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27
28#include "hydrogen-canonicalize.h"
29
30namespace v8 {
31namespace internal {
32
33void HCanonicalizePhase::Run() {
34  const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
35  // Before removing no-op instructions, save their semantic value.
36  // We must be careful not to set the flag unnecessarily, because GVN
37  // cannot identify two instructions when their flag value differs.
38  for (int i = 0; i < blocks->length(); ++i) {
39    for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
40      HInstruction* instr = it.Current();
41      if (instr->IsArithmeticBinaryOperation()) {
42        if (instr->representation().IsInteger32()) {
43          if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
44                  HInstruction::kTruncatingToInt32)) {
45            instr->SetFlag(HInstruction::kAllUsesTruncatingToInt32);
46          }
47        } else if (instr->representation().IsSmi()) {
48          if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
49                  HInstruction::kTruncatingToSmi)) {
50            instr->SetFlag(HInstruction::kAllUsesTruncatingToSmi);
51          }
52        }
53      }
54    }
55  }
56  // Perform actual Canonicalization pass.
57  for (int i = 0; i < blocks->length(); ++i) {
58    for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
59      HInstruction* instr = it.Current();
60      HValue* value = instr->Canonicalize();
61      if (value != instr) instr->DeleteAndReplaceWith(value);
62    }
63  }
64}
65
66} }  // namespace v8::internal
67