[MemCpyOpt] Do not exchange llvm.lifetime.start and llvm.memcpy

Reviewers: iteratee

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21087

llvm-svn: 272192

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 3c421d2365d..3ab892f7529 100644
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -788,6 +788,11 @@ bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy,
   // src only holds uninitialized values at the moment of the call, meaning that
   // the memcpy can be discarded rather than moved.
 
+  // Lifetime marks shouldn't be operated on.
+  if (Function *F = C->getCalledFunction())
+    if (F->isIntrinsic() && F->getIntrinsicID() == Intrinsic::lifetime_start)
+      return false;
+
   // Deliberately get the source and destination with bitcasts stripped away,
   // because we'll need to do type comparisons based on the underlying type.
   CallSite CS(C);