Revert "Revert "Enable store elimination for singleton objects.""

This reverts commit 55d02cf056f993aeafebd54e7b7c68c7a48507c9, and
makes the following change:
Currently we leverage loop side effects to decide whether heap values are
killed by the loop. Stores need to be kept if heap values may be killed
by loops and the corresponding loads cannot be eliminated. Similar thing
need to be done for each predecessor when we merge predecessor heap values.
To do that, the HInstanceFieldSet instruction itself is put in the heap
value array instead of the value of the store instruction. The store
instruction may be added to possibly_removed_stores_ first, but can later
be removed from possibly_removed_stores_ when it's found out that the store
needs to be kept due to merging/loop side effects.

Change-Id: I4f7bb1960f7b47240873e00ff1adac46fc102a02

1 files changed, 11 insertions, 5 deletions

diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index 167c35d075..3257de1858 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -1449,7 +1449,8 @@ void HGraphBuilder::BuildFilledNewArray(uint32_t dex_pc,
                                         uint32_t* args,
                                         uint32_t register_index) {
   HInstruction* length = graph_->GetIntConstant(number_of_vreg_arguments, dex_pc);
-  QuickEntrypointEnum entrypoint = NeedsAccessCheck(type_index)
+  bool finalizable;
+  QuickEntrypointEnum entrypoint = NeedsAccessCheck(type_index, &finalizable)
       ? kQuickAllocArrayWithAccessCheck
       : kQuickAllocArray;
   HInstruction* object = new (arena_) HNewArray(length,
@@ -1629,9 +1630,9 @@ void HGraphBuilder::BuildTypeCheck(const Instruction& instruction,
   }
 }
 
-bool HGraphBuilder::NeedsAccessCheck(uint32_t type_index) const {
+bool HGraphBuilder::NeedsAccessCheck(uint32_t type_index, bool* finalizable) const {
   return !compiler_driver_->CanAccessInstantiableTypeWithoutChecks(
-      dex_compilation_unit_->GetDexMethodIndex(), *dex_file_, type_index);
+      dex_compilation_unit_->GetDexMethodIndex(), *dex_file_, type_index, finalizable);
 }
 
 void HGraphBuilder::BuildSwitchJumpTable(const SwitchTable& table,
@@ -2508,7 +2509,9 @@ bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, uint32
         current_block_->AddInstruction(fake_string);
         UpdateLocal(register_index, fake_string, dex_pc);
       } else {
-        QuickEntrypointEnum entrypoint = NeedsAccessCheck(type_index)
+        bool finalizable;
+        bool can_throw = NeedsAccessCheck(type_index, &finalizable);
+        QuickEntrypointEnum entrypoint = can_throw
             ? kQuickAllocObjectWithAccessCheck
             : kQuickAllocObject;
 
@@ -2517,6 +2520,8 @@ bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, uint32
             dex_pc,
             type_index,
             *dex_compilation_unit_->GetDexFile(),
+            can_throw,
+            finalizable,
             entrypoint));
         UpdateLocal(instruction.VRegA(), current_block_->GetLastInstruction(), dex_pc);
       }
@@ -2526,7 +2531,8 @@ bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, uint32
     case Instruction::NEW_ARRAY: {
       uint16_t type_index = instruction.VRegC_22c();
       HInstruction* length = LoadLocal(instruction.VRegB_22c(), Primitive::kPrimInt, dex_pc);
-      QuickEntrypointEnum entrypoint = NeedsAccessCheck(type_index)
+      bool finalizable;
+      QuickEntrypointEnum entrypoint = NeedsAccessCheck(type_index, &finalizable)
           ? kQuickAllocArrayWithAccessCheck
           : kQuickAllocArray;
       current_block_->AddInstruction(new (arena_) HNewArray(length,