+		buf2 := &bytes.Buffer{}
+		for _, instr := range b.Instrs {
+			buf.WriteString("\t")
+			switch v := instr.(type) {
+			case Value:
+				// Left-align the instruction.
+				if name := v.Name(); name != "" {
+					fmt.Fprintf(buf, "%s = ", name)
+				}
+				buf.WriteString(instr.String())
+			case nil:
+				// Be robust against bad transforms.
+				buf.WriteString("<deleted>")
+			default:
+				buf.WriteString(instr.String())
+			}
+			buf.WriteString("\n")
+
+			if f.Prog.mode&PrintSource != 0 {
+				if s := instr.Source(); s != nil {
+					buf2.Reset()
+					format.Node(buf2, f.Prog.Fset, s)
+					for {
+						line, err := buf2.ReadString('\n')
+						if len(line) == 0 {
+							break
+						}
+						buf.WriteString("\t\t> ")
+						buf.WriteString(line)
+						if line[len(line)-1] != '\n' {
+							buf.WriteString("\n")
+						}
+						if err != nil {
+							break
+						}
+					}
+				}
+			}
+		}
+		buf.WriteString("\n")
+	}
+}
+
+// newBasicBlock adds to f a new basic block and returns it.  It does
+// not automatically become the current block for subsequent calls to emit.
+// comment is an optional string for more readable debugging output.
+//
+func (f *Function) newBasicBlock(comment string) *BasicBlock {
+	b := &BasicBlock{
+		Index:   len(f.Blocks),
+		Comment: comment,
+		parent:  f,
+	}
+	b.Succs = b.succs2[:0]
+	f.Blocks = append(f.Blocks, b)
+	return b
+}
+
+// NewFunction returns a new synthetic Function instance belonging to
+// prog, with its name and signature fields set as specified.
+//
+// The caller is responsible for initializing the remaining fields of
+// the function object, e.g. Pkg, Params, Blocks.
+//
+// It is practically impossible for clients to construct well-formed
+// IR functions/packages/programs directly, so we assume this is the
+// job of the Builder alone.  NewFunction exists to provide clients a
+// little flexibility.  For example, analysis tools may wish to
+// construct fake Functions for the root of the callgraph, a fake
+// "reflect" package, etc.
+//
+// TODO(adonovan): think harder about the API here.
+//
+func (prog *Program) NewFunction(name string, sig *types.Signature, provenance string) *Function {
+	return &Function{Prog: prog, name: name, Signature: sig, Synthetic: provenance}
+}
+
+//lint:ignore U1000 we may make use of this for functions loaded from export data
+type extentNode [2]token.Pos
+
+func (n extentNode) Pos() token.Pos { return n[0] }
+func (n extentNode) End() token.Pos { return n[1] }
+
+func (f *Function) initHTML(name string) {
+	if name == "" {
+		return
+	}
+	if rel := f.RelString(nil); rel == name {
+		f.wr = NewHTMLWriter("ir.html", rel, "")
+	}
+}

vendor/honnef.co/go/tools/ir/identical.go

@@ -0,0 +1,7 @@
+// +build go1.8
+
+package ir
+
+import "go/types"
+
+var structTypesIdentical = types.IdenticalIgnoreTags

vendor/honnef.co/go/tools/ir/identical_17.go

@@ -0,0 +1,7 @@
+// +build !go1.8
+
+package ir
+
+import "go/types"
+
+var structTypesIdentical = types.Identical

vendor/honnef.co/go/tools/ir/irutil/load.go

@@ -0,0 +1,183 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil
+
+// This file defines utility functions for constructing programs in IR form.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/packages"
+	"honnef.co/go/tools/ir"
+)
+
+type Options struct {
+	// Which function, if any, to print in HTML form
+	PrintFunc string
+}
+
+// Packages creates an IR program for a set of packages.
+//
+// The packages must have been loaded from source syntax using the
+// golang.org/x/tools/go/packages.Load function in LoadSyntax or
+// LoadAllSyntax mode.
+//
+// Packages creates an IR package for each well-typed package in the
+// initial list, plus all their dependencies. The resulting list of
+// packages corresponds to the list of initial packages, and may contain
+// a nil if IR code could not be constructed for the corresponding initial
+// package due to type errors.
+//
+// Code for bodies of functions is not built until Build is called on
+// the resulting Program. IR code is constructed only for the initial
+// packages with well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+func Packages(initial []*packages.Package, mode ir.BuilderMode, opts *Options) (*ir.Program, []*ir.Package) {
+	return doPackages(initial, mode, false, opts)
+}
+
+// AllPackages creates an IR program for a set of packages plus all
+// their dependencies.
+//
+// The packages must have been loaded from source syntax using the
+// golang.org/x/tools/go/packages.Load function in LoadAllSyntax mode.
+//
+// AllPackages creates an IR package for each well-typed package in the
+// initial list, plus all their dependencies. The resulting list of
+// packages corresponds to the list of initial packages, and may contain
+// a nil if IR code could not be constructed for the corresponding
+// initial package due to type errors.
+//
+// Code for bodies of functions is not built until Build is called on
+// the resulting Program. IR code is constructed for all packages with
+// well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+func AllPackages(initial []*packages.Package, mode ir.BuilderMode, opts *Options) (*ir.Program, []*ir.Package) {
+	return doPackages(initial, mode, true, opts)
+}
+
+func doPackages(initial []*packages.Package, mode ir.BuilderMode, deps bool, opts *Options) (*ir.Program, []*ir.Package) {
+
+	var fset *token.FileSet
+	if len(initial) > 0 {
+		fset = initial[0].Fset
+	}
+
+	prog := ir.NewProgram(fset, mode)
+	if opts != nil {
+		prog.PrintFunc = opts.PrintFunc
+	}
+
+	isInitial := make(map[*packages.Package]bool, len(initial))
+	for _, p := range initial {
+		isInitial[p] = true
+	}
+
+	irmap := make(map[*packages.Package]*ir.Package)
+	packages.Visit(initial, nil, func(p *packages.Package) {
+		if p.Types != nil && !p.IllTyped {
+			var files []*ast.File
+			if deps || isInitial[p] {
+				files = p.Syntax
+			}
+			irmap[p] = prog.CreatePackage(p.Types, files, p.TypesInfo, true)
+		}
+	})
+
+	var irpkgs []*ir.Package
+	for _, p := range initial {
+		irpkgs = append(irpkgs, irmap[p]) // may be nil
+	}
+	return prog, irpkgs
+}
+
+// CreateProgram returns a new program in IR form, given a program
+// loaded from source.  An IR package is created for each transitively
+// error-free package of lprog.
+//
+// Code for bodies of functions is not built until Build is called
+// on the result.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+// Deprecated: use golang.org/x/tools/go/packages and the Packages
+// function instead; see ir.ExampleLoadPackages.
+//
+func CreateProgram(lprog *loader.Program, mode ir.BuilderMode) *ir.Program {
+	prog := ir.NewProgram(lprog.Fset, mode)
+
+	for _, info := range lprog.AllPackages {
+		if info.TransitivelyErrorFree {
+			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
+		}
+	}
+
+	return prog
+}
+
+// BuildPackage builds an IR program with IR for a single package.
+//
+// It populates pkg by type-checking the specified file ASTs.  All
+// dependencies are loaded using the importer specified by tc, which
+// typically loads compiler export data; IR code cannot be built for
+// those packages.  BuildPackage then constructs an ir.Program with all
+// dependency packages created, and builds and returns the IR package
+// corresponding to pkg.
+//
+// The caller must have set pkg.Path() to the import path.
+//
+// The operation fails if there were any type-checking or import errors.
+//
+// See ../ir/example_test.go for an example.
+//
+func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ir.BuilderMode) (*ir.Package, *types.Info, error) {
+	if fset == nil {
+		panic("no token.FileSet")
+	}
+	if pkg.Path() == "" {
+		panic("package has no import path")
+	}
+
+	info := &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Implicits:  make(map[ast.Node]types.Object),
+		Scopes:     make(map[ast.Node]*types.Scope),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
+		return nil, nil, err
+	}
+
+	prog := ir.NewProgram(fset, mode)
+
+	// Create IR packages for all imports.
+	// Order is not significant.
+	created := make(map[*types.Package]bool)
+	var createAll func(pkgs []*types.Package)
+	createAll = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !created[p] {
+				created[p] = true
+				prog.CreatePackage(p, nil, nil, true)
+				createAll(p.Imports())
+			}
+		}
+	}
+	createAll(pkg.Imports())
+
+	// Create and build the primary package.
+	irpkg := prog.CreatePackage(pkg, files, info, false)
+	irpkg.Build()
+	return irpkg, info, nil
+}

