56a486c322
- this avoids using relative include paths which are forbidden by the style guide - makes the code more readable since it's clear which header is meant - allows for starting to use checkdeps BUG=none R=jkummerow@chromium.org, danno@chromium.org LOG=n Review URL: https://codereview.chromium.org/304153016 git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21625 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
56 lines
2.3 KiB
C++
56 lines
2.3 KiB
C++
// Copyright 2013 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/hydrogen-canonicalize.h"
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#include "src/hydrogen-redundant-phi.h"
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namespace v8 {
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namespace internal {
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void HCanonicalizePhase::Run() {
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const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
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// Before removing no-op instructions, save their semantic value.
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// We must be careful not to set the flag unnecessarily, because GVN
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// cannot identify two instructions when their flag value differs.
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for (int i = 0; i < blocks->length(); ++i) {
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for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
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HInstruction* instr = it.Current();
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if (instr->IsArithmeticBinaryOperation()) {
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if (instr->representation().IsInteger32()) {
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if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
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HInstruction::kTruncatingToInt32)) {
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instr->SetFlag(HInstruction::kAllUsesTruncatingToInt32);
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}
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} else if (instr->representation().IsSmi()) {
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if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
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HInstruction::kTruncatingToSmi)) {
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instr->SetFlag(HInstruction::kAllUsesTruncatingToSmi);
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} else if (instr->HasAtLeastOneUseWithFlagAndNoneWithout(
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HInstruction::kTruncatingToInt32)) {
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// Avoid redundant minus zero check
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instr->SetFlag(HInstruction::kAllUsesTruncatingToInt32);
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}
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}
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}
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}
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}
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// Perform actual Canonicalization pass.
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HRedundantPhiEliminationPhase redundant_phi_eliminator(graph());
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for (int i = 0; i < blocks->length(); ++i) {
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// Eliminate redundant phis in the block first; changes to their inputs
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// might have made them redundant, and eliminating them creates more
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// opportunities for constant folding and strength reduction.
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redundant_phi_eliminator.ProcessBlock(blocks->at(i));
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// Now canonicalize each instruction.
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for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
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HInstruction* instr = it.Current();
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HValue* value = instr->Canonicalize();
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if (value != instr) instr->DeleteAndReplaceWith(value);
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}
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}
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}
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} } // namespace v8::internal
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