ART: Remove incorrect HFakeString optimization
Simplification of HFakeString assumes that it cannot be used until
String.<init> is called which is not true and causes different
behaviour between the compiler and the interpreter. This patch
removes the optimization together with the HFakeString instruction.
Instead, HNewInstance is generated and an empty String allocated
until it is replaced with the result of the StringFactory call. This
is consistent with the behaviour of the interpreter but is too
conservative. A follow-up CL will attempt to optimize out the initial
allocation when possible.
Bug: 26457745
Bug: 26486014
Change-Id: I7139e37ed00a880715bfc234896a930fde670c44
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index a3150d3..5e905fc 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -1032,13 +1032,6 @@
Primitive::Type type = instruction->GetType();
DCHECK_NE(type, Primitive::kPrimVoid);
- if (instruction->IsFakeString()) {
- // The fake string is an alias for null.
- DCHECK(IsBaseline());
- instruction = locations->Out().GetConstant();
- DCHECK(instruction->IsNullConstant()) << instruction->DebugName();
- }
-
if (instruction->IsCurrentMethod()) {
MoveLocation(location,
Location::DoubleStackSlot(kCurrentMethodStackOffset),
@@ -4061,19 +4054,33 @@
LocationSummary* locations =
new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kCall);
InvokeRuntimeCallingConvention calling_convention;
- locations->SetInAt(0, LocationFrom(calling_convention.GetRegisterAt(0)));
- locations->SetInAt(1, LocationFrom(calling_convention.GetRegisterAt(1)));
+ if (instruction->IsStringAlloc()) {
+ locations->AddTemp(LocationFrom(kArtMethodRegister));
+ } else {
+ locations->SetInAt(0, LocationFrom(calling_convention.GetRegisterAt(0)));
+ locations->SetInAt(1, LocationFrom(calling_convention.GetRegisterAt(1)));
+ }
locations->SetOut(calling_convention.GetReturnLocation(Primitive::kPrimNot));
}
void InstructionCodeGeneratorARM64::VisitNewInstance(HNewInstance* instruction) {
// Note: if heap poisoning is enabled, the entry point takes cares
// of poisoning the reference.
- codegen_->InvokeRuntime(instruction->GetEntrypoint(),
- instruction,
- instruction->GetDexPc(),
- nullptr);
- CheckEntrypointTypes<kQuickAllocObjectWithAccessCheck, void*, uint32_t, ArtMethod*>();
+ if (instruction->IsStringAlloc()) {
+ // String is allocated through StringFactory. Call NewEmptyString entry point.
+ Location temp = instruction->GetLocations()->GetTemp(0);
+ MemberOffset code_offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(kArm64WordSize);
+ __ Ldr(XRegisterFrom(temp), MemOperand(tr, QUICK_ENTRY_POINT(pNewEmptyString)));
+ __ Ldr(lr, MemOperand(XRegisterFrom(temp), code_offset.Int32Value()));
+ __ Blr(lr);
+ codegen_->RecordPcInfo(instruction, instruction->GetDexPc());
+ } else {
+ codegen_->InvokeRuntime(instruction->GetEntrypoint(),
+ instruction,
+ instruction->GetDexPc(),
+ nullptr);
+ CheckEntrypointTypes<kQuickAllocObjectWithAccessCheck, void*, uint32_t, ArtMethod*>();
+ }
}
void LocationsBuilderARM64::VisitNot(HNot* instruction) {
@@ -4559,18 +4566,6 @@
LOG(FATAL) << "Unreachable";
}
-void LocationsBuilderARM64::VisitFakeString(HFakeString* instruction) {
- DCHECK(codegen_->IsBaseline());
- LocationSummary* locations =
- new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
- locations->SetOut(Location::ConstantLocation(GetGraph()->GetNullConstant()));
-}
-
-void InstructionCodeGeneratorARM64::VisitFakeString(HFakeString* instruction ATTRIBUTE_UNUSED) {
- DCHECK(codegen_->IsBaseline());
- // Will be generated at use site.
-}
-
// Simple implementation of packed switch - generate cascaded compare/jumps.
void LocationsBuilderARM64::VisitPackedSwitch(HPackedSwitch* switch_instr) {
LocationSummary* locations =