Initialize module and dependencies

vendor/golang.org/x/tools/go/ssa/ssautil/deprecated.go

@@ -0,0 +1,36 @@
+// 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 ssautil
+
+// This file contains deprecated public APIs.
+// We discourage their use.
+
+import (
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/ssa"
+)
+
+// CreateProgram returns a new program in SSA form, given a program
+// loaded from source.  An SSA 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 SSA construction.
+//
+// Deprecated: Use [golang.org/x/tools/go/packages] and the [Packages]
+// function instead; see ssa.Example_loadPackages.
+func CreateProgram(lprog *loader.Program, mode ssa.BuilderMode) *ssa.Program {
+	prog := ssa.NewProgram(lprog.Fset, mode)
+
+	for _, info := range lprog.AllPackages {
+		if info.TransitivelyErrorFree {
+			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
+		}
+	}
+
+	return prog
+}

vendor/golang.org/x/tools/go/ssa/ssautil/load.go

@@ -0,0 +1,189 @@
+// 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 ssautil
+
+// This file defines utility functions for constructing programs in SSA form.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/go/ssa"
+)
+
+// Packages creates an SSA program for a set of packages.
+//
+// The packages must have been loaded from source syntax using the
+// [packages.Load] function in [packages.LoadSyntax] or
+// [packages.LoadAllSyntax] mode.
+//
+// Packages creates an SSA 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 SSA code could not be constructed for the corresponding initial
+// package due to type errors.
+//
+// Code for bodies of functions is not built until [Program.Build] is
+// called on the resulting Program. SSA code is constructed only for
+// the initial packages with well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during SSA construction.
+func Packages(initial []*packages.Package, mode ssa.BuilderMode) (*ssa.Program, []*ssa.Package) {
+	// TODO(adonovan): opt: this calls CreatePackage far more than
+	// necessary: for all dependencies, not just the (non-initial)
+	// direct dependencies of the initial packages.
+	//
+	// But can it reasonably be changed without breaking the
+	// spirit and/or letter of the law above? Clients may notice
+	// if we call CreatePackage less, as methods like
+	// Program.FuncValue will return nil. Or must we provide a new
+	// function (and perhaps deprecate this one)? Is it worth it?
+	//
+	// Tim King makes the interesting point that it would be
+	// possible to entirely alleviate the client from the burden
+	// of calling CreatePackage for non-syntax packages, if we
+	// were to treat vars and funcs lazily in the same way we now
+	// treat methods. (In essence, try to move away from the
+	// notion of ssa.Packages, and make the Program answer
+	// all reasonable questions about any types.Object.)
+
+	return doPackages(initial, mode, false)
+}
+
+// AllPackages creates an SSA program for a set of packages plus all
+// their dependencies.
+//
+// The packages must have been loaded from source syntax using the
+// [packages.Load] function in [packages.LoadAllSyntax] mode.
+//
+// AllPackages creates an SSA 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 SSA 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. SSA code is constructed for all packages with
+// well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during SSA construction.
+func AllPackages(initial []*packages.Package, mode ssa.BuilderMode) (*ssa.Program, []*ssa.Package) {
+	return doPackages(initial, mode, true)
+}
+
+func doPackages(initial []*packages.Package, mode ssa.BuilderMode, deps bool) (*ssa.Program, []*ssa.Package) {
+
+	var fset *token.FileSet
+	if len(initial) > 0 {
+		fset = initial[0].Fset
+	}
+
+	prog := ssa.NewProgram(fset, mode)
+
+	isInitial := make(map[*packages.Package]bool, len(initial))
+	for _, p := range initial {
+		isInitial[p] = true
+	}
+
+	ssamap := make(map[*packages.Package]*ssa.Package)
+	packages.Visit(initial, nil, func(p *packages.Package) {
+		if p.Types != nil && !p.IllTyped {
+			var files []*ast.File
+			var info *types.Info
+			if deps || isInitial[p] {
+				files = p.Syntax
+				info = p.TypesInfo
+			}
+			ssamap[p] = prog.CreatePackage(p.Types, files, info, true)
+		}
+	})
+
+	var ssapkgs []*ssa.Package
+	for _, p := range initial {
+		ssapkgs = append(ssapkgs, ssamap[p]) // may be nil
+	}
+	return prog, ssapkgs
+}
+
+// BuildPackage builds an SSA program with SSA intermediate
+// representation (IR) for all functions of a single package.
+//
+// It populates pkg by type-checking the specified file syntax trees.  All
+// dependencies are loaded using the importer specified by tc, which
+// typically loads compiler export data; SSA code cannot be built for
+// those packages.  BuildPackage then constructs an [ssa.Program] with all
+// dependency packages created, and builds and returns the SSA 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 ../example_test.go for an example.
+func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.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),
+		Instances:    make(map[*ast.Ident]types.Instance),
+		Scopes:       make(map[ast.Node]*types.Scope),
+		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
+		FileVersions: make(map[*ast.File]string),
+	}
+	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
+		return nil, nil, err
+	}
+
+	prog := ssa.NewProgram(fset, mode)
+
+	// Create SSA 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())
+
+	// TODO(adonovan): we could replace createAll with just:
+	//
+	// // Create SSA packages for all imports.
+	// for _, p := range pkg.Imports() {
+	// 	prog.CreatePackage(p, nil, nil, true)
+	// }
+	//
+	// (with minor changes to changes to ../builder_test.go as
+	// shown in CL 511715 PS 10.) But this would strictly violate
+	// the letter of the doc comment above, which says "all
+	// dependencies created".
+	//
+	// Tim makes the good point with some extra work we could
+	// remove the need for any CreatePackage calls except the
+	// ones with syntax (i.e. primary packages). Of course
+	// You wouldn't have ssa.Packages and Members for as
+	// many things but no-one really uses that anyway.
+	// I wish I had done this from the outset.
+
+	// Create and build the primary package.
+	ssapkg := prog.CreatePackage(pkg, files, info, false)
+	ssapkg.Build()
+	return ssapkg, info, nil
+}

