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 17 target datalayout = "n16" 18 19 @a = external global i16, align 1 20 21 define void @f1() { 22 entry: 23 br label %for.cond 24 25 for.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 29 for.cond.cleanup: ; preds = %for.cond 30 ret void 31 32 for.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 37 land.rhs: ; preds = %for.body 38 unreachable 39 40 land.end: ; preds = %for.body 41 %dec = add nsw i16 %c.0, -1 42 br label %for.cond 43 } 44
