Duncan deftly points out that readnone functions aren't

invalidated by stores, so they can be handled as 'simple'
operations.

llvm-svn: 122785

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
index 6c2ea39896a..3d3f17b26fc 100644
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -56,6 +56,9 @@ namespace {
     }
     
     static bool canHandle(Instruction *Inst) {
+      // This can only handle non-void readnone functions.
+      if (CallInst *CI = dyn_cast<CallInst>(Inst))
+        return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
       return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
              isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
              isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
@@ -105,7 +108,8 @@ unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) {
       Res ^= *I;
   } else {
     // nothing extra to hash in.
-    assert((isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
+    assert((isa<CallInst>(Inst) ||
+            isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
             isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
             isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst)) &&
            "Invalid/unknown instruction");