Test that the instruction combiner can fold away a cast in a GEP instruction.

This occurs in 164.gzip, as a result of it declaring arrays extern.

llvm-svn: 11701

llvm/test/Regression/Transforms/InstCombine/cast.ll

@@ -2,6 +2,8 @@
 
 ; RUN: llvm-as < %s | opt -instcombine -die | llvm-dis | grep '%c' | not grep cast
 
+%inbuf = external global [32832 x ubyte]
+
 implementation
 
 int %test1(int %A) {
@@ -79,3 +81,9 @@ int* %test12() {
 	%c = cast [4 x sbyte]* %p to int*
 	ret int* %c
 }
+
+
+ubyte *%test13(long %A) {
+	%c = getelementptr [0 x ubyte]* cast ([32832 x ubyte]*  %inbuf to [0 x ubyte]*), long 0, long %A
+	ret ubyte* %c
+}