5104731254
BUG= R=verwaest@chromium.org Review URL: https://codereview.chromium.org/25896006 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17124 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
79 lines
3.7 KiB
C++
79 lines
3.7 KiB
C++
// Copyright 2013 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "hydrogen-canonicalize.h"
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#include "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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