1 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
2 ; RUN: opt < %s -passes=loop-vectorize -mcpu=corei7-avx -S -vectorizer-min-trip-count=21 | FileCheck %s
4 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
5 target triple = "x86_64-unknown-linux"
8 ; The source code for the test:
10 ; void foo(ptr restrict A, ptr restrict B)
12 ; for (int i = 0; i < 20; ++i) A[i] += B[i];
17 ; This loop will be vectorized, although the trip count is below the threshold, but
18 ; vectorization is explicitly forced in metadata. The trip count of 4 is chosen as
19 ; it more nicely divides the loop count of 20, produce a lower total cost.
21 define void @vectorized(ptr noalias nocapture %A, ptr noalias nocapture readonly %B) {
22 ; CHECK-LABEL: @vectorized(
23 ; CHECK-NEXT: iter.check:
24 ; CHECK-NEXT: br i1 false, label [[VEC_EPILOG_SCALAR_PH:%.*]], label [[VECTOR_MAIN_LOOP_ITER_CHECK:%.*]]
25 ; CHECK: vector.main.loop.iter.check:
26 ; CHECK-NEXT: br i1 false, label [[VEC_EPILOG_PH:%.*]], label [[VECTOR_PH:%.*]]
28 ; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
30 ; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
31 ; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
32 ; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds float, ptr [[B:%.*]], i64 [[TMP0]]
33 ; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds float, ptr [[TMP1]], i32 0
34 ; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds float, ptr [[TMP1]], i32 4
35 ; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds float, ptr [[TMP1]], i32 8
36 ; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds float, ptr [[TMP1]], i32 12
37 ; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x float>, ptr [[TMP2]], align 4, !llvm.access.group [[ACC_GRP0:![0-9]+]]
38 ; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = load <4 x float>, ptr [[TMP3]], align 4, !llvm.access.group [[ACC_GRP0]]
39 ; CHECK-NEXT: [[WIDE_LOAD2:%.*]] = load <4 x float>, ptr [[TMP4]], align 4, !llvm.access.group [[ACC_GRP0]]
40 ; CHECK-NEXT: [[WIDE_LOAD3:%.*]] = load <4 x float>, ptr [[TMP5]], align 4, !llvm.access.group [[ACC_GRP0]]
41 ; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds float, ptr [[A:%.*]], i64 [[TMP0]]
42 ; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds float, ptr [[TMP6]], i32 0
43 ; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds float, ptr [[TMP6]], i32 4
44 ; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds float, ptr [[TMP6]], i32 8
45 ; CHECK-NEXT: [[TMP10:%.*]] = getelementptr inbounds float, ptr [[TMP6]], i32 12
46 ; CHECK-NEXT: [[WIDE_LOAD4:%.*]] = load <4 x float>, ptr [[TMP7]], align 4, !llvm.access.group [[ACC_GRP0]]
47 ; CHECK-NEXT: [[WIDE_LOAD5:%.*]] = load <4 x float>, ptr [[TMP8]], align 4, !llvm.access.group [[ACC_GRP0]]
48 ; CHECK-NEXT: [[WIDE_LOAD6:%.*]] = load <4 x float>, ptr [[TMP9]], align 4, !llvm.access.group [[ACC_GRP0]]
49 ; CHECK-NEXT: [[WIDE_LOAD7:%.*]] = load <4 x float>, ptr [[TMP10]], align 4, !llvm.access.group [[ACC_GRP0]]
50 ; CHECK-NEXT: [[TMP11:%.*]] = fadd fast <4 x float> [[WIDE_LOAD]], [[WIDE_LOAD4]]
51 ; CHECK-NEXT: [[TMP12:%.*]] = fadd fast <4 x float> [[WIDE_LOAD1]], [[WIDE_LOAD5]]
52 ; CHECK-NEXT: [[TMP13:%.*]] = fadd fast <4 x float> [[WIDE_LOAD2]], [[WIDE_LOAD6]]
53 ; CHECK-NEXT: [[TMP14:%.*]] = fadd fast <4 x float> [[WIDE_LOAD3]], [[WIDE_LOAD7]]
54 ; CHECK-NEXT: store <4 x float> [[TMP11]], ptr [[TMP7]], align 4, !llvm.access.group [[ACC_GRP0]]
55 ; CHECK-NEXT: store <4 x float> [[TMP12]], ptr [[TMP8]], align 4, !llvm.access.group [[ACC_GRP0]]
56 ; CHECK-NEXT: store <4 x float> [[TMP13]], ptr [[TMP9]], align 4, !llvm.access.group [[ACC_GRP0]]
57 ; CHECK-NEXT: store <4 x float> [[TMP14]], ptr [[TMP10]], align 4, !llvm.access.group [[ACC_GRP0]]
58 ; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 16
59 ; CHECK-NEXT: [[TMP15:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
