diff options
Diffstat (limited to 'compiler/optimizing/scheduler.cc')
-rw-r--r-- | compiler/optimizing/scheduler.cc | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/compiler/optimizing/scheduler.cc b/compiler/optimizing/scheduler.cc index 1aa16f45bc..df897a4904 100644 --- a/compiler/optimizing/scheduler.cc +++ b/compiler/optimizing/scheduler.cc @@ -280,6 +280,23 @@ bool SchedulingGraph::HasSideEffectDependency(HInstruction* node, return false; } +// Check if the specified instruction is a better candidate which more likely will +// have other instructions depending on it. +static bool IsBetterCandidateWithMoreLikelyDependencies(HInstruction* new_candidate, + HInstruction* old_candidate) { + if (!new_candidate->GetSideEffects().Includes(old_candidate->GetSideEffects())) { + // Weaker side effects. + return false; + } + if (old_candidate->GetSideEffects().Includes(new_candidate->GetSideEffects())) { + // Same side effects, check if `new_candidate` has stronger `CanThrow()`. + return new_candidate->CanThrow() && !old_candidate->CanThrow(); + } else { + // Stronger side effects, check if `new_candidate` has at least as strong `CanThrow()`. + return new_candidate->CanThrow() || !old_candidate->CanThrow(); + } +} + void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_scheduling_barrier) { SchedulingNode* instruction_node = GetNode(instruction); @@ -331,6 +348,7 @@ void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_schedul // Side effect dependencies. if (!instruction->GetSideEffects().DoesNothing() || instruction->CanThrow()) { + HInstruction* dep_chain_candidate = nullptr; for (HInstruction* other = instruction->GetNext(); other != nullptr; other = other->GetNext()) { SchedulingNode* other_node = GetNode(other); if (other_node->IsSchedulingBarrier()) { @@ -340,7 +358,18 @@ void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_schedul break; } if (HasSideEffectDependency(other, instruction)) { - AddOtherDependency(other_node, instruction_node); + if (dep_chain_candidate != nullptr && + HasSideEffectDependency(other, dep_chain_candidate)) { + // Skip an explicit dependency to reduce memory usage, rely on the transitive dependency. + } else { + AddOtherDependency(other_node, instruction_node); + } + // Check if `other` is a better candidate which more likely will have other instructions + // depending on it. + if (dep_chain_candidate == nullptr || + IsBetterCandidateWithMoreLikelyDependencies(other, dep_chain_candidate)) { + dep_chain_candidate = other; + } } } } |