Don't generate a slow path for strings in the dex cache.

Change-Id: I1d258f1a89bf0ec7c7ddd134be9215d480f0b09a

9 files changed, 90 insertions, 52 deletions

diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index a05105b84e..a1a92aa7a4 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -1134,15 +1134,21 @@ bool CompilerDriver::CanAssumeStringIsPresentInDexCache(const DexFile& dex_file,
   // See also Compiler::ResolveDexFile
 
   bool result = false;
-  if (IsBootImage()) {
-    // We resolve all const-string strings when building for the image.
+  if (IsBootImage() || Runtime::Current()->UseJit()) {
     ScopedObjectAccess soa(Thread::Current());
     StackHandleScope<1> hs(soa.Self());
     ClassLinker* const class_linker = Runtime::Current()->GetClassLinker();
     Handle<mirror::DexCache> dex_cache(hs.NewHandle(class_linker->FindDexCache(
         soa.Self(), dex_file, false)));
-    class_linker->ResolveString(dex_file, string_idx, dex_cache);
-    result = true;
+    if (IsBootImage()) {
+      // We resolve all const-string strings when building for the image.
+      class_linker->ResolveString(dex_file, string_idx, dex_cache);
+      result = true;
+    } else {
+      // Just check whether the dex cache already has the string.
+      DCHECK(Runtime::Current()->UseJit());
+      result = (dex_cache->GetResolvedString(string_idx) != nullptr);
+    }
   }
   if (result) {
     stats_->StringInDexCache();
diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index e1404ce59c..1178d0fb25 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -2841,15 +2841,21 @@ bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, uint32
     }
 
     case Instruction::CONST_STRING: {
+      uint32_t string_index = instruction.VRegB_21c();
+      bool in_dex_cache = compiler_driver_->CanAssumeStringIsPresentInDexCache(
+          *dex_file_, string_index);
       current_block_->AddInstruction(
-          new (arena_) HLoadString(graph_->GetCurrentMethod(), instruction.VRegB_21c(), dex_pc));
+          new (arena_) HLoadString(graph_->GetCurrentMethod(), string_index, dex_pc, in_dex_cache));
       UpdateLocal(instruction.VRegA_21c(), current_block_->GetLastInstruction(), dex_pc);
       break;
     }
 
     case Instruction::CONST_STRING_JUMBO: {
+      uint32_t string_index = instruction.VRegB_31c();
+      bool in_dex_cache = compiler_driver_->CanAssumeStringIsPresentInDexCache(
+          *dex_file_, string_index);
       current_block_->AddInstruction(
-          new (arena_) HLoadString(graph_->GetCurrentMethod(), instruction.VRegB_31c(), dex_pc));
+          new (arena_) HLoadString(graph_->GetCurrentMethod(), string_index, dex_pc, in_dex_cache));
       UpdateLocal(instruction.VRegA_31c(), current_block_->GetLastInstruction(), dex_pc);
       break;
     }
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 0a26786a87..a999c4c369 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -5067,16 +5067,15 @@ void InstructionCodeGeneratorARM::GenerateClassInitializationCheck(
 }
 
 void LocationsBuilderARM::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorARM::VisitLoadString(HLoadString* load) {
-  SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathARM(load);
-  codegen_->AddSlowPath(slow_path);
-
   LocationSummary* locations = load->GetLocations();
   Location out_loc = locations->Out();
   Register out = out_loc.AsRegister<Register>();
@@ -5107,8 +5106,12 @@ void InstructionCodeGeneratorARM::VisitLoadString(HLoadString* load) {
     __ LoadFromOffset(kLoadWord, out, out, cache_offset);
   }
 
