ARM64: Introspection Baker RB for volatile fields.

Test: Already covered by 160-read-barrier-stress.
Test: m test-art-host-gtest
Test: Pixel 2 XL boots.
Test: m test-art-target-gtest
Test: testrunner.py --target --optimizing --jit --64
Bug: 36141117
Change-Id: I2f9a707587d1ee27c0efb19d77becba7ec7ffec4

1 files changed, 13 insertions, 3 deletions

diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index 5aeb0b4034..6a358a4306 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -797,9 +797,10 @@ class CodeGeneratorARM64 : public CodeGenerator {
   // Encoding of thunk type and data for link-time generated thunks for Baker read barriers.
 
   enum class BakerReadBarrierKind : uint8_t {
-    kField,   // Field get or array get with constant offset (i.e. constant index).
-    kArray,   // Array get with index in register.
-    kGcRoot,  // GC root load.
+    kField,     // Field get or array get with constant offset (i.e. constant index).
+    kAcquire,   // Volatile field get.
+    kArray,     // Array get with index in register.
+    kGcRoot,    // GC root load.
     kLast = kGcRoot
   };
 
@@ -832,6 +833,15 @@ class CodeGeneratorARM64 : public CodeGenerator {
            BakerReadBarrierSecondRegField::Encode(holder_reg);
   }
 
+  static inline uint32_t EncodeBakerReadBarrierAcquireData(uint32_t base_reg, uint32_t holder_reg) {
+    CheckValidReg(base_reg);
+    CheckValidReg(holder_reg);
+    DCHECK_NE(base_reg, holder_reg);
+    return BakerReadBarrierKindField::Encode(BakerReadBarrierKind::kAcquire) |
+           BakerReadBarrierFirstRegField::Encode(base_reg) |
+           BakerReadBarrierSecondRegField::Encode(holder_reg);
+  }
+
   static inline uint32_t EncodeBakerReadBarrierArrayData(uint32_t base_reg) {
     CheckValidReg(base_reg);
     return BakerReadBarrierKindField::Encode(BakerReadBarrierKind::kArray) |