1 // Copyright 2013 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 // An optional pass for sanity-checking invariants of the IR representation.
8 // Currently it checks CFG invariants but little at the instruction level.
22 instrs map[Instruction]struct{}
26 // sanityCheck performs integrity checking of the IR representation
27 // of the function fn and returns true if it was valid. Diagnostics
28 // are written to reporter if non-nil, os.Stderr otherwise. Some
29 // diagnostics are only warnings and do not imply a negative result.
31 // Sanity-checking is intended to facilitate the debugging of code
32 // transformation passes.
34 func sanityCheck(fn *Function, reporter io.Writer) bool {
38 return (&sanity{reporter: reporter}).checkFunction(fn)
41 // mustSanityCheck is like sanityCheck but panics instead of returning
44 func mustSanityCheck(fn *Function, reporter io.Writer) {
45 if !sanityCheck(fn, reporter) {
47 panic("SanityCheck failed")
51 func (s *sanity) diagnostic(prefix, format string, args ...interface{}) {
52 fmt.Fprintf(s.reporter, "%s: function %s", prefix, s.fn)
54 fmt.Fprintf(s.reporter, ", block %s", s.block)
56 io.WriteString(s.reporter, ": ")
57 fmt.Fprintf(s.reporter, format, args...)
58 io.WriteString(s.reporter, "\n")
61 func (s *sanity) errorf(format string, args ...interface{}) {
63 s.diagnostic("Error", format, args...)
66 func (s *sanity) warnf(format string, args ...interface{}) {
67 s.diagnostic("Warning", format, args...)
70 // findDuplicate returns an arbitrary basic block that appeared more
71 // than once in blocks, or nil if all were unique.
72 func findDuplicate(blocks []*BasicBlock) *BasicBlock {
76 if blocks[0] == blocks[1] {
80 m := make(map[*BasicBlock]bool)
81 for _, b := range blocks {
90 func (s *sanity) checkInstr(idx int, instr Instruction) {
91 switch instr := instr.(type) {
92 case *If, *Jump, *Return, *Panic, *Unreachable, *ConstantSwitch:
93 s.errorf("control flow instruction not at end of block")
96 prev := s.block.Instrs[idx-1]
97 if _, ok := prev.(*Sigma); !ok {
98 s.errorf("Sigma instruction follows a non-Sigma: %T", prev)
103 // It suffices to apply this check to just the first phi node.
104 if dup := findDuplicate(s.block.Preds); dup != nil {
105 s.errorf("phi node in block with duplicate predecessor %s", dup)
108 prev := s.block.Instrs[idx-1]
112 s.errorf("Phi instruction follows a non-Phi, non-Sigma: %T", prev)
115 if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
116 s.errorf("phi node has %d edges but %d predecessors", ne, np)
119 for i, e := range instr.Edges {
121 s.errorf("phi node '%v' has no value for edge #%d from %s", instr, i, s.block.Preds[i])
129 for _, l := range s.fn.Locals {
136 s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
142 case *ChangeInterface:
145 if _, ok := instr.X.Type().Underlying().(*types.Basic); !ok {
146 if _, ok := instr.Type().Underlying().(*types.Basic); !ok {
147 s.errorf("convert %s -> %s: at least one type must be basic", instr.X.Type(), instr.Type())
162 numFree := len(instr.Fn.(*Function).FreeVars)
163 numBind := len(instr.Bindings)
164 if numFree != numBind {
165 s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
166 numBind, instr.Fn, numFree)
169 if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
170 s.errorf("MakeClosure's type includes receiver %s", recv.Type())
194 panic(fmt.Sprintf("Unknown instruction type: %T", instr))
197 if call, ok := instr.(CallInstruction); ok {
198 if call.Common().Signature() == nil {
199 s.errorf("nil signature: %s", call)
203 // Check that value-defining instructions have valid types
204 // and a valid referrer list.
205 if v, ok := instr.(Value); ok {
208 s.errorf("no type: %s = %s", v.Name(), v)
209 } else if t == tRangeIter {
210 // not a proper type; ignore.
211 } else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
212 if _, ok := v.(*Const); !ok {
213 s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
216 s.checkReferrerList(v)
219 // Untyped constants are legal as instruction Operands(),
223 // if wordsize==64 {...}
225 // All other non-Instruction Values can be found via their
226 // enclosing Function or Package.