vendor/honnef.co/go/tools/ir/irutil/switch.go

@@ -0,0 +1,264 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil
+
+// This file implements discovery of switch and type-switch constructs
+// from low-level control flow.
+//
+// Many techniques exist for compiling a high-level switch with
+// constant cases to efficient machine code.  The optimal choice will
+// depend on the data type, the specific case values, the code in the
+// body of each case, and the hardware.
+// Some examples:
+// - a lookup table (for a switch that maps constants to constants)
+// - a computed goto
+// - a binary tree
+// - a perfect hash
+// - a two-level switch (to partition constant strings by their first byte).
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/ir"
+)
+
+// A ConstCase represents a single constant comparison.
+// It is part of a Switch.
+type ConstCase struct {
+	Block *ir.BasicBlock // block performing the comparison
+	Body  *ir.BasicBlock // body of the case
+	Value *ir.Const      // case comparand
+}
+
+// A TypeCase represents a single type assertion.
+// It is part of a Switch.
+type TypeCase struct {
+	Block   *ir.BasicBlock // block performing the type assert
+	Body    *ir.BasicBlock // body of the case
+	Type    types.Type     // case type
+	Binding ir.Value       // value bound by this case
+}
+
+// A Switch is a logical high-level control flow operation
+// (a multiway branch) discovered by analysis of a CFG containing
+// only if/else chains.  It is not part of the ir.Instruction set.
+//
+// One of ConstCases and TypeCases has length >= 2;
+// the other is nil.
+//
+// In a value switch, the list of cases may contain duplicate constants.
+// A type switch may contain duplicate types, or types assignable
+// to an interface type also in the list.
+// TODO(adonovan): eliminate such duplicates.
+//
+type Switch struct {
+	Start      *ir.BasicBlock // block containing start of if/else chain
+	X          ir.Value       // the switch operand
+	ConstCases []ConstCase    // ordered list of constant comparisons
+	TypeCases  []TypeCase     // ordered list of type assertions
+	Default    *ir.BasicBlock // successor if all comparisons fail
+}
+
+func (sw *Switch) String() string {
+	// We represent each block by the String() of its
+	// first Instruction, e.g. "print(42:int)".
+	var buf bytes.Buffer
+	if sw.ConstCases != nil {
+		fmt.Fprintf(&buf, "switch %s {\n", sw.X.Name())
+		for _, c := range sw.ConstCases {
+			fmt.Fprintf(&buf, "case %s: %s\n", c.Value.Name(), c.Body.Instrs[0])
+		}
+	} else {
+		fmt.Fprintf(&buf, "switch %s.(type) {\n", sw.X.Name())
+		for _, c := range sw.TypeCases {
+			fmt.Fprintf(&buf, "case %s %s: %s\n",
+				c.Binding.Name(), c.Type, c.Body.Instrs[0])
+		}
+	}
+	if sw.Default != nil {
+		fmt.Fprintf(&buf, "default: %s\n", sw.Default.Instrs[0])
+	}
+	fmt.Fprintf(&buf, "}")
+	return buf.String()
+}
+
+// Switches examines the control-flow graph of fn and returns the
+// set of inferred value and type switches.  A value switch tests an
+// ir.Value for equality against two or more compile-time constant
+// values.  Switches involving link-time constants (addresses) are
+// ignored.  A type switch type-asserts an ir.Value against two or
+// more types.
+//
+// The switches are returned in dominance order.
+//
+// The resulting switches do not necessarily correspond to uses of the
+// 'switch' keyword in the source: for example, a single source-level
+// switch statement with non-constant cases may result in zero, one or
+// many Switches, one per plural sequence of constant cases.
+// Switches may even be inferred from if/else- or goto-based control flow.
+// (In general, the control flow constructs of the source program
+// cannot be faithfully reproduced from the IR.)
+//
+func Switches(fn *ir.Function) []Switch {
+	// Traverse the CFG in dominance order, so we don't
+	// enter an if/else-chain in the middle.
+	var switches []Switch
+	seen := make(map[*ir.BasicBlock]bool) // TODO(adonovan): opt: use ir.blockSet
+	for _, b := range fn.DomPreorder() {
+		if x, k := isComparisonBlock(b); x != nil {
+			// Block b starts a switch.
+			sw := Switch{Start: b, X: x}
+			valueSwitch(&sw, k, seen)
+			if len(sw.ConstCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+
+		if y, x, T := isTypeAssertBlock(b); y != nil {
+			// Block b starts a type switch.
+			sw := Switch{Start: b, X: x}
+			typeSwitch(&sw, y, T, seen)
+			if len(sw.TypeCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+	}
+	return switches
+}
+
+func isSameX(x1 ir.Value, x2 ir.Value) bool {
+	if x1 == x2 {
+		return true
+	}
+	if x2, ok := x2.(*ir.Sigma); ok {
+		return isSameX(x1, x2.X)
+	}
+	return false
+}
+
+func valueSwitch(sw *Switch, k *ir.Const, seen map[*ir.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for isSameX(sw.X, x) {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.ConstCases = append(sw.ConstCases, ConstCase{
+			Block: b,
+			Body:  b.Succs[0],
+			Value: k,
+		})
+		b = b.Succs[1]
+		n := 0
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case *ir.If, *ir.BinOp:
+				n++
+			case *ir.Sigma, *ir.Phi, *ir.DebugRef:
+			default:
+				n += 1000
+			}
+		}
+		if n != 2 {
+			// Block b contains not just 'if x == k' and σ/ϕ nodes,
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		x, k = isComparisonBlock(b)
+	}
+	sw.Default = b
+}
+
+func typeSwitch(sw *Switch, y ir.Value, T types.Type, seen map[*ir.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for isSameX(sw.X, x) {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.TypeCases = append(sw.TypeCases, TypeCase{
+			Block:   b,
+			Body:    b.Succs[0],
+			Type:    T,
+			Binding: y,
+		})
+		b = b.Succs[1]
+		n := 0
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case *ir.TypeAssert, *ir.Extract, *ir.If:
+				n++
+			case *ir.Sigma, *ir.Phi:
+			default:
+				n += 1000
+			}
+		}
+		if n != 4 {
+			// Block b contains not just
+			//  {TypeAssert; Extract #0; Extract #1; If}
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		y, x, T = isTypeAssertBlock(b)
+	}
+	sw.Default = b
+}
+
+// isComparisonBlock returns the operands (v, k) if a block ends with
+// a comparison v==k, where k is a compile-time constant.
+//
+func isComparisonBlock(b *ir.BasicBlock) (v ir.Value, k *ir.Const) {
+	if n := len(b.Instrs); n >= 2 {
+		if i, ok := b.Instrs[n-1].(*ir.If); ok {
+			if binop, ok := i.Cond.(*ir.BinOp); ok && binop.Block() == b && binop.Op == token.EQL {
+				if k, ok := binop.Y.(*ir.Const); ok {
+					return binop.X, k
+				}
+				if k, ok := binop.X.(*ir.Const); ok {
+					return binop.Y, k
+				}
+			}
+		}
+	}
+	return
+}
+
+// isTypeAssertBlock returns the operands (y, x, T) if a block ends with
+// a type assertion "if y, ok := x.(T); ok {".
+//
+func isTypeAssertBlock(b *ir.BasicBlock) (y, x ir.Value, T types.Type) {
+	if n := len(b.Instrs); n >= 4 {
+		if i, ok := b.Instrs[n-1].(*ir.If); ok {
+			if ext1, ok := i.Cond.(*ir.Extract); ok && ext1.Block() == b && ext1.Index == 1 {
+				if ta, ok := ext1.Tuple.(*ir.TypeAssert); ok && ta.Block() == b {
+					// hack: relies upon instruction ordering.
+					if ext0, ok := b.Instrs[n-3].(*ir.Extract); ok {
+						return ext0, ta.X, ta.AssertedType
+					}
+				}
+			}
+		}
+	}
+	return
+}

vendor/honnef.co/go/tools/ir/irutil/util.go

@@ -0,0 +1,70 @@
+package irutil
+
+import (
+	"honnef.co/go/tools/ir"
+)
+
+func Reachable(from, to *ir.BasicBlock) bool {
+	if from == to {
+		return true
+	}
+	if from.Dominates(to) {
+		return true
+	}
+
+	found := false
+	Walk(from, func(b *ir.BasicBlock) bool {
+		if b == to {
+			found = true
+			return false
+		}
+		return true
+	})
+	return found
+}
+
+func Walk(b *ir.BasicBlock, fn func(*ir.BasicBlock) bool) {
+	seen := map[*ir.BasicBlock]bool{}
+	wl := []*ir.BasicBlock{b}
+	for len(wl) > 0 {
+		b := wl[len(wl)-1]
+		wl = wl[:len(wl)-1]
+		if seen[b] {
+			continue
+		}
+		seen[b] = true
+		if !fn(b) {
+			continue
+		}
+		wl = append(wl, b.Succs...)
+	}
+}
+
+func Vararg(x *ir.Slice) ([]ir.Value, bool) {
+	var out []ir.Value
+	slice, ok := x.X.(*ir.Alloc)
+	if !ok {
+		return nil, false
+	}
+	for _, ref := range *slice.Referrers() {
+		if ref == x {
+			continue
+		}
+		if ref.Block() != x.Block() {
+			return nil, false
+		}
+		idx, ok := ref.(*ir.IndexAddr)
+		if !ok {
+			return nil, false
+		}
+		if len(*idx.Referrers()) != 1 {
+			return nil, false
+		}
+		store, ok := (*idx.Referrers())[0].(*ir.Store)
+		if !ok {
+			return nil, false
+		}
+		out = append(out, store.Val)
+	}
+	return out, true
+}

vendor/honnef.co/go/tools/ir/irutil/visit.go

@@ -0,0 +1,79 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil // import "honnef.co/go/tools/ir/irutil"
+
+import "honnef.co/go/tools/ir"
+
+// This file defines utilities for visiting the IR of
+// a Program.
+//
+// TODO(adonovan): test coverage.
+
+// AllFunctions finds and returns the set of functions potentially
+// needed by program prog, as determined by a simple linker-style
+// reachability algorithm starting from the members and method-sets of
+// each package.  The result may include anonymous functions and
+// synthetic wrappers.
+//
+// Precondition: all packages are built.
+//
+func AllFunctions(prog *ir.Program) map[*ir.Function]bool {
+	visit := visitor{
+		prog: prog,
+		seen: make(map[*ir.Function]bool),
+	}
+	visit.program()
+	return visit.seen
+}
+
+type visitor struct {
+	prog *ir.Program
+	seen map[*ir.Function]bool
+}
+
+func (visit *visitor) program() {
+	for _, pkg := range visit.prog.AllPackages() {
+		for _, mem := range pkg.Members {
+			if fn, ok := mem.(*ir.Function); ok {
+				visit.function(fn)
+			}
+		}
+	}
+	for _, T := range visit.prog.RuntimeTypes() {
+		mset := visit.prog.MethodSets.MethodSet(T)
+		for i, n := 0, mset.Len(); i < n; i++ {
+			visit.function(visit.prog.MethodValue(mset.At(i)))
+		}
+	}
+}
+
+func (visit *visitor) function(fn *ir.Function) {
+	if !visit.seen[fn] {
+		visit.seen[fn] = true
+		var buf [10]*ir.Value // avoid alloc in common case
+		for _, b := range fn.Blocks {
+			for _, instr := range b.Instrs {
+				for _, op := range instr.Operands(buf[:0]) {
+					if fn, ok := (*op).(*ir.Function); ok {
+						visit.function(fn)
+					}
+				}
+			}
+		}
+	}
+}
+
+// MainPackages returns the subset of the specified packages
+// named "main" that define a main function.
+// The result may include synthetic "testmain" packages.
+func MainPackages(pkgs []*ir.Package) []*ir.Package {
+	var mains []*ir.Package
+	for _, pkg := range pkgs {
+		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
+			mains = append(mains, pkg)
+		}
+	}
+	return mains
+}

