http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58833
--- Comment #3 from ro at CeBiTec dot Uni-Bielefeld.DE ro at CeBiTec dot
Uni-Bielefeld.DE ---
--- Comment #1 from Eric Botcazou ebotcazou at gcc dot gnu.org ---
Would it be possible for GCC in Solaris to auto-configure itself as a 64-bit
native compiler by default (instead of the current 32-bit native compiler
default)?
The decision was made years ago not to do so, at least on SPARC, because the
64-bit compiler was measurably slower than the 32-bit compiler.
That's my experience as well, both on SPARC and x86. When some users
loudly clamored for a 64-bit-default Solaris/x86 configuration, one
argument was that a 64-bit gcc would be faster due to a larger register
set. My experience is just the opposite: a amd64-pc-solaris2.11
bootstrap is considerably slower that i386-pc-solaris2.11. I've not
even started investigating in detail, so this is just one data point.
The output of `uname -p` in Solaris is always 'i386' or 'sparc', regardless
of whether or not the kernel is 32-bit or 64-bit. In Solaris 11 and later,
kernels are 64-bit only, so the output of `uname -p` does not really reflect
reality.
Given that the 32-bit compiler is biarch by default, at least on SPARC, I'm
not
sure there is really an incentive for switching to 64-bit by default.
Agreed: on the opposite, I see a number of counter arguments:
* Studio (at least until the current 12.3) defaults to 32-bit. Why
would gcc be different on just one OS version?
* I think the user experience would be terrible: consider a user who
used to work on Solaris 10 with gcc x.y. Now he switches to Solaris
11, rebuilds gcc x.y and suddenly all his objects are 64-bit, with
nothing else changed. He has to modify his build environment to
retain interoperability with his existing objects and libraries. Not
exactly what I'd call seamless.
Given all this, I think users who really need (or think they need) a
64-bit-default gcc on Solaris can get it today, but the default should
remain 32-bit.
Rainer
