1 files changed, 41 insertions, 0 deletions
diff --git a/test/Analysis/ScalarEvolution/nw-sub-is-not-nw-add.ll b/test/Analysis/ScalarEvolution/nw-sub-is-not-nw-add.ll
new file mode 100644
index 0000000..41b07d5
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/nw-sub-is-not-nw-add.ll
@@ -0,0 +1,41 @@
+; RUN: opt -S -indvars < %s | FileCheck %s
+
+; Check that SCEV does not assume sub nuw X Y == add nuw X, -Y
+define void @f(i32* %loc) {
+; CHECK-LABEL: @f
+ entry:
+  br label %loop
+
+ loop:
+  %idx = phi i32 [ 6, %entry ], [ %idx.dec, %loop ]
+  store i32 %idx, i32* %loc
+  %idx.dec = sub nuw i32 %idx, 1
+  %cond = icmp uge i32 %idx.dec, 5
+  br i1 %cond, label %loop, label %exit
+; CHECK-NOT: br i1 true, label %loop, label %exit
+
+ exit:
+  ret void
+}
+
+declare void @use_i1(i1)
+
+; Check that SCEV does not assume sub nsw X Y == add nsw X, -Y
+define void @g(i32 %lim) {
+; CHECK-LABEL: @g
+ entry:
+  br label %loop
+
+ loop:
+  %idx = phi i32 [ -1, %entry ], [ %idx.dec, %loop ]
+  %t = icmp sgt i32 %idx, 0
+; CHECK-NOT:   call void @use_i1(i1 false)
+; CHECK: call void @use_i1(i1 %t)
+  call void @use_i1(i1 %t)
+  %idx.dec = sub nsw i32 %idx, -2147483648
+  %cond = icmp eq i32 %idx.dec, %lim
+  br i1 %cond, label %loop, label %exit
+
+ exit:
+  ret void
+}