With -mcpu=generic the loop alignment is currently 4.

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.

    gcc/
	* 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

From-SVN: r247608

gcc/ChangeLog

+2017-05-04  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* config/aarch64/aarch64.c (generic_tunings): Set jump alignment to 4.
+	Set loop alignment to 8.
+
 2017-05-04  Martin Sebor  <msebor@redhat.com>
 
 	PR translation/80280

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.  */