20cedf9a4b
R=titzer@chromium.org Review URL: https://codereview.chromium.org/15533004 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14938 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
95 lines
3.9 KiB
C++
95 lines
3.9 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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#ifndef V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_
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#define V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_
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#include "hydrogen.h"
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namespace v8 {
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namespace internal {
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// Trims live ranges of environment slots by doing explicit liveness analysis.
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// Values in the environment are kept alive by every subsequent LInstruction
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// that is assigned an LEnvironment, which creates register pressure and
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// unnecessary spill slot moves. Therefore it is beneficial to trim the
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// live ranges of environment slots by zapping them with a constant after
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// the last lookup that refers to them.
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// Slots are identified by their index and only affected if whitelisted in
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// HOptimizedGraphBuilder::IsEligibleForEnvironmentLivenessAnalysis().
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class EnvironmentSlotLivenessAnalyzer {
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public:
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explicit EnvironmentSlotLivenessAnalyzer(HGraph* graph);
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void AnalyzeAndTrim();
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private:
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void ZapEnvironmentSlot(int index, HSimulate* simulate);
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void ZapEnvironmentSlotsInSuccessors(HBasicBlock* block, BitVector* live);
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void ZapEnvironmentSlotsForInstruction(HEnvironmentMarker* marker);
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void UpdateLivenessAtBlockEnd(HBasicBlock* block, BitVector* live);
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void UpdateLivenessAtInstruction(HInstruction* instr, BitVector* live);
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Zone* zone() { return &zone_; }
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HGraph* graph_;
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// Use a dedicated Zone for this phase, with a ZoneScope to ensure it
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// gets freed.
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Zone zone_;
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ZoneScope zone_scope_;
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int block_count_;
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// Largest number of local variables in any environment in the graph
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// (including inlined environments).
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int maximum_environment_size_;
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// Per-block data. All these lists are indexed by block_id.
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ZoneList<BitVector*>* live_at_block_start_;
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ZoneList<HSimulate*>* first_simulate_;
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ZoneList<BitVector*>* first_simulate_invalid_for_index_;
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// List of all HEnvironmentMarker instructions for quick iteration/deletion.
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// It is populated during the first pass over the graph, controlled by
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// |collect_markers_|.
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ZoneList<HEnvironmentMarker*>* markers_;
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bool collect_markers_;
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// Keeps track of the last simulate seen, as well as the environment slots
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// for which a new live range has started since (so they must not be zapped
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// in that simulate when the end of another live range of theirs is found).
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HSimulate* last_simulate_;
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BitVector* went_live_since_last_simulate_;
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};
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} } // namespace v8::internal
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#endif /* V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ */
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