fix a warning in the optimized build

llvm-svn: 20920
diff --git a/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp b/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp
index fcd8f43..d408db3 100644
--- a/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp
+++ b/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp
@@ -729,6 +729,8 @@
     if (sext && byte) {
       Tmp3 = Result;
       Result = MakeReg(MVT::i32);
+    } else {
+      Tmp3 = 0;  // Silence GCC warning.
     }
     if(Address.getOpcode() == ISD::FrameIndex) {
       BuildMI(BB, Opc, 2, Result)