Preserving 'nonnull' metadata in SimplifyCFG

When we hoist two loads above an if, we can preserve the nonnull metadata.  We could also do the same for sinking them, but we appear to not handle metadata at all in that case.

Thanks to Hal for the review.

Differential Revision: http://reviews.llvm.org/D5910

llvm-svn: 220392

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index d79f4ce013f012dca3aaf0f39aa1408149f3716e..0e4d779c52ea8bba158b7bf99c6ae02cb84f484b 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1061,7 +1061,8 @@ static bool HoistThenElseCodeToIf(BranchInst *BI, const DataLayout *DL) {
       LLVMContext::MD_tbaa,
       LLVMContext::MD_range,
       LLVMContext::MD_fpmath,
-      LLVMContext::MD_invariant_load
+      LLVMContext::MD_invariant_load,
+      LLVMContext::MD_nonnull
     };
     combineMetadata(I1, I2, KnownIDs);
     I2->eraseFromParent();
@@ -1311,6 +1312,8 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
     if (!I2->use_empty())
       I2->replaceAllUsesWith(I1);
     I1->intersectOptionalDataWith(I2);
+    // TODO: Use combineMetadata here to preserve what metadata we can
+    // (analogous to the hoisting case above).
     I2->eraseFromParent();
 
     if (UpdateRE1)