[AArch64] Set jump alignment to 4 for Cortex cores

Message ID AM5PR0802MB2610486B43A3DC157F1ED831831B0@AM5PR0802MB2610.eurprd08.prod.outlook.com
State New
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Commit Message

Wilco Dijkstra April 20, 2017, 3:40 p.m.
ping

From: Wilco Dijkstra
Sent: 12 April 2017 13:50
To: GCC Patches
Cc: nd; James Greenhalgh
Subject: [PATCH][AArch64] Set jump alignment to 4 for Cortex cores
    
Set jump alignment to 4 for Cortex cores as it reduces codesize by 0.4% on average
with no obvious performance difference.  See original discussion of the overheads
of various alignments:  https://gcc.gnu.org/ml/gcc-patches/2016-06/msg02075.html

Bootstrap OK, OK for stage 1?

ChangeLog:
2017-04-12  Wilco Dijkstra  <wdijkstr@arm.com>

        * config/aarch64/aarch64.c (cortexa35_tunings): Set jump alignment to 4.
        (cortexa53_tunings): Likewise.
        (cortexa57_tunings): Likewise.
        (cortexa72_tunings): Likewise.
        (cortexa73_tunings): Likewise.

--

Patch

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index a6004e6e283ba7157e65b678cf668f8a47e21abb..a8b3a29dd2e242a35f37b8c6a6fb30699ace5e01 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -564,7 +564,7 @@  static const struct tune_params cortexa35_tunings =
   (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_MOV_MOVK | AARCH64_FUSE_ADRP_ADD
    | AARCH64_FUSE_MOVK_MOVK | AARCH64_FUSE_ADRP_LDR), /* fusible_ops  */
   16,  /* function_align.  */
-  8,   /* jump_align.  */
+  4,   /* jump_align.  */
   8,   /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
@@ -590,7 +590,7 @@  static const struct tune_params cortexa53_tunings =
   (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_MOV_MOVK | AARCH64_FUSE_ADRP_ADD
    | AARCH64_FUSE_MOVK_MOVK | AARCH64_FUSE_ADRP_LDR), /* fusible_ops  */
   16,  /* function_align.  */
-  8,   /* jump_align.  */
+  4,   /* jump_align.  */
   8,   /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
@@ -616,7 +616,7 @@  static const struct tune_params cortexa57_tunings =
   (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_MOV_MOVK | AARCH64_FUSE_ADRP_ADD
    | AARCH64_FUSE_MOVK_MOVK), /* fusible_ops  */
   16,  /* function_align.  */
-  8,   /* jump_align.  */
+  4,   /* jump_align.  */
   8,   /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
@@ -642,7 +642,7 @@  static const struct tune_params cortexa72_tunings =
   (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_MOV_MOVK | AARCH64_FUSE_ADRP_ADD
    | AARCH64_FUSE_MOVK_MOVK), /* fusible_ops  */
   16,  /* function_align.  */
-  8,   /* jump_align.  */
+  4,   /* jump_align.  */
   8,   /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
@@ -668,7 +668,7 @@  static const struct tune_params cortexa73_tunings =
   (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_MOV_MOVK | AARCH64_FUSE_ADRP_ADD
    | AARCH64_FUSE_MOVK_MOVK | AARCH64_FUSE_ADRP_LDR), /* fusible_ops  */
   16,  /* function_align.  */
-  8,   /* jump_align.  */
+  4,   /* jump_align.  */
   8,   /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */