Remove string init map.
Partial revert of the String init change.
- Make Quick bailout in the presence of String allocation.
- Rely on the compiler for knowing when dex registers alias.
bug:27173201
Change-Id: I0bf58ba3825c71cef110b53f3a0a6f567cb2ef9a
diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc
index 43f2499..09ca8b7 100644
--- a/compiler/optimizing/ssa_builder.cc
+++ b/compiler/optimizing/ssa_builder.cc
@@ -422,6 +422,34 @@
return true;
}
+static bool HasAliasInEnvironments(HInstruction* instruction) {
+ for (HUseIterator<HEnvironment*> use_it(instruction->GetEnvUses());
+ !use_it.Done();
+ use_it.Advance()) {
+ HEnvironment* use = use_it.Current()->GetUser();
+ HUseListNode<HEnvironment*>* next = use_it.Current()->GetNext();
+ if (next != nullptr && next->GetUser() == use) {
+ return true;
+ }
+ }
+
+ if (kIsDebugBuild) {
+ // Do a quadratic search to ensure same environment uses are next
+ // to each other.
+ for (HUseIterator<HEnvironment*> use_it(instruction->GetEnvUses());
+ !use_it.Done();
+ use_it.Advance()) {
+ HUseListNode<HEnvironment*>* current = use_it.Current();
+ HUseListNode<HEnvironment*>* next = current->GetNext();
+ while (next != nullptr) {
+ DCHECK(next->GetUser() != current->GetUser());
+ next = next->GetNext();
+ }
+ }
+ }
+ return false;
+}
+
void SsaBuilder::RemoveRedundantUninitializedStrings() {
if (GetGraph()->IsDebuggable()) {
// Do not perform the optimization for consistency with the interpreter
@@ -433,7 +461,7 @@
// Replace NewInstance of String with NullConstant if not used prior to
// calling StringFactory. In case of deoptimization, the interpreter is
// expected to skip null check on the `this` argument of the StringFactory call.
- if (!new_instance->HasNonEnvironmentUses()) {
+ if (!new_instance->HasNonEnvironmentUses() && !HasAliasInEnvironments(new_instance)) {
new_instance->ReplaceWith(GetGraph()->GetNullConstant());
new_instance->GetBlock()->RemoveInstruction(new_instance);