[llvm] [VPlan] Sink single-scalar VPI to replicate regions (PR #208906)

[Florian Hahn via llvm-commits]

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@@ -23,25 +23,32 @@ define i8 @predicated_replicate_feeding_cast(i16 %n, i1 %c1, i1 %c2, i16 %a, i8
 ; CHECK-NEXT:    br i1 [[TMP3]], label %[[PRED_SDIV_IF:.*]], label %[[PRED_SDIV_CONTINUE:.*]]
 ; CHECK:       [[PRED_SDIV_IF]]:
 ; CHECK-NEXT:    [[TMP5:%.*]] = sdiv i16 1, [[A]]
+; CHECK-NEXT:    [[TMP6:%.*]] = insertelement <2 x i16> poison, i16 [[TMP5]], i64 0
 ; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE]]
 ; CHECK:       [[PRED_SDIV_CONTINUE]]:
-; CHECK-NEXT:    [[TMP6:%.*]] = phi i16 [ poison, %[[VECTOR_BODY]] ], [ [[TMP5]], %[[PRED_SDIV_IF]] ]
+; CHECK-NEXT:    [[TMP7:%.*]] = phi <2 x i16> [ poison, %[[VECTOR_BODY]] ], [ [[TMP6]], %[[PRED_SDIV_IF]] ]
 ; CHECK-NEXT:    br i1 [[TMP3]], label %[[PRED_SDIV_IF1:.*]], label %[[PRED_SDIV_CONTINUE2:.*]]
 ; CHECK:       [[PRED_SDIV_IF1]]:
+; CHECK-NEXT:    [[TMP8:%.*]] = sdiv i16 1, [[A]]
+; CHECK-NEXT:    [[TMP9:%.*]] = insertelement <2 x i16> [[TMP7]], i16 [[TMP8]], i64 1
 ; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE2]]
 ; CHECK:       [[PRED_SDIV_CONTINUE2]]:
-; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[C1]], i16 0, i16 [[TMP6]]
-; CHECK-NEXT:    [[TMP12:%.*]] = trunc i16 [[TMP11]] to i8
+; CHECK-NEXT:    [[TMP10:%.*]] = phi <2 x i16> [ [[TMP7]], %[[PRED_SDIV_CONTINUE]] ], [ [[TMP9]], %[[PRED_SDIV_IF1]] ]
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select i1 [[C1]], <2 x i16> zeroinitializer, <2 x i16> [[TMP10]]
 ; CHECK-NEXT:    br i1 [[TMP4]], label %[[PRED_SDIV_IF3:.*]], label %[[PRED_SDIV_CONTINUE4:.*]]
 ; CHECK:       [[PRED_SDIV_IF3]]:
+; CHECK-NEXT:    [[TMP11:%.*]] = extractelement <2 x i16> [[PREDPHI]], i64 0
+; CHECK-NEXT:    [[TMP12:%.*]] = trunc i16 [[TMP11]] to i8
 ; CHECK-NEXT:    [[TMP13:%.*]] = sdiv i8 [[TMP12]], [[B]]
 ; CHECK-NEXT:    [[TMP14:%.*]] = insertelement <2 x i8> poison, i8 [[TMP13]], i64 0
 ; CHECK-NEXT:    br label %[[PRED_SDIV_CONTINUE4]]
 ; CHECK:       [[PRED_SDIV_CONTINUE4]]:
 ; CHECK-NEXT:    [[TMP15:%.*]] = phi <2 x i8> [ poison, %[[PRED_SDIV_CONTINUE2]] ], [ [[TMP14]], %[[PRED_SDIV_IF3]] ]
 ; CHECK-NEXT:    br i1 [[TMP4]], label %[[PRED_SDIV_IF5:.*]], label %[[PRED_SDIV_CONTINUE6]]
 ; CHECK:       [[PRED_SDIV_IF5]]:
-; CHECK-NEXT:    [[TMP18:%.*]] = sdiv i8 [[TMP12]], [[B]]
+; CHECK-NEXT:    [[TMP16:%.*]] = extractelement <2 x i16> [[PREDPHI]], i64 1
+; CHECK-NEXT:    [[TMP17:%.*]] = trunc i16 [[TMP16]] to i8
+; CHECK-NEXT:    [[TMP18:%.*]] = sdiv i8 [[TMP17]], [[B]]
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fhahn wrote:

this looks like a regression?

https://github.com/llvm/llvm-project/pull/208906