xref: /external/chromium_org/v8/src/hydrogen-canonicalize.cc

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#include "hydrogen-canonicalize.h"

namespace v8 {
namespace internal {

void HCanonicalizePhase::Run() {
  const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
  // Before removing no-op instructions, save their semantic value.
  // We must be careful not to set the flag unnecessarily, because GVN
  // cannot identify two instructions when their flag value differs.
  for (int i = 0; i < blocks->length(); ++i) {
    for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
      HInstruction* instr = it.Current();
      if (instr->IsArithmeticBinaryOperation()) {
        if (instr->representation().IsInteger32()) {
          if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
                  HInstruction::kTruncatingToInt32)) {
            instr->SetFlag(HInstruction::kAllUsesTruncatingToInt32);
          }
        } else if (instr->representation().IsSmi()) {
          if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
                  HInstruction::kTruncatingToSmi)) {
            instr->SetFlag(HInstruction::kAllUsesTruncatingToSmi);
          }
        }
      }
    }
  }
  // Perform actual Canonicalization pass.
  for (int i = 0; i < blocks->length(); ++i) {
    for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
      HInstruction* instr = it.Current();
      HValue* value = instr->Canonicalize();
      if (value != instr) instr->DeleteAndReplaceWith(value);
    }
  }
}

} }  // namespace v8::internal