Enable -fstrict-aliasing for optimized builds

RESOLVED WORKSFORME

Status

Camino Graveyard
General
RESOLVED WORKSFORME
16 years ago
14 years ago

People

(Reporter: Brian Ryner (not reading), Assigned: Brian Ryner (not reading))

Tracking

unspecified
Camino0.8
PowerPC
Mac OS X

Details

(Assignee)

Description

16 years ago
We should go ahead and turn on -fstrict-aliasing for optimized Chimera and
Mach-O builds.  It allows for some additional optimizations, and I'm fairly sure
there aren't any strict aliasing bugs lurking in the code since it's the default
for RedHat 7.x.
(Assignee)

Updated

16 years ago
Status: NEW → ASSIGNED
Target Milestone: --- → Chimera0.6
Are you sure about -fstrict-aliasing being the default for RH7.x?  I thought
that they had turned it off early in the gcc2.96 development cycle since it
caused problems when compiling the kernel at that time.  A 'gcc -S
-fverbose-asm' on my RH7.2 box doesn't show -fstrict-aliasing as one of the
options that are enabled.  
-fstrict-aliasing has been the default for ages, but only with -O2 (which, of
course, isn't the default, because of egcs/gcc2.95). cls, I do see that option
with when using -O2 -S. It may have been turned off for RH7.0, but it was
definately on for 7.2. Anyone got a 7.0 box arround?

There are enough people arround who do unix -O2 (and thus -fstrict-aliasing)
builds who would have noticed major problems, I suspect. The only possible
problems would then be in mac-only code

However, on osx, where you get to use a modern compiler, why not use -O2
directly? That gives you a 7-10% speed improvement basically for free, since you
don't have the backwards compat issues with plugins/java which linux does.
(Assignee)

Comment 3

16 years ago
We already do, for the nightlies and release builds.  We should probably make
that the default.  However, Apple decided not to make -fstrict-aliasing happen
automatically for -O2.
Ah, didn't know that.
Any idea on the status of this bug should it stay open , be closed ?

Updated

14 years ago
Target Milestone: Chimera0.6 → Camino0.8
Mike, what should be done with this one ?

Comment 7

14 years ago
In Xcode1.1 (gcc3.3) which is needed by build of Camino, if -O2 are specified, I
will think that it is automatic and -fstrict-aliasing is contained.
http://developer.apple.com/documentation/Darwin/Reference/ManPages/html/gcc.1.html

so, it optimizes like the following Camino build pages. When build is performed,
I think that this option is effective.
http://www.mozilla.org/ports/fizzilla/ChimChim.html
good catch. we use -O2 so this is enabled already. WFM.
Status: ASSIGNED → RESOLVED
Last Resolved: 14 years ago
Resolution: --- → WORKSFORME
You need to log in before you can comment on or make changes to this bug.