[PATCH] D108201: [AggressiveInstCombine] Add logical shift right instr to `TruncInstCombine` DAG

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added a comment.

In D108201#2956220 <https://reviews.llvm.org/D108201#2956220>, @akhuang wrote:

> looks like this caused a crash in some chromium code

Hi @akhuang , I'm not able to reproduce this crash. Could you please decribe your environment/crash output/stack trace?

  > opt -aggressive-instcombine -S repro.ll 
  ; ModuleID = 'repro.ll'
  source_filename = "repro.cpp"
  target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
  target triple = "x86_64-unknown-linux-gnu"
  
  @k = local_unnamed_addr global i32 0, align 4
  @l = local_unnamed_addr global i32 0, align 4
  @m = local_unnamed_addr global i32 0, align 4
  @n = local_unnamed_addr global i32 0, align 4
  
  ; Function Attrs: mustprogress nofree norecurse nosync nounwind null_pointer_is_valid optforfuzzing willreturn
  define dso_local void @_Z1ov() local_unnamed_addr #0 {
  entry:
    store i8 8, i8* null, align 536870912, !tbaa !2
    ret void
  }
  
  attributes #0 = { mustprogress nofree norecurse nosync nounwind null_pointer_is_valid optforfuzzing willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" }
  
  !llvm.module.flags = !{!0}
  !llvm.ident = !{!1}
  
  !0 = !{i32 1, !"wchar_size", i32 4}
  !1 = !{!"clang version 14.0.0 (git at github.com:llvm/llvm-project.git b3a45e286fdfa73dd758472363dfafe7543cc077)"}
  !2 = !{!3, !3, i64 0}
  !3 = !{!"omnipotent char", !4, i64 0}
  !4 = !{!"Simple C++ TBAA"}
  
  > clang -cc1 -fno-delete-null-pointer-checks -O3 -fsanitize=fuzzer-no-link -emit-llvm  t.cpp
  > cat t.ll
  (the same output)


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