[LV] Add tests for argmin/argmax with epilogue vectorization. (NFC)

Add additional test coverage for vectorizing argmin/argmax with epilogue
vectorization.
diff --git a/llvm/test/Transforms/LoopVectorize/select-min-max-last-index-epilogue.ll b/llvm/test/Transforms/LoopVectorize/select-min-max-last-index-epilogue.ll
new file mode 100644
index 0000000..18c6c73
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/select-min-max-last-index-epilogue.ll
@@ -0,0 +1,370 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 6
+; RUN: opt -passes=loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -epilogue-vectorization-force-VF=4 -S < %s | FileCheck %s
+
+define i64 @test_vectorize_select_umax_idx(ptr %src, i64 %n) {
+; CHECK-LABEL: define i64 @test_vectorize_select_umax_idx(
+; CHECK-SAME: ptr [[SRC:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT:  [[ITER_CHECK:.*]]:
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH:.*]], label %[[VECTOR_MAIN_LOOP_ITER_CHECK:.*]]
+; CHECK:       [[VECTOR_MAIN_LOOP_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_ITERS_CHECK1:%.*]] = icmp ult i64 [[N]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK1]], label %[[VEC_EPILOG_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[IV1:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i64> [ splat (i64 -9223372036854775808), %[[VECTOR_PH]] ], [ [[TMP4:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI1:%.*]] = phi <4 x i64> [ zeroinitializer, %[[VECTOR_PH]] ], [ [[TMP3:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV1]]
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i64>, ptr [[GEP1]], align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ule <4 x i64> [[VEC_PHI1]], [[WIDE_LOAD]]
+; CHECK-NEXT:    [[TMP3]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> [[VEC_PHI1]], <4 x i64> [[WIDE_LOAD]])
+; CHECK-NEXT:    [[TMP4]] = select <4 x i1> [[TMP2]], <4 x i64> [[VEC_IND]], <4 x i64> [[VEC_PHI]]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[IV1]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add nuw nsw <4 x i64> [[VEC_IND]], splat (i64 4)
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP5]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP6:%.*]] = call i64 @llvm.vector.reduce.umax.v4i64(<4 x i64> [[TMP3]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[TMP6]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp eq <4 x i64> [[TMP3]], [[BROADCAST_SPLAT]]
+; CHECK-NEXT:    [[TMP8:%.*]] = select <4 x i1> [[TMP7]], <4 x i64> [[TMP4]], <4 x i64> splat (i64 -9223372036854775808)
+; CHECK-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vector.reduce.smax.v4i64(<4 x i64> [[TMP8]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP:%.*]] = icmp ne i64 [[TMP9]], -9223372036854775808
+; CHECK-NEXT:    [[RDX_SELECT:%.*]] = select i1 [[RDX_SELECT_CMP]], i64 [[TMP9]], i64 0
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[VEC_EPILOG_ITER_CHECK:.*]]
+; CHECK:       [[VEC_EPILOG_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ult i64 [[N_MOD_VF]], 4
+; CHECK-NEXT:    br i1 [[MIN_EPILOG_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH]], label %[[VEC_EPILOG_PH]], !prof [[PROF3:![0-9]+]]
+; 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:    [[BC_MERGE_RDX:%.*]] = phi i64 [ [[RDX_SELECT]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX3:%.*]] = phi i64 [ [[TMP6]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i64 [[BC_MERGE_RDX]], 0
+; CHECK-NEXT:    [[TMP10:%.*]] = select i1 [[TMP11]], i64 -9223372036854775808, i64 [[BC_MERGE_RDX]]
+; CHECK-NEXT:    [[N_MOD_VF4:%.*]] = urem i64 [[N]], 4