vendor/honnef.co/go/tools/ir/lvalue.go

@@ -0,0 +1,116 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// lvalues are the union of addressable expressions and map-index
+// expressions.
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// An lvalue represents an assignable location that may appear on the
+// left-hand side of an assignment.  This is a generalization of a
+// pointer to permit updates to elements of maps.
+//
+type lvalue interface {
+	store(fn *Function, v Value, source ast.Node) // stores v into the location
+	load(fn *Function, source ast.Node) Value     // loads the contents of the location
+	address(fn *Function) Value                   // address of the location
+	typ() types.Type                              // returns the type of the location
+}
+
+// An address is an lvalue represented by a true pointer.
+type address struct {
+	addr Value
+	expr ast.Expr // source syntax of the value (not address) [debug mode]
+}
+
+func (a *address) load(fn *Function, source ast.Node) Value {
+	return emitLoad(fn, a.addr, source)
+}
+
+func (a *address) store(fn *Function, v Value, source ast.Node) {
+	store := emitStore(fn, a.addr, v, source)
+	if a.expr != nil {
+		// store.Val is v, converted for assignability.
+		emitDebugRef(fn, a.expr, store.Val, false)
+	}
+}
+
+func (a *address) address(fn *Function) Value {
+	if a.expr != nil {
+		emitDebugRef(fn, a.expr, a.addr, true)
+	}
+	return a.addr
+}
+
+func (a *address) typ() types.Type {
+	return deref(a.addr.Type())
+}
+
+// An element is an lvalue represented by m[k], the location of an
+// element of a map.  These locations are not addressable
+// since pointers cannot be formed from them, but they do support
+// load() and store().
+//
+type element struct {
+	m, k Value      // map
+	t    types.Type // map element type
+}
+
+func (e *element) load(fn *Function, source ast.Node) Value {
+	l := &MapLookup{
+		X:     e.m,
+		Index: e.k,
+	}
+	l.setType(e.t)
+	return fn.emit(l, source)
+}
+
+func (e *element) store(fn *Function, v Value, source ast.Node) {
+	up := &MapUpdate{
+		Map:   e.m,
+		Key:   e.k,
+		Value: emitConv(fn, v, e.t, source),
+	}
+	fn.emit(up, source)
+}
+
+func (e *element) address(fn *Function) Value {
+	panic("map elements are not addressable")
+}
+
+func (e *element) typ() types.Type {
+	return e.t
+}
+
+// A blank is a dummy variable whose name is "_".
+// It is not reified: loads are illegal and stores are ignored.
+//
+type blank struct{}
+
+func (bl blank) load(fn *Function, source ast.Node) Value {
+	panic("blank.load is illegal")
+}
+
+func (bl blank) store(fn *Function, v Value, source ast.Node) {
+	s := &BlankStore{
+		Val: v,
+	}
+	fn.emit(s, source)
+}
+
+func (bl blank) address(fn *Function) Value {
+	panic("blank var is not addressable")
+}
+
+func (bl blank) typ() types.Type {
+	// This should be the type of the blank Ident; the typechecker
+	// doesn't provide this yet, but fortunately, we don't need it
+	// yet either.
+	panic("blank.typ is unimplemented")
+}

vendor/honnef.co/go/tools/ir/methods.go

@@ -0,0 +1,239 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines utilities for population of method sets.
+
+import (
+	"fmt"
+	"go/types"
+)
+
+// MethodValue returns the Function implementing method sel, building
+// wrapper methods on demand.  It returns nil if sel denotes an
+// abstract (interface) method.
+//
+// Precondition: sel.Kind() == MethodVal.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) MethodValue(sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodVal {
+		panic(fmt.Sprintf("MethodValue(%s) kind != MethodVal", sel))
+	}
+	T := sel.Recv()
+	if isInterface(T) {
+		return nil // abstract method
+	}
+	if prog.mode&LogSource != 0 {
+		defer logStack("MethodValue %s %v", T, sel)()
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	return prog.addMethod(prog.createMethodSet(T), sel)
+}
+
+// LookupMethod returns the implementation of the method of type T
+// identified by (pkg, name).  It returns nil if the method exists but
+// is abstract, and panics if T has no such method.
+//
+func (prog *Program) LookupMethod(T types.Type, pkg *types.Package, name string) *Function {
+	sel := prog.MethodSets.MethodSet(T).Lookup(pkg, name)
+	if sel == nil {
+		panic(fmt.Sprintf("%s has no method %s", T, types.Id(pkg, name)))
+	}
+	return prog.MethodValue(sel)
+}
+
+// methodSet contains the (concrete) methods of a non-interface type.
+type methodSet struct {
+	mapping  map[string]*Function // populated lazily
+	complete bool                 // mapping contains all methods
+}
+
+// Precondition: !isInterface(T).
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) createMethodSet(T types.Type) *methodSet {
+	mset, ok := prog.methodSets.At(T).(*methodSet)
+	if !ok {
+		mset = &methodSet{mapping: make(map[string]*Function)}
+		prog.methodSets.Set(T, mset)
+	}
+	return mset
+}
+
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) addMethod(mset *methodSet, sel *types.Selection) *Function {
+	if sel.Kind() == types.MethodExpr {
+		panic(sel)
+	}
+	id := sel.Obj().Id()
+	fn := mset.mapping[id]
+	if fn == nil {
+		obj := sel.Obj().(*types.Func)
+
+		needsPromotion := len(sel.Index()) > 1
+		needsIndirection := !isPointer(recvType(obj)) && isPointer(sel.Recv())
+		if needsPromotion || needsIndirection {
+			fn = makeWrapper(prog, sel)
+		} else {
+			fn = prog.declaredFunc(obj)
+		}
+		if fn.Signature.Recv() == nil {
+			panic(fn) // missing receiver
+		}
+		mset.mapping[id] = fn
+	}
+	return fn
+}
+
+// RuntimeTypes returns a new unordered slice containing all
+// concrete types in the program for which a complete (non-empty)
+// method set is required at run-time.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) RuntimeTypes() []types.Type {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	var res []types.Type
+	prog.methodSets.Iterate(func(T types.Type, v interface{}) {
+		if v.(*methodSet).complete {
+			res = append(res, T)
+		}
+	})
+	return res
+}
+
+// declaredFunc returns the concrete function/method denoted by obj.
+// Panic ensues if there is none.
+//
+func (prog *Program) declaredFunc(obj *types.Func) *Function {
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Function)
+	}
+	panic("no concrete method: " + obj.String())
+}
+
+// needMethodsOf ensures that runtime type information (including the
+// complete method set) is available for the specified type T and all
+// its subcomponents.
+//
+// needMethodsOf must be called for at least every type that is an
+// operand of some MakeInterface instruction, and for the type of
+// every exported package member.
+//
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+//
+// Thread-safe.  (Called via emitConv from multiple builder goroutines.)
+//
+// TODO(adonovan): make this faster.  It accounts for 20% of SSA build time.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethodsOf(T types.Type) {
+	prog.methodsMu.Lock()
+	prog.needMethods(T, false)
+	prog.methodsMu.Unlock()
+}
+
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+// Recursive case: skip => don't create methods for T.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethods(T types.Type, skip bool) {
+	// Each package maintains its own set of types it has visited.
+	if prevSkip, ok := prog.runtimeTypes.At(T).(bool); ok {
+		// needMethods(T) was previously called
+		if !prevSkip || skip {
+			return // already seen, with same or false 'skip' value
+		}
+	}
+	prog.runtimeTypes.Set(T, skip)
+
+	tmset := prog.MethodSets.MethodSet(T)
+
+	if !skip && !isInterface(T) && tmset.Len() > 0 {
+		// Create methods of T.
+		mset := prog.createMethodSet(T)
+		if !mset.complete {
+			mset.complete = true
+			n := tmset.Len()
+			for i := 0; i < n; i++ {
+				prog.addMethod(mset, tmset.At(i))
+			}
+		}
+	}
+
+	// Recursion over signatures of each method.
+	for i := 0; i < tmset.Len(); i++ {
+		sig := tmset.At(i).Type().(*types.Signature)
+		prog.needMethods(sig.Params(), false)
+		prog.needMethods(sig.Results(), false)
+	}
+
+	switch t := T.(type) {
+	case *types.Basic:
+		// nop
+
+	case *types.Interface:
+		// nop---handled by recursion over method set.
+
+	case *types.Pointer:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Slice:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Chan:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Map:
+		prog.needMethods(t.Key(), false)
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Signature:
+		if t.Recv() != nil {
+			panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
+		}
+		prog.needMethods(t.Params(), false)
+		prog.needMethods(t.Results(), false)
+
+	case *types.Named:
+		// A pointer-to-named type can be derived from a named
+		// type via reflection.  It may have methods too.
+		prog.needMethods(types.NewPointer(T), false)
+
+		// Consider 'type T struct{S}' where S has methods.
+		// Reflection provides no way to get from T to struct{S},
+		// only to S, so the method set of struct{S} is unwanted,
+		// so set 'skip' flag during recursion.
+		prog.needMethods(t.Underlying(), true)
+
+	case *types.Array:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Struct:
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			prog.needMethods(t.Field(i).Type(), false)
+		}
+
+	case *types.Tuple:
+		for i, n := 0, t.Len(); i < n; i++ {
+			prog.needMethods(t.At(i).Type(), false)
+		}
+
+	default:
+		panic(T)
+	}
+}

