[JumpThreading] PRE unordered loads

Summary: Extend JumpThreading's PRE to unordered atomic loads.

Reviewers: hfinkel, reames

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D22326

llvm-svn: 275456

1 files changed, 6 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index de1d7d50384..b9e717cf763 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -924,8 +924,8 @@ bool JumpThreadingPass::ProcessImpliedCondition(BasicBlock *BB) {
 /// important optimization that encourages jump threading, and needs to be run
 /// interlaced with other jump threading tasks.
 bool JumpThreadingPass::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
-  // Don't hack volatile/atomic loads.
-  if (!LI->isSimple()) return false;
+  // Don't hack volatile and ordered loads.
+  if (!LI->isUnordered()) return false;
 
   // If the load is defined in a block with exactly one predecessor, it can't be
   // partially redundant.
@@ -1055,9 +1055,10 @@ bool JumpThreadingPass::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
   if (UnavailablePred) {
     assert(UnavailablePred->getTerminator()->getNumSuccessors() == 1 &&
            "Can't handle critical edge here!");
-    LoadInst *NewVal = new LoadInst(LoadedPtr, LI->getName()+".pr", false,
-                                 LI->getAlignment(),
-                                 UnavailablePred->getTerminator());
+    LoadInst *NewVal =
+        new LoadInst(LoadedPtr, LI->getName() + ".pr", false,
+                     LI->getAlignment(), LI->getOrdering(), LI->getSynchScope(),
+                     UnavailablePred->getTerminator());
     NewVal->setDebugLoc(LI->getDebugLoc());
     if (AATags)
       NewVal->setAAMetadata(AATags);