+; CHECK-NEXT:    [[N_VEC5:%.*]] = sub i64 [[N]], [[N_MOD_VF4]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT6:%.*]] = insertelement <4 x i64> poison, i64 [[TMP10]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT7:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT6]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT8:%.*]] = insertelement <4 x i64> poison, i64 [[BC_MERGE_RDX3]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT9:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT8]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT10:%.*]] = insertelement <4 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT11:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT10]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[INDUCTION:%.*]] = add nuw nsw <4 x i64> [[BROADCAST_SPLAT11]], <i64 0, i64 1, i64 2, i64 3>
+; CHECK-NEXT:    br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
+; CHECK:       [[VEC_EPILOG_VECTOR_BODY]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT17:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND13:%.*]] = phi <4 x i64> [ [[INDUCTION]], %[[VEC_EPILOG_PH]] ], [ [[VEC_IND_NEXT18:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI14:%.*]] = phi <4 x i64> [ [[BROADCAST_SPLAT7]], %[[VEC_EPILOG_PH]] ], [ [[TMP14:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI15:%.*]] = phi <4 x i64> [ [[BROADCAST_SPLAT9]], %[[VEC_EPILOG_PH]] ], [ [[TMP13:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV]]
+; CHECK-NEXT:    [[WIDE_LOAD16:%.*]] = load <4 x i64>, ptr [[GEP]], align 4
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ule <4 x i64> [[VEC_PHI15]], [[WIDE_LOAD16]]
+; CHECK-NEXT:    [[TMP13]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> [[VEC_PHI15]], <4 x i64> [[WIDE_LOAD16]])
+; CHECK-NEXT:    [[TMP14]] = select <4 x i1> [[TMP12]], <4 x i64> [[VEC_IND13]], <4 x i64> [[VEC_PHI14]]
+; CHECK-NEXT:    [[INDEX_NEXT17]] = add nuw i64 [[IV]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT18]] = add nuw nsw <4 x i64> [[VEC_IND13]], splat (i64 4)
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i64 [[INDEX_NEXT17]], [[N_VEC5]]
+; CHECK-NEXT:    br i1 [[TMP15]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK:       [[VEC_EPILOG_MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP16:%.*]] = call i64 @llvm.vector.reduce.umax.v4i64(<4 x i64> [[TMP13]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT19:%.*]] = insertelement <4 x i64> poison, i64 [[TMP16]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT20:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT19]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq <4 x i64> [[TMP13]], [[BROADCAST_SPLAT20]]
+; CHECK-NEXT:    [[TMP18:%.*]] = select <4 x i1> [[TMP17]], <4 x i64> [[TMP14]], <4 x i64> splat (i64 -9223372036854775808)
+; CHECK-NEXT:    [[TMP19:%.*]] = call i64 @llvm.vector.reduce.smax.v4i64(<4 x i64> [[TMP18]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP21:%.*]] = icmp ne i64 [[TMP19]], -9223372036854775808
+; CHECK-NEXT:    [[RDX_SELECT22:%.*]] = select i1 [[RDX_SELECT_CMP21]], i64 [[TMP19]], i64 0
+; CHECK-NEXT:    [[CMP_N23:%.*]] = icmp eq i64 [[N]], [[N_VEC5]]
+; CHECK-NEXT:    br i1 [[CMP_N23]], label %[[EXIT]], label %[[VEC_EPILOG_SCALAR_PH]]
+; CHECK:       [[VEC_EPILOG_SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL24:%.*]] = phi i64 [ [[N_VEC5]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[N_VEC]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX25:%.*]] = phi i64 [ [[RDX_SELECT22]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[RDX_SELECT]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX26:%.*]] = phi i64 [ [[TMP16]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[TMP6]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV2:%.*]] = phi i64 [ [[BC_RESUME_VAL24]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[MAX_IDX:%.*]] = phi i64 [ [[BC_MERGE_RDX25]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[MAX_IDX_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[MIN_VAL:%.*]] = phi i64 [ [[BC_MERGE_RDX26]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[MIN_VAL_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV2]]