vendor/honnef.co/go/tools/ir/mode.go

@@ -0,0 +1,98 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines the BuilderMode type and its command-line flag.
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// BuilderMode is a bitmask of options for diagnostics and checking.
+//
+// *BuilderMode satisfies the flag.Value interface.  Example:
+//
+// 	var mode = ir.BuilderMode(0)
+// 	func init() { flag.Var(&mode, "build", ir.BuilderModeDoc) }
+//
+type BuilderMode uint
+
+const (
+	PrintPackages        BuilderMode = 1 << iota // Print package inventory to stdout
+	PrintFunctions                               // Print function IR code to stdout
+	PrintSource                                  // Print source code when printing function IR
+	LogSource                                    // Log source locations as IR builder progresses
+	SanityCheckFunctions                         // Perform sanity checking of function bodies
+	NaiveForm                                    // Build naïve IR form: don't replace local loads/stores with registers
+	GlobalDebug                                  // Enable debug info for all packages
+)
+
+const BuilderModeDoc = `Options controlling the IR builder.
+The value is a sequence of zero or more of these letters:
+C	perform sanity [C]hecking of the IR form.
+D	include [D]ebug info for every function.
+P	print [P]ackage inventory.
+F	print [F]unction IR code.
+A	print [A]ST nodes responsible for IR instructions
+S	log [S]ource locations as IR builder progresses.
+N	build [N]aive IR form: don't replace local loads/stores with registers.
+`
+
+func (m BuilderMode) String() string {
+	var buf bytes.Buffer
+	if m&GlobalDebug != 0 {
+		buf.WriteByte('D')
+	}
+	if m&PrintPackages != 0 {
+		buf.WriteByte('P')
+	}
+	if m&PrintFunctions != 0 {
+		buf.WriteByte('F')
+	}
+	if m&PrintSource != 0 {
+		buf.WriteByte('A')
+	}
+	if m&LogSource != 0 {
+		buf.WriteByte('S')
+	}
+	if m&SanityCheckFunctions != 0 {
+		buf.WriteByte('C')
+	}
+	if m&NaiveForm != 0 {
+		buf.WriteByte('N')
+	}
+	return buf.String()
+}
+
+// Set parses the flag characters in s and updates *m.
+func (m *BuilderMode) Set(s string) error {
+	var mode BuilderMode
+	for _, c := range s {
+		switch c {
+		case 'D':
+			mode |= GlobalDebug
+		case 'P':
+			mode |= PrintPackages
+		case 'F':
+			mode |= PrintFunctions
+		case 'A':
+			mode |= PrintSource
+		case 'S':
+			mode |= LogSource
+		case 'C':
+			mode |= SanityCheckFunctions
+		case 'N':
+			mode |= NaiveForm
+		default:
+			return fmt.Errorf("unknown BuilderMode option: %q", c)
+		}
+	}
+	*m = mode
+	return nil
+}
+
+// Get returns m.
+func (m BuilderMode) Get() interface{} { return m }

vendor/honnef.co/go/tools/ir/print.go

@@ -0,0 +1,472 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file implements the String() methods for all Value and
+// Instruction types.
+
+import (
+	"bytes"
+	"fmt"
+	"go/types"
+	"io"
+	"reflect"
+	"sort"
+
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// relName returns the name of v relative to i.
+// In most cases, this is identical to v.Name(), but references to
+// Functions (including methods) and Globals use RelString and
+// all types are displayed with relType, so that only cross-package
+// references are package-qualified.
+//
+func relName(v Value, i Instruction) string {
+	if v == nil {
+		return "<nil>"
+	}
+	var from *types.Package
+	if i != nil {
+		from = i.Parent().pkg()
+	}
+	switch v := v.(type) {
+	case Member: // *Function or *Global
+		return v.RelString(from)
+	}
+	return v.Name()
+}
+
+func relType(t types.Type, from *types.Package) string {
+	return types.TypeString(t, types.RelativeTo(from))
+}
+
+func relString(m Member, from *types.Package) string {
+	// NB: not all globals have an Object (e.g. init$guard),
+	// so use Package().Object not Object.Package().
+	if pkg := m.Package().Pkg; pkg != nil && pkg != from {
+		return fmt.Sprintf("%s.%s", pkg.Path(), m.Name())
+	}
+	return m.Name()
+}
+
+// Value.String()
+//
+// This method is provided only for debugging.
+// It never appears in disassembly, which uses Value.Name().
+
+func (v *Parameter) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Parameter <%s> {%s}", relType(v.Type(), from), v.name)
+}
+
+func (v *FreeVar) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("FreeVar <%s> %s", relType(v.Type(), from), v.Name())
+}
+
+func (v *Builtin) String() string {
+	return fmt.Sprintf("Builtin %s", v.Name())
+}
+
+// Instruction.String()
+
+func (v *Alloc) String() string {
+	from := v.Parent().pkg()
+	storage := "Stack"
+	if v.Heap {
+		storage = "Heap"
+	}
+	return fmt.Sprintf("%sAlloc <%s>", storage, relType(v.Type(), from))
+}
+
+func (v *Sigma) String() string {
+	from := v.Parent().pkg()
+	s := fmt.Sprintf("Sigma <%s> [b%d] %s", relType(v.Type(), from), v.From.Index, v.X.Name())
+	return s
+}
+
+func (v *Phi) String() string {
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "Phi <%s>", v.Type())
+	for i, edge := range v.Edges {
+		b.WriteString(" ")
+		// Be robust against malformed CFG.
+		if v.block == nil {
+			b.WriteString("??")
+			continue
+		}
+		block := -1
+		if i < len(v.block.Preds) {
+			block = v.block.Preds[i].Index
+		}
+		fmt.Fprintf(&b, "%d:", block)
+		edgeVal := "<nil>" // be robust
+		if edge != nil {
+			edgeVal = relName(edge, v)
+		}
+		b.WriteString(edgeVal)
+	}
+	return b.String()
+}
+
+func printCall(v *CallCommon, prefix string, instr Instruction) string {
+	var b bytes.Buffer
+	if !v.IsInvoke() {
+		if value, ok := instr.(Value); ok {
+			fmt.Fprintf(&b, "%s <%s> %s", prefix, relType(value.Type(), instr.Parent().pkg()), relName(v.Value, instr))
+		} else {
+			fmt.Fprintf(&b, "%s %s", prefix, relName(v.Value, instr))
+		}
+	} else {
+		if value, ok := instr.(Value); ok {
+			fmt.Fprintf(&b, "%sInvoke <%s> %s.%s", prefix, relType(value.Type(), instr.Parent().pkg()), relName(v.Value, instr), v.Method.Name())
+		} else {
+			fmt.Fprintf(&b, "%sInvoke %s.%s", prefix, relName(v.Value, instr), v.Method.Name())
+		}
+	}
+	for _, arg := range v.Args {
+		b.WriteString(" ")
+		b.WriteString(relName(arg, instr))
+	}
+	return b.String()
+}
+
+func (c *CallCommon) String() string {
+	return printCall(c, "", nil)
+}
+
+func (v *Call) String() string {
+	return printCall(&v.Call, "Call", v)
+}
+
+func (v *BinOp) String() string {
+	return fmt.Sprintf("BinOp <%s> {%s} %s %s", relType(v.Type(), v.Parent().pkg()), v.Op.String(), relName(v.X, v), relName(v.Y, v))
+}
+
+func (v *UnOp) String() string {
+	return fmt.Sprintf("UnOp <%s> {%s} %s", relType(v.Type(), v.Parent().pkg()), v.Op.String(), relName(v.X, v))
+}
+
+func (v *Load) String() string {
+	return fmt.Sprintf("Load <%s> %s", relType(v.Type(), v.Parent().pkg()), relName(v.X, v))
+}
+
+func printConv(prefix string, v, x Value) string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("%s <%s> %s",
+		prefix,
+		relType(v.Type(), from),
+		relName(x, v.(Instruction)))
+}
+
+func (v *ChangeType) String() string      { return printConv("ChangeType", v, v.X) }
+func (v *Convert) String() string         { return printConv("Convert", v, v.X) }
+func (v *ChangeInterface) String() string { return printConv("ChangeInterface", v, v.X) }
+func (v *MakeInterface) String() string   { return printConv("MakeInterface", v, v.X) }
+
+func (v *MakeClosure) String() string {
+	from := v.Parent().pkg()
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "MakeClosure <%s> %s", relType(v.Type(), from), relName(v.Fn, v))
+	if v.Bindings != nil {
+		for _, c := range v.Bindings {
+			b.WriteString(" ")
+			b.WriteString(relName(c, v))
+		}
+	}
+	return b.String()
+}
+
+func (v *MakeSlice) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeSlice <%s> %s %s",
+		relType(v.Type(), from),
+		relName(v.Len, v),
+		relName(v.Cap, v))
+}
+
+func (v *Slice) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Slice <%s> %s %s %s %s",
+		relType(v.Type(), from), relName(v.X, v), relName(v.Low, v), relName(v.High, v), relName(v.Max, v))
+}
+
+func (v *MakeMap) String() string {
+	res := ""
+	if v.Reserve != nil {
+		res = relName(v.Reserve, v)
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeMap <%s> %s", relType(v.Type(), from), res)
+}
+
+func (v *MakeChan) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeChan <%s> %s", relType(v.Type(), from), relName(v.Size, v))
+}
+
+func (v *FieldAddr) String() string {
+	from := v.Parent().pkg()
+	st := deref(v.X.Type()).Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	return fmt.Sprintf("FieldAddr <%s> [%d] (%s) %s", relType(v.Type(), from), v.Field, name, relName(v.X, v))
+}
+
+func (v *Field) String() string {
+	st := v.X.Type().Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Field <%s> [%d] (%s) %s", relType(v.Type(), from), v.Field, name, relName(v.X, v))
+}
+
+func (v *IndexAddr) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("IndexAddr <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Index) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Index <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *MapLookup) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MapLookup <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *StringLookup) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("StringLookup <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Range) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Range <%s> %s", relType(v.Type(), from), relName(v.X, v))
+}
+
+func (v *Next) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Next <%s> %s", relType(v.Type(), from), relName(v.Iter, v))
+}
+
+func (v *TypeAssert) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("TypeAssert <%s> %s", relType(v.Type(), from), relName(v.X, v))
+}
+
+func (v *Extract) String() string {
+	from := v.Parent().pkg()
+	name := v.Tuple.Type().(*types.Tuple).At(v.Index).Name()
+	return fmt.Sprintf("Extract <%s> [%d] (%s) %s", relType(v.Type(), from), v.Index, name, relName(v.Tuple, v))
+}
+
+func (s *Jump) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	str := fmt.Sprintf("Jump → b%d", block)
+	if s.Comment != "" {
+		str = fmt.Sprintf("%s # %s", str, s.Comment)
+	}
+	return str
+}
+
+func (s *Unreachable) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	return fmt.Sprintf("Unreachable → b%d", block)
+}
+
+func (s *If) String() string {
+	// Be robust against malformed CFG.
+	tblock, fblock := -1, -1
+	if s.block != nil && len(s.block.Succs) == 2 {
+		tblock = s.block.Succs[0].Index
+		fblock = s.block.Succs[1].Index
+	}
+	return fmt.Sprintf("If %s → b%d b%d", relName(s.Cond, s), tblock, fblock)
+}
+
+func (s *ConstantSwitch) String() string {
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "ConstantSwitch %s", relName(s.Tag, s))
+	for _, cond := range s.Conds {
+		fmt.Fprintf(&b, " %s", relName(cond, s))
+	}
+	fmt.Fprint(&b, " →")
+	for _, succ := range s.block.Succs {
+		fmt.Fprintf(&b, " b%d", succ.Index)
+	}
+	return b.String()
+}
+
+func (s *TypeSwitch) String() string {
+	from := s.Parent().pkg()
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "TypeSwitch <%s> %s", relType(s.typ, from), relName(s.Tag, s))
+	for _, cond := range s.Conds {
+		fmt.Fprintf(&b, " %q", relType(cond, s.block.parent.pkg()))
+	}
+	return b.String()
+}
+
+func (s *Go) String() string {
+	return printCall(&s.Call, "Go", s)
+}
+
+func (s *Panic) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	return fmt.Sprintf("Panic %s → b%d", relName(s.X, s), block)
+}
+
+func (s *Return) String() string {
+	var b bytes.Buffer
+	b.WriteString("Return")
+	for _, r := range s.Results {
+		b.WriteString(" ")
+		b.WriteString(relName(r, s))
+	}
+	return b.String()
+}
+
+func (*RunDefers) String() string {
+	return "RunDefers"
+}
+
+func (s *Send) String() string {
+	return fmt.Sprintf("Send %s %s", relName(s.Chan, s), relName(s.X, s))
+}
+
+func (recv *Recv) String() string {
+	from := recv.Parent().pkg()
+	return fmt.Sprintf("Recv <%s> %s", relType(recv.Type(), from), relName(recv.Chan, recv))
+}
+
+func (s *Defer) String() string {
+	return printCall(&s.Call, "Defer", s)
+}
+
+func (s *Select) String() string {
+	var b bytes.Buffer
+	for i, st := range s.States {
+		if i > 0 {
+			b.WriteString(", ")
+		}
+		if st.Dir == types.RecvOnly {
+			b.WriteString("<-")
+			b.WriteString(relName(st.Chan, s))
+		} else {
+			b.WriteString(relName(st.Chan, s))
+			b.WriteString("<-")
+			b.WriteString(relName(st.Send, s))
+		}
+	}
+	non := ""
+	if !s.Blocking {
+		non = "Non"
+	}
+	from := s.Parent().pkg()
+	return fmt.Sprintf("Select%sBlocking <%s> [%s]", non, relType(s.Type(), from), b.String())
+}
+
+func (s *Store) String() string {
+	return fmt.Sprintf("Store {%s} %s %s",
+		s.Val.Type(), relName(s.Addr, s), relName(s.Val, s))
+}
+
+func (s *BlankStore) String() string {
+	return fmt.Sprintf("BlankStore %s", relName(s.Val, s))
+}
+
+func (s *MapUpdate) String() string {
+	return fmt.Sprintf("MapUpdate %s %s %s", relName(s.Map, s), relName(s.Key, s), relName(s.Value, s))
+}
+
+func (s *DebugRef) String() string {
+	p := s.Parent().Prog.Fset.Position(s.Pos())
+	var descr interface{}
+	if s.object != nil {
+		descr = s.object // e.g. "var x int"
+	} else {
+		descr = reflect.TypeOf(s.Expr) // e.g. "*ast.CallExpr"
+	}
+	var addr string
+	if s.IsAddr {
+		addr = "address of "
+	}
+	return fmt.Sprintf("; %s%s @ %d:%d is %s", addr, descr, p.Line, p.Column, s.X.Name())
+}
+
+func (p *Package) String() string {
+	return "package " + p.Pkg.Path()
+}
+
+var _ io.WriterTo = (*Package)(nil) // *Package implements io.Writer
+
+func (p *Package) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+	WritePackage(&buf, p)
+	n, err := w.Write(buf.Bytes())
+	return int64(n), err
+}
+
+// WritePackage writes to buf a human-readable summary of p.
+func WritePackage(buf *bytes.Buffer, p *Package) {
+	fmt.Fprintf(buf, "%s:\n", p)
+
+	var names []string
+	maxname := 0
+	for name := range p.Members {
+		if l := len(name); l > maxname {
+			maxname = l
+		}
+		names = append(names, name)
+	}
+
+	from := p.Pkg
+	sort.Strings(names)
+	for _, name := range names {
+		switch mem := p.Members[name].(type) {
+		case *NamedConst:
+			fmt.Fprintf(buf, "  const %-*s %s = %s\n",
+				maxname, name, mem.Name(), mem.Value.RelString(from))
+
+		case *Function:
+			fmt.Fprintf(buf, "  func  %-*s %s\n",
+				maxname, name, relType(mem.Type(), from))
+
+		case *Type:
+			fmt.Fprintf(buf, "  type  %-*s %s\n",
+				maxname, name, relType(mem.Type().Underlying(), from))
+			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
+				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
+			}
+
+		case *Global:
+			fmt.Fprintf(buf, "  var   %-*s %s\n",
+				maxname, name, relType(mem.Type().(*types.Pointer).Elem(), from))
+		}
+	}
+
+	fmt.Fprintf(buf, "\n")
+}