-  __ CompareAndBranchIfZero(out, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+  if (!load->IsInDexCache()) {
+    SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathARM(load);
+    codegen_->AddSlowPath(slow_path);
+    __ CompareAndBranchIfZero(out, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 static int32_t GetExceptionTlsOffset() {
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 227f4be642..f6834d4772 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -3850,16 +3850,15 @@ void InstructionCodeGeneratorARM64::VisitLoadLocal(HLoadLocal* load ATTRIBUTE_UN
 }
 
 void LocationsBuilderARM64::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorARM64::VisitLoadString(HLoadString* load) {
-  SlowPathCodeARM64* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathARM64(load);
-  codegen_->AddSlowPath(slow_path);
-
   Location out_loc = load->GetLocations()->Out();
   Register out = OutputRegister(load);
   Register current_method = InputRegisterAt(load, 0);
@@ -3889,8 +3888,12 @@ void InstructionCodeGeneratorARM64::VisitLoadString(HLoadString* load) {
     __ Ldr(out, MemOperand(out.X(), cache_offset));
   }
 
-  __ Cbz(out, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+  if (!load->IsInDexCache()) {
+    SlowPathCodeARM64* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathARM64(load);
+    codegen_->AddSlowPath(slow_path);
+    __ Cbz(out, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 void LocationsBuilderARM64::VisitLocal(HLocal* local) {
diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index d092de9421..b000c77c79 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -3413,24 +3413,28 @@ void InstructionCodeGeneratorMIPS::VisitLoadLocal(HLoadLocal* load ATTRIBUTE_UNU
 }
 
 void LocationsBuilderMIPS::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorMIPS::VisitLoadString(HLoadString* load) {
-  SlowPathCodeMIPS* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathMIPS(load);
-  codegen_->AddSlowPath(slow_path);
-
   LocationSummary* locations = load->GetLocations();
   Register out = locations->Out().AsRegister<Register>();
   Register current_method = locations->InAt(0).AsRegister<Register>();
   __ LoadFromOffset(kLoadWord, out, current_method, ArtMethod::DeclaringClassOffset().Int32Value());
   __ LoadFromOffset(kLoadWord, out, out, mirror::Class::DexCacheStringsOffset().Int32Value());
   __ LoadFromOffset(kLoadWord, out, out, CodeGenerator::GetCacheOffset(load->GetStringIndex()));
-  __ Beqz(out, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+
+  if (!load->IsInDexCache()) {
+    SlowPathCodeMIPS* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathMIPS(load);
+    codegen_->AddSlowPath(slow_path);
+    __ Beqz(out, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 void LocationsBuilderMIPS::VisitLocal(HLocal* local) {
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index 78f5644cfb..9f8558df9a 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -3105,16 +3105,15 @@ void InstructionCodeGeneratorMIPS64::VisitLoadLocal(HLoadLocal* load ATTRIBUTE_U
 }
 
 void LocationsBuilderMIPS64::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorMIPS64::VisitLoadString(HLoadString* load) {
-  SlowPathCodeMIPS64* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathMIPS64(load);
-  codegen_->AddSlowPath(slow_path);
-
   LocationSummary* locations = load->GetLocations();
   GpuRegister out = locations->Out().AsRegister<GpuRegister>();
   GpuRegister current_method = locations->InAt(0).AsRegister<GpuRegister>();
@@ -3123,8 +3122,13 @@ void InstructionCodeGeneratorMIPS64::VisitLoadString(HLoadString* load) {
   __ LoadFromOffset(kLoadDoubleword, out, out, mirror::Class::DexCacheStringsOffset().Int32Value());
   __ LoadFromOffset(kLoadUnsignedWord, out, out, CodeGenerator::GetCacheOffset(load->GetStringIndex()));
   // TODO: We will need a read barrier here.
-  __ Beqzc(out, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+
+  if (!load->IsInDexCache()) {
+    SlowPathCodeMIPS64* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathMIPS64(load);
+    codegen_->AddSlowPath(slow_path);
+    __ Beqzc(out, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 void LocationsBuilderMIPS64::VisitLocal(HLocal* local) {
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 19f03df2a0..8c50650c2b 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -5611,16 +5611,15 @@ void InstructionCodeGeneratorX86::GenerateClassInitializationCheck(
 }
 
