+++ /dev/null
-// 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))
- }
- }
- }
-}
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