vendor/honnef.co/go/tools/ir/sanity.go

@@ -0,0 +1,555 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// An optional pass for sanity-checking invariants of the IR representation.
+// Currently it checks CFG invariants but little at the instruction level.
+
+import (
+	"fmt"
+	"go/types"
+	"io"
+	"os"
+	"strings"
+)
+
+type sanity struct {
+	reporter io.Writer
+	fn       *Function
+	block    *BasicBlock
+	instrs   map[Instruction]struct{}
+	insane   bool
+}
+
+// sanityCheck performs integrity checking of the IR representation
+// of the function fn and returns true if it was valid.  Diagnostics
+// are written to reporter if non-nil, os.Stderr otherwise.  Some
+// diagnostics are only warnings and do not imply a negative result.
+//
+// Sanity-checking is intended to facilitate the debugging of code
+// transformation passes.
+//
+func sanityCheck(fn *Function, reporter io.Writer) bool {
+	if reporter == nil {
+		reporter = os.Stderr
+	}
+	return (&sanity{reporter: reporter}).checkFunction(fn)
+}
+
+// mustSanityCheck is like sanityCheck but panics instead of returning
+// a negative result.
+//
+func mustSanityCheck(fn *Function, reporter io.Writer) {
+	if !sanityCheck(fn, reporter) {
+		fn.WriteTo(os.Stderr)
+		panic("SanityCheck failed")
+	}
+}
+
+func (s *sanity) diagnostic(prefix, format string, args ...interface{}) {
+	fmt.Fprintf(s.reporter, "%s: function %s", prefix, s.fn)
+	if s.block != nil {
+		fmt.Fprintf(s.reporter, ", block %s", s.block)
+	}
+	io.WriteString(s.reporter, ": ")
+	fmt.Fprintf(s.reporter, format, args...)
+	io.WriteString(s.reporter, "\n")
+}
+
+func (s *sanity) errorf(format string, args ...interface{}) {
+	s.insane = true
+	s.diagnostic("Error", format, args...)
+}
+
+func (s *sanity) warnf(format string, args ...interface{}) {
+	s.diagnostic("Warning", format, args...)
+}
+
+// findDuplicate returns an arbitrary basic block that appeared more
+// than once in blocks, or nil if all were unique.
+func findDuplicate(blocks []*BasicBlock) *BasicBlock {
+	if len(blocks) < 2 {
+		return nil
+	}
+	if blocks[0] == blocks[1] {
+		return blocks[0]
+	}
+	// Slow path:
+	m := make(map[*BasicBlock]bool)
+	for _, b := range blocks {
+		if m[b] {
+			return b
+		}
+		m[b] = true
+	}
+	return nil
+}
+
+func (s *sanity) checkInstr(idx int, instr Instruction) {
+	switch instr := instr.(type) {
+	case *If, *Jump, *Return, *Panic, *Unreachable, *ConstantSwitch:
+		s.errorf("control flow instruction not at end of block")
+	case *Sigma:
+		if idx > 0 {
+			prev := s.block.Instrs[idx-1]
+			if _, ok := prev.(*Sigma); !ok {
+				s.errorf("Sigma instruction follows a non-Sigma: %T", prev)
+			}
+		}
+	case *Phi:
+		if idx == 0 {
+			// It suffices to apply this check to just the first phi node.
+			if dup := findDuplicate(s.block.Preds); dup != nil {
+				s.errorf("phi node in block with duplicate predecessor %s", dup)
+			}
+		} else {
+			prev := s.block.Instrs[idx-1]
+			switch prev.(type) {
+			case *Phi, *Sigma:
+			default:
+				s.errorf("Phi instruction follows a non-Phi, non-Sigma: %T", prev)
+			}
+		}
+		if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
+			s.errorf("phi node has %d edges but %d predecessors", ne, np)
+
+		} else {
+			for i, e := range instr.Edges {
+				if e == nil {
+					s.errorf("phi node '%v' has no value for edge #%d from %s", instr, i, s.block.Preds[i])
+				}
+			}
+		}
+
+	case *Alloc:
+		if !instr.Heap {
+			found := false
+			for _, l := range s.fn.Locals {
+				if l == instr {
+					found = true
+					break
+				}
+			}
+			if !found {
+				s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
+			}
+		}
+
+	case *BinOp:
+	case *Call:
+	case *ChangeInterface:
+	case *ChangeType:
+	case *Convert:
+		if _, ok := instr.X.Type().Underlying().(*types.Basic); !ok {
+			if _, ok := instr.Type().Underlying().(*types.Basic); !ok {
+				s.errorf("convert %s -> %s: at least one type must be basic", instr.X.Type(), instr.Type())
+			}
+		}
+
+	case *Defer:
+	case *Extract:
+	case *Field:
+	case *FieldAddr:
+	case *Go:
+	case *Index:
+	case *IndexAddr:
+	case *MapLookup:
+	case *StringLookup:
+	case *MakeChan:
+	case *MakeClosure:
+		numFree := len(instr.Fn.(*Function).FreeVars)
+		numBind := len(instr.Bindings)
+		if numFree != numBind {
+			s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
+				numBind, instr.Fn, numFree)
+
+		}
+		if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
+			s.errorf("MakeClosure's type includes receiver %s", recv.Type())
+		}
+
+	case *MakeInterface:
+	case *MakeMap:
+	case *MakeSlice:
+	case *MapUpdate:
+	case *Next:
+	case *Range:
+	case *RunDefers:
+	case *Select:
+	case *Send:
+	case *Slice:
+	case *Store:
+	case *TypeAssert:
+	case *UnOp:
+	case *DebugRef:
+	case *BlankStore:
+	case *Load:
+	case *Parameter:
+	case *Const:
+	case *Recv:
+	case *TypeSwitch:
+	default:
+		panic(fmt.Sprintf("Unknown instruction type: %T", instr))
+	}
+
+	if call, ok := instr.(CallInstruction); ok {
+		if call.Common().Signature() == nil {
+			s.errorf("nil signature: %s", call)
+		}
+	}
+
+	// Check that value-defining instructions have valid types
+	// and a valid referrer list.
+	if v, ok := instr.(Value); ok {
+		t := v.Type()
+		if t == nil {
+			s.errorf("no type: %s = %s", v.Name(), v)
+		} else if t == tRangeIter {
+			// not a proper type; ignore.
+		} else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
+			if _, ok := v.(*Const); !ok {
+				s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
+			}
+		}
+		s.checkReferrerList(v)
+	}
+
+	// Untyped constants are legal as instruction Operands(),
+	// for example:
+	//   _ = "foo"[0]
+	// or:
+	//   if wordsize==64 {...}
+
+	// All other non-Instruction Values can be found via their
+	// enclosing Function or Package.
+}
+
+func (s *sanity) checkFinalInstr(instr Instruction) {
+	switch instr := instr.(type) {
+	case *If:
+		if nsuccs := len(s.block.Succs); nsuccs != 2 {
+			s.errorf("If-terminated block has %d successors; expected 2", nsuccs)
+			return
+		}
+		if s.block.Succs[0] == s.block.Succs[1] {
+			s.errorf("If-instruction has same True, False target blocks: %s", s.block.Succs[0])
+			return
+		}
+
+	case *Jump:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Jump-terminated block has %d successors; expected 1", nsuccs)
+			return
+		}
+
+	case *Return:
+		if nsuccs := len(s.block.Succs); nsuccs != 0 {
+			s.errorf("Return-terminated block has %d successors; expected none", nsuccs)
+			return
+		}
+		if na, nf := len(instr.Results), s.fn.Signature.Results().Len(); nf != na {
+			s.errorf("%d-ary return in %d-ary function", na, nf)
+		}
+
+	case *Panic:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Panic-terminated block has %d successors; expected one", nsuccs)
+			return
+		}
+
+	case *Unreachable:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Unreachable-terminated block has %d successors; expected one", nsuccs)
+			return
+		}
+
+	case *ConstantSwitch:
+
+	default:
+		s.errorf("non-control flow instruction at end of block")
+	}
+}
+
+func (s *sanity) checkBlock(b *BasicBlock, index int) {
+	s.block = b
+
+	if b.Index != index {
+		s.errorf("block has incorrect Index %d", b.Index)
+	}
+	if b.parent != s.fn {
+		s.errorf("block has incorrect parent %s", b.parent)
+	}
+
+	// Check all blocks are reachable.
+	// (The entry block is always implicitly reachable, the exit block may be unreachable.)
+	if index > 1 && len(b.Preds) == 0 {
+		s.warnf("unreachable block")
+		if b.Instrs == nil {
+			// Since this block is about to be pruned,
+			// tolerating transient problems in it
+			// simplifies other optimizations.
