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
| ; Specifically exercise the cost modeling for non-trivial loop unswitching.
;
; RUN: opt -passes='loop(unswitch<nontrivial>),verify<loops>' -unswitch-threshold=5 -S < %s | FileCheck %s
; RUN: opt -passes='loop-mssa(unswitch<nontrivial>),verify<loops>' -unswitch-threshold=5 -S < %s | FileCheck %s
; RUN: opt -simple-loop-unswitch -enable-nontrivial-unswitch -unswitch-threshold=5 -S < %s | FileCheck %s
; RUN: opt -simple-loop-unswitch -enable-nontrivial-unswitch -unswitch-threshold=5 -enable-mssa-loop-dependency=true -verify-memoryssa -S < %s | FileCheck %s
declare void @a()
declare void @b()
declare void @x()
; First establish enough code size in the duplicated 'loop_begin' block to
; suppress unswitching.
define void @test_no_unswitch(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_no_unswitch(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %loop_begin
;
; We shouldn't have unswitched into any other block either.
; CHECK-NOT: br i1 %cond
loop_begin:
call void @x()
call void @x()
call void @x()
call void @x()
br i1 %cond, label %loop_a, label %loop_b
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br i1 %cond, label %loop_a, label %loop_b
loop_a:
call void @a()
br label %loop_latch
loop_b:
call void @b()
br label %loop_latch
loop_latch:
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
ret void
}
; Now check that the smaller formulation of 'loop_begin' does in fact unswitch
; with our low threshold.
define void @test_unswitch(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_unswitch(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b
loop_a:
call void @a()
br label %loop_latch
; The 'loop_a' unswitched loop.
;
; CHECK: entry.split.us:
; CHECK-NEXT: br label %loop_begin.us
;
; CHECK: loop_begin.us:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_a.us
;
; CHECK: loop_a.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_latch.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
;
; CHECK: loop_exit.split.us:
; CHECK-NEXT: br label %loop_exit
loop_b:
call void @b()
br label %loop_latch
; The 'loop_b' unswitched loop.
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
;
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_b
;
; CHECK: loop_b:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: br label %loop_latch
;
; CHECK: loop_latch:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
;
; CHECK: loop_exit.split:
; CHECK-NEXT: br label %loop_exit
loop_latch:
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
ret void
; CHECK: loop_exit:
; CHECK-NEXT: ret void
}
; Check that even with large amounts of code on either side of the unswitched
; branch, if that code would be kept in only one of the unswitched clones it
; doesn't contribute to the cost.
define void @test_unswitch_non_dup_code(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_unswitch_non_dup_code(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b
loop_a:
call void @a()
call void @a()
call void @a()
call void @a()
br label %loop_latch
; The 'loop_a' unswitched loop.
;
; CHECK: entry.split.us:
; CHECK-NEXT: br label %loop_begin.us
;
; CHECK: loop_begin.us:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_a.us
;
; CHECK: loop_a.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: call void @a()
; CHECK-NEXT: call void @a()
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_latch.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
;
; CHECK: loop_exit.split.us:
; CHECK-NEXT: br label %loop_exit
loop_b:
call void @b()
call void @b()
call void @b()
call void @b()
br label %loop_latch
; The 'loop_b' unswitched loop.
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
;
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_b
;
; CHECK: loop_b:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: br label %loop_latch
;
; CHECK: loop_latch:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
;
; CHECK: loop_exit.split:
; CHECK-NEXT: br label %loop_exit
loop_latch:
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
ret void
; CHECK: loop_exit:
; CHECK-NEXT: ret void
}
; Much like with non-duplicated code directly in the successor, we also won't
; duplicate even interesting CFGs.
define void @test_unswitch_non_dup_code_in_cfg(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_unswitch_non_dup_code_in_cfg(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b
loop_a:
%v1 = load i1, i1* %ptr
br i1 %v1, label %loop_a_a, label %loop_a_b
loop_a_a:
call void @a()
br label %loop_latch
loop_a_b:
call void @a()
br label %loop_latch
; The 'loop_a' unswitched loop.
;
; CHECK: entry.split.us:
; CHECK-NEXT: br label %loop_begin.us
;
; CHECK: loop_begin.us:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_a.us
;
; CHECK: loop_a.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_a_a.us, label %loop_a_b.us
;
; CHECK: loop_a_b.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_a_a.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_latch.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
;
; CHECK: loop_exit.split.us:
; CHECK-NEXT: br label %loop_exit
loop_b:
%v2 = load i1, i1* %ptr
br i1 %v2, label %loop_b_a, label %loop_b_b
loop_b_a:
call void @b()
br label %loop_latch
loop_b_b:
call void @b()
br label %loop_latch
; The 'loop_b' unswitched loop.
