[unordered] sink unordered stores at end of blocks

The existing code turned out to be completely correct when auditted.  Thus, only minor code changes and adding a couple of tests.

llvm-svn: 267215

1 files changed, 3 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index aa72244463e..e8314006dd1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -1193,10 +1193,6 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
   if (isa<UndefValue>(Val))
     return eraseInstFromFunction(SI);
 
-  // The code below needs to be audited and adjusted for unordered atomics
-  if (!SI.isSimple())
-    return nullptr;
-
   // If this store is the last instruction in the basic block (possibly
   // excepting debug info instructions), and if the block ends with an
   // unconditional branch, try to move it to the successor block.
@@ -1222,6 +1218,9 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
 /// into a phi node with a store in the successor.
 ///
 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
+  assert(SI.isUnordered() &&
+         "this code has not been auditted for volatile or ordered store case");
+  
   BasicBlock *StoreBB = SI.getParent();
 
   // Check to see if the successor block has exactly two incoming edges.  If