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// Copyright 2016 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.
#include "src/base/hashmap.h"
#include "src/compiler/bytecode-liveness-map.h"
#include "src/handles/handles.h"
#include "src/interpreter/bytecode-register.h"
#include "src/utils/bit-vector.h"
#include "src/utils/utils.h"
#include "src/zone/zone-containers.h"
namespace v8 {
namespace internal {
class BytecodeArray;
namespace compiler {
class V8_EXPORT_PRIVATE BytecodeLoopAssignments {
BytecodeLoopAssignments(int parameter_count, int register_count, Zone* zone);
void Add(interpreter::Register r);
void AddList(interpreter::Register r, uint32_t count);
void Union(const BytecodeLoopAssignments& other);
bool ContainsParameter(int index) const;
bool ContainsLocal(int index) const;
int parameter_count() const { return parameter_count_; }
int local_count() const { return bit_vector_->length() - parameter_count_; }
int const parameter_count_;
BitVector* const bit_vector_;
// Jump targets for resuming a suspended generator.
class V8_EXPORT_PRIVATE ResumeJumpTarget {
// Create a resume jump target representing an actual resume.
static ResumeJumpTarget Leaf(int suspend_id, int target_offset);
// Create a resume jump target at a loop header, which will have another
// resume jump after the loop header is crossed.
static ResumeJumpTarget AtLoopHeader(int loop_header_offset,
const ResumeJumpTarget& next);
int suspend_id() const { return suspend_id_; }
int target_offset() const { return target_offset_; }
bool is_leaf() const { return target_offset_ == final_target_offset_; }
// The suspend id of the resume.
int suspend_id_;
// The target offset of this resume jump.
int target_offset_;
// The final offset of this resume, which may be across multiple jumps.
int final_target_offset_;
ResumeJumpTarget(int suspend_id, int target_offset, int final_target_offset);
struct V8_EXPORT_PRIVATE LoopInfo {
LoopInfo(int parent_offset, int parameter_count, int register_count,
Zone* zone)
: parent_offset_(parent_offset),
assignments_(parameter_count, register_count, zone),
resume_jump_targets_(zone) {}
int parent_offset() const { return parent_offset_; }
const ZoneVector<ResumeJumpTarget>& resume_jump_targets() const {
return resume_jump_targets_;
void AddResumeTarget(const ResumeJumpTarget& target) {
BytecodeLoopAssignments& assignments() { return assignments_; }
const BytecodeLoopAssignments& assignments() const { return assignments_; }
// The offset to the parent loop, or -1 if there is no parent.
int parent_offset_;
BytecodeLoopAssignments assignments_;
ZoneVector<ResumeJumpTarget> resume_jump_targets_;
// Analyze the bytecodes to find the loop ranges, loop nesting, loop assignments
// and liveness. NOTE: The broker/serializer relies on the fact that an
// analysis for OSR (osr_bailout_id is not None) subsumes an analysis for
// non-OSR (osr_bailout_id is None).
class V8_EXPORT_PRIVATE BytecodeAnalysis : public ZoneObject {
BytecodeAnalysis(Handle<BytecodeArray> bytecode_array, Zone* zone,
BailoutId osr_bailout_id, bool analyze_liveness);
BytecodeAnalysis(const BytecodeAnalysis&) = delete;
BytecodeAnalysis& operator=(const BytecodeAnalysis&) = delete;
// Return true if the given offset is a loop header
bool IsLoopHeader(int offset) const;
// Get the loop header offset of the containing loop for arbitrary
// {offset}, or -1 if the {offset} is not inside any loop.
int GetLoopOffsetFor(int offset) const;
// Get the loop info of the loop header at {header_offset}.
const LoopInfo& GetLoopInfoFor(int header_offset) const;
// Get the top-level resume jump targets.
const ZoneVector<ResumeJumpTarget>& resume_jump_targets() const {
return resume_jump_targets_;
// Gets the in-/out-liveness for the bytecode at {offset}.
const BytecodeLivenessState* GetInLivenessFor(int offset) const;
const BytecodeLivenessState* GetOutLivenessFor(int offset) const;
// In the case of OSR, the analysis also computes the (bytecode offset of the)
// OSR entry point from the {osr_bailout_id} that was given to the
// constructor.
int osr_entry_point() const {
CHECK_LE(0, osr_entry_point_);
return osr_entry_point_;
// Return the osr_bailout_id (for verification purposes).
BailoutId osr_bailout_id() const { return osr_bailout_id_; }
// Return whether liveness analysis was performed (for verification purposes).
bool liveness_analyzed() const { return analyze_liveness_; }
struct LoopStackEntry {
int header_offset;
LoopInfo* loop_info;
void Analyze();
void PushLoop(int loop_header, int loop_end);
bool ResumeJumpTargetsAreValid();
bool ResumeJumpTargetLeavesResolveSuspendIds(
int parent_offset,
const ZoneVector<ResumeJumpTarget>& resume_jump_targets,
std::map<int, int>* unresolved_suspend_ids);
bool LivenessIsValid();
Zone* zone() const { return zone_; }
Handle<BytecodeArray> bytecode_array() const { return bytecode_array_; }
std::ostream& PrintLivenessTo(std::ostream& os) const;
Handle<BytecodeArray> const bytecode_array_;
Zone* const zone_;
BailoutId const osr_bailout_id_;
bool const analyze_liveness_;
ZoneStack<LoopStackEntry> loop_stack_;
ZoneVector<int> loop_end_index_queue_;
ZoneVector<ResumeJumpTarget> resume_jump_targets_;
ZoneMap<int, int> end_to_header_;
ZoneMap<int, LoopInfo> header_to_info_;
int osr_entry_point_;
BytecodeLivenessMap liveness_map_;
} // namespace compiler
} // namespace internal
} // namespace v8