60 ; CHECK-NEXT: br i1 [[TMP15]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP1:![0-9]+]]
61 ; CHECK: middle.block:
62 ; CHECK-NEXT: br i1 false, label [[FOR_END:%.*]], label [[VEC_EPILOG_ITER_CHECK:%.*]]
63 ; CHECK: vec.epilog.iter.check:
64 ; CHECK-NEXT: br i1 false, label [[VEC_EPILOG_SCALAR_PH]], label [[VEC_EPILOG_PH]]
65 ; CHECK: vec.epilog.ph:
66 ; CHECK-NEXT: [[VEC_EPILOG_RESUME_VAL:%.*]] = phi i64 [ 16, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
67 ; CHECK-NEXT: br label [[VEC_EPILOG_VECTOR_BODY:%.*]]
68 ; CHECK: vec.epilog.vector.body:
69 ; CHECK-NEXT: [[INDEX8:%.*]] = phi i64 [ [[VEC_EPILOG_RESUME_VAL]], [[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT11:%.*]], [[VEC_EPILOG_VECTOR_BODY]] ]
70 ; CHECK-NEXT: [[TMP16:%.*]] = add i64 [[INDEX8]], 0
71 ; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[TMP16]]
72 ; CHECK-NEXT: [[TMP18:%.*]] = getelementptr inbounds float, ptr [[TMP17]], i32 0
73 ; CHECK-NEXT: [[WIDE_LOAD9:%.*]] = load <4 x float>, ptr [[TMP18]], align 4, !llvm.access.group [[ACC_GRP0]]
74 ; CHECK-NEXT: [[TMP19:%.*]] = getelementptr inbounds float, ptr [[A]], i64 [[TMP16]]
75 ; CHECK-NEXT: [[TMP20:%.*]] = getelementptr inbounds float, ptr [[TMP19]], i32 0
76 ; CHECK-NEXT: [[WIDE_LOAD10:%.*]] = load <4 x float>, ptr [[TMP20]], align 4, !llvm.access.group [[ACC_GRP0]]
77 ; CHECK-NEXT: [[TMP21:%.*]] = fadd fast <4 x float> [[WIDE_LOAD9]], [[WIDE_LOAD10]]
78 ; CHECK-NEXT: store <4 x float> [[TMP21]], ptr [[TMP20]], align 4, !llvm.access.group [[ACC_GRP0]]
79 ; CHECK-NEXT: [[INDEX_NEXT11]] = add nuw i64 [[INDEX8]], 4
80 ; CHECK-NEXT: [[TMP22:%.*]] = icmp eq i64 [[INDEX_NEXT11]], 20
81 ; CHECK-NEXT: br i1 [[TMP22]], label [[VEC_EPILOG_MIDDLE_BLOCK:%.*]], label [[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP5:![0-9]+]]
82 ; CHECK: vec.epilog.middle.block:
83 ; CHECK-NEXT: br i1 true, label [[FOR_END]], label [[VEC_EPILOG_SCALAR_PH]]
84 ; CHECK: vec.epilog.scalar.ph:
85 ; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 20, [[VEC_EPILOG_MIDDLE_BLOCK]] ], [ 16, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[ITER_CHECK:%.*]] ]
86 ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
88 ; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[VEC_EPILOG_SCALAR_PH]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
89 ; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[INDVARS_IV]]
90 ; CHECK-NEXT: [[TMP23:%.*]] = load float, ptr [[ARRAYIDX]], align 4, !llvm.access.group [[ACC_GRP0]]
91 ; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds float, ptr [[A]], i64 [[INDVARS_IV]]
92 ; CHECK-NEXT: [[TMP24:%.*]] = load float, ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP0]]
93 ; CHECK-NEXT: [[ADD:%.*]] = fadd fast float [[TMP23]], [[TMP24]]
94 ; CHECK-NEXT: store float [[ADD]], ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP0]]
95 ; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
96 ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 20
97 ; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
99 ; CHECK-NEXT: ret void
105 %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
106 %arrayidx = getelementptr inbounds float, ptr %B, i64 %indvars.iv
107 %0 = load float, ptr %arrayidx, align 4, !llvm.access.group !11
108 %arrayidx2 = getelementptr inbounds float, ptr %A, i64 %indvars.iv
109 %1 = load float, ptr %arrayidx2, align 4, !llvm.access.group !11
110 %add = fadd fast float %0, %1
111 store float %add, ptr %arrayidx2, align 4, !llvm.access.group !11
112 %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
113 %exitcond = icmp eq i64 %indvars.iv.next, 20
114 br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !1
120 !1 = !{!1, !2, !{!"llvm.loop.parallel_accesses", !11}}
121 !2 = !{!"llvm.loop.vectorize.enable", i1 true}
125 ; This loop will be vectorized as the trip count is below the threshold but no
126 ; scalar iterations are needed thanks to folding its tail.
