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// 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 ssa
import (
"math"
"math/bits"
)
// checkFunc checks invariants of f.
func checkFunc(f *Func) {
blockMark := make([]bool, f.NumBlocks())
valueMark := make([]bool, f.NumValues())
for _, b := range f.Blocks {
if blockMark[b.ID] {
f.Fatalf("block %s appears twice in %s!", b, f.Name)
}
blockMark[b.ID] = true
if b.Func != f {
f.Fatalf("%s.Func=%s, want %s", b, b.Func.Name, f.Name)
}
for i, e := range b.Preds {
if se := e.b.Succs[e.i]; se.b != b || se.i != i {
f.Fatalf("block pred/succ not crosslinked correctly %d:%s %d:%s", i, b, se.i, se.b)
}
}
for i, e := range b.Succs {
if pe := e.b.Preds[e.i]; pe.b != b || pe.i != i {
f.Fatalf("block succ/pred not crosslinked correctly %d:%s %d:%s", i, b, pe.i, pe.b)
}
}
switch b.Kind {
case BlockExit:
if len(b.Succs) != 0 {
f.Fatalf("exit block %s has successors", b)
}
if b.Control == nil {
f.Fatalf("exit block %s has no control value", b)
}
if !b.Control.Type.IsMemory() {
f.Fatalf("exit block %s has non-memory control value %s", b, b.Control.LongString())
}
case BlockRet:
if len(b.Succs) != 0 {
f.Fatalf("ret block %s has successors", b)
}
if b.Control == nil {
f.Fatalf("ret block %s has nil control", b)
}
if !b.Control.Type.IsMemory() {
f.Fatalf("ret block %s has non-memory control value %s", b, b.Control.LongString())
}
case BlockRetJmp:
if len(b.Succs) != 0 {
f.Fatalf("retjmp block %s len(Succs)==%d, want 0", b, len(b.Succs))
}
if b.Control == nil {
f.Fatalf("retjmp block %s has nil control", b)
}
if !b.Control.Type.IsMemory() {
f.Fatalf("retjmp block %s has non-memory control value %s", b, b.Control.LongString())
}
if b.Aux == nil {
f.Fatalf("retjmp block %s has nil Aux field", b)
}
case BlockPlain:
if len(b.Succs) != 1 {
f.Fatalf("plain block %s len(Succs)==%d, want 1", b, len(b.Succs))
}
if b.Control != nil {
f.Fatalf("plain block %s has non-nil control %s", b, b.Control.LongString())
}
case BlockIf:
if len(b.Succs) != 2 {
f.Fatalf("if block %s len(Succs)==%d, want 2", b, len(b.Succs))
}
if b.Control == nil {
f.Fatalf("if block %s has no control value", b)
}
if !b.Control.Type.IsBoolean() {
f.Fatalf("if block %s has non-bool control value %s", b, b.Control.LongString())
}
case BlockDefer:
if len(b.Succs) != 2 {
f.Fatalf("defer block %s len(Succs)==%d, want 2", b, len(b.Succs))
}
if b.Control == nil {
f.Fatalf("defer block %s has no control value", b)
}
if !b.Control.Type.IsMemory() {
f.Fatalf("defer block %s has non-memory control value %s", b, b.Control.LongString())
}
case BlockFirst:
if len(b.Succs) != 2 {
f.Fatalf("plain/dead block %s len(Succs)==%d, want 2", b, len(b.Succs))
}
if b.Control != nil {
f.Fatalf("plain/dead block %s has a control value", b)
}
}
if len(b.Succs) != 2 && b.Likely != BranchUnknown {
f.Fatalf("likeliness prediction %d for block %s with %d successors", b.Likely, b, len(b.Succs))
}
for _, v := range b.Values {
// Check to make sure argument count makes sense (argLen of -1 indicates
// variable length args)
nArgs := opcodeTable[v.Op].argLen
if nArgs != -1 && int32(len(v.Args)) != nArgs {
f.Fatalf("value %s has %d args, expected %d", v.LongString(),
len(v.Args), nArgs)
}
// Check to make sure aux values make sense.
