Add support for Baker read barriers in UnsafeCASObject intrinsics.
Prior to doing the compare-and-swap operation, ensure the
expected reference stored in the holding object's field is
in the to-space by loading it, emitting a read barrier and
updating that field with a strong compare-and-set operation
with relaxed memory synchronization ordering (if needed).
Test: ART host and target tests and Nexus 5X boot test with Baker read barriers.
Bug: 29516905
Bug: 12687968
Change-Id: I480f6a9b59547f11d0a04777406b9bfeb905bfd2
diff --git a/compiler/optimizing/code_generator_x86_64.h b/compiler/optimizing/code_generator_x86_64.h
index 57ef83f..70e22f9 100644
--- a/compiler/optimizing/code_generator_x86_64.h
+++ b/compiler/optimizing/code_generator_x86_64.h
@@ -434,13 +434,25 @@
uint32_t data_offset,
Location index,
bool needs_null_check);
- // Factored implementation used by GenerateFieldLoadWithBakerReadBarrier
- // and GenerateArrayLoadWithBakerReadBarrier.
+ // Factored implementation, used by GenerateFieldLoadWithBakerReadBarrier,
+ // GenerateArrayLoadWithBakerReadBarrier and some intrinsics.
+ //
+ // Load the object reference located at address `src`, held by
+ // object `obj`, into `ref`, and mark it if needed. The base of
+ // address `src` must be `obj`.
+ //
+ // If `always_update_field` is true, the value of the reference is
+ // atomically updated in the holder (`obj`). This operation
+ // requires two temporary registers, which must be provided as
+ // non-null pointers (`temp1` and `temp2`).
void GenerateReferenceLoadWithBakerReadBarrier(HInstruction* instruction,
Location ref,
CpuRegister obj,
const Address& src,
- bool needs_null_check);
+ bool needs_null_check,
+ bool always_update_field = false,
+ CpuRegister* temp1 = nullptr,
+ CpuRegister* temp2 = nullptr);
// Generate a read barrier for a heap reference within `instruction`
// using a slow path.