+			return
+		}
+	}
+
+	// Check predecessor and successor relations are dual,
+	// and that all blocks in CFG belong to same function.
+	for _, a := range b.Preds {
+		found := false
+		for _, bb := range a.Succs {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected successor edge in predecessor %s; found only: %s", a, a.Succs)
+		}
+		if a.parent != s.fn {
+			s.errorf("predecessor %s belongs to different function %s", a, a.parent)
+		}
+	}
+	for _, c := range b.Succs {
+		found := false
+		for _, bb := range c.Preds {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected predecessor edge in successor %s; found only: %s", c, c.Preds)
+		}
+		if c.parent != s.fn {
+			s.errorf("successor %s belongs to different function %s", c, c.parent)
+		}
+	}
+
+	// Check each instruction is sane.
+	n := len(b.Instrs)
+	if n == 0 {
+		s.errorf("basic block contains no instructions")
+	}
+	var rands [10]*Value // reuse storage
+	for j, instr := range b.Instrs {
+		if instr == nil {
+			s.errorf("nil instruction at index %d", j)
+			continue
+		}
+		if b2 := instr.Block(); b2 == nil {
+			s.errorf("nil Block() for instruction at index %d", j)
+			continue
+		} else if b2 != b {
+			s.errorf("wrong Block() (%s) for instruction at index %d ", b2, j)
+			continue
+		}
+		if j < n-1 {
+			s.checkInstr(j, instr)
+		} else {
+			s.checkFinalInstr(instr)
+		}
+
+		// Check Instruction.Operands.
+	operands:
+		for i, op := range instr.Operands(rands[:0]) {
+			if op == nil {
+				s.errorf("nil operand pointer %d of %s", i, instr)
+				continue
+			}
+			val := *op
+			if val == nil {
+				continue // a nil operand is ok
+			}
+
+			// Check that "untyped" types only appear on constant operands.
+			if _, ok := (*op).(*Const); !ok {
+				if basic, ok := (*op).Type().(*types.Basic); ok {
+					if basic.Info()&types.IsUntyped != 0 {
+						s.errorf("operand #%d of %s is untyped: %s", i, instr, basic)
+					}
+				}
+			}
+
+			// Check that Operands that are also Instructions belong to same function.
+			// TODO(adonovan): also check their block dominates block b.
+			if val, ok := val.(Instruction); ok {
+				if val.Block() == nil {
+					s.errorf("operand %d of %s is an instruction (%s) that belongs to no block", i, instr, val)
+				} else if val.Parent() != s.fn {
+					s.errorf("operand %d of %s is an instruction (%s) from function %s", i, instr, val, val.Parent())
+				}
+			}
+
+			// Check that each function-local operand of
+			// instr refers back to instr.  (NB: quadratic)
+			switch val := val.(type) {
+			case *Const, *Global, *Builtin:
+				continue // not local
+			case *Function:
+				if val.parent == nil {
+					continue // only anon functions are local
+				}
+			}
+
+			// TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.
+
+			if refs := val.Referrers(); refs != nil {
+				for _, ref := range *refs {
+					if ref == instr {
+						continue operands
+					}
+				}
+				s.errorf("operand %d of %s (%s) does not refer to us", i, instr, val)
+			} else {
+				s.errorf("operand %d of %s (%s) has no referrers", i, instr, val)
+			}
+		}
+	}
+}
+
+func (s *sanity) checkReferrerList(v Value) {
+	refs := v.Referrers()
+	if refs == nil {
+		s.errorf("%s has missing referrer list", v.Name())
+		return
+	}
+	for i, ref := range *refs {
+		if _, ok := s.instrs[ref]; !ok {
+			if val, ok := ref.(Value); ok {
+				s.errorf("%s.Referrers()[%d] = %s = %s is not an instruction belonging to this function", v.Name(), i, val.Name(), val)
+			} else {
+				s.errorf("%s.Referrers()[%d] = %s is not an instruction belonging to this function", v.Name(), i, ref)
+			}
+		}
+	}
+}
+
+func (s *sanity) checkFunction(fn *Function) bool {
+	// TODO(adonovan): check Function invariants:
+	// - check params match signature
+	// - check transient fields are nil
+	// - warn if any fn.Locals do not appear among block instructions.
+	s.fn = fn
+	if fn.Prog == nil {
+		s.errorf("nil Prog")
+	}
+
+	_ = fn.String()            // must not crash
+	_ = fn.RelString(fn.pkg()) // must not crash
+
+	// All functions have a package, except delegates (which are
+	// shared across packages, or duplicated as weak symbols in a
+	// separate-compilation model), and error.Error.
+	if fn.Pkg == nil {
+		if strings.HasPrefix(fn.Synthetic, "wrapper ") ||
+			strings.HasPrefix(fn.Synthetic, "bound ") ||
+			strings.HasPrefix(fn.Synthetic, "thunk ") ||
+			strings.HasSuffix(fn.name, "Error") {
+			// ok
+		} else {
+			s.errorf("nil Pkg")
+		}
+	}
+	if src, syn := fn.Synthetic == "", fn.source != nil; src != syn {
+		s.errorf("got fromSource=%t, hasSyntax=%t; want same values", src, syn)
+	}
+	for i, l := range fn.Locals {
+		if l.Parent() != fn {
+			s.errorf("Local %s at index %d has wrong parent", l.Name(), i)
+		}
+		if l.Heap {
+			s.errorf("Local %s at index %d has Heap flag set", l.Name(), i)
+		}
+	}
+	// Build the set of valid referrers.
+	s.instrs = make(map[Instruction]struct{})
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			s.instrs[instr] = struct{}{}
+		}
+	}
+	for i, p := range fn.Params {
+		if p.Parent() != fn {
+			s.errorf("Param %s at index %d has wrong parent", p.Name(), i)
+		}
+		// Check common suffix of Signature and Params match type.
+		if sig := fn.Signature; sig != nil {
+			j := i - len(fn.Params) + sig.Params().Len() // index within sig.Params
+			if j < 0 {
+				continue
+			}
+			if !types.Identical(p.Type(), sig.Params().At(j).Type()) {
+				s.errorf("Param %s at index %d has wrong type (%s, versus %s in Signature)", p.Name(), i, p.Type(), sig.Params().At(j).Type())
+
+			}
+		}
+
+		s.checkReferrerList(p)
+	}
+	for i, fv := range fn.FreeVars {
+		if fv.Parent() != fn {
+			s.errorf("FreeVar %s at index %d has wrong parent", fv.Name(), i)
+		}
+		s.checkReferrerList(fv)
+	}
+
+	if fn.Blocks != nil && len(fn.Blocks) == 0 {
+		// Function _had_ blocks (so it's not external) but
+		// they were "optimized" away, even the entry block.
+		s.errorf("Blocks slice is non-nil but empty")
+	}
+	for i, b := range fn.Blocks {
+		if b == nil {
+			s.warnf("nil *BasicBlock at f.Blocks[%d]", i)
+			continue
+		}
+		s.checkBlock(b, i)
+	}
+
+	s.block = nil
+	for i, anon := range fn.AnonFuncs {
+		if anon.Parent() != fn {
+			s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
+		}
+	}
+	s.fn = nil
+	return !s.insane
+}
+
+// sanityCheckPackage checks invariants of packages upon creation.
+// It does not require that the package is built.
+// Unlike sanityCheck (for functions), it just panics at the first error.
+func sanityCheckPackage(pkg *Package) {
+	if pkg.Pkg == nil {
+		panic(fmt.Sprintf("Package %s has no Object", pkg))
+	}
+	_ = pkg.String() // must not crash
+
+	for name, mem := range pkg.Members {
+		if name != mem.Name() {
+			panic(fmt.Sprintf("%s: %T.Name() = %s, want %s",
+				pkg.Pkg.Path(), mem, mem.Name(), name))
+		}
+		obj := mem.Object()
+		if obj == nil {
+			// This check is sound because fields
+			// {Global,Function}.object have type
+			// types.Object.  (If they were declared as
+			// *types.{Var,Func}, we'd have a non-empty
+			// interface containing a nil pointer.)
+
+			continue // not all members have typechecker objects
+		}
+		if obj.Name() != name {
+			if obj.Name() == "init" && strings.HasPrefix(mem.Name(), "init#") {
+				// Ok.  The name of a declared init function varies between
+				// its types.Func ("init") and its ir.Function ("init#%d").
+			} else {
+				panic(fmt.Sprintf("%s: %T.Object().Name() = %s, want %s",
+					pkg.Pkg.Path(), mem, obj.Name(), name))
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/ir/source.go