canHaveAux := false
canHaveAuxInt := false
switch opcodeTable[v.Op].auxType {
case auxNone:
case auxBool:
if v.AuxInt < 0 || v.AuxInt > 1 {
f.Fatalf("bad bool AuxInt value for %v", v)
}
canHaveAuxInt = true
case auxInt8:
if v.AuxInt != int64(int8(v.AuxInt)) {
f.Fatalf("bad int8 AuxInt value for %v", v)
}
canHaveAuxInt = true
case auxInt16:
if v.AuxInt != int64(int16(v.AuxInt)) {
f.Fatalf("bad int16 AuxInt value for %v", v)
}
canHaveAuxInt = true
case auxInt32:
if v.AuxInt != int64(int32(v.AuxInt)) {
f.Fatalf("bad int32 AuxInt value for %v", v)
}
canHaveAuxInt = true
case auxInt64, auxFloat64:
canHaveAuxInt = true
case auxInt128:
// AuxInt must be zero, so leave canHaveAuxInt set to false.
case auxFloat32:
canHaveAuxInt = true
if !isExactFloat32(v.AuxFloat()) {
f.Fatalf("value %v has an AuxInt value that is not an exact float32", v)
}
case auxString, auxSym, auxTyp:
canHaveAux = true
case auxSymOff, auxSymValAndOff, auxTypSize:
canHaveAuxInt = true
canHaveAux = true
case auxSymInt32:
if v.AuxInt != int64(int32(v.AuxInt)) {
f.Fatalf("bad int32 AuxInt value for %v", v)
}
canHaveAuxInt = true
canHaveAux = true
case auxCCop:
if _, ok := v.Aux.(Op); !ok {
f.Fatalf("bad type %T for CCop in %v", v.Aux, v)
}
canHaveAux = true
default:
f.Fatalf("unknown aux type for %s", v.Op)
}
if !canHaveAux && v.Aux != nil {
f.Fatalf("value %s has an Aux value %v but shouldn't", v.LongString(), v.Aux)
}
if !canHaveAuxInt && v.AuxInt != 0 {
f.Fatalf("value %s has an AuxInt value %d but shouldn't", v.LongString(), v.AuxInt)
}
for i, arg := range v.Args {
if arg == nil {
f.Fatalf("value %s has nil arg", v.LongString())
}
if v.Op != OpPhi {
// For non-Phi ops, memory args must be last, if present
if arg.Type.IsMemory() && i != len(v.Args)-1 {
f.Fatalf("value %s has non-final memory arg (%d < %d)", v.LongString(), i, len(v.Args)-1)
}
}
}
if valueMark[v.ID] {
f.Fatalf("value %s appears twice!", v.LongString())
}
valueMark[v.ID] = true
if v.Block != b {
f.Fatalf("%s.block != %s", v, b)
}
if v.Op == OpPhi && len(v.Args) != len(b.Preds) {
f.Fatalf("phi length %s does not match pred length %d for block %s", v.LongString(), len(b.Preds), b)
}
if v.Op == OpAddr {
if len(v.Args) == 0 {
f.Fatalf("no args for OpAddr %s", v.LongString())
}
if v.Args[0].Op != OpSB {
f.Fatalf("bad arg to OpAddr %v", v)
}
}
if v.Op == OpLocalAddr {
if len(v.Args) != 2 {
f.Fatalf("wrong # of args for OpLocalAddr %s", v.LongString())
}
if v.Args[0].Op != OpSP {
f.Fatalf("bad arg 0 to OpLocalAddr %v", v)
}
if !v.Args[1].Type.IsMemory() {
f.Fatalf("bad arg 1 to OpLocalAddr %v", v)
}
}
if f.RegAlloc != nil && f.Config.SoftFloat && v.Type.IsFloat() {
f.Fatalf("unexpected floating-point type %v", v.LongString())
}
// Check types.
