[PATCH v2][ARM] Disable code hoisting with -O3 (PR80155)

[Wilco Dijkstra]

Hi,

While code hoisting generally improves codesize, it can affect performance
negatively. Benchmarking shows it doesn't help SPEC and negatively affects
embedded benchmarks. Since the impact is relatively small with -O2 and mainly
affects -O3, the simplest option is to disable code hoisting for -O3 and higher.

OK for commit?

ChangeLog:
2019-11-26  Wilco Dijkstra  <wdijk...@arm.com>

        PR tree-optimization/80155
        * common/config/arm/arm-common.c (arm_option_optimization_table):
        Disable -fcode-hoisting with -O3.
--

diff --git a/gcc/common/config/arm/arm-common.c 
b/gcc/common/config/arm/arm-common.c
index 
b761d3abd670a144a593c4b410b1e7fbdcb52f56..3e11f21b7dd76cc071b645c32a6fdb4a92511279
 100644
--- a/gcc/common/config/arm/arm-common.c
+++ b/gcc/common/config/arm/arm-common.c
@@ -39,6 +39,8 @@ static const struct default_options 
arm_option_optimization_table[] =
     /* Enable section anchors by default at -O1 or higher.  */
     { OPT_LEVELS_1_PLUS, OPT_fsection_anchors, NULL, 1 },
     { OPT_LEVELS_FAST, OPT_fsched_pressure, NULL, 1 },
+    /* Disable code hoisting with -O3 or higher.  */
+    { OPT_LEVELS_3_PLUS, OPT_fcode_hoisting, NULL, 0 },
     { OPT_LEVELS_NONE, 0, NULL, 0 }
   };