Merge V8 5.2.361.47 DO NOT MERGE
https://chromium.googlesource.com/v8/v8/+/5.2.361.47
FPIIM-449
Change-Id: Ibec421b85a9b88cb3a432ada642e469fe7e78346
(cherry picked from commit bcf72ee8e3b26f1d0726869c7ddb3921c68b09a8)
diff --git a/src/compiler/register-allocator-verifier.h b/src/compiler/register-allocator-verifier.h
index f3ab54f..06d9029 100644
--- a/src/compiler/register-allocator-verifier.h
+++ b/src/compiler/register-allocator-verifier.h
@@ -14,6 +14,153 @@
class InstructionOperand;
class InstructionSequence;
+// The register allocator validator traverses instructions in the instruction
+// sequence, and verifies the correctness of machine operand substitutions of
+// virtual registers. It collects the virtual register instruction signatures
+// before register allocation. Then, after the register allocation pipeline
+// completes, it compares the operand substitutions against the pre-allocation
+// data.
+// At a high level, validation works as follows: we iterate through each block,
+// and, in a block, through each instruction; then:
+// - when an operand is the output of an instruction, we associate it to the
+// virtual register that the instruction sequence declares as its output. We
+// use the concept of "FinalAssessment" to model this.
+// - when an operand is used in an instruction, we check that the assessment
+// matches the expectation of the instruction
+// - moves simply copy the assessment over to the new operand
+// - blocks with more than one predecessor associate to each operand a "Pending"
+// assessment. The pending assessment remembers the operand and block where it
+// was created. Then, when the value is used (which may be as a different
+// operand, because of moves), we check that the virtual register at the use
+// site matches the definition of this pending operand: either the phi inputs
+// match, or, if it's not a phi, all the predecessors at the point the pending
+// assessment was defined have that operand assigned to the given virtual
+// register.
+// If a block is a loop header - so one or more of its predecessors are it or
+// below - we still treat uses of operands as above, but we record which operand
+// assessments haven't been made yet, and what virtual register they must
+// correspond to, and verify that when we are done with the respective
+// predecessor blocks.
+// This way, the algorithm always makes a final decision about the operands
+// in an instruction, ensuring convergence.
+// Operand assessments are recorded per block, as the result at the exit from
+// the block. When moving to a new block, we copy assessments from its single
+// predecessor, or, if the block has multiple predecessors, the mechanism was
+// described already.
+
+enum AssessmentKind { Final, Pending };
+
+class Assessment : public ZoneObject {
+ public:
+ AssessmentKind kind() const { return kind_; }
+
+ protected:
+ explicit Assessment(AssessmentKind kind) : kind_(kind) {}
+ AssessmentKind kind_;
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(Assessment);
+};
+
+// PendingAssessments are associated to operands coming from the multiple
+// predecessors of a block. We only record the operand and the block, and
+// will determine if the way the operand is defined (from the predecessors)
+// matches a particular use. This handles scenarios where multiple phis are
+// defined with identical operands, and the move optimizer moved down the moves
+// separating the 2 phis in the block defining them.
+class PendingAssessment final : public Assessment {
+ public:
+ explicit PendingAssessment(const InstructionBlock* origin,
+ InstructionOperand operand)
+ : Assessment(Pending), origin_(origin), operand_(operand) {}
+
+ static const PendingAssessment* cast(const Assessment* assessment) {
+ CHECK(assessment->kind() == Pending);
+ return static_cast<const PendingAssessment*>(assessment);
+ }
+
+ const InstructionBlock* origin() const { return origin_; }
+ InstructionOperand operand() const { return operand_; }
+
+ private:
+ const InstructionBlock* const origin_;
+ InstructionOperand operand_;
+
+ DISALLOW_COPY_AND_ASSIGN(PendingAssessment);
+};
+
+// FinalAssessmens are associated to operands that we know to be a certain
+// virtual register.
