Hi,
Currently, tree unrolling pass(cunroll) does not allow any code
size growth in O2 mode. Code size growth is permitted only if O3 or
funroll-loops/fpeel-loops is used. I have created a patch to allow
partial code size increase in O2 mode. With funroll-loops the maximum
allowed code growth is 400 unrolled insns. I have set it to 200
unrolled insns in O2 mode. This patch improves an image processing
benchmark by 20%. It improves most benchmarks by 1-2%. The code size
increase is <1% for all the benchmarks except the image processing
benchmark which increases by 6% (perf improves by 20%).
I am working on getting this patch reviewed for trunk. Here is
the disussion on this:
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg02643.html I have
incorporated the comments on making the patch simpler. I will
follow-up on that patch to trunk by also getting data on limiting
complete peeling with O2.
Is this ok for the google branch?
Thanks
Sri
Index: opts.c
===================================================================
--- opts.c (revision 206638)
+++ opts.c (working copy)
@@ -855,6 +855,19 @@ finish_options (struct gcc_options *opts, struct g
0, opts->x_param_values, opts_set->x_param_values);
}
+ /* Set PARAM_MAX_COMPLETELY_PEELED_INSNS to half its original value during
+ -O2 when -funroll-loops and -fpeel-loops are not set. */
+ if (optimize == 2 && !opts->x_flag_unroll_loops && !opts->x_flag_peel_loops
+ && !opts->x_flag_unroll_all_loops)
+
+ {
+ unsigned HOST_WIDE_INT max_completely_peeled_insns
+ = (PARAM_VALUE (PARAM_MAX_COMPLETELY_PEELED_INSNS) / 2);
+ maybe_set_param_value (PARAM_MAX_COMPLETELY_PEELED_INSNS,
+ max_completely_peeled_insns,
+ opts->x_param_values, opts_set->x_param_values);
+ }
+
/* Set PARAM_MAX_STORES_TO_SINK to 0 if either vectorization or if-conversion
is disabled. */
if ((!opts->x_flag_tree_loop_vectorize && !opts->x_flag_tree_slp_vectorize)
Index: tree-ssa-loop.c
===================================================================
--- tree-ssa-loop.c (revision 206638)
+++ tree-ssa-loop.c (working copy)
@@ -467,7 +467,7 @@ tree_complete_unroll (void)
return tree_unroll_loops_completely (flag_unroll_loops
|| flag_peel_loops
- || optimize >= 3, true);
+ || optimize >= 2, true);
}
static bool
