This patch unsets -freorder-blocks-and-partition when -fprofile-use
is not specified. Function splitting was not actually being performed
in that case, as probably_never_executed_bb_p does not distinguish
any basic blocks as being cold vs hot when there is no profile data.
Leaving it enabled, however, causes the assembly code generator to create
(empty) cold sections and labels, leading to unnecessary size overhead.
Bootstrapped and tested on x86-64-unknown-linux-gnu. Ok for trunk?
Thanks,
Teresa
2015-09-24 Teresa Johnson <tejohn...@google.com>
* opts.c (finish_options): Unset -freorder-blocks-and-partition
if not using profile.
Index: opts.c
===================================================================
--- opts.c (revision 228062)
+++ opts.c (working copy)
@@ -821,7 +821,17 @@ finish_options (struct gcc_options *opts, struct g
opts->x_flag_reorder_blocks = 1;
}
+ /* Disable -freorder-blocks-and-partition when -fprofile-use is not in
+ effect. Function splitting was not actually being performed in that case,
+ as probably_never_executed_bb_p does not distinguish any basic blocks as
+ being cold vs hot when there is no profile data. Leaving it enabled,
+ however, causes the assembly code generator to create (empty) cold
+ sections and labels, leading to unnecessary size overhead. */
if (opts->x_flag_reorder_blocks_and_partition
+ && !opts_set->x_flag_profile_use)
+ opts->x_flag_reorder_blocks_and_partition = 0;
+
+ if (opts->x_flag_reorder_blocks_and_partition
&& !opts_set->x_flag_reorder_functions)
opts->x_flag_reorder_functions = 1;
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
