[PATCH] D62266: [DAGCombine][X86][AArch64][ARM] (C - x) + y -> (y - x) + C fold

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

Hello. I found this code that seems to loop forever:

  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
  target triple = "thumbv6m-arm-none-eabi"
  
  @a = dso_local local_unnamed_addr global i32 0, align 4
  @b = dso_local local_unnamed_addr global i32 0, align 4
  
  ; Function Attrs: minsize nounwind optsize
  define dso_local i32 @c() local_unnamed_addr #0 {
  entry:
    %0 = load i32, i32* @a, align 4
    %sub = sub nsw i32 2000, %0
    %call = tail call i32 bitcast (i32 (...)* @d to i32 (i32)*)(i32 %sub) #2
    %1 = load i32, i32* @b, align 4
    %cmp = icmp sgt i32 %1, 1999
    br i1 %cmp, label %if.then, label %if.end
  
  if.then:                                          ; preds = %entry
    %call1 = tail call i32 bitcast (i32 (...)* @e to i32 ()*)() #2
    br label %if.end
  
  if.end:                                           ; preds = %if.then, %entry
    ret i32 undef
  }
  
  declare dso_local i32 @d(...) local_unnamed_addr #1
  declare dso_local i32 @e(...) local_unnamed_addr #1


Repository:
  rL LLVM

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https://reviews.llvm.org/D62266