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Re: [PATCH][AArch64] Enable AES fusion with -mcpu=generic
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, James Greenhalgh <James dot Greenhalgh at arm dot com>
- Cc: nd <nd at arm dot com>, Evandro Menezes <e dot menezes at samsung dot com>, "Andrew dot pinski at cavium dot com" <Andrew dot pinski at cavium dot com>, "jim dot wilson at linaro dot org" <jim dot wilson at linaro dot org>
- Date: Thu, 20 Apr 2017 15:53:20 +0000
- Subject: Re: [PATCH][AArch64] Enable AES fusion with -mcpu=generic
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From: Wilco Dijkstra
Sent: 16 March 2017 17:22
To: GCC Patches; Evandro Menezes; Andrew.pinski@cavium.com; jim.wilson@linaro.org
Cc: nd
Subject: [PATCH][AArch64] Enable AES fusion with -mcpu=generic
Many supported cores implement fusion of AES instructions. When fusion
happens it can give a significant performance gain. If not, scheduling
fusion candidates next to each other has almost no effect on performance.
Due to the high benefit/low cost it makes sense to enable AES fusion with
-mcpu=generic so that cores that support it always benefit. Any objections?
Bootstrapped on AArch64, no regressions.
ChangeLog:
2017-03-16 Wilco Dijkstra <wdijkstr@arm.com>
* gcc/config/aarch64/aarch64.c (generic_tunings): Add AES fusion.
--
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 728ce7029f1e2b5161d9f317d10e564dd5a5f472..c8cf7169a5d387de336920b50c83761dc0c96f3a 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -536,7 +536,7 @@ static const struct tune_params generic_tunings =
&generic_approx_modes,
4, /* memmov_cost */
2, /* issue_rate */
- AARCH64_FUSE_NOTHING, /* fusible_ops */
+ (AARCH64_FUSE_AES_AESMC), /* fusible_ops */
8, /* function_align. */
8, /* jump_align. */
4, /* loop_align. */