Hi, With Hongtao's help (thanks), we got the SPEC2017 performance evaluation result on x86_64 (see [1]), this new parameter ira-consider-dup-in-all-alts has negative effects on i386. Since we observed it can benefit ports aarch64 and rs6000, the param is set as 1 by default, this patch is to disable it on i386 explicitly to avoid performance degradation there.
Bootstrapped & regtested on x86_64-redhat-linux. Is it ok for trunk? BR, Kewen [1] https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573986.html -----
From 457c7b3032e20ea0f9d8c8d2980e7da6daeedb13 Mon Sep 17 00:00:00 2001 From: Kewen Lin <li...@linux.ibm.com> Date: Mon, 21 Jun 2021 22:51:09 -0500 Subject: [PATCH 2/2] i386: Disable param ira-consider-dup-in-all-alts [PR100328] With Hongtao's SPEC2017 performance evaluation result here: https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573986.html this new parameter ira-consider-dup-in-all-alts has negative effects on i386, this patch is to disable it explicitly on i386. Bootstrapped & regtested on x86_64-redhat-linux. gcc/ChangeLog: PR rtl-optimization/100328 * config/i386/i386-options.c (ix86_option_override_internal): Set param_ira_consider_dup_in_all_alts to 0. --- gcc/config/i386/i386-options.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c index 0eccb549c22..7a35c468da3 100644 --- a/gcc/config/i386/i386-options.c +++ b/gcc/config/i386/i386-options.c @@ -2831,6 +2831,8 @@ ix86_option_override_internal (bool main_args_p, if (ix86_indirect_branch != indirect_branch_keep) SET_OPTION_IF_UNSET (opts, opts_set, flag_jump_tables, 0); + SET_OPTION_IF_UNSET (opts, opts_set, param_ira_consider_dup_in_all_alts, 0); + return true; } -- 2.17.1
