Test to ensure sub -> neg promotion is working and why.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2631 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/Reassociate/subtest.ll

@@ -0,0 +1,13 @@
+; With sub reassociation, constant folding can eliminate the 12 and -12 constants.
+;
+; RUN: if as < %s | opt -reassociate -constprop -instcombine -die | dis | grep add
+; RUN: then exit 1
+; RUN: else exit 0
+; RUN: fi
+
+int "test"(int %A, int %B) {
+	%X = add int -12, %A
+	%Y = sub int %X, %B
+	%Z = add int %Y, 12
+	ret int %Z
+}