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author | Ben Noordhuis <info@bnoordhuis.nl> | 2013-11-10 02:02:27 +0100 |
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committer | Ben Noordhuis <info@bnoordhuis.nl> | 2013-11-11 02:40:36 +0100 |
commit | f230a1cf749e984439b5bb9729d9db9f48472827 (patch) | |
tree | 153596de2251b717ad79823f23fabf4c140d6d35 /deps/v8/src/hydrogen-flow-engine.h | |
parent | a12870c823b9b67110b27a470fcac342cf1dfbd6 (diff) | |
download | node-f230a1cf749e984439b5bb9729d9db9f48472827.tar.gz |
v8: upgrade to 3.22.24
This commit removes the simple/test-event-emitter-memory-leak test for
being unreliable with the new garbage collector: the memory pressure
exerted by the test case is too low for the garbage collector to kick
in. It can be made to work again by limiting the heap size with the
--max_old_space_size=x flag but that won't be very reliable across
platforms and architectures.
Diffstat (limited to 'deps/v8/src/hydrogen-flow-engine.h')
-rw-r--r-- | deps/v8/src/hydrogen-flow-engine.h | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/deps/v8/src/hydrogen-flow-engine.h b/deps/v8/src/hydrogen-flow-engine.h new file mode 100644 index 000000000..dfe43ec6c --- /dev/null +++ b/deps/v8/src/hydrogen-flow-engine.h @@ -0,0 +1,235 @@ +// Copyright 2013 the V8 project authors. All rights reserved. +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following +// disclaimer in the documentation and/or other materials provided +// with the distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived +// from this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#ifndef V8_HYDROGEN_FLOW_ENGINE_H_ +#define V8_HYDROGEN_FLOW_ENGINE_H_ + +#include "hydrogen.h" +#include "hydrogen-instructions.h" +#include "zone.h" + +namespace v8 { +namespace internal { + +// An example implementation of effects that doesn't collect anything. +class NoEffects : public ZoneObject { + public: + explicit NoEffects(Zone* zone) { } + + inline bool Disabled() { + return true; // Nothing to do. + } + template <class State> + inline void Apply(State* state) { + // do nothing. + } + inline void Process(HInstruction* value, Zone* zone) { + // do nothing. + } + inline void Union(NoEffects* other, Zone* zone) { + // do nothing. + } +}; + + +// An example implementation of state that doesn't track anything. +class NoState { + public: + inline NoState* Copy(HBasicBlock* succ, Zone* zone) { + return this; + } + inline NoState* Process(HInstruction* value, Zone* zone) { + return this; + } + inline NoState* Merge(HBasicBlock* succ, NoState* other, Zone* zone) { + return this; + } +}; + + +// This class implements an engine that can drive flow-sensitive analyses +// over a graph of basic blocks, either one block at a time (local analysis) +// or over the entire graph (global analysis). The flow engine is parameterized +// by the type of the state and the effects collected while walking over the +// graph. +// +// The "State" collects which facts are known while passing over instructions +// in control flow order, and the "Effects" collect summary information about +// which facts could be invalidated on other control flow paths. The effects +// are necessary to correctly handle loops in the control flow graph without +// doing a fixed-point iteration. Thus the flow engine is guaranteed to visit +// each block at most twice; once for state, and optionally once for effects. +// +// The flow engine requires the State and Effects classes to implement methods +// like the example NoState and NoEffects above. It's not necessary to provide +// an effects implementation for local analysis. +template <class State, class Effects> +class HFlowEngine { + public: + HFlowEngine(HGraph* graph, Zone* zone) + : graph_(graph), + zone_(zone), +#if DEBUG + pred_counts_(graph->blocks()->length(), zone), +#endif + block_states_(graph->blocks()->length(), zone), + loop_effects_(graph->blocks()->length(), zone) { + loop_effects_.AddBlock(NULL, graph_->blocks()->length(), zone); + } + + // Local analysis. Iterates over the instructions in the given block. + State* AnalyzeOneBlock(HBasicBlock* block, State* state) { + // Go through all instructions of the current block, updating the state. + for (HInstructionIterator it(block); !it.Done(); it.Advance()) { + state = state->Process(it.Current(), zone_); + } + return state; + } + + // Global analysis. Iterates over all blocks that are dominated by the given + // block, starting with the initial state. Computes effects for nested loops. + void AnalyzeDominatedBlocks(HBasicBlock* root, State* initial) { + InitializeStates(); + SetStateAt(root, initial); + + // Iterate all dominated blocks starting from the given start block. + for (int i = root->block_id(); i < graph_->blocks()->length(); i++) { + HBasicBlock* block = graph_->blocks()->at(i); + + // Skip blocks not dominated by the root node. + if (SkipNonDominatedBlock(root, block)) continue; + State* state = StateAt(block); + + if (block->IsLoopHeader()) { + // Apply loop effects before analyzing loop body. + ComputeLoopEffects(block)->Apply(state); + } else { + // Must have visited all predecessors before this block. + CheckPredecessorCount(block); + } + + // Go through all instructions of the current block, updating the state. + for (HInstructionIterator it(block); !it.Done(); it.Advance()) { + state = state->Process(it.Current(), zone_); + } + + // Propagate the block state forward to all successor blocks. + for (int i = 0; i < block->end()->SuccessorCount(); i++) { + HBasicBlock* succ = block->end()->SuccessorAt(i); + IncrementPredecessorCount(succ); + if (StateAt(succ) == NULL) { + // This is the first state to reach the successor. + SetStateAt(succ, state->Copy(succ, zone_)); + } else { + // Merge the current state with the state already at the successor. + SetStateAt(succ, state->Merge(succ, StateAt(succ), zone_)); + } + } + } + } + + private: + // Computes and caches the loop effects for the loop which has the given + // block as its loop header. + Effects* ComputeLoopEffects(HBasicBlock* block) { + ASSERT(block->IsLoopHeader()); + Effects* effects = loop_effects_[block->block_id()]; + if (effects != NULL) return effects; // Already analyzed this loop. + + effects = new(zone_) Effects(zone_); + loop_effects_[block->block_id()] = effects; + if (effects->Disabled()) return effects; // No effects for this analysis. + + HLoopInformation* loop = block->loop_information(); + int end = loop->GetLastBackEdge()->block_id(); + // Process the blocks between the header and the end. + for (int i = block->block_id(); i <= end; i++) { + HBasicBlock* member = graph_->blocks()->at(i); + if (i != block->block_id() && member->IsLoopHeader()) { + // Recursively compute and cache the effects of the nested loop. + ASSERT(member->loop_information()->parent_loop() == loop); + Effects* nested = ComputeLoopEffects(member); + effects->Union(nested, zone_); + // Skip the nested loop's blocks. + i = member->loop_information()->GetLastBackEdge()->block_id(); + } else { + // Process all the effects of the block. + ASSERT(member->current_loop() == loop); + for (HInstructionIterator it(member); !it.Done(); it.Advance()) { + effects->Process(it.Current(), zone_); + } + } + } + return effects; + } + + inline bool SkipNonDominatedBlock(HBasicBlock* root, HBasicBlock* other) { + if (root->block_id() == 0) return false; // Visit the whole graph. + if (root == other) return false; // Always visit the root. + return !root->Dominates(other); // Only visit dominated blocks. + } + + inline State* StateAt(HBasicBlock* block) { + return block_states_.at(block->block_id()); + } + + inline void SetStateAt(HBasicBlock* block, State* state) { + block_states_.Set(block->block_id(), state); + } + + inline void InitializeStates() { +#if DEBUG + pred_counts_.Rewind(0); + pred_counts_.AddBlock(0, graph_->blocks()->length(), zone_); +#endif + block_states_.Rewind(0); + block_states_.AddBlock(NULL, graph_->blocks()->length(), zone_); + } + + inline void CheckPredecessorCount(HBasicBlock* block) { + ASSERT(block->predecessors()->length() == pred_counts_[block->block_id()]); + } + + inline void IncrementPredecessorCount(HBasicBlock* block) { +#if DEBUG + pred_counts_[block->block_id()]++; +#endif + } + + HGraph* graph_; // The hydrogen graph. + Zone* zone_; // Temporary zone. +#if DEBUG + ZoneList<int> pred_counts_; // Finished predecessors (by block id). +#endif + ZoneList<State*> block_states_; // Block states (by block id). + ZoneList<Effects*> loop_effects_; // Loop effects (by block id). +}; + + +} } // namespace v8::internal + +#endif // V8_HYDROGEN_FLOW_ENGINE_H_ |