llvm.org GIT mirror llvm / release_80 test / Analysis / ScalarEvolution / flags-from-poison.ll
release_80

Tree @release_80 (Download .tar.gz)

flags-from-poison.ll @release_80raw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
; RUN: opt < %s -S -analyze -scalar-evolution | FileCheck %s

; Positive and negative tests for inferring flags like nsw from
; reasoning about how a poison value from overflow would trigger
; undefined behavior.

define void @foo() {
  ret void
}

; Example where an add should get the nsw flag, so that a sext can be
; distributed over the add.
define void @test-add-nsw(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-nsw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

; CHECK: %index64 =
; CHECK: --> {(sext i32 %offset to i64),+,1}<nsw>
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  call void @foo()
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example where an add should get the nuw flag.
define void @test-add-nuw(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-nuw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nuw>
  %index32 = add nuw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nuw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

exit:
  ret void
}

define void @test-add-nuw-from-icmp(float* %input, i32 %offset,
                                    i32 %numIterations) {
; CHECK-LABEL: @test-add-nuw-from-icmp
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nuw>
  %index32 = add nuw i32 %i, %offset
  %cmp = icmp sgt i32 %index32, 0
  %cmp.idx = sext i1 %cmp to i32

  %ptr = getelementptr inbounds float, float* %input, i32 %cmp.idx
  %nexti = add nuw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

exit:
  ret void
}

; With no load to trigger UB from poison, we cannot infer nsw.
define void @test-add-no-load(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-no-load
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nuw i32 %i, 1
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

exit:
  ret void
}

; The current code is only supposed to look at the loop header, so
; it should not infer nsw in this case, as that would require looking
; outside the loop header.
define void @test-add-not-header(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-not-header
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]
  br label %loop2
loop2:

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Same thing as test-add-not-header, but in this case only the load
; instruction is outside the loop header.
define void @test-add-not-header2(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-not-header2
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  br label %loop2
loop2:
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Similar to test-add-not-header, but in this case the load
; instruction may not be executed.
define void @test-add-not-header3(float* %input, i32 %offset, i32 %numIterations,
                                 i1* %cond_buf) {
; CHECK-LABEL: @test-add-not-header3
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  %cond = load volatile i1, i1* %cond_buf
  br i1 %cond, label %loop2, label %exit
loop2:
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Same thing as test-add-not-header2, except we have a few extra
; blocks.
define void @test-add-not-header4(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-not-header4
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  br label %loop3
loop3:
  br label %loop4
loop4:
  br label %loop2
loop2:
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Demonstrate why we need a Visited set in llvm::programUndefinedIfFullPoison.
define void @test-add-not-header5(float* %input, i32 %offset) {
; CHECK-LABEL: @test-add-not-header5
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  br label %loop

exit:
  ret void
}

; The call instruction makes it not guaranteed that the add will be
; executed, since it could run forever or throw an exception, so we
; cannot assume that the UB is realized.
define void @test-add-call(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-call
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  call void @foo()
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Same issue as test-add-call, but this time the call is between the
; producer of poison and the load that consumes it.
define void @test-add-call2(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-call2
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  call void @foo()
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Any poison input makes getelementptr produce poison
define void @test-gep-propagates-poison(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-gep-propagates-poison
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Multiplication by a non-zero constant propagates poison if there is
; a nuw or nsw flag on the multiplication.
define void @test-add-mul-propagates(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-mul-propagates
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %indexmul = mul nuw i32 %index32, 2
  %ptr = getelementptr inbounds float, float* %input, i32 %indexmul
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Any poison input to multiplication propages poison.
define void @test-mul-propagates-poison(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-mul-propagates-poison
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %indexmul = mul nsw i32 %index32, %offset
  %ptr = getelementptr inbounds float, float* %input, i32 %indexmul
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

define void @test-mul-propagates-poison-2(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-mul-propagates-poison-2
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %indexmul = mul i32 %index32, 2
  %ptr = getelementptr inbounds float, float* %input, i32 %indexmul
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Division by poison triggers UB.
define void @test-add-div(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-div
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %j =
; CHECK: --> {%offset,+,1}<nsw>
  %j = add nsw i32 %i, %offset

  %q = sdiv i32 %numIterations, %j
  %nexti = add nsw i32 %i, 1
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Remainder of poison by non-poison divisor does not trigger UB.
define void @test-add-div2(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-div2
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %j =
; CHECK: --> {%offset,+,1}<nw>
  %j = add nsw i32 %i, %offset

  %q = sdiv i32 %j, %numIterations
  %nexti = add nsw i32 %i, 1
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Store to poison address triggers UB.
define void @test-add-store(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-store
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {%offset,+,1}<nsw>
  %index32 = add nsw i32 %i, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  store float 1.0, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Three sequential adds where the middle add should have nsw. There is
; a special case for sequential adds and this test covers that. We have to
; put the final add first in the program since otherwise the special case
; is not triggered, hence the strange basic block ordering.
define void @test-add-twice(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-add-twice
entry:
  br label %loop
loop2:
; CHECK: %seq =
; CHECK: --> {(2 + %offset),+,1}<nw>
  %seq = add nsw nuw i32 %index32, 1
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]