+; CHECK-NEXT:    [[L:%.*]] = load i64, ptr [[GEP2]], align 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ule i64 [[MIN_VAL]], [[L]]
+; CHECK-NEXT:    [[MIN_VAL_NEXT]] = tail call i64 @llvm.umax.i64(i64 [[MIN_VAL]], i64 [[L]])
+; CHECK-NEXT:    [[MAX_IDX_NEXT]] = select i1 [[CMP]], i64 [[IV2]], i64 [[MAX_IDX]]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV2]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[IV_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[RES:%.*]] = phi i64 [ [[MAX_IDX_NEXT]], %[[LOOP]] ], [ [[RDX_SELECT]], %[[MIDDLE_BLOCK]] ], [ [[RDX_SELECT22]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    ret i64 [[RES]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %max.idx = phi i64 [ 0, %entry ], [ %max.idx.next, %loop ]
+  %max.val = phi i64 [ 0, %entry ], [ %max.val.next, %loop ]
+  %gep = getelementptr i64, ptr %src, i64 %iv
+  %l = load i64, ptr %gep
+  %cmp = icmp ule i64 %max.val, %l
+  %max.val.next = tail call i64 @llvm.umax.i64(i64 %max.val, i64 %l)
+  %max.idx.next = select i1 %cmp, i64 %iv, i64 %max.idx
+  %iv.next = add nuw nsw i64 %iv, 1
+  %exitcond.not = icmp eq i64 %iv.next, %n
+  br i1 %exitcond.not, label %exit, label %loop
+
+exit:
+  %res = phi i64 [ %max.idx.next, %loop ]
+  ret i64 %res
+}
+
+define i64 @test_vectorize_select_umax_idx_cond_flipped(ptr %src, i64 %n) {
+; CHECK-LABEL: define i64 @test_vectorize_select_umax_idx_cond_flipped(
+; CHECK-SAME: ptr [[SRC:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT:  [[ITER_CHECK:.*]]:
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH:.*]], label %[[VECTOR_MAIN_LOOP_ITER_CHECK:.*]]
+; CHECK:       [[VECTOR_MAIN_LOOP_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_ITERS_CHECK1:%.*]] = icmp ult i64 [[N]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK1]], label %[[VEC_EPILOG_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i64> [ splat (i64 -9223372036854775808), %[[VECTOR_PH]] ], [ [[TMP4:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI1:%.*]] = phi <4 x i64> [ zeroinitializer, %[[VECTOR_PH]] ], [ [[TMP3:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV]]
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i64>, ptr [[GEP]], align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp uge <4 x i64> [[WIDE_LOAD]], [[VEC_PHI1]]
+; CHECK-NEXT:    [[TMP3]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> [[VEC_PHI1]], <4 x i64> [[WIDE_LOAD]])
+; CHECK-NEXT:    [[TMP4]] = select <4 x i1> [[TMP2]], <4 x i64> [[VEC_IND]], <4 x i64> [[VEC_PHI]]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[IV]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add nuw nsw <4 x i64> [[VEC_IND]], splat (i64 4)
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP5]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP6:%.*]] = call i64 @llvm.vector.reduce.umax.v4i64(<4 x i64> [[TMP3]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[TMP6]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp eq <4 x i64> [[TMP3]], [[BROADCAST_SPLAT]]
+; CHECK-NEXT:    [[TMP8:%.*]] = select <4 x i1> [[TMP7]], <4 x i64> [[TMP4]], <4 x i64> splat (i64 -9223372036854775808)
+; CHECK-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vector.reduce.smax.v4i64(<4 x i64> [[TMP8]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP:%.*]] = icmp ne i64 [[TMP9]], -9223372036854775808
+; CHECK-NEXT:    [[RDX_SELECT:%.*]] = select i1 [[RDX_SELECT_CMP]], i64 [[TMP9]], i64 0
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[VEC_EPILOG_ITER_CHECK:.*]]