vendor/golang.org/x/tools/go/ssa/ssautil/switch.go

@@ -0,0 +1,230 @@
+// 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 ssautil
+
+// 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"
+
+	"golang.org/x/tools/go/ssa"
+)
+
+// A ConstCase represents a single constant comparison.
+// It is part of a Switch.
+type ConstCase struct {
+	Block *ssa.BasicBlock // block performing the comparison
+	Body  *ssa.BasicBlock // body of the case
+	Value *ssa.Const      // case comparand
+}
+
+// A TypeCase represents a single type assertion.
+// It is part of a Switch.
+type TypeCase struct {
+	Block   *ssa.BasicBlock // block performing the type assert
+	Body    *ssa.BasicBlock // body of the case
+	Type    types.Type      // case type
+	Binding ssa.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 ssa.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      *ssa.BasicBlock // block containing start of if/else chain
+	X          ssa.Value       // the switch operand
+	ConstCases []ConstCase     // ordered list of constant comparisons
+	TypeCases  []TypeCase      // ordered list of type assertions
+	Default    *ssa.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, 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
+// ssa.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 ssa.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 SSA representation.)
+func Switches(fn *ssa.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[*ssa.BasicBlock]bool) // TODO(adonovan): opt: use ssa.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 valueSwitch(sw *Switch, k *ssa.Const, seen map[*ssa.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for x == sw.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]
+		if len(b.Instrs) > 2 {
+			// Block b contains not just 'if x == k',
+			// 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 ssa.Value, T types.Type, seen map[*ssa.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for x == sw.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]
+		if len(b.Instrs) > 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 *ssa.BasicBlock) (v ssa.Value, k *ssa.Const) {
+	if n := len(b.Instrs); n >= 2 {
+		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
+			if binop, ok := i.Cond.(*ssa.BinOp); ok && binop.Block() == b && binop.Op == token.EQL {
+				if k, ok := binop.Y.(*ssa.Const); ok {
+					return binop.X, k
+				}
+				if k, ok := binop.X.(*ssa.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 *ssa.BasicBlock) (y, x ssa.Value, T types.Type) {
+	if n := len(b.Instrs); n >= 4 {
+		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
+			if ext1, ok := i.Cond.(*ssa.Extract); ok && ext1.Block() == b && ext1.Index == 1 {
+				if ta, ok := ext1.Tuple.(*ssa.TypeAssert); ok && ta.Block() == b {
+					// hack: relies upon instruction ordering.
+					if ext0, ok := b.Instrs[n-3].(*ssa.Extract); ok {
+						return ext0, ta.X, ta.AssertedType
+					}
+				}
+			}
+		}
+	}
+	return
+}

