[llvm] r232889 - MemoryDependenceAnalysis: Don't miscompile atomics

[Tobias Grosser]

On 03/21/2015 07:19 AM, David Majnemer wrote:
> Author: majnemer
> Date: Sat Mar 21 01:19:17 2015
> New Revision: 232889
>
> URL: http://llvm.org/viewvc/llvm-project?rev=232889&view=rev
> Log:
> MemoryDependenceAnalysis: Don't miscompile atomics
>
> r216771 introduced a change to MemoryDependenceAnalysis that allowed it
> to reason about acquire/release operations.  However, this change does
> not ensure that the acquire/release operations pair.  Unfortunately,
> this leads to miscompiles as we won't see an acquire load as properly
> memory effecting.  This largely reverts r216771.
>
> This fixes PR22708.

CCing Robin who might be interested in this issue.

Cheers,
Tobias