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; RUN: opt %s -passes=indvars,loop-instsimplify,loop-reduce
; We are only checking that there is no crash!
; https://bugs.llvm.org/show_bug.cgi?id=37936
; The problem is as follows:
; 1. indvars marks %dec as NUW.
; 2. loop-instsimplify runs instsimplify, which constant-folds %dec to -1
; 3. loop-reduce tries to do some further modification, but crashes
; with an type assertion in cast, because %dec is no longer an Instruction,
; even though the SCEV data indicated it was.
; If the runline is split into two, i.e. -indvars -loop-instsimplify first, that
; stored into a file, and then -loop-reduce is run on that, there is no crash.
; So it looks like the problem is due to -loop-instsimplify not discarding SCEV.
target datalayout = "n16"
@a = external global i16, align 1
define void @f1() {
entry:
br label %for.cond
for.cond: ; preds = %land.end, %entry
%c.0 = phi i16 [ 0, %entry ], [ %dec, %land.end ]
br i1 undef, label %for.body, label %for.cond.cleanup
for.cond.cleanup: ; preds = %for.cond
ret void
for.body: ; preds = %for.cond
%0 = load i16, ptr @a, align 1
%cmp = icmp sgt i16 %0, %c.0
br i1 %cmp, label %land.rhs, label %land.end
land.rhs: ; preds = %for.body
unreachable
land.end: ; preds = %for.body
%dec = add nsw i16 %c.0, -1
br label %for.cond
}
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