5fd94c9ba1
R=hpayer@chromium.org Review URL: https://codereview.chromium.org/18816002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15531 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
63 lines
2.6 KiB
C++
63 lines
2.6 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-sce.h"
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#include "v8.h"
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namespace v8 {
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namespace internal {
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void HStackCheckEliminationPhase::Run() {
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// For each loop block walk the dominator tree from the backwards branch to
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// the loop header. If a call instruction is encountered the backwards branch
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// is dominated by a call and the stack check in the backwards branch can be
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// removed.
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for (int i = 0; i < graph()->blocks()->length(); i++) {
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HBasicBlock* block = graph()->blocks()->at(i);
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if (block->IsLoopHeader()) {
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HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge();
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HBasicBlock* dominator = back_edge;
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while (true) {
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for (HInstructionIterator it(dominator); !it.Done(); it.Advance()) {
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if (it.Current()->IsCall()) {
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block->loop_information()->stack_check()->Eliminate();
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break;
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}
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}
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// Done when the loop header is processed.
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if (dominator == block) break;
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// Move up the dominator tree.
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dominator = dominator->dominator();
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}
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}
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}
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}
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} } // namespace v8::internal
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