/* { dg-do compile } */ /* { dg-options "-O2 -ftree-loop-distribution -fdump-tree-ldist-all" } */ int loop1 (int k) { unsigned int i; int a[1000], b[1000], c[1000], d[1000]; for (i = 2; i < (1000-1); i ++) { a[i] = k * i; /* S1 */ b[i] = a[i-2] + k; /* S2 */ c[i] = b[i-1] + a[i+1]; /* S3 */ d[i] = c[i-1] + k + i; /* S4 */ } /* Dependences: S1->S2 (flow, level 1) S2->S3 (flow, level 1) S3->S1 (anti, level 1) S3->S4 (flow, level 1) There are two partitions: {S1, S2, S3} and {S4}. {S1, S2, S3} have to be in the same partition because: - S1 (i) has to be executed before S2 (i+2), as S1 produces a[i] that is then consumed 2 iterations later by S2. - S2 (i) has to be executed before S3 (i+1), as S2 produces b[i] that is then consumed one iteration later by S3, - S3 (i) has to be executed before S1 (i+1), as a[i+1] has to execute before the update to a[i], {S4} is the consumer partition: it consumes the values from array "c" produced in S3. The cost model should fuse all the tasks together as the cost of fetching data from caches is too high. */ return a[1000-2] + b[1000-1] + c[1000-2] + d[1000-2]; } /* { dg-final { scan-tree-dump-times "distributed: split to 2 loops" 0 "ldist" } } */ /* { dg-final { cleanup-tree-dump "ldist" } } */