@@ -0,0 +1,270 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines utilities for working with source positions
+// or source-level named entities ("objects").
+
+// TODO(adonovan): test that {Value,Instruction}.Pos() positions match
+// the originating syntax, as specified.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// EnclosingFunction returns the function that contains the syntax
+// node denoted by path.
+//
+// Syntax associated with package-level variable specifications is
+// enclosed by the package's init() function.
+//
+// Returns nil if not found; reasons might include:
+//    - the node is not enclosed by any function.
+//    - the node is within an anonymous function (FuncLit) and
+//      its IR function has not been created yet
+//      (pkg.Build() has not yet been called).
+//
+func EnclosingFunction(pkg *Package, path []ast.Node) *Function {
+	// Start with package-level function...
+	fn := findEnclosingPackageLevelFunction(pkg, path)
+	if fn == nil {
+		return nil // not in any function
+	}
+
+	// ...then walk down the nested anonymous functions.
+	n := len(path)
+outer:
+	for i := range path {
+		if lit, ok := path[n-1-i].(*ast.FuncLit); ok {
+			for _, anon := range fn.AnonFuncs {
+				if anon.Pos() == lit.Type.Func {
+					fn = anon
+					continue outer
+				}
+			}
+			// IR function not found:
+			// - package not yet built, or maybe
+			// - builder skipped FuncLit in dead block
+			//   (in principle; but currently the Builder
+			//   generates even dead FuncLits).
+			return nil
+		}
+	}
+	return fn
+}
+
+// HasEnclosingFunction returns true if the AST node denoted by path
+// is contained within the declaration of some function or
+// package-level variable.
+//
+// Unlike EnclosingFunction, the behaviour of this function does not
+// depend on whether IR code for pkg has been built, so it can be
+// used to quickly reject check inputs that will cause
+// EnclosingFunction to fail, prior to IR building.
+//
+func HasEnclosingFunction(pkg *Package, path []ast.Node) bool {
+	return findEnclosingPackageLevelFunction(pkg, path) != nil
+}
+
+// findEnclosingPackageLevelFunction returns the Function
+// corresponding to the package-level function enclosing path.
+//
+func findEnclosingPackageLevelFunction(pkg *Package, path []ast.Node) *Function {
+	if n := len(path); n >= 2 { // [... {Gen,Func}Decl File]
+		switch decl := path[n-2].(type) {
+		case *ast.GenDecl:
+			if decl.Tok == token.VAR && n >= 3 {
+				// Package-level 'var' initializer.
+				return pkg.init
+			}
+
+		case *ast.FuncDecl:
+			// Declared function/method.
+			fn := findNamedFunc(pkg, decl.Pos())
+			if fn == nil && decl.Recv == nil && decl.Name.Name == "init" {
+				// Hack: return non-nil when IR is not yet
+				// built so that HasEnclosingFunction works.
+				return pkg.init
+			}
+			return fn
+		}
+	}
+	return nil // not in any function
+}
+
+// findNamedFunc returns the named function whose FuncDecl.Ident is at
+// position pos.
+//
+func findNamedFunc(pkg *Package, pos token.Pos) *Function {
+	for _, fn := range pkg.Functions {
+		if fn.Pos() == pos {
+			return fn
+		}
+	}
+	return nil
+}
+
+// ValueForExpr returns the IR Value that corresponds to non-constant
+// expression e.
+//
+// It returns nil if no value was found, e.g.
+//    - the expression is not lexically contained within f;
+//    - f was not built with debug information; or
+//    - e is a constant expression.  (For efficiency, no debug
+//      information is stored for constants. Use
+//      go/types.Info.Types[e].Value instead.)
+//    - e is a reference to nil or a built-in function.
+//    - the value was optimised away.
+//
+// If e is an addressable expression used in an lvalue context,
+// value is the address denoted by e, and isAddr is true.
+//
+// The types of e (or &e, if isAddr) and the result are equal
+// (modulo "untyped" bools resulting from comparisons).
+//
+// (Tip: to find the ir.Value given a source position, use
+// astutil.PathEnclosingInterval to locate the ast.Node, then
+// EnclosingFunction to locate the Function, then ValueForExpr to find
+// the ir.Value.)
+//
+func (f *Function) ValueForExpr(e ast.Expr) (value Value, isAddr bool) {
+	if f.debugInfo() { // (opt)
+		e = unparen(e)
+		for _, b := range f.Blocks {
+			for _, instr := range b.Instrs {
+				if ref, ok := instr.(*DebugRef); ok {
+					if ref.Expr == e {
+						return ref.X, ref.IsAddr
+					}
+				}
+			}
+		}
+	}
+	return
+}
+
+// --- Lookup functions for source-level named entities (types.Objects) ---
+
+// Package returns the IR Package corresponding to the specified
+// type-checker package object.
+// It returns nil if no such IR package has been created.
+//
+func (prog *Program) Package(obj *types.Package) *Package {
+	return prog.packages[obj]
+}
+
+// packageLevelValue returns the package-level value corresponding to
+// the specified named object, which may be a package-level const
+// (*Const), var (*Global) or func (*Function) of some package in
+// prog.  It returns nil if the object is not found.
+//
+func (prog *Program) packageLevelValue(obj types.Object) Value {
+	if pkg, ok := prog.packages[obj.Pkg()]; ok {
+		return pkg.values[obj]
+	}
+	return nil
+}
+
+// FuncValue returns the concrete Function denoted by the source-level
+// named function obj, or nil if obj denotes an interface method.
+//
+// TODO(adonovan): check the invariant that obj.Type() matches the
+// result's Signature, both in the params/results and in the receiver.
+//
+func (prog *Program) FuncValue(obj *types.Func) *Function {
+	fn, _ := prog.packageLevelValue(obj).(*Function)
+	return fn
+}
+
+// ConstValue returns the IR Value denoted by the source-level named
+// constant obj.
+//
+func (prog *Program) ConstValue(obj *types.Const) *Const {
+	// TODO(adonovan): opt: share (don't reallocate)
+	// Consts for const objects and constant ast.Exprs.
+
+	// Universal constant? {true,false,nil}
+	if obj.Parent() == types.Universe {
+		return NewConst(obj.Val(), obj.Type())
+	}
+	// Package-level named constant?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Const)
+	}
+	return NewConst(obj.Val(), obj.Type())
+}
+
+// VarValue returns the IR Value that corresponds to a specific
+// identifier denoting the source-level named variable obj.
+//
+// VarValue returns nil if a local variable was not found, perhaps
+// because its package was not built, the debug information was not
+// requested during IR construction, or the value was optimized away.
+//
+// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
+// and that ident must resolve to obj.
+//
+// pkg is the package enclosing the reference.  (A reference to a var
+// always occurs within a function, so we need to know where to find it.)
+//
+// If the identifier is a field selector and its base expression is
+// non-addressable, then VarValue returns the value of that field.
+// For example:
+//    func f() struct {x int}
+//    f().x  // VarValue(x) returns a *Field instruction of type int
+//
+// All other identifiers denote addressable locations (variables).
+// For them, VarValue may return either the variable's address or its
+// value, even when the expression is evaluated only for its value; the
+// situation is reported by isAddr, the second component of the result.
+//
+// If !isAddr, the returned value is the one associated with the
+// specific identifier.  For example,
+//       var x int    // VarValue(x) returns Const 0 here
+//       x = 1        // VarValue(x) returns Const 1 here
+//
+// It is not specified whether the value or the address is returned in
+// any particular case, as it may depend upon optimizations performed
+// during IR code generation, such as registerization, constant
+// folding, avoidance of materialization of subexpressions, etc.
+//
+func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) {
+	// All references to a var are local to some function, possibly init.
+	fn := EnclosingFunction(pkg, ref)
+	if fn == nil {
+		return // e.g. def of struct field; IR not built?
+	}
+
+	id := ref[0].(*ast.Ident)
+
+	// Defining ident of a parameter?
+	if id.Pos() == obj.Pos() {
+		for _, param := range fn.Params {
+			if param.Object() == obj {
+				return param, false
+			}
+		}
+	}
+
+	// Other ident?
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			if dr, ok := instr.(*DebugRef); ok {
+				if dr.Pos() == id.Pos() {
+					return dr.X, dr.IsAddr
+				}
+			}
+		}
+	}
+
+	// Defining ident of package-level var?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Global), true
+	}
+
+	return // e.g. debug info not requested, or var optimized away
+}

vendor/honnef.co/go/tools/ir/staticcheck.conf

@@ -0,0 +1,3 @@
+# ssa/... is mostly imported from upstream and we don't want to
+# deviate from it too much, hence disabling SA1019
+checks = ["inherit", "-SA1019"]

