arm: Fix VarHandle.compareAndSet/long intrinsic...

... for big-endian array views. Undo the byte swap for all
situations where we swapped bytes in arguments.

Test: testrunner.py --target --32 --optimizing -t 712
Bug: 71781600
Change-Id: Ide4736032f8a4875e14be66727c00dd79beb230c

1 files changed, 6 insertions, 4 deletions

diff --git a/compiler/optimizing/intrinsics_arm_vixl.cc b/compiler/optimizing/intrinsics_arm_vixl.cc
index a3ad409fc7..2b3d48b1a6 100644
--- a/compiler/optimizing/intrinsics_arm_vixl.cc
+++ b/compiler/optimizing/intrinsics_arm_vixl.cc
@@ -4913,14 +4913,16 @@ static void GenerateVarHandleCompareAndSetOrExchange(HInvoke* invoke,
         seq_cst_barrier ? MemBarrierKind::kAnyAny : MemBarrierKind::kLoadAny);
   }
 
+  if (byte_swap && value_type == DataType::Type::kInt64) {
+    // Undo byte swapping in `expected` and `new_value`. We do not have the
+    // information whether the value in these registers shall be needed later.
+    GenerateReverseBytesInPlaceForEachWord(assembler, expected);
+    GenerateReverseBytesInPlaceForEachWord(assembler, new_value);
+  }
   if (!return_success) {
     if (byte_swap) {
       if (value_type == DataType::Type::kInt64) {
         GenerateReverseBytesInPlaceForEachWord(assembler, old_value);
-        // Undo byte swapping in `expected` and `new_value`. We do not have the
-        // information whether the value in these registers shall be needed later.
-        GenerateReverseBytesInPlaceForEachWord(assembler, expected);
-        GenerateReverseBytesInPlaceForEachWord(assembler, new_value);
       } else {
         GenerateReverseBytes(assembler, value_type, old_value, out);
       }