229 func (s *sanity) checkFinalInstr(instr Instruction) {
230 switch instr := instr.(type) {
232 if nsuccs := len(s.block.Succs); nsuccs != 2 {
233 s.errorf("If-terminated block has %d successors; expected 2", nsuccs)
236 if s.block.Succs[0] == s.block.Succs[1] {
237 s.errorf("If-instruction has same True, False target blocks: %s", s.block.Succs[0])
242 if nsuccs := len(s.block.Succs); nsuccs != 1 {
243 s.errorf("Jump-terminated block has %d successors; expected 1", nsuccs)
248 if nsuccs := len(s.block.Succs); nsuccs != 0 {
249 s.errorf("Return-terminated block has %d successors; expected none", nsuccs)
252 if na, nf := len(instr.Results), s.fn.Signature.Results().Len(); nf != na {
253 s.errorf("%d-ary return in %d-ary function", na, nf)
257 if nsuccs := len(s.block.Succs); nsuccs != 1 {
258 s.errorf("Panic-terminated block has %d successors; expected one", nsuccs)
263 if nsuccs := len(s.block.Succs); nsuccs != 1 {
264 s.errorf("Unreachable-terminated block has %d successors; expected one", nsuccs)
268 case *ConstantSwitch:
271 s.errorf("non-control flow instruction at end of block")
275 func (s *sanity) checkBlock(b *BasicBlock, index int) {
278 if b.Index != index {
279 s.errorf("block has incorrect Index %d", b.Index)
281 if b.parent != s.fn {
282 s.errorf("block has incorrect parent %s", b.parent)
285 // Check all blocks are reachable.
286 // (The entry block is always implicitly reachable, the exit block may be unreachable.)
287 if index > 1 && len(b.Preds) == 0 {
288 s.warnf("unreachable block")
290 // Since this block is about to be pruned,
291 // tolerating transient problems in it
292 // simplifies other optimizations.
297 // Check predecessor and successor relations are dual,
298 // and that all blocks in CFG belong to same function.
299 for _, a := range b.Preds {
301 for _, bb := range a.Succs {
308 s.errorf("expected successor edge in predecessor %s; found only: %s", a, a.Succs)
310 if a.parent != s.fn {
311 s.errorf("predecessor %s belongs to different function %s", a, a.parent)
314 for _, c := range b.Succs {
316 for _, bb := range c.Preds {
323 s.errorf("expected predecessor edge in successor %s; found only: %s", c, c.Preds)
325 if c.parent != s.fn {
326 s.errorf("successor %s belongs to different function %s", c, c.parent)
330 // Check each instruction is sane.
333 s.errorf("basic block contains no instructions")
335 var rands [10]*Value // reuse storage
336 for j, instr := range b.Instrs {
338 s.errorf("nil instruction at index %d", j)
341 if b2 := instr.Block(); b2 == nil {
342 s.errorf("nil Block() for instruction at index %d", j)
345 s.errorf("wrong Block() (%s) for instruction at index %d ", b2, j)
349 s.checkInstr(j, instr)
351 s.checkFinalInstr(instr)
354 // Check Instruction.Operands.
356 for i, op := range instr.Operands(rands[:0]) {
358 s.errorf("nil operand pointer %d of %s", i, instr)
363 continue // a nil operand is ok
366 // Check that "untyped" types only appear on constant operands.
367 if _, ok := (*op).(*Const); !ok {
368 if basic, ok := (*op).Type().(*types.Basic); ok {
369 if basic.Info()&types.IsUntyped != 0 {
370 s.errorf("operand #%d of %s is untyped: %s", i, instr, basic)
375 // Check that Operands that are also Instructions belong to same function.
376 // TODO(adonovan): also check their block dominates block b.
377 if val, ok := val.(Instruction); ok {
378 if val.Block() == nil {
379 s.errorf("operand %d of %s is an instruction (%s) that belongs to no block", i, instr, val)
380 } else if val.Parent() != s.fn {
381 s.errorf("operand %d of %s is an instruction (%s) from function %s", i, instr, val, val.Parent())
385 // Check that each function-local operand of
386 // instr refers back to instr. (NB: quadratic)
387 switch val := val.(type) {
388 case *Const, *Global, *Builtin:
389 continue // not local
391 if val.parent == nil {
392 continue // only anon functions are local
396 // TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.