 void LocationsBuilderX86::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorX86::VisitLoadString(HLoadString* load) {
-  SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathX86(load);
-  codegen_->AddSlowPath(slow_path);
-
   LocationSummary* locations = load->GetLocations();
   Location out_loc = locations->Out();
   Register out = out_loc.AsRegister<Register>();
@@ -5651,9 +5650,13 @@ void InstructionCodeGeneratorX86::VisitLoadString(HLoadString* load) {
     __ movl(out, Address(out, cache_offset));
   }
 
-  __ testl(out, out);
-  __ j(kEqual, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+  if (!load->IsInDexCache()) {
+    SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathX86(load);
+    codegen_->AddSlowPath(slow_path);
+    __ testl(out, out);
+    __ j(kEqual, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 static Address GetExceptionTlsAddress() {
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 44a51ea6e2..9cb6a2c6f8 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -5220,16 +5220,15 @@ void InstructionCodeGeneratorX86_64::VisitClinitCheck(HClinitCheck* check) {
 }
 
 void LocationsBuilderX86_64::VisitLoadString(HLoadString* load) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kCallOnSlowPath);
+  LocationSummary::CallKind call_kind = (!load->IsInDexCache() || kEmitCompilerReadBarrier)
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(load, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetOut(Location::RequiresRegister());
 }
 
 void InstructionCodeGeneratorX86_64::VisitLoadString(HLoadString* load) {
-  SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathX86_64(load);
-  codegen_->AddSlowPath(slow_path);
-
   LocationSummary* locations = load->GetLocations();
   Location out_loc = locations->Out();
   CpuRegister out = out_loc.AsRegister<CpuRegister>();
@@ -5260,9 +5259,13 @@ void InstructionCodeGeneratorX86_64::VisitLoadString(HLoadString* load) {
     __ movl(out, Address(out, cache_offset));
   }
 
-  __ testl(out, out);
-  __ j(kEqual, slow_path->GetEntryLabel());
-  __ Bind(slow_path->GetExitLabel());
+  if (!load->IsInDexCache()) {
+    SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathX86_64(load);
+    codegen_->AddSlowPath(slow_path);
+    __ testl(out, out);
+    __ j(kEqual, slow_path->GetEntryLabel());
+    __ Bind(slow_path->GetExitLabel());
+  }
 }
 
 static Address GetExceptionTlsAddress() {
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 3e38e9f2a4..accd89e8d1 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -4925,9 +4925,13 @@ class HLoadClass : public HExpression<1> {
 
 class HLoadString : public HExpression<1> {
  public:
-  HLoadString(HCurrentMethod* current_method, uint32_t string_index, uint32_t dex_pc)
+  HLoadString(HCurrentMethod* current_method,
+              uint32_t string_index,
+              uint32_t dex_pc,
+              bool is_in_dex_cache)
       : HExpression(Primitive::kPrimNot, SideEffectsForArchRuntimeCalls(), dex_pc),
-        string_index_(string_index) {
+        string_index_(string_index),
+        is_in_dex_cache_(is_in_dex_cache) {
     SetRawInputAt(0, current_method);
   }
 
@@ -4945,6 +4949,7 @@ class HLoadString : public HExpression<1> {
   bool NeedsEnvironment() const OVERRIDE { return false; }
   bool NeedsDexCacheOfDeclaringClass() const OVERRIDE { return true; }
   bool CanBeNull() const OVERRIDE { return false; }
+  bool IsInDexCache() const { return is_in_dex_cache_; }
 
   static SideEffects SideEffectsForArchRuntimeCalls() {
     return SideEffects::CanTriggerGC();
@@ -4954,6 +4959,7 @@ class HLoadString : public HExpression<1> {
 
  private:
   const uint32_t string_index_;
+  const bool is_in_dex_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(HLoadString);
 };