// TODO: more type checks?
switch c := f.Config; v.Op {
case OpSP, OpSB:
if v.Type != c.Types.Uintptr {
f.Fatalf("bad %s type: want uintptr, have %s",
v.Op, v.Type.String())
}
}
// TODO: check for cycles in values
}
}
// Check to make sure all Blocks referenced are in the function.
if !blockMark[f.Entry.ID] {
f.Fatalf("entry block %v is missing", f.Entry)
}
for _, b := range f.Blocks {
for _, c := range b.Preds {
if !blockMark[c.b.ID] {
f.Fatalf("predecessor block %v for %v is missing", c, b)
}
}
for _, c := range b.Succs {
if !blockMark[c.b.ID] {
f.Fatalf("successor block %v for %v is missing", c, b)
}
}
}
if len(f.Entry.Preds) > 0 {
f.Fatalf("entry block %s of %s has predecessor(s) %v", f.Entry, f.Name, f.Entry.Preds)
}
// Check to make sure all Values referenced are in the function.
for _, b := range f.Blocks {
for _, v := range b.Values {
for i, a := range v.Args {
if !valueMark[a.ID] {
f.Fatalf("%v, arg %d of %s, is missing", a, i, v.LongString())
}
}
}
if b.Control != nil && !valueMark[b.Control.ID] {
f.Fatalf("control value for %s is missing: %v", b, b.Control)
}
}
for b := f.freeBlocks; b != nil; b = b.succstorage[0].b {
if blockMark[b.ID] {
f.Fatalf("used block b%d in free list", b.ID)
}
}
for v := f.freeValues; v != nil; v = v.argstorage[0] {
if valueMark[v.ID] {
f.Fatalf("used value v%d in free list", v.ID)
}
}
// Check to make sure all args dominate uses.
if f.RegAlloc == nil {
// Note: regalloc introduces non-dominating args.
// See TODO in regalloc.go.
sdom := f.sdom()
for _, b := range f.Blocks {
for _, v := range b.Values {
for i, arg := range v.Args {
x := arg.Block
y := b
if v.Op == OpPhi {
y = b.Preds[i].b
}
if !domCheck(f, sdom, x, y) {
f.Fatalf("arg %d of value %s does not dominate, arg=%s", i, v.LongString(), arg.LongString())
}
}
}
if b.Control != nil && !domCheck(f, sdom, b.Control.Block, b) {
f.Fatalf("control value %s for %s doesn't dominate", b.Control, b)
}
}
}
// Check loop construction
if f.RegAlloc == nil && f.pass != nil { // non-nil pass allows better-targeted debug printing
ln := f.loopnest()
if !ln.hasIrreducible {
po := f.postorder() // use po to avoid unreachable blocks.
for _, b := range po {
for _, s := range b.Succs {
bb := s.Block()
if ln.b2l[b.ID] == nil && ln.b2l[bb.ID] != nil && bb != ln.b2l[bb.ID].header {
f.Fatalf("block %s not in loop branches to non-header block %s in loop", b.String(), bb.String())
}
if ln.b2l[b.ID] != nil && ln.b2l[bb.ID] != nil && bb != ln.b2l[bb.ID].header && !ln.b2l[b.ID].isWithinOrEq(ln.b2l[bb.ID]) {
f.Fatalf("block %s in loop branches to non-header block %s in non-containing loop", b.String(), bb.String())
}
}
}
}
}
// Check use counts
uses := make([]int32, f.NumValues())
for _, b := range f.Blocks {
for _, v := range b.Values {
for _, a := range v.Args {
uses[a.ID]++
}
}
if b.Control != nil {
uses[b.Control.ID]++
}
}
for _, b := range f.Blocks {
for _, v := range b.Values {
if v.Uses != uses[v.ID] {
f.Fatalf("%s has %d uses, but has Uses=%d", v, uses[v.ID], v.Uses)
}
}
}
memCheck(f)
}
func memCheck(f *Func) {
// Check that if a tuple has a memory type, it is second.
for _, b := range f.Blocks {
for _, v := range b.Values {
if v.Type.IsTuple() && v.Type.FieldType(0).IsMemory() {
f.Fatalf("memory is first in a tuple: %s\n", v.LongString())
}
}
}
// Single live memory checks.
// These checks only work if there are no memory copies.
// (Memory copies introduce ambiguity about which mem value is really live.
