Hi!
On Tue, Nov 05, 2019 at 04:33:23PM +0800, Jiufu Guo wrote:
> --- gcc/common/config/rs6000/rs6000-common.c (revision 277765)
> +++ gcc/common/config/rs6000/rs6000-common.c (working copy)
> @@ -35,7 +35,9 @@ static const struct default_options rs6000_option_
> { OPT_LEVELS_ALL, OPT_fsplit_wide_types_early, NULL, 1 },
> /* Enable -fsched-pressure for first pass instruction scheduling. */
> { OPT_LEVELS_1_PLUS, OPT_fsched_pressure, NULL, 1 },
> - { OPT_LEVELS_2_PLUS, OPT_funroll_loops, NULL, 1 },
> + /* Enable -funroll-loops with -munroll-small-loops. */
> + { OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_funroll_loops, NULL, 1 },
> + { OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_munroll_small_loops, NULL, 1 },
I guess the comment should say what we enable here more than the generic
code does. Something like
/* Enable -funroll-loops at -O2 already. Also enable
-munroll-small-loops. */
> + /* Explicit funroll-loops turns -munroll-small-loops off.
> + Implicit funroll-loops does not turn fweb or frename-registers on. */
> + if ((global_options_set.x_flag_unroll_loops && flag_unroll_loops)
> + || (global_options_set.x_flag_unroll_all_loops
> + && flag_unroll_all_loops))
> {
> + if (!global_options_set.x_unroll_small_loops)
> + unroll_small_loops = 0;
> + }
> + else
> + {
> if (!global_options_set.x_flag_web)
> + flag_web = 0;
> if (!global_options_set.x_flag_rename_registers)
> + flag_rename_registers = 0;
> }
So unroll-small-loops should better be called unroll-only-small-loops?
Why does explicit unroll-loops turns on web and rnreg? Why only explicit?
Isn't it good and/or bad in all the same cases, implicit and explicit?
> +munroll-small-loops
> +Target Undocumented Var(unroll_small_loops) Init(0) Save
> +Use conservative small loop unrolling.
Undocumented means undocumented, so you don't have a comment string in
here. But you can comment it:
; Use conservative small loop unrolling.
Segher
