[llvm] VPlan: use worklist in simplifyRecipes (PR #93998)

[Ramkumar Ramachandra via llvm-commits]

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@@ -7,135 +7,109 @@ define void @test(ptr %p, i40 %a) {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
 ; CHECK:       vector.ph:
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <16 x i40> poison, i40 [[A]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <16 x i40> [[BROADCAST_SPLATINSERT1]], <16 x i40> poison, <16 x i32> zeroinitializer
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[PRED_STORE_CONTINUE32:%.*]] ]
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <16 x i32> poison, i32 [[INDEX]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <16 x i32> [[BROADCAST_SPLATINSERT]], <16 x i32> poison, <16 x i32> zeroinitializer
 ; CHECK-NEXT:    [[VEC_IV:%.*]] = add <16 x i32> [[BROADCAST_SPLAT]], <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:    [[TMP0:%.*]] = icmp ule <16 x i32> [[VEC_IV]], <i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9, i32 9>
-; CHECK-NEXT:    [[TMP1:%.*]] = shl <16 x i40> [[BROADCAST_SPLAT2]], <i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24, i40 24>
-; CHECK-NEXT:    [[TMP2:%.*]] = ashr <16 x i40> [[TMP1]], <i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28, i40 28>
-; CHECK-NEXT:    [[TMP3:%.*]] = trunc <16 x i40> [[TMP2]] to <16 x i32>
-; CHECK-NEXT:    [[TMP4:%.*]] = trunc <16 x i32> [[TMP3]] to <16 x i1>
-; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq <16 x i1> [[TMP4]], zeroinitializer
-; CHECK-NEXT:    [[TMP6:%.*]] = icmp ult <16 x i1> zeroinitializer, [[TMP5]]
-; CHECK-NEXT:    [[TMP7:%.*]] = or <16 x i1> [[TMP6]], <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>
-; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt <16 x i1> [[TMP7]], zeroinitializer
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artagnon wrote:

Okay, I stepped through the ConstantFolder, and figured out that `icmp sgt true, false` is read as `-1 > 0`, since the APInt representation of true is `(1b, 1u, -1s)`, and we're asking for a signed comparison. I seriously doubt there's a bug so deep in the code, so I think the transformation is correct, and we just got confused.

https://github.com/llvm/llvm-project/pull/93998