[PATCH] D98995: [CGAtomic] Lift stronger requirements on cmpxch and add support for acquire failure mode

[Julian Lettner via Phabricator via llvm-commits]

yln added inline comments.


================
Comment at: clang/lib/CodeGen/CGAtomic.cpp:444-447
+    // Prior to c++17, "the failure argument shall be no stronger than the
+    // success argument". This condition has been lifted and the only
+    // precondition is 31.7.2.18. Effectively treat this as a DR and skip
+    // language version checks.
----------------
Should the following assert in `AtomicCmpXchgInst::Init()` have been changed as well?
```
assert(!isStrongerThan(FailureOrdering, SuccessOrdering) &&
       "AtomicCmpXchg failure argument shall be no stronger than the success "
       "argument");
```
https://github.com/llvm/llvm-project/blob/dad5caa59e6b2bde8d6cf5b64a972c393c526c82/llvm/lib/IR/Instructions.cpp#L1561

I am observing a crash on an internal code base most likely caused by this.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98995/new/

https://reviews.llvm.org/D98995