1 ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s 2 3 ; ScalarEvolution should be able to understand the loop and eliminate the casts. 4 5 ; CHECK: {%d,+,4} 6 7 define void @foo(i32* nocapture %d, i32 %n) nounwind { 8 entry: 9 %0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1] 10 br i1 %0, label %bb.nph, label %return 11 12 bb.nph: ; preds = %entry 13 br label %bb 14 15 bb: ; preds = %bb1, %bb.nph 16 %i.02 = phi i32 [ %5, %bb1 ], [ 0, %bb.nph ] ; <i32> [#uses=2] 17 %p.01 = phi i8 [ %4, %bb1 ], [ -1, %bb.nph ] ; <i8> [#uses=2] 18 %1 = sext i8 %p.01 to i32 ; <i32> [#uses=1] 19 %2 = sext i32 %i.02 to i64 ; <i64> [#uses=1] 20 %3 = getelementptr i32, i32* %d, i64 %2 ; <i32*> [#uses=1] 21 store i32 %1, i32* %3, align 4 22 %4 = add i8 %p.01, 1 ; <i8> [#uses=1] 23 %5 = add i32 %i.02, 1 ; <i32> [#uses=2] 24 br label %bb1 25 26 bb1: ; preds = %bb 27 %6 = icmp slt i32 %5, %n ; <i1> [#uses=1] 28 br i1 %6, label %bb, label %bb1.return_crit_edge 29 30 bb1.return_crit_edge: ; preds = %bb1 31 br label %return 32 33 return: ; preds = %bb1.return_crit_edge, %entry 34 ret void 35 } 36 37 ; ScalarEvolution should be able to find the maximum tripcount 38 ; of this multiple-exit loop, and if it doesn't know the exact 39 ; count, it should say so. 40 41 ; PR7845 42 ; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count. 43 ; CHECK: Loop %for.cond: max backedge-taken count is 5 44 45 @.str = private constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=2] 46 47 define i32 @main() nounwind { 48 entry: 49 br label %for.cond 50 51 for.cond: ; preds = %for.inc, %entry 52 %g_4.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] ; <i32> [#uses=5] 53 %cmp = icmp slt i32 %g_4.0, 5 ; <i1> [#uses=1] 54 br i1 %cmp, label %for.body, label %for.end 55 56 for.body: ; preds = %for.cond 57 %conv = trunc i32 %g_4.0 to i16 ; <i16> [#uses=1] 58 %tobool.not = icmp eq i16 %conv, 0 ; <i1> [#uses=1] 59 %tobool3 = icmp ne i32 %g_4.0, 0 ; <i1> [#uses=1] 60 %or.cond = and i1 %tobool.not, %tobool3 ; <i1> [#uses=1] 61 br i1 %or.cond, label %for.end, label %for.inc 62 63 for.inc: ; preds = %for.body 64 %add = add nsw i32 %g_4.0, 1 ; <i32> [#uses=1] 65 br label %for.cond 66 67 for.end: ; preds = %for.body, %for.cond 68 %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i32 %g_4.0) nounwind ; <i32> [#uses=0] 69 ret i32 0 70 } 71 72 declare i32 @printf(i8*, ...) 73 74 define void @test(i8* %a, i32 %n) nounwind { 75 entry: 76 %cmp1 = icmp sgt i32 %n, 0 77 br i1 %cmp1, label %for.body.lr.ph, label %for.end 78 79 for.body.lr.ph: ; preds = %entry 80 %tmp = zext i32 %n to i64 81 br label %for.body 82 83 for.body: ; preds = %for.body, %for.body.lr.ph 84 %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.lr.ph ] 85 %arrayidx = getelementptr i8, i8* %a, i64 %indvar 86 store i8 0, i8* %arrayidx, align 1 87 %indvar.next = add i64 %indvar, 1 88 %exitcond = icmp ne i64 %indvar.next, %tmp 89 br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge 90 91 for.cond.for.end_crit_edge: ; preds = %for.body 92 br label %for.end 93 94 for.end: ; preds = %for.cond.for.end_crit_edge, %entry 95 ret void 96 } 97 98 ; CHECK: Determining loop execution counts for: @test 99 ; CHECK-NEXT: backedge-taken count is 100 ; CHECK-NEXT: max backedge-taken count is -1 101 102 ; PR19799: Indvars miscompile due to an incorrect max backedge taken count from SCEV. 103 ; CHECK-LABEL: @pr19799 104 ; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count. 