+; CHECK:       [[VEC_EPILOG_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ult i64 [[N_MOD_VF]], 4
+; CHECK-NEXT:    br i1 [[MIN_EPILOG_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH]], label %[[VEC_EPILOG_PH]], !prof [[PROF3]]
+; 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:    [[BC_MERGE_RDX:%.*]] = phi i64 [ [[RDX_SELECT]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX3:%.*]] = phi i64 [ [[TMP6]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i64 [[BC_MERGE_RDX]], 0
+; CHECK-NEXT:    [[TMP10:%.*]] = select i1 [[TMP11]], i64 -9223372036854775808, i64 [[BC_MERGE_RDX]]
+; CHECK-NEXT:    [[N_MOD_VF4:%.*]] = urem i64 [[N]], 4
+; CHECK-NEXT:    [[N_VEC5:%.*]] = sub i64 [[N]], [[N_MOD_VF4]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT6:%.*]] = insertelement <4 x i64> poison, i64 [[TMP10]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT7:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT6]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT8:%.*]] = insertelement <4 x i64> poison, i64 [[BC_MERGE_RDX3]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT9:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT8]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT10:%.*]] = insertelement <4 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT11:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT10]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[INDUCTION:%.*]] = add nuw nsw <4 x i64> [[BROADCAST_SPLAT11]], <i64 0, i64 1, i64 2, i64 3>
+; CHECK-NEXT:    br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
+; CHECK:       [[VEC_EPILOG_VECTOR_BODY]]:
+; CHECK-NEXT:    [[IV1:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT17:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND13:%.*]] = phi <4 x i64> [ [[INDUCTION]], %[[VEC_EPILOG_PH]] ], [ [[VEC_IND_NEXT18:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI14:%.*]] = phi <4 x i64> [ [[BROADCAST_SPLAT7]], %[[VEC_EPILOG_PH]] ], [ [[TMP14:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI15:%.*]] = phi <4 x i64> [ [[BROADCAST_SPLAT9]], %[[VEC_EPILOG_PH]] ], [ [[TMP13:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV1]]
+; CHECK-NEXT:    [[WIDE_LOAD16:%.*]] = load <4 x i64>, ptr [[GEP1]], align 4
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp uge <4 x i64> [[WIDE_LOAD16]], [[VEC_PHI15]]
+; CHECK-NEXT:    [[TMP13]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> [[VEC_PHI15]], <4 x i64> [[WIDE_LOAD16]])
+; CHECK-NEXT:    [[TMP14]] = select <4 x i1> [[TMP12]], <4 x i64> [[VEC_IND13]], <4 x i64> [[VEC_PHI14]]
+; CHECK-NEXT:    [[INDEX_NEXT17]] = add nuw i64 [[IV1]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT18]] = add nuw nsw <4 x i64> [[VEC_IND13]], splat (i64 4)
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i64 [[INDEX_NEXT17]], [[N_VEC5]]
+; CHECK-NEXT:    br i1 [[TMP15]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP7:![0-9]+]]
+; CHECK:       [[VEC_EPILOG_MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP16:%.*]] = call i64 @llvm.vector.reduce.umax.v4i64(<4 x i64> [[TMP13]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT19:%.*]] = insertelement <4 x i64> poison, i64 [[TMP16]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT20:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT19]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq <4 x i64> [[TMP13]], [[BROADCAST_SPLAT20]]
+; CHECK-NEXT:    [[TMP18:%.*]] = select <4 x i1> [[TMP17]], <4 x i64> [[TMP14]], <4 x i64> splat (i64 -9223372036854775808)
+; CHECK-NEXT:    [[TMP19:%.*]] = call i64 @llvm.vector.reduce.smax.v4i64(<4 x i64> [[TMP18]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP21:%.*]] = icmp ne i64 [[TMP19]], -9223372036854775808