vendor/honnef.co/go/tools/ir/util.go

@@ -0,0 +1,89 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines a number of miscellaneous utility functions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+//// AST utilities
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
+
+// isBlankIdent returns true iff e is an Ident with name "_".
+// They have no associated types.Object, and thus no type.
+//
+func isBlankIdent(e ast.Expr) bool {
+	id, ok := e.(*ast.Ident)
+	return ok && id.Name == "_"
+}
+
+//// Type utilities.  Some of these belong in go/types.
+
+// isPointer returns true for types whose underlying type is a pointer.
+func isPointer(typ types.Type) bool {
+	_, ok := typ.Underlying().(*types.Pointer)
+	return ok
+}
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }
+
+// deref returns a pointer's element type; otherwise it returns typ.
+func deref(typ types.Type) types.Type {
+	if p, ok := typ.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return typ
+}
+
+// recvType returns the receiver type of method obj.
+func recvType(obj *types.Func) types.Type {
+	return obj.Type().(*types.Signature).Recv().Type()
+}
+
+// logStack prints the formatted "start" message to stderr and
+// returns a closure that prints the corresponding "end" message.
+// Call using 'defer logStack(...)()' to show builder stack on panic.
+// Don't forget trailing parens!
+//
+func logStack(format string, args ...interface{}) func() {
+	msg := fmt.Sprintf(format, args...)
+	io.WriteString(os.Stderr, msg)
+	io.WriteString(os.Stderr, "\n")
+	return func() {
+		io.WriteString(os.Stderr, msg)
+		io.WriteString(os.Stderr, " end\n")
+	}
+}
+
+// newVar creates a 'var' for use in a types.Tuple.
+func newVar(name string, typ types.Type) *types.Var {
+	return types.NewParam(token.NoPos, nil, name, typ)
+}
+
+// anonVar creates an anonymous 'var' for use in a types.Tuple.
+func anonVar(typ types.Type) *types.Var {
+	return newVar("", typ)
+}
+
+var lenResults = types.NewTuple(anonVar(tInt))
+
+// makeLen returns the len builtin specialized to type func(T)int.
+func makeLen(T types.Type) *Builtin {
+	lenParams := types.NewTuple(anonVar(T))
+	return &Builtin{
+		name: "len",
+		sig:  types.NewSignature(nil, lenParams, lenResults, false),
+	}
+}

vendor/honnef.co/go/tools/ir/wrappers.go

@@ -0,0 +1,292 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines synthesis of Functions that delegate to declared
+// methods; they come in three kinds:
+//
+// (1) wrappers: methods that wrap declared methods, performing
+//     implicit pointer indirections and embedded field selections.
+//
+// (2) thunks: funcs that wrap declared methods.  Like wrappers,
+//     thunks perform indirections and field selections. The thunk's
+//     first parameter is used as the receiver for the method call.
+//
+// (3) bounds: funcs that wrap declared methods.  The bound's sole
+//     free variable, supplied by a closure, is used as the receiver
+//     for the method call.  No indirections or field selections are
+//     performed since they can be done before the call.
+
+import (
+	"fmt"
+
+	"go/types"
+)
+
+// -- wrappers -----------------------------------------------------------
+
+// makeWrapper returns a synthetic method that delegates to the
+// declared method denoted by meth.Obj(), first performing any
+// necessary pointer indirections or field selections implied by meth.
+//
+// The resulting method's receiver type is meth.Recv().
+//
+// This function is versatile but quite subtle!  Consider the
+// following axes of variation when making changes:
+//   - optional receiver indirection
+//   - optional implicit field selections
+//   - meth.Obj() may denote a concrete or an interface method
+//   - the result may be a thunk or a wrapper.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func makeWrapper(prog *Program, sel *types.Selection) *Function {
+	obj := sel.Obj().(*types.Func)       // the declared function
+	sig := sel.Type().(*types.Signature) // type of this wrapper
+
+	var recv *types.Var // wrapper's receiver or thunk's params[0]
+	name := obj.Name()
+	var description string
+	var start int // first regular param
+	if sel.Kind() == types.MethodExpr {
+		name += "$thunk"
+		description = "thunk"
+		recv = sig.Params().At(0)
+		start = 1
+	} else {
+		description = "wrapper"
+		recv = sig.Recv()
+	}
+
+	description = fmt.Sprintf("%s for %s", description, sel.Obj())
+	if prog.mode&LogSource != 0 {
+		defer logStack("make %s to (%s)", description, recv.Type())()
+	}
+	fn := &Function{
+		name:         name,
+		method:       sel,
+		object:       obj,
+		Signature:    sig,
+		Synthetic:    description,
+		Prog:         prog,
+		functionBody: new(functionBody),
+	}
+	fn.initHTML(prog.PrintFunc)
+	fn.startBody()
+	fn.addSpilledParam(recv, nil)
+	createParams(fn, start)
+
+	indices := sel.Index()
+
+	var v Value = fn.Locals[0] // spilled receiver
+	if isPointer(sel.Recv()) {
+		v = emitLoad(fn, v, nil)
+
+		// For simple indirection wrappers, perform an informative nil-check:
+		// "value method (T).f called using nil *T pointer"
+		if len(indices) == 1 && !isPointer(recvType(obj)) {
+			var c Call
+			c.Call.Value = &Builtin{
+				name: "ir:wrapnilchk",
+				sig: types.NewSignature(nil,
+					types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)),
+					types.NewTuple(anonVar(sel.Recv())), false),
+			}
+			c.Call.Args = []Value{
+				v,
+				emitConst(fn, stringConst(deref(sel.Recv()).String())),
+				emitConst(fn, stringConst(sel.Obj().Name())),
+			}
+			c.setType(v.Type())
+			v = fn.emit(&c, nil)
+		}
+	}
+
+	// Invariant: v is a pointer, either
+	//   value of *A receiver param, or
+	// address of  A spilled receiver.
+
+	// We use pointer arithmetic (FieldAddr possibly followed by
+	// Load) in preference to value extraction (Field possibly
+	// preceded by Load).
+
+	v = emitImplicitSelections(fn, v, indices[:len(indices)-1], nil)
+
+	// Invariant: v is a pointer, either
+	//   value of implicit *C field, or
+	// address of implicit  C field.
+
+	var c Call
+	if r := recvType(obj); !isInterface(r) { // concrete method
+		if !isPointer(r) {
+			v = emitLoad(fn, v, nil)
+		}
+		c.Call.Value = prog.declaredFunc(obj)
+		c.Call.Args = append(c.Call.Args, v)
+	} else {
+		c.Call.Method = obj
+		c.Call.Value = emitLoad(fn, v, nil)
+	}
+	for _, arg := range fn.Params[1:] {
+		c.Call.Args = append(c.Call.Args, arg)
+	}
+	emitTailCall(fn, &c, nil)
+	fn.finishBody()
+	return fn
+}
+
+// createParams creates parameters for wrapper method fn based on its
+// Signature.Params, which do not include the receiver.
+// start is the index of the first regular parameter to use.
+//
+func createParams(fn *Function, start int) {
+	tparams := fn.Signature.Params()
+	for i, n := start, tparams.Len(); i < n; i++ {
+		fn.addParamObj(tparams.At(i), nil)
+	}
+}
+
+// -- bounds -----------------------------------------------------------
+
+// makeBound returns a bound method wrapper (or "bound"), a synthetic
+// function that delegates to a concrete or interface method denoted
+// by obj.  The resulting function has no receiver, but has one free
+// variable which will be used as the method's receiver in the
+// tail-call.
+//
+// Use MakeClosure with such a wrapper to construct a bound method
+// closure.  e.g.:
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   var t T
+//   f := t.meth
+//   f() // calls t.meth()
+//
+// f is a closure of a synthetic wrapper defined as if by:
+//
+//   f := func() { return t.meth() }
+//
+// Unlike makeWrapper, makeBound need perform no indirection or field
+// selections because that can be done before the closure is
+// constructed.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeBound(prog *Program, obj *types.Func) *Function {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+	fn, ok := prog.bounds[obj]
+	if !ok {
+		description := fmt.Sprintf("bound method wrapper for %s", obj)
+		if prog.mode&LogSource != 0 {
+			defer logStack("%s", description)()
+		}
+		fn = &Function{
+			name:         obj.Name() + "$bound",
+			object:       obj,
+			Signature:    changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
+			Synthetic:    description,
+			Prog:         prog,
+			functionBody: new(functionBody),
+		}
+		fn.initHTML(prog.PrintFunc)
+
+		fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn}
+		fn.FreeVars = []*FreeVar{fv}
+		fn.startBody()
+		createParams(fn, 0)
+		var c Call
+
+		if !isInterface(recvType(obj)) { // concrete
+			c.Call.Value = prog.declaredFunc(obj)
+			c.Call.Args = []Value{fv}
+		} else {
+			c.Call.Value = fv
+			c.Call.Method = obj
+		}
+		for _, arg := range fn.Params {
+			c.Call.Args = append(c.Call.Args, arg)
+		}
+		emitTailCall(fn, &c, nil)
+		fn.finishBody()
+
+		prog.bounds[obj] = fn
+	}
+	return fn
+}
+
+// -- thunks -----------------------------------------------------------
+
+// makeThunk returns a thunk, a synthetic function that delegates to a
+// concrete or interface method denoted by sel.Obj().  The resulting
+// function has no receiver, but has an additional (first) regular
+// parameter.
+//
+// Precondition: sel.Kind() == types.MethodExpr.
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   f := T.meth
+//   var t T
+//   f(t) // calls t.meth()
+//
+// f is a synthetic wrapper defined as if by:
+//
+//   f := func(t T) { return t.meth() }
+//
+// TODO(adonovan): opt: currently the stub is created even when used
+// directly in a function call: C.f(i, 0).  This is less efficient
+// than inlining the stub.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeThunk(prog *Program, sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodExpr {
+		panic(sel)
+	}
+
+	key := selectionKey{
+		kind:     sel.Kind(),
+		recv:     sel.Recv(),
+		obj:      sel.Obj(),
+		index:    fmt.Sprint(sel.Index()),
+		indirect: sel.Indirect(),
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	// Canonicalize key.recv to avoid constructing duplicate thunks.
+	canonRecv, ok := prog.canon.At(key.recv).(types.Type)
+	if !ok {
+		canonRecv = key.recv
+		prog.canon.Set(key.recv, canonRecv)
+	}
+	key.recv = canonRecv
+
+	fn, ok := prog.thunks[key]
+	if !ok {
+		fn = makeWrapper(prog, sel)
+		if fn.Signature.Recv() != nil {
+			panic(fn) // unexpected receiver
+		}
+		prog.thunks[key] = fn
+	}
+	return fn
+}
+
+func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
+	return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic())
+}
+
+// selectionKey is like types.Selection but a usable map key.
+type selectionKey struct {
+	kind     types.SelectionKind
+	recv     types.Type // canonicalized via Program.canon
+	obj      types.Object
+	index    string
+	indirect bool
+}

vendor/honnef.co/go/tools/ir/write.go

@@ -0,0 +1,5 @@
+package ir
+
+func NewJump(parent *BasicBlock) *Jump {
+	return &Jump{anInstruction{block: parent}, ""}
+}