Stan Shebs <shebs@apple.com> writes:
As some of you may know, Mac OS X has long been using gas 1.38, pre-BFD
and all, as its system assembler, heavily hacked to do Mach-O and
support all of Apple's various extensions. Recently I had occasion
to look at the some of the barbaric expression code in our version,
and thinking "surely the latest code is much improved", went and looked
at the latest version, and it didn't really seem changed by that much,
which was disappointing. In fact, quite a bit of 1.38 seems the same as
current gas sources.
Up to now I've been generally assuming that staying on the old gas was
a poor strategy, and that the massive effort that would be needed to get
Mach-O into latest gas would be an investment quickly repaid in better
quality, better error-checking, etc. But now I'm not so sure. We really
only have the one target (PPC), plus x86 for Darwin, so portability
arguments aren't that compelling, and the assembler is pretty much in
the noise compile-time-wise already.
So what are the features of latest gas vs 1.38 that would make my
management whip out the checkbook for a merge/upgrade project?
I would say that the major new features are for people who program in
assembler: macros, better conditionals, better error handling, more
pseudo-ops. For C/C++ code, I would say that as long as you stick
with Mach-O, you aren't going to see much improvement by upgrading to
the current assembler. I don't even know whether the current
assembler is faster--the pre-2.0 versions were pretty fast.
Over time you might some savings as other people do work for
you--adding support for new processor variants, fixing bugs, speeding
up the assembler, etc.