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