From 9094d4a46f518bb5f37c654d2119a00ecdd2b5bb Mon Sep 17 00:00:00 2001 From: Wilco Dijkstra Date: Wed, 22 Mar 2017 18:12:05 +0000 Subject: [PATCH] Recently we've put a lot of effort into improving ifcvt to use CSEL on AArch64. In https://gcc.gnu.org/ml/gcc-patches/2015-11/msg01639.html James determined the best value for AArch64 code generation. Although this setting is used when explicitly targeting Cortex cores, it is not otherwise used. This means by default GCC will not use (F)CSEL in many common cases. Change the generic_branch_cost to be the same as cortexa57_branch_cost so that all supported cores benefit from CSEL. This is generally faster and smaller. On one benchmark the new setting fixes a regression since GCC6 and improves performance by 49%. gcc/ * config/aarch64/aarch64.c (generic_branch_cost): Copy cortexa57_branch_cost. From-SVN: r246397 --- gcc/ChangeLog | 5 +++++ gcc/config/aarch64/aarch64.c | 4 ++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a4d5a9a560e..9d52b253966 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2017-03-22 Wilco Dijkstra + + * config/aarch64/aarch64.c (generic_branch_cost): + Copycortexa57_branch_cost. + 2017-03-22 Wilco Dijkstra * config/aarch64/aarch64.c (generic_tunings): Add AES fusion. diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index eb0095d6b6d..4f769a40a4e 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -484,8 +484,8 @@ static const struct cpu_vector_cost thunderx2t99_vector_cost = /* Generic costs for branch instructions. */ static const struct cpu_branch_cost generic_branch_cost = { - 2, /* Predictable. */ - 2 /* Unpredictable. */ + 1, /* Predictable. */ + 3 /* Unpredictable. */ }; /* Branch costs for Cortex-A57. */ -- 2.30.2