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1; RUN: opt %s -passes=indvars,loop-instsimplify,loop-reduce2; We are only checking that there is no crash!3 4; https://bugs.llvm.org/show_bug.cgi?id=379365 6; The problem is as follows:7; 1. indvars marks %dec as NUW.8; 2. loop-instsimplify runs instsimplify, which constant-folds %dec to -19; 3. loop-reduce tries to do some further modification, but crashes10; 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, that14; 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 120 21define void @f1(i1 %arg) {22entry:23 br label %for.cond24 25for.cond: ; preds = %land.end, %entry26 %c.0 = phi i16 [ 0, %entry ], [ %dec, %land.end ]27 br i1 %arg, label %for.body, label %for.cond.cleanup28 29for.cond.cleanup: ; preds = %for.cond30 ret void31 32for.body: ; preds = %for.cond33 %0 = load i16, ptr @a, align 134 %cmp = icmp sgt i16 %0, %c.035 br i1 %cmp, label %land.rhs, label %land.end36 37land.rhs: ; preds = %for.body38 unreachable39 40land.end: ; preds = %for.body41 %dec = add nsw i16 %c.0, -142 br label %for.cond43}44