diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/ssa/func.go')
| -rw-r--r-- | vendor/golang.org/x/tools/go/ssa/func.go | 689 |
1 files changed, 0 insertions, 689 deletions
diff --git a/vendor/golang.org/x/tools/go/ssa/func.go b/vendor/golang.org/x/tools/go/ssa/func.go deleted file mode 100644 index b21ff4e..0000000 --- a/vendor/golang.org/x/tools/go/ssa/func.go +++ /dev/null @@ -1,689 +0,0 @@ -// 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 ssa - -// This file implements the Function and BasicBlock types. - -import ( - "bytes" - "fmt" - "go/ast" - "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) -} - -// 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) Value { - 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)) -} - -// hasPhi returns true if b.Instrs contains φ-nodes. -func (b *BasicBlock) hasPhi() bool { - _, ok := b.Instrs[0].(*Phi) - return ok -} - -// 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, pos token.Pos) *Parameter { - v := &Parameter{ - name: name, - typ: typ, - pos: pos, - parent: f, - } - f.Params = append(f.Params, v) - return v -} - -func (f *Function) addParamObj(obj types.Object) *Parameter { - name := obj.Name() - if name == "" { - name = fmt.Sprintf("arg%d", len(f.Params)) - } - param := f.addParam(name, obj.Type(), obj.Pos()) - 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) { - param := f.addParamObj(obj) - spill := &Alloc{Comment: obj.Name()} - spill.setType(types.NewPointer(obj.Type())) - spill.setPos(obj.Pos()) - f.objects[obj] = spill - f.Locals = append(f.Locals, spill) - f.emit(spill) - f.emit(&Store{Addr: spill, Val: param}) -} - -// startBody initializes the function prior to generating SSA code for its body. -// Precondition: f.Type() already set. -// -func (f *Function) startBody() { - f.currentBlock = f.newBasicBlock("entry") - f.objects = make(map[types.Object]Value) // needed for some synthetics, e.g. init -} - -// 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]) - } - // Anonymous receiver? No need to spill. - if field.Names == nil { - f.addParamObj(f.Signature.Recv()) - } - } - } - - // 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]) - } - // Anonymous parameter? No need to spill. - if field.Names == nil { - f.addParamObj(f.Signature.Params().At(len(f.Params) - n)) - } - } - } - - // 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)) - } - } - } -} - -// numberRegisters assigns numbers to all SSA registers -// (value-defining Instructions) in f, to aid debugging. -// (Non-Instruction Values are named at construction.) -// -func numberRegisters(f *Function) { - v := 0 - for _, b := range f.Blocks { - for _, instr := range b.Instrs { - switch instr.(type) { - case Value: - instr.(interface { - setNum(int) - }).setNum(v) - v++ - } - } - } -} - -// 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) - } - } - } - } - } -} - -// finishBody() finalizes the function after SSA code generation of its body. -func (f *Function) finishBody() { - f.objects = nil - f.currentBlock = nil - f.lblocks = nil - - // Don't pin the AST in memory (except in debug mode). - if n := f.syntax; n != nil && !f.debugInfo() { - f.syntax = extentNode{n.Pos(), n.End()} - } - - // 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) - - if f.Prog.mode&NaiveForm == 0 { - // For debugging pre-state of lifting pass: - // numberRegisters(f) - // f.WriteTo(os.Stderr) - lift(f) - } - - f.namedResults = nil // (used by lifting) - - numberRegisters(f) - - if f.Prog.mode&PrintFunctions != 0 { - printMu.Lock() - f.WriteTo(os.Stdout) - printMu.Unlock() - } - - if f.Prog.mode&SanityCheckFunctions != 0 { - mustSanityCheck(f, nil) - } -} - -// 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) *Alloc { - l := f.addLocal(obj.Type(), obj.Pos()) - l.Comment = obj.Name() - f.objects[obj] = l - return l -} - -func (f *Function) addLocalForIdent(id *ast.Ident) *Alloc { - return f.addNamedLocal(f.Pkg.info.Defs[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, pos token.Pos) *Alloc { - v := &Alloc{} - v.setType(types.NewPointer(typ)) - v.setPos(pos) - f.Locals = append(f.Locals, v) - f.emit(v) - 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 ssa.Value for " + obj.String()) - } - outer := f.parent.lookup(obj, true) // escaping - v := &FreeVar{ - name: obj.Name(), - typ: outer.Type(), - pos: outer.Pos(), - 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) Value { - return f.currentBlock.emit(instr) -} - -// 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()) - } - - if f.Recover != nil { - fmt.Fprintf(buf, "# Recover: %s\n", f.Recover) - } - - 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") - } - - // NB. column calculations are confused by non-ASCII - // characters and assume 8-space tabs. - const punchcard = 80 // for old time's sake. - const tabwidth = 8 - for _, b := range f.Blocks { - if b == nil { - // Corrupt CFG. - fmt.Fprintf(buf, ".nil:\n") - continue - } - n, _ := fmt.Fprintf(buf, "%d:", b.Index) - bmsg := fmt.Sprintf("%s P:%d S:%d", b.Comment, len(b.Preds), len(b.Succs)) - fmt.Fprintf(buf, "%*s%s\n", punchcard-1-n-len(bmsg), "", bmsg) - - if false { // CFG debugging - fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs) - } - for _, instr := range b.Instrs { - buf.WriteString("\t") - switch v := instr.(type) { - case Value: - l := punchcard - tabwidth - // Left-align the instruction. - if name := v.Name(); name != "" { - n, _ := fmt.Fprintf(buf, "%s = ", name) - l -= n - } - n, _ := buf.WriteString(instr.String()) - l -= n - // Right-align the type if there's space. - if t := v.Type(); t != nil { - buf.WriteByte(' ') - ts := relType(t, from) - l -= len(ts) + len(" ") // (spaces before and after type) - if l > 0 { - fmt.Fprintf(buf, "%*s", l, "") - } - buf.WriteString(ts) - } - case nil: - // Be robust against bad transforms. - buf.WriteString("<deleted>") - default: - buf.WriteString(instr.String()) - } - buf.WriteString("\n") - } - } - fmt.Fprintf(buf, "\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 -// SSA 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} -} - -type extentNode [2]token.Pos - -func (n extentNode) Pos() token.Pos { return n[0] } -func (n extentNode) End() token.Pos { return n[1] } - -// Syntax returns an ast.Node whose Pos/End methods provide the -// lexical extent of the function if it was defined by Go source code -// (f.Synthetic==""), or nil otherwise. -// -// If f was built with debug information (see Package.SetDebugRef), -// the result is the *ast.FuncDecl or *ast.FuncLit that declared the -// function. Otherwise, it is an opaque Node providing only position -// information; this avoids pinning the AST in memory. -// -func (f *Function) Syntax() ast.Node { return f.syntax } |