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Diffstat (limited to 'deps/v8/src/compiler/bytecode-branch-analysis.h')
-rw-r--r-- | deps/v8/src/compiler/bytecode-branch-analysis.h | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/deps/v8/src/compiler/bytecode-branch-analysis.h b/deps/v8/src/compiler/bytecode-branch-analysis.h new file mode 100644 index 0000000000..0ef33b640c --- /dev/null +++ b/deps/v8/src/compiler/bytecode-branch-analysis.h @@ -0,0 +1,79 @@ +// Copyright 2015 the V8 project authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_ +#define V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_ + +#include "src/bit-vector.h" +#include "src/handles.h" +#include "src/zone-containers.h" + +namespace v8 { +namespace internal { + +class BytecodeArray; + +namespace compiler { + +class BytecodeBranchInfo; + +// A class for identifying the branch targets and their branch sites +// within a bytecode array and also identifying which bytecodes are +// reachable. This information can be used to construct the local +// control flow logic for high-level IR graphs built from bytecode. +// +// NB This class relies on the only backwards branches in bytecode +// being jumps back to loop headers. +class BytecodeBranchAnalysis BASE_EMBEDDED { + public: + BytecodeBranchAnalysis(Handle<BytecodeArray> bytecode_array, Zone* zone); + + // Analyze the bytecodes to find the branch sites and their + // targets. No other methods in this class return valid information + // until this has been called. + void Analyze(); + + // Offsets of bytecodes having a backward branch to the bytecode at |offset|. + const ZoneVector<int>* BackwardBranchesTargetting(int offset) const; + + // Offsets of bytecodes having a forward branch to the bytecode at |offset|. + const ZoneVector<int>* ForwardBranchesTargetting(int offset) const; + + // Returns true if the bytecode at |offset| is reachable. + bool is_reachable(int offset) const { return reachable_.Contains(offset); } + + // Returns true if there are any forward branches to the bytecode at + // |offset|. + bool forward_branches_target(int offset) const { + const ZoneVector<int>* sites = ForwardBranchesTargetting(offset); + return sites != nullptr && sites->size() > 0; + } + + // Returns true if there are any backward branches to the bytecode + // at |offset|. + bool backward_branches_target(int offset) const { + const ZoneVector<int>* sites = BackwardBranchesTargetting(offset); + return sites != nullptr && sites->size() > 0; + } + + private: + void AddBranch(int origin_offset, int target_offset); + + Zone* zone() const { return zone_; } + Handle<BytecodeArray> bytecode_array() const { return bytecode_array_; } + + ZoneMap<int, BytecodeBranchInfo*> branch_infos_; + Handle<BytecodeArray> bytecode_array_; + BitVector reachable_; + Zone* zone_; + + DISALLOW_COPY_AND_ASSIGN(BytecodeBranchAnalysis); +}; + + +} // namespace compiler +} // namespace internal +} // namespace v8 + +#endif // V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_ |