Hi,
Previously -fweb was disabled if only unroll small loops. After that
we find there is cases where it could help to rename pseudos and aovid
some anti-dependence which may occur after unroll.
Below is a patch to disable -fweb during loop unrolling.
Bootstrap and regtest pass on powerpc, spec2017 run shows no performance
downgrade.
Is this ok for trunk?
BR,
Jiufu
gcc/
2020-04-20 Jiufu Guo <guoji...@cn.ibm.com>
* common/config/rs6000/rs6000-common.c
(rs6000_option_optimization_table)[OPT_LEVELS_ALL]: Remove turn off
-fweb.
* config/rs6000/rs6000.c (rs6000_option_override_internal): Avoid to
set flag_web.
---
gcc/common/config/rs6000/rs6000-common.c | 5 ++---
gcc/config/rs6000/rs6000.c | 4 +---
2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/gcc/common/config/rs6000/rs6000-common.c
b/gcc/common/config/rs6000/rs6000-common.c
index 4f38d566844..87f7fda940a 100644
--- a/gcc/common/config/rs6000/rs6000-common.c
+++ b/gcc/common/config/rs6000/rs6000-common.c
@@ -38,9 +38,8 @@ static const struct default_options
rs6000_option_optimization_table[] =
loops at -O2 and above by default. */
{ OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_funroll_loops, NULL, 1 },
{ OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_munroll_only_small_loops, NULL, 1 },
- /* -fweb and -frename-registers are useless in general for rs6000,
- turn them off. */
- { OPT_LEVELS_ALL, OPT_fweb, NULL, 0 },
+
+ /* -frename-registers is not very helpful for rs6000, turn it off. */
{ OPT_LEVELS_ALL, OPT_frename_registers, NULL, 0 },
/* Double growth factor to counter reduced min jump length. */
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index a2992e682c8..6a9e701bd60 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4543,7 +4543,7 @@ rs6000_option_override_internal (bool global_init_p)
SCHED_PRESSURE_MODEL);
/* Explicit -funroll-loops turns -munroll-only-small-loops off, and
- turns -fweb and -frename-registers on. */
+ turns -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))
@@ -4552,8 +4552,6 @@ rs6000_option_override_internal (bool global_init_p)
unroll_only_small_loops = 0;
if (!global_options_set.x_flag_rename_registers)
flag_rename_registers = 1;
- if (!global_options_set.x_flag_web)
- flag_web = 1;
}
/* If using typedef char *va_list, signal that
--
2.17.1
