Tweak the check for promotable alloca's to handle

debug intrinsics correctly.

llvm-svn: 66225

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
index cc626ae71f5..e3dd72daf70 100644
--- a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -81,9 +81,15 @@ bool llvm::isAllocaPromotable(const AllocaInst *AI) {
       if (SI->isVolatile())
         return false;
     } else if (const BitCastInst *BC = dyn_cast<BitCastInst>(*UI)) {
-      // Uses by dbg info shouldn't inhibit promotion.
+      // A bitcast that does not feed into debug info inhibits promotion.
       if (!BC->hasOneUse() || !isa<DbgInfoIntrinsic>(*BC->use_begin()))
         return false;
+      // If the only use is by debug info, this alloca will not exist in
+      // non-debug code, so don't try to promote; this ensures the same
+      // codegen with debug info.  Otherwise, debug info should not
+      // inhibit promotion (but we must examine other uses).
+      if (AI->hasOneUse())
+        return false;
     } else {
       return false;
     }