Enable allocation elimination as part of LSE
After load-store elimination, an allocation may not be used any more
and may be eliminated.
Change-Id: I7fcaaefa9d6ec2c611e46119c5799293770a917c
diff --git a/compiler/optimizing/load_store_elimination.cc b/compiler/optimizing/load_store_elimination.cc
index e1977b1..ac7ed86 100644
--- a/compiler/optimizing/load_store_elimination.cc
+++ b/compiler/optimizing/load_store_elimination.cc
@@ -480,7 +480,7 @@
// alias analysis and won't be as effective.
bool has_volatile_; // If there are volatile field accesses.
bool has_monitor_operations_; // If there are monitor operations.
- bool may_deoptimize_;
+ bool may_deoptimize_; // Only true for HDeoptimize with single-frame deoptimization.
DISALLOW_COPY_AND_ASSIGN(HeapLocationCollector);
};
@@ -551,19 +551,20 @@
}
// At this point, stores in possibly_removed_stores_ can be safely removed.
- size = possibly_removed_stores_.size();
- for (size_t i = 0; i < size; i++) {
+ for (size_t i = 0, e = possibly_removed_stores_.size(); i < e; i++) {
HInstruction* store = possibly_removed_stores_[i];
DCHECK(store->IsInstanceFieldSet() || store->IsStaticFieldSet() || store->IsArraySet());
store->GetBlock()->RemoveInstruction(store);
}
- // TODO: remove unnecessary allocations.
- // Eliminate instructions in singleton_new_instances_ that:
- // - don't have uses,
- // - don't have finalizers,
- // - are instantiable and accessible,
- // - have no/separate clinit check.
+ // Eliminate allocations that are not used.
+ for (size_t i = 0, e = singleton_new_instances_.size(); i < e; i++) {
+ HInstruction* new_instance = singleton_new_instances_[i];
+ if (!new_instance->HasNonEnvironmentUses()) {
+ new_instance->RemoveEnvironmentUsers();
+ new_instance->GetBlock()->RemoveInstruction(new_instance);
+ }
+ }
}
private:
@@ -969,8 +970,8 @@
if (!heap_location_collector_.MayDeoptimize() &&
ref_info->IsSingletonAndNotReturned() &&
!new_instance->IsFinalizable() &&
- !new_instance->CanThrow()) {
- // TODO: add new_instance to singleton_new_instances_ and enable allocation elimination.
+ !new_instance->NeedsAccessCheck()) {
+ singleton_new_instances_.push_back(new_instance);
}
ArenaVector<HInstruction*>& heap_values =
heap_values_for_[new_instance->GetBlock()->GetBlockId()];