ART: Generate path to entrypoints in VisitLoadString for x86

Code size unmeasured, presumably ~-1%.

Generate code to go into string dex cache entrypoints in VisitLoadString
instead of with slow paths, since we now go into entrypoints almost
every time.

Change-Id: Ic4335a23934547737dbda12111f672da1e6c0ef7
Tests: test-art-host CC baker

1 files changed, 10 insertions, 39 deletions

diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index b3b648f137..5953badb07 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -213,35 +213,6 @@ class SuspendCheckSlowPathX86 : public SlowPathCode {
   DISALLOW_COPY_AND_ASSIGN(SuspendCheckSlowPathX86);
 };
 
-class LoadStringSlowPathX86 : public SlowPathCode {
- public:
-  explicit LoadStringSlowPathX86(HLoadString* instruction): SlowPathCode(instruction) {}
-
-  void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
-    LocationSummary* locations = instruction_->GetLocations();
-    DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(locations->Out().reg()));
-
-    CodeGeneratorX86* x86_codegen = down_cast<CodeGeneratorX86*>(codegen);
-    __ Bind(GetEntryLabel());
-    SaveLiveRegisters(codegen, locations);
-
-    InvokeRuntimeCallingConvention calling_convention;
-    const uint32_t string_index = instruction_->AsLoadString()->GetStringIndex();
-    __ movl(calling_convention.GetRegisterAt(0), Immediate(string_index));
-    x86_codegen->InvokeRuntime(kQuickResolveString, instruction_, instruction_->GetDexPc(), this);
-    CheckEntrypointTypes<kQuickResolveString, void*, uint32_t>();
-    x86_codegen->Move32(locations->Out(), Location::RegisterLocation(EAX));
-    RestoreLiveRegisters(codegen, locations);
-
-    __ jmp(GetExitLabel());
-  }
-
-  const char* GetDescription() const OVERRIDE { return "LoadStringSlowPathX86"; }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(LoadStringSlowPathX86);
-};
-
 class LoadClassSlowPathX86 : public SlowPathCode {
  public:
   LoadClassSlowPathX86(HLoadClass* cls,
@@ -6135,20 +6106,20 @@ HLoadString::LoadKind CodeGeneratorX86::GetSupportedLoadStringKind(
 
 void LocationsBuilderX86::VisitLoadString(HLoadString* load) {
   LocationSummary::CallKind call_kind = (load->NeedsEnvironment() || kEmitCompilerReadBarrier)
-      ? LocationSummary::kCallOnSlowPath
+      ? LocationSummary::kCallOnMainOnly
       : LocationSummary::kNoCall;
   LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
-  if (kUseBakerReadBarrier && !load->NeedsEnvironment()) {
-    locations->SetCustomSlowPathCallerSaves(RegisterSet());  // No caller-save registers.
-  }
-
   HLoadString::LoadKind load_kind = load->GetLoadKind();
   if (load_kind == HLoadString::LoadKind::kDexCacheViaMethod ||
       load_kind == HLoadString::LoadKind::kBootImageLinkTimePcRelative ||
       load_kind == HLoadString::LoadKind::kDexCachePcRelative) {
     locations->SetInAt(0, Location::RequiresRegister());
   }
-  locations->SetOut(Location::RequiresRegister());
+  if (load_kind == HLoadString::LoadKind::kDexCacheViaMethod) {
+    locations->SetOut(Location::RegisterLocation(EAX));
+  } else {
+    locations->SetOut(Location::RequiresRegister());
+  }
 }
 
 void InstructionCodeGeneratorX86::VisitLoadString(HLoadString* load) {
@@ -6183,10 +6154,10 @@ void InstructionCodeGeneratorX86::VisitLoadString(HLoadString* load) {
   }
 
   // TODO: Re-add the compiler code to do string dex cache lookup again.
-  SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathX86(load);
-  codegen_->AddSlowPath(slow_path);
-  __ jmp(slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+  InvokeRuntimeCallingConvention calling_convention;
+  __ movl(calling_convention.GetRegisterAt(0), Immediate(load->GetStringIndex()));
+  codegen_->InvokeRuntime(kQuickResolveString, load, load->GetDexPc());
+  CheckEntrypointTypes<kQuickResolveString, void*, uint32_t>();
 }
 
 static Address GetExceptionTlsAddress() {