105 ; CHECK: Loop %for.body.i: max backedge-taken count is 1 106 @a = common global i32 0, align 4 107 108 define i32 @pr19799() { 109 entry: 110 store i32 -1, i32* @a, align 4 111 br label %for.body.i 112 113 for.body.i: ; preds = %for.cond.i, %entry 114 %storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ] 115 %tobool.i = icmp eq i32 %storemerge1.i, 0 116 %add.i.i = add nsw i32 %storemerge1.i, 2 117 br i1 %tobool.i, label %bar.exit, label %for.cond.i 118 119 for.cond.i: ; preds = %for.body.i 120 store i32 %add.i.i, i32* @a, align 4 121 %cmp.i = icmp slt i32 %storemerge1.i, 0 122 br i1 %cmp.i, label %for.body.i, label %bar.exit 123 124 bar.exit: ; preds = %for.cond.i, %for.body.i 125 ret i32 0 126 } 127 128 ; PR18886: Indvars miscompile due to an incorrect max backedge taken count from SCEV. 129 ; CHECK-LABEL: @pr18886 130 ; CHECK: Loop %for.body: <multiple exits> Unpredictable backedge-taken count. 131 ; CHECK: Loop %for.body: max backedge-taken count is 3 132 @aa = global i64 0, align 8 133 134 define i32 @pr18886() { 135 entry: 136 store i64 -21, i64* @aa, align 8 137 br label %for.body 138 139 for.body: 140 %storemerge1 = phi i64 [ -21, %entry ], [ %add, %for.cond ] 141 %tobool = icmp eq i64 %storemerge1, 0 142 %add = add nsw i64 %storemerge1, 8 143 br i1 %tobool, label %return, label %for.cond 144 145 for.cond: 146 store i64 %add, i64* @aa, align 8 147 %cmp = icmp slt i64 %add, 9 148 br i1 %cmp, label %for.body, label %return 149 150 return: 151 %retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ] 152 ret i32 %retval.0 153 } 154 155 ; Here we have a must-exit loop latch that is not computable and a 156 ; may-exit early exit that can only have one non-exiting iteration 157 ; before the check is forever skipped. 158 ; 159 ; CHECK-LABEL: @cannot_compute_mustexit 160 ; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count. 161 ; CHECK: Loop %for.body.i: Unpredictable max backedge-taken count. 162 @b = common global i32 0, align 4 163 164 define i32 @cannot_compute_mustexit() { 165 entry: 166 store i32 -1, i32* @a, align 4 167 br label %for.body.i 168 169 for.body.i: ; preds = %for.cond.i, %entry 170 %storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ] 171 %tobool.i = icmp eq i32 %storemerge1.i, 0 172 %add.i.i = add nsw i32 %storemerge1.i, 2 173 br i1 %tobool.i, label %bar.exit, label %for.cond.i 174 175 for.cond.i: ; preds = %for.body.i 176 store i32 %add.i.i, i32* @a, align 4 177 %ld = load volatile i32, i32* @b 178 %cmp.i = icmp ne i32 %ld, 0 179 br i1 %cmp.i, label %for.body.i, label %bar.exit 180 181 bar.exit: ; preds = %for.cond.i, %for.body.i 182 ret i32 0 183 } 184 185 ; This loop has two must-exits, both of which dominate the latch. The 186 ; MaxBECount should be the minimum of them. 187 ; 188 ; CHECK-LABEL: @two_mustexit 189 ; CHECK: Loop %for.body.i: <multiple exits> backedge-taken count is 1 190 ; CHECK: Loop %for.body.i: max backedge-taken count is 1 191 define i32 @two_mustexit() { 192 entry: 193 store i32 -1, i32* @a, align 4 194 br label %for.body.i 195 196 for.body.i: ; preds = %for.cond.i, %entry 197 %storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ] 198 %tobool.i = icmp sgt i32 %storemerge1.i, 0 199 %add.i.i = add nsw i32 %storemerge1.i, 2 200 br i1 %tobool.i, label %bar.exit, label %for.cond.i 201 202 for.cond.i: ; preds = %for.body.i 203 store i32 %add.i.i, i32* @a, align 4 204 %cmp.i = icmp slt i32 %storemerge1.i, 3 205 br i1 %cmp.i, label %for.body.i, label %bar.exit 206 207 bar.exit: ; preds = %for.cond.i, %for.body.i 208 ret i32 0 209 } 210 211 ; CHECK-LABEL: @ne_max_trip_count_1 212 ; CHECK: Loop %for.body: max backedge-taken count is 7 213 define i32 @ne_max_trip_count_1(i32 %n) { 214 entry: 215 %masked = and i32 %n, 7 216 br label %for.body 217 218 for.body: 219 %i = phi i32 [ 0, %entry ], [ %add, %for.body ] 220 %add = add nsw i32 %i, 1 221 %cmp = icmp ne i32 %i, %masked 222 br i1 %cmp, label %for.body, label %bar.exit 223 224 bar.exit: 225 ret i32 0 226 } 227 228 ; CHECK-LABEL: @ne_max_trip_count_2 229 ; CHECK: Loop %for.body: max backedge-taken count is -1 230 define i32 @ne_max_trip_count_2(i32 %n) { 231 entry: 232 %masked = and i32 %n, 7 233 br label %for.body 234 235 for.body: 236 %i = phi i32 [ 0, %entry ], [ %add, %for.body ] 237 %add = add nsw i32 %i, 1 238 %cmp = icmp ne i32 %add, %masked 239 br i1 %cmp, label %for.body, label %bar.exit 240 241 bar.exit: 242 ret i32 0 243 } 244 245 ; CHECK-LABEL: @ne_max_trip_count_3 246 ; CHECK: Loop %for.body: max backedge-taken count is 6 247 define i32 @ne_max_trip_count_3(i32 %n) { 248 entry: 249 %masked = and i32 %n, 7 250 %guard = icmp eq i32 %masked, 0 251 br i1 %guard, label %exit, label %for.preheader 252 253 for.preheader: 254 br label %for.body 255 256 for.body: 257 %i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ] 258 %add = add nsw i32 %i, 1 259 %cmp = icmp ne i32 %add, %masked 260 br i1 %cmp, label %for.body, label %loop.exit 261 262 loop.exit: 263 br label %exit 264 265 exit: 266 ret i32 0 267 } 268 269 ; CHECK-LABEL: @ne_max_trip_count_4 270 ; CHECK: Loop %for.body: max backedge-taken count is -2 271 define i32 @ne_max_trip_count_4(i32 %n) { 272 entry: 273 %guard = icmp eq i32 %n, 0 274 br i1 %guard, label %exit, label %for.preheader 275 276 for.preheader: 277 br label %for.body 278 279 for.body: 280 %i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ] 281 %add = add nsw i32 %i, 1 282 %cmp = icmp ne i32 %add, %n 283 br i1 %cmp, label %for.body, label %loop.exit 284 285 loop.exit: 286 br label %exit 287 288 exit: 289 ret i32 0 290 } 291 292 ; The end bound of the loop can change between iterations, so the exact trip 293 ; count is unknown, but SCEV can calculate the max trip count. 294 define void @changing_end_bound(i32* %n_addr, i32* %addr) { 295 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound 296 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 297 ; CHECK: Loop %loop: max backedge-taken count is 2147483646 298 entry: 299 br label %loop 300 301 loop: 302 %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ] 303 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 304 %val = load atomic i32, i32* %addr unordered, align 4 305 fence acquire 306 %acc.next = add i32 %acc, %val 307 %iv.next = add nsw i32 %iv, 1 308 %n = load atomic i32, i32* %n_addr unordered, align 4 309 %cmp = icmp slt i32 %iv.next, %n 310 br i1 %cmp, label %loop, label %loop.exit 311 312 loop.exit: 313 ret void 314 } 315 316 ; Similar test as above, but unknown start value. 317 ; Also, there's no nsw on the iv.next, but SCEV knows 318 ; the termination condition is LT, so the IV cannot wrap. 319 define void @changing_end_bound2(i32 %start, i32* %n_addr, i32* %addr) { 320 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound2 321 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 322 ; CHECK: Loop %loop: max backedge-taken count is -1 323 entry: 324 br label %loop 325 326 loop: 327 %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ] 328 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 329 %val = load atomic i32, i32* %addr unordered, align 4 330 fence acquire 331 %acc.next = add i32 %acc, %val 332 %iv.next = add i32 %iv, 1 333 %n = load atomic i32, i32* %n_addr unordered, align 4 334 %cmp = icmp slt i32 %iv.next, %n 335 br i1 %cmp, label %loop, label %loop.exit 336 337 loop.exit: 338 ret void 339 } 340 341 ; changing end bound and greater than one stride 342 define void @changing_end_bound3(i32 %start, i32* %n_addr, i32* %addr) { 343 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound3 344 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 345 ; CHECK: Loop %loop: max backedge-taken count is 1073741823 346 entry: 347 br label %loop 348 349 loop: 350 %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ] 351 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 352 %val = load atomic i32, i32* %addr unordered, align 4 353 fence acquire 354 %acc.next = add i32 %acc, %val 355 %iv.next = add nsw i32 %iv, 4 356 %n = load atomic i32, i32* %n_addr unordered, align 4 357 %cmp = icmp slt i32 %iv.next, %n 358 br i1 %cmp, label %loop, label %loop.exit 359 360 loop.exit: 361 ret void 362 } 363 364 ; same as above test, but the IV can wrap around. 365 ; so the max backedge taken count is unpredictable. 366 define void @changing_end_bound4(i32 %start, i32* %n_addr, i32* %addr) { 367 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound4 368 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 369 ; CHECK: Loop %loop: Unpredictable max backedge-taken count. 370 entry: 371 br label %loop 372 373 loop: 374 %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ] 375 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 376 %val = load atomic i32, i32* %addr unordered, align 4 377 fence acquire 378 %acc.next = add i32 %acc, %val 379 %iv.next = add i32 %iv, 4 380 %n = load atomic i32, i32* %n_addr unordered, align 4 381 %cmp = icmp slt i32 %iv.next, %n 382 br i1 %cmp, label %loop, label %loop.exit 383 384 loop.exit: 385 ret void 386 } 387 388 ; unknown stride. Since it's not knownPositive, we do not estimate the max 389 ; backedge taken count. 390 define void @changing_end_bound5(i32 %stride, i32 %start, i32* %n_addr, i32* %addr) { 391 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound5 392 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 393 ; CHECK: Loop %loop: Unpredictable max backedge-taken count. 394 entry: 395 br label %loop 396 397 loop: 398 %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ] 399 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 400 %val = load atomic i32, i32* %addr unordered, align 4 401 fence acquire 402 %acc.next = add i32 %acc, %val 403 %iv.next = add nsw i32 %iv, %stride 404 %n = load atomic i32, i32* %n_addr unordered, align 4 405 %cmp = icmp slt i32 %iv.next, %n 406 br i1 %cmp, label %loop, label %loop.exit 407 408 loop.exit: 409 ret void 410 } 411 412 ; negative stride value 413 define void @changing_end_bound6(i32 %start, i32* %n_addr, i32* %addr) { 414 ; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound6 415 ; CHECK: Loop %loop: Unpredictable backedge-taken count. 416 ; CHECK: Loop %loop: Unpredictable max backedge-taken count. 417 entry: 418 br label %loop 419 420 loop: 421 %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ] 422 %acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ] 423 %val = load atomic i32, i32* %addr unordered, align 4 424 fence acquire 425 %acc.next = add i32 %acc, %val 426 %iv.next = add nsw i32 %iv, -1 427 %n = load atomic i32, i32* %n_addr unordered, align 4 428 %cmp = icmp slt i32 %iv.next, %n 429 br i1 %cmp, label %loop, label %loop.exit 430 431 loop.exit: 432 ret void 433 } 434
