re PR c/57182 (Documentation implies -fprofile-arcs required to create .text.unlikely sections)

2018-11-26  Sandra Loosemore  <sandra@codesourcery.com>

	PR c/57182

	gcc/
	* doc/invoke.texi (Optimize Options): Document that
	-freorder-functions also uses "hot" and "cold" attributes.

From-SVN: r266473

gcc/ChangeLog

+2018-11-26  Sandra Loosemore  <sandra@codesourcery.com>
+
+	PR c/57182
+	* doc/invoke.texi (Optimize Options): Document that
+	-freorder-functions also uses "hot" and "cold" attributes.
+
 2018-11-26  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* config/aarch64/aarch64.c (aarch64_mangle_type): Fix typo in comment.

gcc/doc/invoke.texi

@@ -9796,8 +9796,9 @@ subsections @code{.text.hot} for most frequently executed functions and
 the linker so object file format must support named sections and linker must
 place them in a reasonable way.
 
-Also profile feedback must be available to make this option effective.  See
-@option{-fprofile-arcs} for details.
+This option isn't effective unless you either provide profile feedback
+(see @option{-fprofile-arcs} for details) or manually annotate functions with 
+@code{hot} or @code{cold} attributes (@pxref{Common Function Attributes}).
 
 Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.