[instcombine][unordered] Implement *-load forwarding for unordered atomics

This builds on 266999 which made FindAvailableValue do the right thing.  Tests included show the newly enabled transforms and those which disabled either due to conservatism or correctness requirements.

llvm-svn: 267006

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index c8556638cec..fc3de6b49f3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -809,10 +809,6 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
       return &LI;
   }
 
-  // None of the following transforms are legal for volatile/atomic loads.
-  // FIXME: Some of it is okay for atomic loads; needs refactoring.
-  if (!LI.isSimple()) return nullptr;
-
   if (Instruction *Res = unpackLoadToAggregate(*this, LI))
     return Res;
 
@@ -840,6 +836,10 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
                                             LI.getName() + ".cast"));
   }
 
+  // None of the following transforms are legal for volatile/atomic loads.
+  // FIXME: Some of it is okay for atomic loads; needs refactoring.
+  if (!LI.isSimple()) return nullptr;
+
   // load(gep null, ...) -> unreachable
   if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
     const Value *GEPI0 = GEPI->getOperand(0);