[llvm] r354800 - [Lanai] Be super conservative about atomics

[Philip Reames via llvm-commits]

Author: reames
Date: Mon Feb 25 09:36:10 2019
New Revision: 354800

URL: http://llvm.org/viewvc/llvm-project?rev=354800&view=rev
Log:
[Lanai] Be super conservative about atomics

As requested during review of D57601 <https://reviews.llvm.org/D57601>, be equally conservative for atomic MMOs as for volatile MMOs in all in tree backends. At the moment, all atomic MMOs are also volatile, but I'm about to change that.

Reviewed as part of https://reviews.llvm.org/D58490, with other backends still pending review.


Modified:
    llvm/trunk/lib/Target/Lanai/LanaiMemAluCombiner.cpp

Modified: llvm/trunk/lib/Target/Lanai/LanaiMemAluCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Lanai/LanaiMemAluCombiner.cpp?rev=354800&r1=354799&r2=354800&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Lanai/LanaiMemAluCombiner.cpp (original)
+++ llvm/trunk/lib/Target/Lanai/LanaiMemAluCombiner.cpp Mon Feb 25 09:36:10 2019
@@ -158,7 +158,8 @@ bool isNonVolatileMemoryOp(const Machine
   const MachineMemOperand *MemOperand = *MI.memoperands_begin();
 
   // Don't move volatile memory accesses
-  if (MemOperand->isVolatile())
+  // TODO: unclear if we need to be as conservative about atomics
+  if (MemOperand->isVolatile() || MemOperand->isAtomic())
     return false;
 
   return true;