128 define void @vectorized1(ptr noalias nocapture %A, ptr noalias nocapture readonly %B) {
129 ; CHECK-LABEL: @vectorized1(
131 ; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
133 ; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
134 ; CHECK: vector.body:
135 ; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
136 ; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
137 ; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <8 x i64> poison, i64 [[INDEX]], i64 0
138 ; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <8 x i64> [[BROADCAST_SPLATINSERT]], <8 x i64> poison, <8 x i32> zeroinitializer
139 ; CHECK-NEXT: [[VEC_IV:%.*]] = add <8 x i64> [[BROADCAST_SPLAT]], <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7>
140 ; CHECK-NEXT: [[TMP1:%.*]] = icmp ule <8 x i64> [[VEC_IV]], splat (i64 19)
141 ; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds float, ptr [[B:%.*]], i64 [[TMP0]]
142 ; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds float, ptr [[TMP2]], i32 0
143 ; CHECK-NEXT: [[WIDE_MASKED_LOAD:%.*]] = call <8 x float> @llvm.masked.load.v8f32.p0(ptr [[TMP3]], i32 4, <8 x i1> [[TMP1]], <8 x float> poison), !llvm.access.group [[ACC_GRP7:![0-9]+]]
144 ; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds float, ptr [[A:%.*]], i64 [[TMP0]]
145 ; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds float, ptr [[TMP4]], i32 0
146 ; CHECK-NEXT: [[WIDE_MASKED_LOAD1:%.*]] = call <8 x float> @llvm.masked.load.v8f32.p0(ptr [[TMP5]], i32 4, <8 x i1> [[TMP1]], <8 x float> poison), !llvm.access.group [[ACC_GRP7]]
147 ; CHECK-NEXT: [[TMP6:%.*]] = fadd fast <8 x float> [[WIDE_MASKED_LOAD]], [[WIDE_MASKED_LOAD1]]
148 ; CHECK-NEXT: call void @llvm.masked.store.v8f32.p0(<8 x float> [[TMP6]], ptr [[TMP5]], i32 4, <8 x i1> [[TMP1]]), !llvm.access.group [[ACC_GRP7]]
149 ; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 8
150 ; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i64 [[INDEX_NEXT]], 24
151 ; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
152 ; CHECK: middle.block:
153 ; CHECK-NEXT: br i1 true, label [[FOR_END:%.*]], label [[SCALAR_PH]]
155 ; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 24, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
156 ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
158 ; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
159 ; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[INDVARS_IV]]
160 ; CHECK-NEXT: [[TMP8:%.*]] = load float, ptr [[ARRAYIDX]], align 4, !llvm.access.group [[ACC_GRP7]]
161 ; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds float, ptr [[A]], i64 [[INDVARS_IV]]
162 ; CHECK-NEXT: [[TMP9:%.*]] = load float, ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP7]]
163 ; CHECK-NEXT: [[ADD:%.*]] = fadd fast float [[TMP8]], [[TMP9]]
164 ; CHECK-NEXT: store float [[ADD]], ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP7]]
165 ; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
166 ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 20
167 ; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP10:![0-9]+]]
169 ; CHECK-NEXT: ret void
175 %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
176 %arrayidx = getelementptr inbounds float, ptr %B, i64 %indvars.iv
177 %0 = load float, ptr %arrayidx, align 4, !llvm.access.group !13
178 %arrayidx2 = getelementptr inbounds float, ptr %A, i64 %indvars.iv
179 %1 = load float, ptr %arrayidx2, align 4, !llvm.access.group !13
180 %add = fadd fast float %0, %1
181 store float %add, ptr %arrayidx2, align 4, !llvm.access.group !13
182 %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
183 %exitcond = icmp eq i64 %indvars.iv.next, 20
184 br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !3
190 !3 = !{!3, !{!"llvm.loop.parallel_accesses", !13}}
194 ; This loop will be vectorized as the trip count is below the threshold but no
195 ; scalar iterations are needed.
