efriedma added inline comments.
================
Comment at: lib/CodeGen/CGBuiltin.cpp:3003
+ case Builtin::BI_InterlockedCompareExchangePointer:
+ case Builtin::BI_InterlockedCompareExchangePointer_nf: {
llvm::Type *RTy;
----------------
mgrang wrote:
> rnk wrote:
> > Is the no fence version really equivalent to this seq_cst version here?
> I don't see InterlockedCompareExchangePointer creating a fence but it should.
> (since it is the fence version). So maybe that needs to be fixed (and
> possibly other fence functions).
>
> InterlockedCompareExchangePointer_nf should not create a fence so the current
> implementation seems correct.
"create a fence" is a little confusing because the AArch64 ldaxr/stlxr have
builtin fences... but presumably the "nf" version should use ldxr/stxr instead.
At the IR level, that corresponds to "monotonic".
Repository:
rC Clang
https://reviews.llvm.org/D52807
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