JNI: Fast-path for decoding returned jobject.

Results for the timeGetBytesAscii#EMPTY benchmark from the
libcore's StringToBytesBenchmark suite on blueline-userdebug
with the cpu frequencies fixed at 1420800 (cpus 0-3; little)
and 1459200 (cpus 4-7; big):
  32-bit little: ~415 -> ~390
  64-bit little: ~415 -> ~390
  32-bit big:    ~180 -> ~170
  64-bit big:    ~180 -> ~170

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --debug --ndebug
Test: run-gtests.sh
Test: testrunner.py --target --optimizing --debug --ndebug
Bug: 172332525
Change-Id: I0e19d583e5141e99a8b8c6fd9ae125fe7c9e02e7

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler/utils/jni_macro_assembler.h b/compiler/utils/jni_macro_assembler.h
index 15a4c3fe67..0c729705dc 100644
--- a/compiler/utils/jni_macro_assembler.h
+++ b/compiler/utils/jni_macro_assembler.h
@@ -158,6 +158,11 @@ class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
   virtual void GetCurrentThread(ManagedRegister dest) = 0;
   virtual void GetCurrentThread(FrameOffset dest_offset) = 0;
 
+  // Decode JNI transition or local `jobject`. For (weak) global `jobject`, jump to slow path.
+  virtual void DecodeJNITransitionOrLocalJObject(ManagedRegister reg,
+                                                 JNIMacroLabel* slow_path,
+                                                 JNIMacroLabel* resume) = 0;
+
   // Heap::VerifyObject on src. In some cases (such as a reference to this) we
   // know that src may not be null.
   virtual void VerifyObject(ManagedRegister src, bool could_be_null) = 0;