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
;
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_b
;
; CHECK: loop_b:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_b_a, label %loop_b_b
;
; CHECK: loop_b_a:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: br label %loop_latch
;
; CHECK: loop_b_b:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: br label %loop_latch
;
; CHECK: loop_latch:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
;
; CHECK: loop_exit.split:
; CHECK-NEXT: br label %loop_exit
loop_latch:
%v3 = load i1, i1* %ptr
br i1 %v3, label %loop_begin, label %loop_exit
loop_exit:
ret void
; CHECK: loop_exit:
; CHECK-NEXT: ret void
}
; Check that even if there is *some* non-duplicated code on one side of an
; unswitch, we don't count any other code in the loop that will in fact have to
; be duplicated.
define void @test_no_unswitch_non_dup_code(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_no_unswitch_non_dup_code(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %loop_begin
;
; We shouldn't have unswitched into any other block either.
; CHECK-NOT: br i1 %cond
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br i1 %cond, label %loop_a, label %loop_b
loop_a:
%v1 = load i1, i1* %ptr
br i1 %v1, label %loop_a_a, label %loop_a_b
loop_a_a:
call void @a()
br label %loop_latch
loop_a_b:
call void @a()
br label %loop_latch
loop_b:
%v2 = load i1, i1* %ptr
br i1 %v2, label %loop_b_a, label %loop_b_b
loop_b_a:
call void @b()
br label %loop_latch
loop_b_b:
call void @b()
br label %loop_latch
loop_latch:
call void @x()
call void @x()
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
ret void
}
; Check that we still unswitch when the exit block contains lots of code, even
; though we do clone the exit block as part of unswitching. This should work
; because we should split the exit block before anything inside it.
define void @test_unswitch_large_exit(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_unswitch_large_exit(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b
loop_a:
call void @a()
br label %loop_latch
; The 'loop_a' unswitched loop.
;
; CHECK: entry.split.us:
; CHECK-NEXT: br label %loop_begin.us
;
; CHECK: loop_begin.us:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_a.us
;
; CHECK: loop_a.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_latch.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
;
; CHECK: loop_exit.split.us:
; CHECK-NEXT: br label %loop_exit
loop_b:
call void @b()
br label %loop_latch
; The 'loop_b' unswitched loop.
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
;
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_b
;
; CHECK: loop_b:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: br label %loop_latch
;
; CHECK: loop_latch:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
;
; CHECK: loop_exit.split:
; CHECK-NEXT: br label %loop_exit
loop_latch:
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
call void @x()
call void @x()
call void @x()
call void @x()
ret void
; CHECK: loop_exit:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: call void @x()
; CHECK-NEXT: ret void
}
; Check that we handle a dedicated exit edge unswitch which is still
; non-trivial and has lots of code in the exit.
define void @test_unswitch_dedicated_exiting(i1* %ptr, i1 %cond) {
; CHECK-LABEL: @test_unswitch_dedicated_exiting(
entry:
br label %loop_begin
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
loop_begin:
call void @x()
br i1 %cond, label %loop_a, label %loop_b_exit
loop_a:
call void @a()
br label %loop_latch
; The 'loop_a' unswitched loop.
;
; CHECK: entry.split.us:
; CHECK-NEXT: br label %loop_begin.us
;
; CHECK: loop_begin.us:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_a.us
;
; CHECK: loop_a.us:
; CHECK-NEXT: call void @a()
; CHECK-NEXT: br label %loop_latch.us
;
; CHECK: loop_latch.us:
; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
;
; CHECK: loop_exit.split.us:
; CHECK-NEXT: br label %loop_exit
loop_b_exit:
call void @b()
call void @b()
call void @b()
call void @b()
ret void
; The 'loop_b_exit' unswitched exit path.
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
;
; CHECK: loop_begin:
; CHECK-NEXT: call void @x()
; CHECK-NEXT: br label %loop_b_exit
;
; CHECK: loop_b_exit:
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: call void @b()
; CHECK-NEXT: ret void
loop_latch:
%v = load i1, i1* %ptr
br i1 %v, label %loop_begin, label %loop_exit
loop_exit:
ret void
; CHECK: loop_exit:
; CHECK-NEXT: ret void
}
|