[llvm-bugs] [Bug 20841] LLVM fails to use flags from atomic instructions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=20841

Simon Pilgrim <llvm-dev at redking.me.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|REOPENED                    |RESOLVED

--- Comment #4 from Simon Pilgrim <llvm-dev at redking.me.uk> ---
(In reply to Craig Topper from comment #3)
> Doesn’t xadd update flags based on the value written to memory, while
> atomicrmw returns the original value read from memory? I’m not sure this is
> a valid optimization.

Yes, I can't believe I didn't realize that! Thanks Craig.

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