[clang] [llvm] [AArch64] Implement the atomic store with hint intrinsic (PR #198316)

[via cfe-commits]

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@@ -18521,7 +18522,25 @@ AArch64TargetLowering::getTargetMMOFlags(const Instruction &I) const {
   if (Subtarget->getProcFamily() == AArch64Subtarget::Falkor &&
       I.hasMetadata(FALKOR_STRIDED_ACCESS_MD))
     return MOStridedAccess;
-  return MachineMemOperand::MONone;
+
+  auto Flags = MachineMemOperand::MONone;
+  const MDNode *AtomicStHint = I.getMetadata(AARCH64_ATOMIC_STORE_HINT_MD);
+  if (AtomicStHint) {
+    unsigned HintVal =
+        cast<ConstantInt>(
+            cast<ConstantAsMetadata>(AtomicStHint->getOperand(0))->getValue())
+            ->getZExtValue();
+    AArch64AtomicStoreHint Hint = getAtomicStoreHintFromMD(HintVal);
+    assert(Hint != AArch64AtomicStoreHint::HINT_NONE &&
+           "Unrecognised atomic hint value requested.");
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Lukacma wrote:

Ah I see the difference now ! Though I am not sure these assertion should exist. As mentioned we should just ignore invalid hint and treat it is as no hint store. 

https://github.com/llvm/llvm-project/pull/198316