Update instcombine for atomic load/store.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137664 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/Transforms/InstCombine/InstCombinePHI.cpp b/lib/Transforms/InstCombine/InstCombinePHI.cpp
index e82b0d2ab3..664546c165 100644
--- a/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -286,7 +286,12 @@ static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
 
 Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
   LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
-  
+
+  // FIXME: This is overconservative; this transform is allowed in some cases
+  // for atomic operations.
+  if (FirstLI->isAtomic())
+    return 0;
+
   // When processing loads, we need to propagate two bits of information to the
   // sunk load: whether it is volatile, and what its alignment is.  We currently
   // don't sink loads when some have their alignment specified and some don't.