  %j = add nsw i32 %i, 1
; CHECK: %index32 =
; CHECK: --> {(1 + %offset)<nsw>,+,1}<nsw>
  %index32 = add nsw i32 %j, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  store float 1.0, float* %ptr, align 4
  br label %loop2
exit:
  ret void
}

; Example where a mul should get the nsw flag, so that a sext can be
; distributed over the mul.
define void @test-mul-nsw(float* %input, i32 %stride, i32 %numIterations) {
; CHECK-LABEL: @test-mul-nsw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {0,+,%stride}<nsw>
  %index32 = mul nsw i32 %i, %stride

; CHECK: %index64 =
; CHECK: --> {0,+,(sext i32 %stride to i64)}<nsw>
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example where a mul should get the nuw flag.
define void @test-mul-nuw(float* %input, i32 %stride, i32 %numIterations) {
; CHECK-LABEL: @test-mul-nuw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {0,+,%stride}<nuw>
  %index32 = mul nuw i32 %i, %stride

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nuw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

exit:
  ret void
}

; Example where a shl should get the nsw flag, so that a sext can be
; distributed over the shl.
define void @test-shl-nsw(float* %input, i32 %start, i32 %numIterations) {
; CHECK-LABEL: @test-shl-nsw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ %start, %entry ]

; CHECK: %index32 =
; CHECK: --> {(256 * %start),+,256}<nsw>
  %index32 = shl nsw i32 %i, 8

; CHECK: %index64 =
; CHECK: --> {(sext i32 (256 * %start) to i64),+,256}<nsw>
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example where a shl should get the nuw flag.
define void @test-shl-nuw(float* %input, i32 %numIterations) {
; CHECK-LABEL: @test-shl-nuw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {0,+,512}<nuw>
  %index32 = shl nuw i32 %i, 9

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nuw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

exit:
  ret void
}

; Example where a sub should *not* get the nsw flag, because of how
; scalar evolution represents A - B as A + (-B) and -B can wrap even
; in cases where A - B does not.
define void @test-sub-no-nsw(float* %input, i32 %start, i32 %sub, i32 %numIterations) {
; CHECK-LABEL: @test-sub-no-nsw
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ %start, %entry ]

; CHECK: %index32 =
; CHECK: --> {((-1 * %sub) + %start),+,1}<nw>
  %index32 = sub nsw i32 %i, %sub
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example where a sub should get the nsw flag as the RHS cannot be the
; minimal signed value.
define void @test-sub-nsw(float* %input, i32 %start, i32 %sub, i32 %numIterations) {
; CHECK-LABEL: @test-sub-nsw
entry:
  %halfsub = ashr i32 %sub, 1
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ %start, %entry ]

; CHECK: %index32 =
; CHECK: --> {((-1 * %halfsub)<nsw> + %start)<nsw>,+,1}<nsw>
  %index32 = sub nsw i32 %i, %halfsub
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example where a sub should get the nsw flag, since the LHS is non-negative,
; which implies that the RHS cannot be the minimal signed value.
define void @test-sub-nsw-lhs-non-negative(float* %input, i32 %sub, i32 %numIterations) {
; CHECK-LABEL: @test-sub-nsw-lhs-non-negative
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %loop ], [ 0, %entry ]

; CHECK: %index32 =
; CHECK: --> {(-1 * %sub),+,1}<nsw>
  %index32 = sub nsw i32 %i, %sub

; CHECK: %index64 =
; CHECK: --> {(-1 * (sext i32 %sub to i64))<nsw>,+,1}<nsw
  %index64 = sext i32 %index32 to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Example checking that a sext is pushed onto a sub's operands if the sub is an
; overflow intrinsic.
define void @test-sext-sub(float* %input, i32 %sub, i32 %numIterations) {
; CHECK-LABEL: @test-sext-sub
entry:
  br label %loop
loop:
  %i = phi i32 [ %nexti, %cont ], [ 0, %entry ]

; CHECK: %val = extractvalue { i32, i1 } %ssub, 0
; CHECK: --> {(-1 * %sub),+,1}<nw>
  %ssub = tail call { i32, i1 } @llvm.ssub.with.overflow.i32(i32 %i, i32 %sub)
  %val = extractvalue { i32, i1 } %ssub, 0
  %ovfl = extractvalue { i32, i1 } %ssub, 1
  br i1 %ovfl, label %trap, label %cont

trap:
  tail call void @llvm.trap()
  unreachable

cont:
; CHECK: %index64 =
; CHECK: --> {(-1 * (sext i32 %sub to i64))<nsw>,+,1}<nsw
  %index64 = sext i32 %val to i64

