1 files changed, 5 insertions, 1 deletions
diff --git a/contrib/llvm-project/llvm/lib/Target/ARM/ARMISelLowering.cpp b/contrib/llvm-project/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 397979b4ab1e..598062672a56 100644
--- a/contrib/llvm-project/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/contrib/llvm-project/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -18661,6 +18661,8 @@ ARMTargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const {
              : AtomicExpansionKind::None;
 }
 
+// Similar to shouldExpandAtomicRMWInIR, ldrex/strex can be used  up to 32
+// bits, and up to 64 bits on the non-M profiles.
 TargetLowering::AtomicExpansionKind
 ARMTargetLowering::shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const {
   // At -O0, fast-regalloc cannot cope with the live vregs necessary to
@@ -18668,9 +18670,11 @@ ARMTargetLowering::shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const {
   // on the stack and close enough to the spill slot, this can lead to a
   // situation where the monitor always gets cleared and the atomic operation
   // can never succeed. So at -O0 we need a late-expanded pseudo-inst instead.
+  unsigned Size = AI->getOperand(1)->getType()->getPrimitiveSizeInBits();
   bool HasAtomicCmpXchg =
       !Subtarget->isThumb() || Subtarget->hasV8MBaselineOps();
-  if (getTargetMachine().getOptLevel() != 0 && HasAtomicCmpXchg)
+  if (getTargetMachine().getOptLevel() != 0 && HasAtomicCmpXchg &&
+      Size <= (Subtarget->isMClass() ? 32U : 64U))
     return AtomicExpansionKind::LLSC;
   return AtomicExpansionKind::None;
 }