[PATCH] D31726: AliasAnalysis: Be less conservative about volatile than atomic.

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added inline comments.


================
Comment at: lib/Analysis/AliasAnalysis.cpp:336
+  // Be conservative in the face of atomic.
+  if (isStrongerThan(L->getOrdering(), AtomicOrdering::NotAtomic))
     return MRI_ModRef;
----------------
sanjoy wrote:
> Why not `isStrongerThan(L->getOrdering(), AtomicOrdering::Unordered)`? (same below)
> 
> OTOH I'm surprised that this did not break any tests.
Honestly:
Because i don't know enough to know if that's okay ;)
If it is, happy to do it.

It breaks 1 optimizations test that i'm looking at:

memcpy/atomic.ll optimizes *less* now.
Which makes no sense at all.  I suspect it was relying on weird aliasing before. I'm debugging.

Otherwise, it does break some memoryssa tests, which i'm updating for the correct answers.
(i'm also still awaiting 3 stage results on linux)



https://reviews.llvm.org/D31726