jni: Add read barrier fast path to jni compiler

Static method dispatch via JNI requires a read barrier
for the ArtMethod::GetDeclaringClass() load before adding it to the
JNI StackHandleScope.

We used to call ReadBarrierJni unconditionally but add a branch
to skip calling it if the GC is not currently in the marking phase.

Test: ART_USE_READ_BARRIER=true make test-art-host test-art-target
Bug: 30437917
Change-Id: I4f505ebde17c0a67209c7bb51b3f39e37a06373a

1 files changed, 61 insertions, 0 deletions

diff --git a/compiler/utils/jni_macro_assembler.h b/compiler/utils/jni_macro_assembler.h
index 0119ae9bfb..59a1a48e20 100644
--- a/compiler/utils/jni_macro_assembler.h
+++ b/compiler/utils/jni_macro_assembler.h
@@ -35,6 +35,12 @@ class ArenaAllocator;
 class DebugFrameOpCodeWriterForAssembler;
 class InstructionSetFeatures;
 class MemoryRegion;
+class JNIMacroLabel;
+
+enum class JNIMacroUnaryCondition {
+  kZero,
+  kNotZero
+};
 
 template <PointerSize kPointerSize>
 class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
@@ -193,6 +199,15 @@ class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
   // and branch to a ExceptionSlowPath if it is.
   virtual void ExceptionPoll(ManagedRegister scratch, size_t stack_adjust) = 0;
 
+  // Create a new label that can be used with Jump/Bind calls.
+  virtual std::unique_ptr<JNIMacroLabel> CreateLabel() = 0;
+  // Emit an unconditional jump to the label.
+  virtual void Jump(JNIMacroLabel* label) = 0;
+  // Emit a conditional jump to the label by applying a unary condition test to the register.
+  virtual void Jump(JNIMacroLabel* label, JNIMacroUnaryCondition cond, ManagedRegister test) = 0;
+  // Code at this offset will serve as the target for the Jump call.
+  virtual void Bind(JNIMacroLabel* label) = 0;
+
   virtual ~JNIMacroAssembler() {}
 
   /**
@@ -205,6 +220,28 @@ class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
   explicit JNIMacroAssembler() {}
 };
 
+// A "Label" class used with the JNIMacroAssembler
+// allowing one to use branches (jumping from one place to another).
+//
+// This is just an interface, so every platform must provide
+// its own implementation of it.
+//
+// It is only safe to use a label created
+// via JNIMacroAssembler::CreateLabel with that same macro assembler.
+class JNIMacroLabel {
+ public:
+  virtual ~JNIMacroLabel() = 0;
+
+  const InstructionSet isa_;
+ protected:
+  explicit JNIMacroLabel(InstructionSet isa) : isa_(isa) {}
+};
+
+inline JNIMacroLabel::~JNIMacroLabel() {
+  // Compulsory definition for a pure virtual destructor
+  // to avoid linking errors.
+}
+
 template <typename T, PointerSize kPointerSize>
 class JNIMacroAssemblerFwd : public JNIMacroAssembler<kPointerSize> {
  public:
@@ -230,6 +267,30 @@ class JNIMacroAssemblerFwd : public JNIMacroAssembler<kPointerSize> {
   T asm_;
 };
 
+template <typename Self, typename PlatformLabel, InstructionSet kIsa>
+class JNIMacroLabelCommon : public JNIMacroLabel {
+ public:
+  static Self* Cast(JNIMacroLabel* label) {
+    CHECK(label != nullptr);
+    CHECK_EQ(kIsa, label->isa_);
+
+    return reinterpret_cast<Self*>(label);
+  }
+
+ protected:
+  PlatformLabel* AsPlatformLabel() {
+    return &label_;
+  }
+
+  JNIMacroLabelCommon() : JNIMacroLabel(kIsa) {
+  }
+
+  virtual ~JNIMacroLabelCommon() OVERRIDE {}
+
+ private:
+  PlatformLabel label_;
+};
+
 }  // namespace art
 
 #endif  // ART_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_