[VPlan] Update scalar induction resume values in VPlan. (llvm#110577)

Updated ILV.createInductionResumeValues (now createInductionResumeVPValue)
to directly update the VPIRInstructions wrapping the original phis with the 
created resume values.

This is the first step towards modeling them completely in VPlan.
Subsequent patches will move creation of the resume values completely
into VPlan.

Depends on llvm#109975.

PR: llvm#110577

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -629,7 +629,10 @@ Value *VPInstruction::generate(VPTransformState &State) {
         State.CFG
             .VPBB2IRBB[cast<VPBasicBlock>(getParent()->getSinglePredecessor())];
     NewPhi->addIncoming(IncomingFromVPlanPred, VPlanPred);
-    for (auto *OtherPred : predecessors(Builder.GetInsertBlock())) {
+    // TODO: Predecessors are temporarily reversed to reduce test changes.
+    // Remove it and update remaining tests after functional change landed.
+    for (auto *OtherPred :
+         reverse(to_vector(predecessors(Builder.GetInsertBlock())))) {
       assert(OtherPred != VPlanPred &&
              "VPlan predecessors should not be connected yet");
       NewPhi->addIncoming(IncomingFromOtherPreds, OtherPred);

llvm/test/Transforms/LoopVectorize/AArch64/epilog-vectorization-widen-inductions.ll

@@ -143,11 +143,10 @@ define void @test_widen_induction(ptr %A, i64 %N) {
 ; CHECK-NEXT:    [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ult i64 [[N_VEC_REMAINING]], 2
 ; CHECK-NEXT:    br i1 [[MIN_EPILOG_ITERS_CHECK]], label [[VEC_EPILOG_SCALAR_PH]], label [[VEC_EPILOG_PH]]
 ; CHECK:       vec.epilog.ph:
-; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; CHECK-NEXT:    [[VEC_EPILOG_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; CHECK-NEXT:    [[N_MOD_VF2:%.*]] = urem i64 [[N]], 2
 ; CHECK-NEXT:    [[N_VEC3:%.*]] = sub i64 [[N]], [[N_MOD_VF2]]
-; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
+; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[VEC_EPILOG_RESUME_VAL]], i64 0
 ; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i64> [[DOTSPLATINSERT]], <2 x i64> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[INDUCTION:%.*]] = add <2 x i64> [[DOTSPLAT]], <i64 0, i64 1>
 ; CHECK-NEXT:    br label [[VEC_EPILOG_VECTOR_BODY:%.*]]
@@ -205,10 +204,10 @@ define void @test_widen_induction_variable_start(ptr %A, i64 %N, i64 %start) {
 ; CHECK:       vector.ph:
 ; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[TMP0]], 4
 ; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[TMP0]], [[N_MOD_VF]]
+; CHECK-NEXT:    [[IND_END:%.*]] = add i64 [[START]], [[N_VEC]]
 ; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[START]], i64 0
 ; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i64> [[DOTSPLATINSERT]], <2 x i64> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[INDUCTION:%.*]] = add <2 x i64> [[DOTSPLAT]], <i64 0, i64 1>
-; CHECK-NEXT:    [[IND_END:%.*]] = add i64 [[START]], [[N_VEC]]
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
@@ -322,11 +321,10 @@ define void @test_widen_induction_step_2(ptr %A, i64 %N, i32 %step) {
 ; CHECK-NEXT:    [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ult i64 [[N_VEC_REMAINING]], 2
 ; CHECK-NEXT:    br i1 [[MIN_EPILOG_ITERS_CHECK]], label [[VEC_EPILOG_SCALAR_PH]], label [[VEC_EPILOG_PH]]
 ; CHECK:       vec.epilog.ph:
-; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[IND_END4]], [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; CHECK-NEXT:    [[VEC_EPILOG_RESUME_VAL:%.*]] = phi i64 [ [[IND_END4]], [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; CHECK-NEXT:    [[N_MOD_VF2:%.*]] = urem i64 [[N]], 2
 ; CHECK-NEXT:    [[IND_END:%.*]] = sub i64 [[N]], [[N_MOD_VF2]]
-; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
+; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[VEC_EPILOG_RESUME_VAL]], i64 0
 ; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i64> [[DOTSPLATINSERT]], <2 x i64> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[INDUCTION:%.*]] = add <2 x i64> [[DOTSPLAT]], <i64 0, i64 1>
 ; CHECK-NEXT:    br label [[VEC_EPILOG_VECTOR_BODY:%.*]]
@@ -433,7 +431,7 @@ define void @test_widen_extended_induction(ptr %dst) {
 ; CHECK:       vec.epilog.middle.block:
 ; CHECK-NEXT:    br i1 true, label [[EXIT]], label [[VEC_EPILOG_SCALAR_PH]]
 ; CHECK:       vec.epilog.scalar.ph:
-; CHECK-NEXT:    [[BC_RESUME_VAL1:%.*]] = phi i8 [ 16, [[VEC_EPILOG_MIDDLE_BLOCK]] ], [ 16, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_SCEVCHECK]] ], [ 0, [[ITER_CHECK:%.*]] ]
+; CHECK-NEXT:    [[BC_RESUME_VAL1:%.*]] = phi i8 [ 16, [[VEC_EPILOG_MIDDLE_BLOCK]] ], [ 16, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[ITER_CHECK:%.*]] ], [ 0, [[VECTOR_SCEVCHECK]] ]
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[BC_RESUME_VAL1]], [[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
@@ -491,9 +489,8 @@ define void @test_widen_truncated_induction(ptr %A) {
 ; CHECK:       vec.epilog.iter.check:
 ; CHECK-NEXT:    br i1 true, label [[VEC_EPILOG_SCALAR_PH]], label [[VEC_EPILOG_PH]]
 ; CHECK:       vec.epilog.ph:
-; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 10000, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; CHECK-NEXT:    [[VEC_EPILOG_RESUME_VAL:%.*]] = phi i64 [ 10000, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
-; CHECK-NEXT:    [[TMP5:%.*]] = trunc i64 [[BC_RESUME_VAL]] to i8
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i64 [[VEC_EPILOG_RESUME_VAL]] to i8
 ; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i8> poison, i8 [[TMP5]], i64 0
 ; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i8> [[DOTSPLATINSERT]], <2 x i8> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[INDUCTION:%.*]] = add <2 x i8> [[DOTSPLAT]], <i8 0, i8 1>