+; CHECK-NEXT:    [[RDX_SELECT22:%.*]] = select i1 [[RDX_SELECT_CMP21]], i64 [[TMP19]], i64 0
+; CHECK-NEXT:    [[CMP_N23:%.*]] = icmp eq i64 [[N]], [[N_VEC5]]
+; CHECK-NEXT:    br i1 [[CMP_N23]], label %[[EXIT]], label %[[VEC_EPILOG_SCALAR_PH]]
+; CHECK:       [[VEC_EPILOG_SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL24:%.*]] = phi i64 [ [[N_VEC5]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[N_VEC]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX25:%.*]] = phi i64 [ [[RDX_SELECT22]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[RDX_SELECT]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX26:%.*]] = phi i64 [ [[TMP16]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[TMP6]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV2:%.*]] = phi i64 [ [[BC_RESUME_VAL24]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[MAX_IDX:%.*]] = phi i64 [ [[BC_MERGE_RDX25]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[MAX_IDX_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[MIN_VAL:%.*]] = phi i64 [ [[BC_MERGE_RDX26]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[MIN_VAL_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i64, ptr [[SRC]], i64 [[IV2]]
+; CHECK-NEXT:    [[L:%.*]] = load i64, ptr [[GEP2]], align 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp uge i64 [[L]], [[MIN_VAL]]
+; CHECK-NEXT:    [[MIN_VAL_NEXT]] = tail call i64 @llvm.umax.i64(i64 [[MIN_VAL]], i64 [[L]])
+; CHECK-NEXT:    [[MAX_IDX_NEXT]] = select i1 [[CMP]], i64 [[IV2]], i64 [[MAX_IDX]]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV2]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[IV_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP8:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[RES:%.*]] = phi i64 [ [[MAX_IDX_NEXT]], %[[LOOP]] ], [ [[RDX_SELECT]], %[[MIDDLE_BLOCK]] ], [ [[RDX_SELECT22]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    ret i64 [[RES]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %max.idx = phi i64 [ 0, %entry ], [ %max.idx.next, %loop ]
+  %max.val = phi i64 [ 0, %entry ], [ %max.val.next, %loop ]
+  %gep = getelementptr i64, ptr %src, i64 %iv
+  %l = load i64, ptr %gep
+  %cmp = icmp uge i64 %l, %max.val
+  %max.val.next = tail call i64 @llvm.umax.i64(i64 %max.val, i64 %l)
+  %max.idx.next = select i1 %cmp, i64 %iv, i64 %max.idx
+  %iv.next = add nuw nsw i64 %iv, 1
+  %exitcond.not = icmp eq i64 %iv.next, %n
+  br i1 %exitcond.not, label %exit, label %loop
+
+exit:
+  %res = phi i64 [ %max.idx.next, %loop ]
+  ret i64 %res
+}
+
+define i32 @test_vectorize_select_smax_idx(i32 %n, i32 %val) {
+; CHECK-LABEL: define i32 @test_vectorize_select_smax_idx(
+; CHECK-SAME: i32 [[N:%.*]], i32 [[VAL:%.*]]) {
+; CHECK-NEXT:  [[ITER_CHECK:.*]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[N]], 1
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[TMP0]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH:.*]], label %[[VECTOR_MAIN_LOOP_ITER_CHECK:.*]]
+; CHECK:       [[VECTOR_MAIN_LOOP_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_ITERS_CHECK1:%.*]] = icmp ult i32 [[TMP0]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK1]], label %[[VEC_EPILOG_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i32 [[TMP0]], 4
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i32 [[TMP0]], [[N_MOD_VF]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> poison, i32 [[VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i32> [ <i32 0, i32 1, i32 2, i32 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i32> [ zeroinitializer, %[[VECTOR_PH]] ], [ [[TMP3:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI2:%.*]] = phi <4 x i32> [ splat (i32 -2147483648), %[[VECTOR_PH]] ], [ [[TMP2:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt <4 x i32> [[BROADCAST_SPLAT]], [[VEC_PHI]]