vendor/golang.org/x/tools/go/ssa/ssautil/visit.go

@@ -0,0 +1,157 @@
+// 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 ssautil // import "golang.org/x/tools/go/ssa/ssautil"
+
+import (
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/ssa"
+
+	_ "unsafe" // for linkname hack
+)
+
+// This file defines utilities for visiting the SSA representation 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.
+//
+// TODO(adonovan): this function is underspecified. It doesn't
+// actually work like a linker, which computes reachability from main
+// using something like go/callgraph/cha (without materializing the
+// call graph). In fact, it treats all public functions and all
+// methods of public non-parameterized types as roots, even though
+// they may be unreachable--but only in packages created from syntax.
+//
+// I think we should deprecate AllFunctions function in favor of two
+// clearly defined ones:
+//
+//  1. The first would efficiently compute CHA reachability from a set
+//     of main packages, making it suitable for a whole-program
+//     analysis context with InstantiateGenerics, in conjunction with
+//     Program.Build.
+//
+//  2. The second would return only the set of functions corresponding
+//     to source Func{Decl,Lit} syntax, like SrcFunctions in
+//     go/analysis/passes/buildssa; this is suitable for
+//     package-at-a-time (or handful of packages) context.
+//     ssa.Package could easily expose it as a field.
+//
+// We could add them unexported for now and use them via the linkname hack.
+func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool {
+	seen := make(map[*ssa.Function]bool)
+
+	var function func(fn *ssa.Function)
+	function = func(fn *ssa.Function) {
+		if !seen[fn] {
+			seen[fn] = true
+			var buf [10]*ssa.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).(*ssa.Function); ok {
+							function(fn)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	// TODO(adonovan): opt: provide a way to share a builder
+	// across a sequence of MethodValue calls.
+
+	methodsOf := func(T types.Type) {
+		if !types.IsInterface(T) {
+			mset := prog.MethodSets.MethodSet(T)
+			for method := range mset.Methods() {
+				function(prog.MethodValue(method))
+			}
+		}
+	}
+
+	// Historically, Program.RuntimeTypes used to include the type
+	// of any exported member of a package loaded from syntax that
+	// has a non-parameterized type, plus all types
+	// reachable from that type using reflection, even though
+	// these runtime types may not be required for them.
+	//
+	// Rather than break existing programs that rely on
+	// AllFunctions visiting extra methods that are unreferenced
+	// by IR and unreachable via reflection, we moved the logic
+	// here, unprincipled though it is.
+	// (See doc comment for better ideas.)
+	//
+	// Nonetheless, after the move, we no longer visit every
+	// method of any type recursively reachable from T, only the
+	// methods of T and *T themselves, and we only apply this to
+	// named types T, and not to the type of every exported
+	// package member.
+	exportedTypeHack := func(t *ssa.Type) {
+		if isSyntactic(t.Package()) &&
+			ast.IsExported(t.Name()) &&
+			!types.IsInterface(t.Type()) {
+			// Consider only named types.
+			// (Ignore aliases and unsafe.Pointer.)
+			if named, ok := t.Type().(*types.Named); ok {
+				if named.TypeParams() == nil {
+					methodsOf(named)                   //  T
+					methodsOf(types.NewPointer(named)) // *T
+				}
+			}
+		}
+	}
+
+	for _, pkg := range prog.AllPackages() {
+		for _, mem := range pkg.Members {
+			switch mem := mem.(type) {
+			case *ssa.Function:
+				// Visit all package-level declared functions.
+				function(mem)
+
+			case *ssa.Type:
+				exportedTypeHack(mem)
+			}
+		}
+	}
+
+	// Visit all methods of types for which runtime types were
+	// materialized, as they are reachable through reflection.
+	for _, T := range prog.RuntimeTypes() {
+		methodsOf(T)
+	}
+
+	return seen
+}
+
+// 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 []*ssa.Package) []*ssa.Package {
+	var mains []*ssa.Package
+	for _, pkg := range pkgs {
+		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
+			mains = append(mains, pkg)
+		}
+	}
+	return mains
+}
+
+// TODO(adonovan): propose a principled API for this. One possibility
+// is a new field, Package.SrcFunctions []*Function, which would
+// contain the list of SrcFunctions described in point 2 of the
+// AllFunctions doc comment, or nil if the package is not from syntax.
+// But perhaps overloading nil vs empty slice is too subtle.
+//
+//go:linkname isSyntactic golang.org/x/tools/go/ssa.isSyntactic
+func isSyntactic(pkg *ssa.Package) bool