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| author | Ira Rosen <irar@il.ibm.com> | 2009-01-08 07:59:40 +0000 |
|---|---|---|
| committer | Ira Rosen <irar@gcc.gnu.org> | 2009-01-08 07:59:40 +0000 |
| commit | 82567e3386ed9d11a425f12d822ed1ee6b1c949b (patch) | |
| tree | 5cd604855fe17a73ebe3eb589b7ab54b64ac8d70 /gcc/tree-vect-transform.c | |
| parent | 9982752346aac68d257d258332591df1f7b7817d (diff) | |
| download | gcc-82567e3386ed9d11a425f12d822ed1ee6b1c949b.zip gcc-82567e3386ed9d11a425f12d822ed1ee6b1c949b.tar.gz gcc-82567e3386ed9d11a425f12d822ed1ee6b1c949b.tar.bz2 | |
re PR tree-optimization/37194 (Autovectorization of small constant iteration loop degrades performance)
PR tree-optimization/37194
* tree-vect-transform.c (vect_estimate_min_profitable_iters):
Don't add the cost of cost model guard in prologue to scalar
outside cost in case of known number of iterations.
From-SVN: r143183
Diffstat (limited to 'gcc/tree-vect-transform.c')
| -rw-r--r-- | gcc/tree-vect-transform.c | 29 |
1 files changed, 12 insertions, 17 deletions
diff --git a/gcc/tree-vect-transform.c b/gcc/tree-vect-transform.c index 2db0167..5b3344a 100644 --- a/gcc/tree-vect-transform.c +++ b/gcc/tree-vect-transform.c @@ -122,7 +122,6 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo) int vec_outside_cost = 0; int scalar_single_iter_cost = 0; int scalar_outside_cost = 0; - bool runtime_test = false; int vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo); struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo); basic_block *bbs = LOOP_VINFO_BBS (loop_vinfo); @@ -141,15 +140,7 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo) return 0; } - /* If the number of iterations is unknown, or the - peeling-for-misalignment amount is unknown, we will have to generate - a runtime test to test the loop count against the threshold. */ - if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo) - || (byte_misalign < 0)) - runtime_test = true; - /* Requires loop versioning tests to handle misalignment. */ - if (VEC_length (gimple, LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo))) { /* FIXME: Make cost depend on complexity of individual check. */ @@ -240,12 +231,11 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo) "peeling for alignment is unknown ."); /* If peeled iterations are unknown, count a taken branch and a not taken - branch per peeled loop. Even if scalar loop iterations are known, - vector iterations are not known since peeled prologue iterations are - not known. Hence guards remain the same. */ + branch per peeled loop. Even if scalar loop iterations are known, + vector iterations are not known since peeled prologue iterations are + not known. Hence guards remain the same. */ peel_guard_costs += 2 * (TARG_COND_TAKEN_BRANCH_COST - + TARG_COND_NOT_TAKEN_BRANCH_COST); - + + TARG_COND_NOT_TAKEN_BRANCH_COST); } else { @@ -337,7 +327,12 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo) conditions/branch directions. Change the estimates below to something more reasonable. */ - if (runtime_test) + /* If the number of iterations is known and we do not do versioning, we can + decide whether to vectorize at compile time. Hence the scalar version + do not carry cost model guard costs. */ + if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo) + || VEC_length (gimple, LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo)) + || VEC_length (ddr_p, LOOP_VINFO_MAY_ALIAS_DDRS (loop_vinfo))) { /* Cost model check occurs at versioning. */ if (VEC_length (gimple, LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo)) @@ -345,8 +340,8 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo) scalar_outside_cost += TARG_COND_NOT_TAKEN_BRANCH_COST; else { - /* Cost model occurs at prologue generation. */ - if (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)) + /* Cost model check occurs at prologue generation. */ + if (LOOP_PEELING_FOR_ALIGNMENT (loop_vinfo) < 0) scalar_outside_cost += 2 * TARG_COND_TAKEN_BRANCH_COST + TARG_COND_NOT_TAKEN_BRANCH_COST; /* Cost model check occurs at epilogue generation. */ |