+; CHECK-NEXT:    [[TMP2]] = select <4 x i1> [[TMP1]], <4 x i32> [[VEC_PHI2]], <4 x i32> [[VEC_IND]]
+; CHECK-NEXT:    [[TMP3]] = call <4 x i32> @llvm.smax.v4i32(<4 x i32> [[BROADCAST_SPLAT]], <4 x i32> [[VEC_PHI]])
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add nsw <4 x i32> [[VEC_IND]], splat (i32 4)
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP4]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP5:%.*]] = call i32 @llvm.vector.reduce.smax.v4i32(<4 x i32> [[TMP3]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <4 x i32> poison, i32 [[TMP5]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT4:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT3]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq <4 x i32> [[TMP3]], [[BROADCAST_SPLAT4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = select <4 x i1> [[TMP6]], <4 x i32> [[TMP2]], <4 x i32> splat (i32 -2147483648)
+; CHECK-NEXT:    [[TMP8:%.*]] = call i32 @llvm.vector.reduce.smax.v4i32(<4 x i32> [[TMP7]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP:%.*]] = icmp ne i32 [[TMP8]], -2147483648
+; CHECK-NEXT:    [[RDX_SELECT5:%.*]] = select i1 [[RDX_SELECT_CMP]], i32 [[TMP8]], i32 0
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP0]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[VEC_EPILOG_ITER_CHECK:.*]]
+; CHECK:       [[VEC_EPILOG_ITER_CHECK]]:
+; CHECK-NEXT:    [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ult i32 [[N_MOD_VF]], 4
+; CHECK-NEXT:    br i1 [[MIN_EPILOG_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH]], label %[[VEC_EPILOG_PH]], !prof [[PROF3]]
+; CHECK:       [[VEC_EPILOG_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX:%.*]] = phi i32 [ [[TMP5]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX6:%.*]] = phi i32 [ [[RDX_SELECT5]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
+; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[BC_MERGE_RDX6]], 0
+; CHECK-NEXT:    [[TMP10:%.*]] = select i1 [[TMP9]], i32 -2147483648, i32 [[BC_MERGE_RDX6]]
+; CHECK-NEXT:    [[N_MOD_VF7:%.*]] = urem i32 [[TMP0]], 4
+; CHECK-NEXT:    [[N_VEC8:%.*]] = sub i32 [[TMP0]], [[N_MOD_VF7]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT9:%.*]] = insertelement <4 x i32> poison, i32 [[VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT10:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT9]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT11:%.*]] = insertelement <4 x i32> poison, i32 [[BC_MERGE_RDX]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT12:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT11]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT13:%.*]] = insertelement <4 x i32> poison, i32 [[TMP10]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT14:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT13]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT15:%.*]] = insertelement <4 x i32> poison, i32 [[BC_RESUME_VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT16:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT15]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[INDUCTION:%.*]] = add nsw <4 x i32> [[BROADCAST_SPLAT16]], <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
+; CHECK:       [[VEC_EPILOG_VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX17:%.*]] = phi i32 [ [[BC_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT21:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND18:%.*]] = phi <4 x i32> [ [[INDUCTION]], %[[VEC_EPILOG_PH]] ], [ [[VEC_IND_NEXT22:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI19:%.*]] = phi <4 x i32> [ [[BROADCAST_SPLAT12]], %[[VEC_EPILOG_PH]] ], [ [[TMP13:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI20:%.*]] = phi <4 x i32> [ [[BROADCAST_SPLAT14]], %[[VEC_EPILOG_PH]] ], [ [[TMP12:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp slt <4 x i32> [[BROADCAST_SPLAT10]], [[VEC_PHI19]]