// probably fixable, but it's easier to avoid the problem.)
// For the same reason, disable this check if some memory ops are unused.
for _, b := range f.Blocks {
for _, v := range b.Values {
if (v.Op == OpCopy || v.Uses == 0) && v.Type.IsMemory() {
return
}
}
if b != f.Entry && len(b.Preds) == 0 {
return
}
}
// Compute live memory at the end of each block.
lastmem := make([]*Value, f.NumBlocks())
ss := newSparseSet(f.NumValues())
for _, b := range f.Blocks {
// Mark overwritten memory values. Those are args of other
// ops that generate memory values.
ss.clear()
for _, v := range b.Values {
if v.Op == OpPhi || !v.Type.IsMemory() {
continue
}
if m := v.MemoryArg(); m != nil {
ss.add(m.ID)
}
}
// There should be at most one remaining unoverwritten memory value.
for _, v := range b.Values {
if !v.Type.IsMemory() {
continue
}
if ss.contains(v.ID) {
continue
}
if lastmem[b.ID] != nil {
f.Fatalf("two live memory values in %s: %s and %s", b, lastmem[b.ID], v)
}
lastmem[b.ID] = v
}
// If there is no remaining memory value, that means there was no memory update.
// Take any memory arg.
if lastmem[b.ID] == nil {
for _, v := range b.Values {
if v.Op == OpPhi {
continue
}
m := v.MemoryArg()
if m == nil {
continue
}
if lastmem[b.ID] != nil && lastmem[b.ID] != m {
f.Fatalf("two live memory values in %s: %s and %s", b, lastmem[b.ID], m)
}
lastmem[b.ID] = m
}
}
}
// Propagate last live memory through storeless blocks.
for {
changed := false
for _, b := range f.Blocks {
if lastmem[b.ID] != nil {
continue
}
for _, e := range b.Preds {
p := e.b
if lastmem[p.ID] != nil {
lastmem[b.ID] = lastmem[p.ID]
changed = true
break
}
}
}
if !changed {
break
}
}
// Check merge points.
for _, b := range f.Blocks {
for _, v := range b.Values {
if v.Op == OpPhi && v.Type.IsMemory() {
for i, a := range v.Args {
if a != lastmem[b.Preds[i].b.ID] {
f.Fatalf("inconsistent memory phi %s %d %s %s", v.LongString(), i, a, lastmem[b.Preds[i].b.ID])
}
}
}
}
}
// Check that only one memory is live at any point.
if f.scheduled {
for _, b := range f.Blocks {
var mem *Value // the current live memory in the block
for _, v := range b.Values {
if v.Op == OpPhi {
if v.Type.IsMemory() {
mem = v
}
continue
}
if mem == nil && len(b.Preds) > 0 {
// If no mem phi, take mem of any predecessor.
mem = lastmem[b.Preds[0].b.ID]
}
for _, a := range v.Args {
if a.Type.IsMemory() && a != mem {
f.Fatalf("two live mems @ %s: %s and %s", v, mem, a)
}
}
if v.Type.IsMemory() {
mem = v
}
}
}
}
// Check that after scheduling, phis are always first in the block.
if f.scheduled {
for _, b := range f.Blocks {
seenNonPhi := false
for _, v := range b.Values {
switch v.Op {
case OpPhi:
if seenNonPhi {
f.Fatalf("phi after non-phi @ %s: %s", b, v)
}
default:
seenNonPhi = true
}
}
}
}
}
// domCheck reports whether x dominates y (including x==y).
func domCheck(f *Func, sdom SparseTree, x, y *Block) bool {
if !sdom.isAncestorEq(f.Entry, y) {
// unreachable - ignore
return true
}
return sdom.isAncestorEq(x, y)
}
// isExactFloat32 reports whether x can be exactly represented as a float32.
func isExactFloat32(x float64) bool {
// Check the mantissa is in range.
if bits.TrailingZeros64(math.Float64bits(x)) < 52-23 {
return false
}
// Check the exponent is in range. The mantissa check above is sufficient for NaN values.
return math.IsNaN(x) || x == float64(float32(x))
}