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| author | Changpeng Fang <changpeng.fang@amd.com> | 2010-06-14 20:51:26 +0000 |
|---|---|---|
| committer | Sebastian Pop <spop@gcc.gnu.org> | 2010-06-14 20:51:26 +0000 |
| commit | d50585233d29f2c9d4fb554b05a21c5556177d05 (patch) | |
| tree | 34ac31c39ea1dbf3dd4dafb1ae6caf840737656b /gcc/tree-ssa-loop-prefetch.c | |
| parent | 33d6748532861388e9644438ac5bc5e3de1222db (diff) | |
| download | gcc-d50585233d29f2c9d4fb554b05a21c5556177d05.zip gcc-d50585233d29f2c9d4fb554b05a21c5556177d05.tar.gz gcc-d50585233d29f2c9d4fb554b05a21c5556177d05.tar.bz2 | |
Account prefetch_mod and unroll_factor for the computation of the prefetch count.
2010-06-14 Changpeng Fang <changpeng.fang@amd.com>
* tree-ssa-loop-prefetch.c (nothing_to_prefetch_p): New. Return
true if no prefetch is going to be generated for a given group.
(estimate_prefetch_count): Use prefetch_mod and unroll_factor to
estimate the prefetch_count.
(loop_prefetch_arrays): Call nothing_to_prefetch_p; estimate the
prefetch count by considering the unroll_factor and prefetch_mod
for is_loop_prefetching_profitable.
From-SVN: r160766
Diffstat (limited to 'gcc/tree-ssa-loop-prefetch.c')
| -rw-r--r-- | gcc/tree-ssa-loop-prefetch.c | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/gcc/tree-ssa-loop-prefetch.c b/gcc/tree-ssa-loop-prefetch.c index 8097124..6547489 100644 --- a/gcc/tree-ssa-loop-prefetch.c +++ b/gcc/tree-ssa-loop-prefetch.c @@ -994,18 +994,40 @@ schedule_prefetches (struct mem_ref_group *groups, unsigned unroll_factor, return any; } -/* Estimate the number of prefetches in the given GROUPS. */ +/* Return TRUE if no prefetch is going to be generated in the given + GROUPS. */ + +static bool +nothing_to_prefetch_p (struct mem_ref_group *groups) +{ + struct mem_ref *ref; + + for (; groups; groups = groups->next) + for (ref = groups->refs; ref; ref = ref->next) + if (should_issue_prefetch_p (ref)) + return false; + + return true; +} + +/* Estimate the number of prefetches in the given GROUPS. + UNROLL_FACTOR is the factor by which LOOP was unrolled. */ static int -estimate_prefetch_count (struct mem_ref_group *groups) +estimate_prefetch_count (struct mem_ref_group *groups, unsigned unroll_factor) { struct mem_ref *ref; + unsigned n_prefetches; int prefetch_count = 0; for (; groups; groups = groups->next) for (ref = groups->refs; ref; ref = ref->next) if (should_issue_prefetch_p (ref)) - prefetch_count++; + { + n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) + / ref->prefetch_mod); + prefetch_count += n_prefetches; + } return prefetch_count; } @@ -1716,8 +1738,7 @@ loop_prefetch_arrays (struct loop *loop) /* Step 2: estimate the reuse effects. */ prune_by_reuse (refs); - prefetch_count = estimate_prefetch_count (refs); - if (prefetch_count == 0) + if (nothing_to_prefetch_p (refs)) goto fail; determine_loop_nest_reuse (loop, refs, no_other_refs); @@ -1733,6 +1754,12 @@ loop_prefetch_arrays (struct loop *loop) ninsns = tree_num_loop_insns (loop, &eni_size_weights); unroll_factor = determine_unroll_factor (loop, refs, ninsns, &desc, est_niter); + + /* Estimate prefetch count for the unrolled loop. */ + prefetch_count = estimate_prefetch_count (refs, unroll_factor); + if (prefetch_count == 0) + goto fail; + if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "Ahead %d, unroll factor %d, trip count " HOST_WIDE_INT_PRINT_DEC "\n" |