Index: CodeGen/CGExprScalar.cpp
===================================================================
--- CodeGen/CGExprScalar.cpp	(revision 46389)
+++ CodeGen/CGExprScalar.cpp	(working copy)
@@ -315,7 +315,11 @@
   if (llvm::ZExtInst *ZI = dyn_cast<llvm::ZExtInst>(Src)) {
     if (ZI->getOperand(0)->getType() == llvm::Type::Int1Ty) {
       Value *Result = ZI->getOperand(0);
-      ZI->eraseFromParent();
+      // If there aren't any more uses, zap the instruction to save space.
+      // Note that there can be more uses, for example if this
+      // is the result of an assignment.
+      if (ZI->use_empty())
+        ZI->eraseFromParent();
       return Result;
     }
   }