[llvm] r346798 - [MemorySSA] Create query after checking if instruction is a fence.

[Alina Sbirlea via llvm-commits]

Author: asbirlea
Date: Tue Nov 13 13:12:49 2018
New Revision: 346798

URL: http://llvm.org/viewvc/llvm-project?rev=346798&view=rev
Log:
[MemorySSA] Create query after checking if instruction is a fence.

The alternative is checking if I is a fence in the Query constructor, so
as to not attempt to get a non-existent MemoryLocation.

Modified:
    llvm/trunk/lib/Analysis/MemorySSA.cpp

Modified: llvm/trunk/lib/Analysis/MemorySSA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemorySSA.cpp?rev=346798&r1=346797&r2=346798&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemorySSA.cpp (original)
+++ llvm/trunk/lib/Analysis/MemorySSA.cpp Tue Nov 13 13:12:49 2018
@@ -2199,13 +2199,14 @@ MemorySSA::CachingWalker::getClobberingM
     return StartingAccess->getOptimized();
 
   const Instruction *I = StartingAccess->getMemoryInst();
-  UpwardsMemoryQuery Q(I, StartingAccess);
   // We can't sanely do anything with a fence, since they conservatively clobber
   // all memory, and have no locations to get pointers from to try to
   // disambiguate.
-  if (!Q.IsCall && I->isFenceLike())
+  if (!ImmutableCallSite(I) && I->isFenceLike())
     return StartingAccess;
 
+  UpwardsMemoryQuery Q(I, StartingAccess);
+
   if (isUseTriviallyOptimizableToLiveOnEntry(*MSSA->AA, I)) {
     MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
     StartingAccess->setOptimized(LiveOnEntry);