[PATCH] D91153: [IndVarSimplify] Fix Modified status when handling dead PHI nodes

[Ta-Wei Tu via Phabricator via llvm-commits]

TaWeiTu added a comment.

IIRC the bug is not MIPS-specific, the following test has the same assertion failure with `opt -S -indvars` on X86 machines:

  @ptr = external global i64
  
  define dso_local void @hoge() local_unnamed_addr {
  entry:                                            ; preds = %entry
    %n = sdiv exact i64 undef, 40
    br label %header
  
  header:                                           ; preds = %latch, %entry
    %idx = phi i64 [ %idx.next, %latch ], [ undef, %entry ]
    %cond = icmp sgt i64 %n, %idx
    br i1 %cond, label %end, label %inner
  
  inner:                                            ; preds = %inner, %header
    %i = phi i64 [ %i.next, %inner ], [ 0, %header ]
    %j = phi i64 [ %j.next, %inner ], [ %n, %header ]
    %i.next = add nsw i64 %i, 1
    %j.next = add nsw i64 %j, 1
    store i64 undef, i64* @ptr
    %cond1 = icmp slt i64 %j, %idx
    br i1 %cond1, label %inner, label %inner_exit
  
  inner_exit:                                       ; preds = %inner
    %indvar = phi i64 [ %i.next, %inner ]
    %indvar_use = add i64 %indvar, 1
    br label %latch
  
  latch:                                            ; preds = %inner_exit
    %idx.next = add nsw i64 %idx, -1
    br label %header
  
  end:                                              ; preds = %header
    ret void
  }


Repository:
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  https://reviews.llvm.org/D91153/new/

https://reviews.llvm.org/D91153