[PATCH] D120026: [ARM] Fix ARM backend to correctly use atomic expansion routines.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/test/CodeGen/ARM/atomic-op.ll:413
+; CHECK-T1-M0: __atomic_load_4
 ; CHECK-T1-M0: dmb
+; CHECK-T1-M0: __atomic_store_4
----------------
nikic wrote:
> Is the dmb still needed if we're going through `__atomic`?
__atomic_load_4 is just supposed to be a sequentially consistent load, and a sequentially consistent load doesn't imply a full fence, even if the load is sequentially consistent.  So there isn't any obvious rule that would allow that transform.

See also https://github.com/llvm/llvm-project/issues/29472, https://github.com/llvm/llvm-project/issues/56450 .


Repository:
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https://reviews.llvm.org/D120026