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Date:      Tue, 22 Oct 2002 10:45:52 -0400 (EDT)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        Ruslan Ermilov <ru@FreeBSD.org>
Cc:        Alexander Kabaev <kan@FreeBSD.org>, "David O'Brien" <obrien@FreeBSD.org>, current@FreeBSD.org
Subject:   Re: Groff problems (was Re: alpha tinderbox failure)
Message-ID:  <15797.25760.427922.700729@grasshopper.cs.duke.edu>
In-Reply-To: <20021022142929.GB48398@sunbay.com>
References:  <200210210942.g9L9gLpM025724@beast.freebsd.org> <15796.17145.909288.498725@grasshopper.cs.duke.edu> <20021022142929.GB48398@sunbay.com>

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Ruslan Ermilov writes:
 > If you remove -fno-exceptions from gnu/usr.bin/groff/Makefile.inc and
 > recompile libgroff and groff, it seems to work (I did not check it
 > thoroughly).  But I think this only has a side effect, because Groff
 > does not seem to have any exception code (please correct me if I am
 > wrong), and why the hell it should depend on -mcpu, if any?
 > 

Interesting.  I wonder of the lack of exceptions is what's confusing
ld?

As to mpcu: On alphas, the compiler has more chance to make mistakes
if its compiled for CPUs < ev56 which do not support byte/word
instructions.  In those cases, it needs to generate shifty/masky code
to pull 8 and 16 bit values out of 32-bit loads and stores.  This has
a history of being more error prone.  Eg, some complex ports work on
stable at high optimization levels with -mcpu=ev56 which don't work
without -mpcu.

If we have to, we can always compile groff as -mcpu=ev56 because we
emulate these instructions in the kernel on older machines.  That
would make groff run about like molases in January on older machines,
though, as each byte/word instruction would generate an illegal
instruction trap and that trap would be handled by the alpha trap
handler..

Drew

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