[PATCH][AArch64] Enable AES fusion with -mcpu=generic

Wilco Dijkstra Wilco.Dijkstra@arm.com
Thu Mar 16 17:22:00 GMT 2017


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.  */



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