197 define void @vectorized2(ptr noalias nocapture %A, ptr noalias nocapture readonly %B) {
198 ; CHECK-LABEL: @vectorized2(
200 ; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
202 ; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
203 ; CHECK: vector.body:
204 ; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
205 ; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
206 ; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds float, ptr [[B:%.*]], i64 [[TMP0]]
207 ; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds float, ptr [[TMP1]], i32 0
208 ; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <8 x float>, ptr [[TMP2]], align 4, !llvm.access.group [[ACC_GRP7]]
209 ; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds float, ptr [[A:%.*]], i64 [[TMP0]]
210 ; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds float, ptr [[TMP3]], i32 0
211 ; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = load <8 x float>, ptr [[TMP4]], align 4, !llvm.access.group [[ACC_GRP7]]
212 ; CHECK-NEXT: [[TMP5:%.*]] = fadd fast <8 x float> [[WIDE_LOAD]], [[WIDE_LOAD1]]
213 ; CHECK-NEXT: store <8 x float> [[TMP5]], ptr [[TMP4]], align 4, !llvm.access.group [[ACC_GRP7]]
214 ; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 8
215 ; CHECK-NEXT: [[TMP6:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
216 ; CHECK-NEXT: br i1 [[TMP6]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP11:![0-9]+]]
217 ; CHECK: middle.block:
218 ; CHECK-NEXT: br i1 true, label [[FOR_END:%.*]], label [[SCALAR_PH]]
220 ; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 16, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
221 ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
223 ; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
224 ; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[INDVARS_IV]]
225 ; CHECK-NEXT: [[TMP7:%.*]] = load float, ptr [[ARRAYIDX]], align 4, !llvm.access.group [[ACC_GRP7]]
226 ; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds float, ptr [[A]], i64 [[INDVARS_IV]]
227 ; CHECK-NEXT: [[TMP8:%.*]] = load float, ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP7]]
228 ; CHECK-NEXT: [[ADD:%.*]] = fadd fast float [[TMP7]], [[TMP8]]
229 ; CHECK-NEXT: store float [[ADD]], ptr [[ARRAYIDX2]], align 4, !llvm.access.group [[ACC_GRP7]]
230 ; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
231 ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 16
232 ; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP12:![0-9]+]]
234 ; CHECK-NEXT: ret void
240 %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
241 %arrayidx = getelementptr inbounds float, ptr %B, i64 %indvars.iv
242 %0 = load float, ptr %arrayidx, align 4, !llvm.access.group !13
243 %arrayidx2 = getelementptr inbounds float, ptr %A, i64 %indvars.iv
244 %1 = load float, ptr %arrayidx2, align 4, !llvm.access.group !13
245 %add = fadd fast float %0, %1
246 store float %add, ptr %arrayidx2, align 4, !llvm.access.group !13
247 %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
248 %exitcond = icmp eq i64 %indvars.iv.next, 16
249 br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !4