1; RUN: opt %s -indvars -loop-instsimplify -loop-reduce
2; We are only checking that there is no crash!
3
4; https://bugs.llvm.org/show_bug.cgi?id=37936
5
6; The problem is as follows:
7; 1. indvars marks %dec as NUW.
8; 2. loop-instsimplify runs instsimplify, which constant-folds %dec to -1
9; 3. loop-reduce tries to do some further modification, but crashes
10;    with an type assertion in cast, because %dec is no longer an Instruction,
11;    even though the SCEV data indicated it was.
12
13; If the runline is split into two, i.e. -indvars -loop-instsimplify first, that
14; stored into a file, and then -loop-reduce is run on that, there is no crash.
15; So it looks like the problem is due to -loop-instsimplify not discarding SCEV.
16
17target datalayout = "n16"
18
19@a = external global i16, align 1
20
21define void @f1() {
22entry:
23  br label %for.cond
24
25for.cond:                                         ; preds = %land.end, %entry
26  %c.0 = phi i16 [ 0, %entry ], [ %dec, %land.end ]
27  br i1 undef, label %for.body, label %for.cond.cleanup
28
29for.cond.cleanup:                                 ; preds = %for.cond
30  ret void
31
32for.body:                                         ; preds = %for.cond
33  %0 = load i16, i16* @a, align 1
34  %cmp = icmp sgt i16 %0, %c.0
35  br i1 %cmp, label %land.rhs, label %land.end
36
37land.rhs:                                         ; preds = %for.body
38  unreachable
39
40land.end:                                         ; preds = %for.body
41  %dec = add nsw i16 %c.0, -1
42  br label %for.cond
43}
44