riscv64: Disable VarHandle.compareAndSet intrinsics.

Strong CAS is known to be broken.

Test: buildbot-build.sh --target
Bug: 283082089
Change-Id: I5517b1bc7d0e74639b6247e0c371ac13896de2c3

1 files changed, 7 insertions, 0 deletions

diff --git a/compiler/optimizing/intrinsics_riscv64.cc b/compiler/optimizing/intrinsics_riscv64.cc
index c5aed1b1da..3af187dbf8 100644
--- a/compiler/optimizing/intrinsics_riscv64.cc
+++ b/compiler/optimizing/intrinsics_riscv64.cc
@@ -2215,6 +2215,13 @@ static void CreateVarHandleCompareAndSetOrExchangeLocations(HInvoke* invoke,
     return;
   }
 
+  if ((true)) {
+    // FIXME(riscv64): Fix the register allocation for strong CAS (SC failure sets the result
+    // to success, so comparison failure on retry returns "true" for a failed CAS).
+    // Review register allocation for weak CAS to make sure it's OK.
+    return;
+  }
+
   LocationSummary* locations = CreateVarHandleCommonLocations(invoke, codegen);
   DCHECK_EQ(expected_index, 1u + GetExpectedVarHandleCoordinatesCount(invoke));