1 files changed, 2 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 43c6f6dda2..3edc447cec 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -577,7 +577,8 @@ struct StrToOpt : public LibCallOptimization {
 
     Value *EndPtr = CI->getArgOperand(1);
     if (isa<ConstantPointerNull>(EndPtr)) {
-      CI->setOnlyReadsMemory();
+      // With a null EndPtr, this function won't capture the main argument.
+      // It would be readonly too, except that it still may write to errno.
       CI->addAttribute(1, Attribute::NoCapture);
     }