add a testcase for a case we do not handle yet

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21789 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/Reassociate/backwards.ll b/test/Transforms/Reassociate/backwards.ll
new file mode 100644 (file)
index 0000000..b1fefc5
--- /dev/null
+++ b/test/Transforms/Reassociate/backwards.ll
@@ -0,0 +1,66 @@
+; RUN:  llvm-as < %s | opt -reassociate -dce -gcse | llvm-dis | grep add | wc -l | grep 8
+; This test corresponds to GCC PR16157.  Reassociate should arrange for 4 additions to be
+; left in each function.
+
+; We currently don't implement this.  This would require looking globally to 
+; find out which expressions are available, which we currently do not do.
+
+; XFAIL: *
+
+%a4 = external global int
+%a3 = external global int
+%a2 = external global int
+%a1 = external global int
+%a0 = external global int
+%b4 = external global int
+%b3 = external global int
+%b2 = external global int
+%b1 = external global int
+
+implementation   ; Functions:
+
+void %test1() {
+       %tmp.0 = load int* %a4          ; <int> [#uses=1]
+       %tmp.1 = load int* %a3          ; <int> [#uses=2]
+       %tmp.2 = add int %tmp.0, %tmp.1         ; <int> [#uses=1]
+       %tmp.3 = load int* %a2          ; <int> [#uses=3]
+       %tmp.4 = add int %tmp.2, %tmp.3         ; <int> [#uses=1]
+       %tmp.5 = load int* %a1          ; <int> [#uses=4]
+       %tmp.6 = add int %tmp.4, %tmp.5         ; <int> [#uses=1]
+       %tmp.7 = load int* %a0          ; <int> [#uses=4]
+       %tmp.8 = add int %tmp.6, %tmp.7         ; <int> [#uses=1]
+       store int %tmp.8, int* %a4
+       %tmp.11 = add int %tmp.1, %tmp.3                ; <int> [#uses=1]
+       %tmp.13 = add int %tmp.11, %tmp.5               ; <int> [#uses=1]
+       %tmp.15 = add int %tmp.13, %tmp.7               ; <int> [#uses=1]
+       store int %tmp.15, int* %a3
+       %tmp.18 = add int %tmp.3, %tmp.5                ; <int> [#uses=1]
+       %tmp.20 = add int %tmp.18, %tmp.7               ; <int> [#uses=1]
+       store int %tmp.20, int* %a2
+       %tmp.23 = add int %tmp.5, %tmp.7                ; <int> [#uses=1]
+       store int %tmp.23, int* %a1
+       ret void
+}
+
+void %test2() {
+       %tmp.0 = load int* %a4          ; <int> [#uses=1]
+       %tmp.1 = load int* %a3          ; <int> [#uses=2]
+       %tmp.2 = add int %tmp.0, %tmp.1         ; <int> [#uses=1]
+       %tmp.3 = load int* %a2          ; <int> [#uses=3]
+       %tmp.4 = add int %tmp.2, %tmp.3         ; <int> [#uses=1]
+       %tmp.5 = load int* %a1          ; <int> [#uses=4]
+       %tmp.6 = add int %tmp.4, %tmp.5         ; <int> [#uses=1]
+       %tmp.7 = load int* %a0          ; <int> [#uses=4]
+       %tmp.8 = add int %tmp.6, %tmp.7         ; <int> [#uses=1]
+       store int %tmp.8, int* %b4
+       %tmp.11 = add int %tmp.1, %tmp.3                ; <int> [#uses=1]
+       %tmp.13 = add int %tmp.11, %tmp.5               ; <int> [#uses=1]
+       %tmp.15 = add int %tmp.13, %tmp.7               ; <int> [#uses=1]
+       store int %tmp.15, int* %b3
+       %tmp.18 = add int %tmp.3, %tmp.5                ; <int> [#uses=1]
+       %tmp.20 = add int %tmp.18, %tmp.7               ; <int> [#uses=1]
+       store int %tmp.20, int* %b2
+       %tmp.23 = add int %tmp.5, %tmp.7                ; <int> [#uses=1]
+       store int %tmp.23, int* %b1
+       ret void
+}