+; CHECK-NEXT:    [[TMP12]] = select <4 x i1> [[TMP11]], <4 x i32> [[VEC_PHI20]], <4 x i32> [[VEC_IND18]]
+; CHECK-NEXT:    [[TMP13]] = call <4 x i32> @llvm.smax.v4i32(<4 x i32> [[BROADCAST_SPLAT10]], <4 x i32> [[VEC_PHI19]])
+; CHECK-NEXT:    [[INDEX_NEXT21]] = add nuw i32 [[INDEX17]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT22]] = add nsw <4 x i32> [[VEC_IND18]], splat (i32 4)
+; CHECK-NEXT:    [[TMP14:%.*]] = icmp eq i32 [[INDEX_NEXT21]], [[N_VEC8]]
+; CHECK-NEXT:    br i1 [[TMP14]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP10:![0-9]+]]
+; CHECK:       [[VEC_EPILOG_MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP15:%.*]] = call i32 @llvm.vector.reduce.smax.v4i32(<4 x i32> [[TMP13]])
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT23:%.*]] = insertelement <4 x i32> poison, i32 [[TMP15]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT24:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT23]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP16:%.*]] = icmp eq <4 x i32> [[TMP13]], [[BROADCAST_SPLAT24]]
+; CHECK-NEXT:    [[TMP17:%.*]] = select <4 x i1> [[TMP16]], <4 x i32> [[TMP12]], <4 x i32> splat (i32 -2147483648)
+; CHECK-NEXT:    [[TMP18:%.*]] = call i32 @llvm.vector.reduce.smax.v4i32(<4 x i32> [[TMP17]])
+; CHECK-NEXT:    [[RDX_SELECT_CMP25:%.*]] = icmp ne i32 [[TMP18]], -2147483648
+; CHECK-NEXT:    [[RDX_SELECT26:%.*]] = select i1 [[RDX_SELECT_CMP25]], i32 [[TMP18]], i32 0
+; CHECK-NEXT:    [[CMP_N27:%.*]] = icmp eq i32 [[TMP0]], [[N_VEC8]]
+; CHECK-NEXT:    br i1 [[CMP_N27]], label %[[EXIT]], label %[[VEC_EPILOG_SCALAR_PH]]
+; CHECK:       [[VEC_EPILOG_SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL28:%.*]] = phi i32 [ [[N_VEC8]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[N_VEC]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX29:%.*]] = phi i32 [ [[TMP15]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[TMP5]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    [[BC_MERGE_RDX30:%.*]] = phi i32 [ [[RDX_SELECT26]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[RDX_SELECT5]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[BC_RESUME_VAL28]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[RDX_SMAX:%.*]] = phi i32 [ [[BC_MERGE_RDX29]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[SMAX:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[RDX_SELECT:%.*]] = phi i32 [ [[BC_MERGE_RDX30]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[SEL:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[VAL]], [[RDX_SMAX]]
+; CHECK-NEXT:    [[SEL]] = select i1 [[CMP]], i32 [[RDX_SELECT]], i32 [[IV]]
+; CHECK-NEXT:    [[SMAX]] = tail call i32 @llvm.smax.i32(i32 [[VAL]], i32 [[RDX_SMAX]])
+; CHECK-NEXT:    [[IV_NEXT]] = add nsw i32 [[IV]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp ult i32 [[IV]], [[N]]
+; CHECK-NEXT:    br i1 [[EC]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP11:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[SEL_LCSSA:%.*]] = phi i32 [ [[SEL]], %[[LOOP]] ], [ [[RDX_SELECT5]], %[[MIDDLE_BLOCK]] ], [ [[RDX_SELECT26]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    ret i32 [[SEL_LCSSA]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %rdx.smax = phi i32 [ 0, %entry ], [ %smax, %loop ]
+  %rdx.select = phi i32 [ 0, %entry ], [ %sel, %loop ]
+  %cmp = icmp slt i32 %val, %rdx.smax
+  %sel = select i1 %cmp, i32 %rdx.select, i32 %iv
+  %smax = tail call i32 @llvm.smax.i32(i32 %val, i32 %rdx.smax)
+  %iv.next = add nsw i32 %iv, 1
+  %ec = icmp ult i32 %iv, %n
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret i32 %sel
+}