  %ptr = getelementptr inbounds float, float* %input, i64 %index64
  %nexti = add nsw i32 %i, 1
  %f = load float, float* %ptr, align 4
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop
exit:
  ret void
}

; Two adds with a sub in the middle and the sub should have nsw. There is
; a special case for sequential adds/subs and this test covers that. We have to
; put the final add first in the program since otherwise the special case
; is not triggered, hence the strange basic block ordering.
define void @test-sub-with-add(float* %input, i32 %offset, i32 %numIterations) {
; CHECK-LABEL: @test-sub-with-add
entry:
  br label %loop
loop2:
; CHECK: %seq =
; CHECK: --> {(2 + (-1 * %offset)),+,1}<nw>
  %seq = add nsw nuw i32 %index32, 1
  %exitcond = icmp eq i32 %nexti, %numIterations
  br i1 %exitcond, label %exit, label %loop

loop:
  %i = phi i32 [ %nexti, %loop2 ], [ 0, %entry ]

  %j = add nsw i32 %i, 1
; CHECK: %index32 =
; CHECK: --> {(1 + (-1 * %offset))<nsw>,+,1}<nsw>
  %index32 = sub nsw i32 %j, %offset

  %ptr = getelementptr inbounds float, float* %input, i32 %index32
  %nexti = add nsw i32 %i, 1
  store float 1.0, float* %ptr, align 4
  br label %loop2
exit:
  ret void
}


; Subtraction of two recurrences. The addition in the SCEV that this
; maps to is NSW, but the negation of the RHS does not since that
; recurrence could be the most negative representable value.
define void @subrecurrences(i32 %outer_l, i32 %inner_l, i32 %val) {
; CHECK-LABEL: @subrecurrences
 entry:
  br label %outer

outer:
  %o_idx = phi i32 [ 0, %entry ], [ %o_idx.inc, %outer.be ]
  %o_idx.inc = add nsw i32 %o_idx, 1
  %cond = icmp eq i32 %o_idx, %val
  br i1 %cond, label %inner, label %outer.be

inner:
  %i_idx = phi i32 [ 0, %outer ], [ %i_idx.inc, %inner ]
  %i_idx.inc = add nsw i32 %i_idx, 1
; CHECK: %v =
; CHECK-NEXT: --> {{[{][{]}}-1,+,-1}<nw><%outer>,+,1}<nsw><%inner>
  %v = sub nsw i32 %i_idx, %o_idx.inc
  %forub = udiv i32 1, %v
  %cond2 = icmp eq i32 %i_idx, %inner_l
  br i1 %cond2, label %outer.be, label %inner

outer.be:
  %cond3 = icmp eq i32 %o_idx, %outer_l
  br i1 %cond3, label %exit, label %outer

exit:
  ret void
}


; PR28932: Don't assert on non-SCEV-able value %2.
%struct.anon = type { i8* }
@a = common global %struct.anon* null, align 8
@b = common global i32 0, align 4
declare { i32, i1 } @llvm.ssub.with.overflow.i32(i32, i32)
declare void @llvm.trap()
define i32 @pr28932() {
entry:
  %.pre = load %struct.anon*, %struct.anon** @a, align 8
  %.pre7 = load i32, i32* @b, align 4
  br label %for.cond

for.cond:                                         ; preds = %cont6, %entry
  %0 = phi i32 [ %3, %cont6 ], [ %.pre7, %entry ]
  %1 = phi %struct.anon* [ %.ph, %cont6 ], [ %.pre, %entry ]
  %tobool = icmp eq %struct.anon* %1, null
  %2 = tail call { i32, i1 } @llvm.ssub.with.overflow.i32(i32 %0, i32 1)
  %3 = extractvalue { i32, i1 } %2, 0
  %4 = extractvalue { i32, i1 } %2, 1
  %idxprom = sext i32 %3 to i64
  %5 = getelementptr inbounds %struct.anon, %struct.anon* %1, i64 0, i32 0
  %6 = load i8*, i8** %5, align 8
  %7 = getelementptr inbounds i8, i8* %6, i64 %idxprom
  %8 = load i8, i8* %7, align 1
  br i1 %tobool, label %if.else, label %if.then

if.then:                                          ; preds = %for.cond
  br i1 %4, label %trap, label %cont6

trap:                                             ; preds = %if.else, %if.then
  tail call void @llvm.trap()
  unreachable

if.else:                                          ; preds = %for.cond
  br i1 %4, label %trap, label %cont1

cont1:                                            ; preds = %if.else
  %conv5 = sext i8 %8 to i64
  %9 = inttoptr i64 %conv5 to %struct.anon*
  store %struct.anon* %9, %struct.anon** @a, align 8
  br label %cont6

cont6:                                            ; preds = %cont1, %if.then
  %.ph = phi %struct.anon* [ %9, %cont1 ], [ %1, %if.then ]
  store i32 %3, i32* @b, align 4
  br label %for.cond
}