Fix miscompilation found in Fhourstones by bugpoint

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5993 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/LICM/2003-05-02-LoadHoist.ll

@@ -0,0 +1,21 @@
+; This testcase tests for a problem where LICM hoists loads out of a loop 
+; despite the fact that calls to unknown functions may modify what is being 
+; loaded from.  Basically if the load gets hoisted, the subtract gets turned
+; into a constant zero.
+;
+; RUN: as < %s | opt -licm -load-vn -gcse -instcombine | llvm-dis | grep load
+
+%X = global int 7
+declare void %foo()
+
+int %test(bool %c) {
+	%A = load int *%X
+	br label %Loop
+Loop:
+	call void %foo()
+	%B = load int *%X  ;; Should not hoist this load!
+	br bool %c, label %Loop, label %Out
+Out:
+	%C = sub int %A, %B
+	ret int %C
+}