398 if refs := val.Referrers(); refs != nil {
399 for _, ref := range *refs {
404 s.errorf("operand %d of %s (%s) does not refer to us", i, instr, val)
406 s.errorf("operand %d of %s (%s) has no referrers", i, instr, val)
412 func (s *sanity) checkReferrerList(v Value) {
413 refs := v.Referrers()
415 s.errorf("%s has missing referrer list", v.Name())
418 for i, ref := range *refs {
419 if _, ok := s.instrs[ref]; !ok {
420 if val, ok := ref.(Value); ok {
421 s.errorf("%s.Referrers()[%d] = %s = %s is not an instruction belonging to this function", v.Name(), i, val.Name(), val)
423 s.errorf("%s.Referrers()[%d] = %s is not an instruction belonging to this function", v.Name(), i, ref)
429 func (s *sanity) checkFunction(fn *Function) bool {
430 // TODO(adonovan): check Function invariants:
431 // - check params match signature
432 // - check transient fields are nil
433 // - warn if any fn.Locals do not appear among block instructions.
439 _ = fn.String() // must not crash
440 _ = fn.RelString(fn.pkg()) // must not crash
442 // All functions have a package, except delegates (which are
443 // shared across packages, or duplicated as weak symbols in a
444 // separate-compilation model), and error.Error.
446 if strings.HasPrefix(fn.Synthetic, "wrapper ") ||
447 strings.HasPrefix(fn.Synthetic, "bound ") ||
448 strings.HasPrefix(fn.Synthetic, "thunk ") ||
449 strings.HasSuffix(fn.name, "Error") {
455 if src, syn := fn.Synthetic == "", fn.source != nil; src != syn {
456 s.errorf("got fromSource=%t, hasSyntax=%t; want same values", src, syn)
458 for i, l := range fn.Locals {
459 if l.Parent() != fn {
460 s.errorf("Local %s at index %d has wrong parent", l.Name(), i)
463 s.errorf("Local %s at index %d has Heap flag set", l.Name(), i)
466 // Build the set of valid referrers.
467 s.instrs = make(map[Instruction]struct{})
468 for _, b := range fn.Blocks {
469 for _, instr := range b.Instrs {
470 s.instrs[instr] = struct{}{}
473 for i, p := range fn.Params {
474 if p.Parent() != fn {
475 s.errorf("Param %s at index %d has wrong parent", p.Name(), i)
477 // Check common suffix of Signature and Params match type.
478 if sig := fn.Signature; sig != nil {
479 j := i - len(fn.Params) + sig.Params().Len() // index within sig.Params
483 if !types.Identical(p.Type(), sig.Params().At(j).Type()) {
484 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())
489 s.checkReferrerList(p)
491 for i, fv := range fn.FreeVars {
492 if fv.Parent() != fn {
493 s.errorf("FreeVar %s at index %d has wrong parent", fv.Name(), i)
495 s.checkReferrerList(fv)
498 if fn.Blocks != nil && len(fn.Blocks) == 0 {
499 // Function _had_ blocks (so it's not external) but
500 // they were "optimized" away, even the entry block.
501 s.errorf("Blocks slice is non-nil but empty")
503 for i, b := range fn.Blocks {
505 s.warnf("nil *BasicBlock at f.Blocks[%d]", i)
512 for i, anon := range fn.AnonFuncs {
513 if anon.Parent() != fn {
514 s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
521 // sanityCheckPackage checks invariants of packages upon creation.
522 // It does not require that the package is built.
523 // Unlike sanityCheck (for functions), it just panics at the first error.
524 func sanityCheckPackage(pkg *Package) {
526 panic(fmt.Sprintf("Package %s has no Object", pkg))
528 _ = pkg.String() // must not crash
530 for name, mem := range pkg.Members {
531 if name != mem.Name() {
532 panic(fmt.Sprintf("%s: %T.Name() = %s, want %s",
533 pkg.Pkg.Path(), mem, mem.Name(), name))
537 // This check is sound because fields
538 // {Global,Function}.object have type
539 // types.Object. (If they were declared as
540 // *types.{Var,Func}, we'd have a non-empty
541 // interface containing a nil pointer.)
543 continue // not all members have typechecker objects
545 if obj.Name() != name {
546 if obj.Name() == "init" && strings.HasPrefix(mem.Name(), "init#") {
547 // Ok. The name of a declared init function varies between
548 // its types.Func ("init") and its ir.Function ("init#%d").
550 panic(fmt.Sprintf("%s: %T.Object().Name() = %s, want %s",
551 pkg.Pkg.Path(), mem, obj.Name(), name))