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From: Wilco Dijkstra Sent: 12 April 2017 13:58 To: GCC Patches Cc: nd; James Greenhalgh; jim.wil...@linaro.org; Evandro Menezes; andrew.pin...@cavium.com Subject: [PATCH][AArch64] Update alignment for -mcpu=generic With -mcpu=generic the loop alignment is currently 4. All but one of the supported cores use 8 or higher. Since using 8 provides performance gains on several cores, it is best to use that by default. As discussed in [1], the jump alignment has no effect on performance, yet has a relatively high codesize cost [2], so setting it to 4 is best. This gives a 0.2% overall codesize improvement as well as performance gains in several benchmarks. Any objections? Bootstrap OK on AArch64, OK for stage 1? ChangeLog: 2017-04-12 Wilco Dijkstra <wdijk...@arm.com> * config/aarch64/aarch64.c (generic_tunings): Set jump alignment to 4. Set loop alignment to 8. [1] https://gcc.gnu.org/ml/gcc-patches/2017-04/msg00574.html [2] https://gcc.gnu.org/ml/gcc-patches/2016-06/msg02075.html --- diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index c8cf7169a5d387de336920b50c83761dc0c96f3a..8b729b1b1f87316e940d7fc657f235a935ffa93e 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -538,8 +538,8 @@ static const struct tune_params generic_tunings = 2, /* issue_rate */ (AARCH64_FUSE_AES_AESMC), /* fusible_ops */ 8, /* function_align. */ - 8, /* jump_align. */ - 4, /* loop_align. */ + 4, /* jump_align. */ + 8, /* loop_align. */ 2, /* int_reassoc_width. */ 4, /* fp_reassoc_width. */ 1, /* vec_reassoc_width. */
