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Patch to clarify that -O2 sets -fstrict-aliasing
- From: Michael Meissner <meissner at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Wed, 20 Mar 2002 17:54:44 -0500
- Subject: Patch to clarify that -O2 sets -fstrict-aliasing
I thought the documentation could be clarified that -O2 turns on
strict aliasing, so I committed the following to the main branch. If
desired, I could commit it to the 3.10 branch as well.
2002-03-20 Michael Meissner <meissner@redhat.com>
* doc/invoke.texi (Optimize Options): Document that -O2 sets
-fstrict-aliasing.
*** gcc/doc/invoke.texi.~1~ Wed Mar 13 19:11:21 2002
--- gcc/doc/invoke.texi Wed Mar 20 17:17:57 2002
*************** perform loop unrolling or function inlin
*** 3170,3179 ****
As compared to @option{-O}, this option increases both compilation time
and the performance of the generated code.
! @option{-O2} turns on all optional optimizations except for loop unrolling,
! function inlining, and register renaming. It also turns on the
! @option{-fforce-mem} option on all machines and frame pointer elimination
! on machines where doing so does not interfere with debugging.
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
--- 3170,3180 ----
As compared to @option{-O}, this option increases both compilation time
and the performance of the generated code.
! @option{-O2} turns on all optional optimizations except for loop
! unrolling, function inlining, and register renaming. It also turns on
! the @option{-fforce-mem} and @option{-fstrict-aliasing} option on all
! machines and frame pointer elimination on machines where doing so does
! not interfere with debugging.
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
*************** should define a function that computes,
*** 3715,3720 ****
--- 3716,3724 ----
node, an alias set for the node. Nodes in different alias sets are not
allowed to alias. For an example, see the C front-end function
@code{c_get_alias_set}.
+
+ For all machines, optimization level 2 and higher enables this flag by
+ default.
@item -falign-functions
@itemx -falign-functions=@var{n}
--
Michael Meissner, Red Hat, Inc.
PMB 198, 174 Littleton Road #3, Westford, Massachusetts 01886, USA
Work: meissner@redhat.com phone: +1 978-486-9304
Non-work: meissner@the-meissners.org fax: +1 978-692-4482