Don't use StringFactory.newEmptyString in compiled code

When compiling debuggable code we would compile a new-instance String
instruction into a StringFactory.newEmptyString invoke. This
additional invoke could be observed using tracing and is inconsistent
with the interpreter, where the string is simply allocated directly.
In order to bring these two modes into alignment we added a new
AllocStringObject quick entrypoint that will be used instead of the
normal AllocObject<...> entrypoints when allocating a string. This
entrypoint directly allocates a new string in the same manner the
interpreter does.

Needs next CL for test to work.

Bug: 110884646
Test: ./test/testrunner/testrunner.py --host --runtime-option=-Xjitthreshold:0 --jit
Test: Manual inspection of compiled code.
Change-Id: I7b4b084bcf7dd9a23485c0e3cd2cd04a04b43d3d

1 files changed, 3 insertions, 20 deletions

diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index f0ef30ee37..c7295e4db1 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -8701,30 +8701,13 @@ void LocationsBuilderMIPS::VisitNewInstance(HNewInstance* instruction) {
   LocationSummary* locations = new (GetGraph()->GetAllocator()) LocationSummary(
       instruction, LocationSummary::kCallOnMainOnly);
   InvokeRuntimeCallingConvention calling_convention;
-  if (instruction->IsStringAlloc()) {
-    locations->AddTemp(Location::RegisterLocation(kMethodRegisterArgument));
-  } else {
-    locations->SetInAt(0, Location::RegisterLocation(calling_convention.GetRegisterAt(0)));
-  }
+  locations->SetInAt(0, Location::RegisterLocation(calling_convention.GetRegisterAt(0)));
   locations->SetOut(calling_convention.GetReturnLocation(DataType::Type::kReference));
 }
 
 void InstructionCodeGeneratorMIPS::VisitNewInstance(HNewInstance* instruction) {
-  // Note: if heap poisoning is enabled, the entry point takes care
-  // of poisoning the reference.
-  if (instruction->IsStringAlloc()) {
-    // String is allocated through StringFactory. Call NewEmptyString entry point.
-    Register temp = instruction->GetLocations()->GetTemp(0).AsRegister<Register>();
-    MemberOffset code_offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(kMipsPointerSize);
-    __ LoadFromOffset(kLoadWord, temp, TR, QUICK_ENTRY_POINT(pNewEmptyString));
-    __ LoadFromOffset(kLoadWord, T9, temp, code_offset.Int32Value());
-    __ Jalr(T9);
-    __ NopIfNoReordering();
-    codegen_->RecordPcInfo(instruction, instruction->GetDexPc());
-  } else {
-    codegen_->InvokeRuntime(instruction->GetEntrypoint(), instruction, instruction->GetDexPc());
-    CheckEntrypointTypes<kQuickAllocObjectWithChecks, void*, mirror::Class*>();
-  }
+  codegen_->InvokeRuntime(instruction->GetEntrypoint(), instruction, instruction->GetDexPc());
+  CheckEntrypointTypes<kQuickAllocObjectWithChecks, void*, mirror::Class*>();
 }
 
 void LocationsBuilderMIPS::VisitNot(HNot* instruction) {