+class FinalAssessment final : public Assessment {
+ public:
+ explicit FinalAssessment(int virtual_register,
+ const PendingAssessment* original_pending = nullptr)
+ : Assessment(Final),
+ virtual_register_(virtual_register),
+ original_pending_assessment_(original_pending) {}
+
+ int virtual_register() const { return virtual_register_; }
+ static const FinalAssessment* cast(const Assessment* assessment) {
+ CHECK(assessment->kind() == Final);
+ return static_cast<const FinalAssessment*>(assessment);
+ }
+
+ const PendingAssessment* original_pending_assessment() const {
+ return original_pending_assessment_;
+ }
+
+ private:
+ int virtual_register_;
+ const PendingAssessment* original_pending_assessment_;
+
+ DISALLOW_COPY_AND_ASSIGN(FinalAssessment);
+};
+
+struct OperandAsKeyLess {
+ bool operator()(const InstructionOperand& a,
+ const InstructionOperand& b) const {
+ return a.CompareCanonicalized(b);
+ }
+};
+
+// Assessments associated with a basic block.
+class BlockAssessments : public ZoneObject {
+ public:
+ typedef ZoneMap<InstructionOperand, Assessment*, OperandAsKeyLess> OperandMap;
+ explicit BlockAssessments(Zone* zone)
+ : map_(zone), map_for_moves_(zone), zone_(zone) {}
+ void Drop(InstructionOperand operand) { map_.erase(operand); }
+ void DropRegisters();
+ void AddDefinition(InstructionOperand operand, int virtual_register) {
+ auto existent = map_.find(operand);
+ if (existent != map_.end()) {
+ // Drop the assignment
+ map_.erase(existent);
+ }
+ map_.insert(
+ std::make_pair(operand, new (zone_) FinalAssessment(virtual_register)));
+ }
+
+ void PerformMoves(const Instruction* instruction);
+ void PerformParallelMoves(const ParallelMove* moves);
+ void CopyFrom(const BlockAssessments* other) {
+ CHECK(map_.empty());
+ CHECK_NOT_NULL(other);
+ map_.insert(other->map_.begin(), other->map_.end());
+ }
+
+ OperandMap& map() { return map_; }
+ const OperandMap& map() const { return map_; }
+ void Print() const;
+
+ private:
+ OperandMap map_;
+ OperandMap map_for_moves_;
+ Zone* zone_;
+
+ DISALLOW_COPY_AND_ASSIGN(BlockAssessments);
+};
+
class RegisterAllocatorVerifier final : public ZoneObject {
public:
RegisterAllocatorVerifier(Zone* zone, const RegisterConfiguration* config,
@@ -53,10 +200,29 @@
OperandConstraint* operand_constraints_;
};
- class BlockMaps;
-
typedef ZoneVector<InstructionConstraint> Constraints;
+ class DelayedAssessments : public ZoneObject {
+ public:
+ explicit DelayedAssessments(Zone* zone) : map_(zone) {}
+
+ const ZoneMap<InstructionOperand, int, OperandAsKeyLess>& map() const {
+ return map_;
+ }
+
+ void AddDelayedAssessment(InstructionOperand op, int vreg) {
+ auto it = map_.find(op);
+ if (it == map_.end()) {
+ map_.insert(std::make_pair(op, vreg));
+ } else {
+ CHECK_EQ(it->second, vreg);
+ }
+ }
+
+ private:
+ ZoneMap<InstructionOperand, int, OperandAsKeyLess> map_;
+ };
+
Zone* zone() const { return zone_; }
const RegisterConfiguration* config() { return config_; }
const InstructionSequence* sequence() const { return sequence_; }
@@ -70,13 +236,25 @@
OperandConstraint* constraint);
void CheckConstraint(const InstructionOperand* op,
const OperandConstraint* constraint);
+ BlockAssessments* CreateForBlock(const InstructionBlock* block);
- void VerifyGapMoves(BlockMaps* outgoing_mappings, bool initial_pass);
+ void ValidatePendingAssessment(RpoNumber block_id, InstructionOperand op,
+ BlockAssessments* current_assessments,
+ const PendingAssessment* assessment,
+ int virtual_register);
+ void ValidateFinalAssessment(RpoNumber block_id, InstructionOperand op,
+ BlockAssessments* current_assessments,
+ const FinalAssessment* assessment,
+ int virtual_register);
+ void ValidateUse(RpoNumber block_id, BlockAssessments* current_assessments,
+ InstructionOperand op, int virtual_register);
Zone* const zone_;
const RegisterConfiguration* config_;
const InstructionSequence* const sequence_;
Constraints constraints_;
+ ZoneMap<RpoNumber, BlockAssessments*> assessments_;
+ ZoneMap<RpoNumber, DelayedAssessments*> outstanding_assessments_;
DISALLOW_COPY_AND_ASSIGN(RegisterAllocatorVerifier);
};