Date: Mon, 7 Apr 2003 17:33:32 -0700 From: Kris Kennaway <kris@obsecurity.org> To: Thomas Moestl <tmoestl@gmx.net> Cc: Kris Kennaway <kris@obsecurity.org> Subject: Re: assembler error in XFree86 snapshot Message-ID: <20030408003332.GA60864@rot13.obsecurity.org> In-Reply-To: <20030116201728.GA279@crow.dom2ip.de> References: <20030116072448.GA29468@rot13.obsecurity.org> <20030116201728.GA279@crow.dom2ip.de>
next in thread | previous in thread | raw e-mail | index | archive | help
--6c2NcOVqGQ03X4Wi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 16, 2003 at 09:17:28PM +0100, Thomas Moestl wrote: > On Wed, 2003/01/15 at 23:24:48 -0800, Kris Kennaway wrote: > > I'm trying to compile anholt's XFree86 4.2.99 snapshot on sparc, and I > > get the following error message: > >=20 > > cc -c -O -pipe -ansi -Dasm=3D__asm -Wall -Wpointer-arith -Wundef -I= /usr/tmp/XFree86-4-libraries-devel/work/xc -I/usr/tmp/XFree86-4-libraries-d= evel/work/xc/exports/include -DCSRG_BASED -DFUNCPROTO=3D15 -DNARROWPROTO= -DXTHREADS -D_REENTRANT -D_THREAD_SAFE -DXUSE_MTSAFE_API -DXNO_MTSAFE_PWD= API -DMALLOC_0_RETURNS_NULL XRes.c > > {standard input}: Assembler messages: > > {standard input}:667: Error: relocation overflow > > *** Error code 1 > >=20 > > line 667 of the .s file is: > >=20 > > > .LL86: > > > umul %o0, 4294967295, %o0 >=20 > This is a arguably a gcc bug. All (13-bit) immediate operands are > sign-extended, even those to instructions which operate on unsigned > values, so umul can handle a range of very small and a range of very > large operands. gcc correctly recognizes that it can use an immediate > here; however, it chooses to output it as an unsigned number and does > not sign-extended it from 32 to 64 bit. >=20 > All sign extensions for instructions are made to the full 64 bit > however (even if umul only happens to use 32 of those), so when the > assembler checks whether a value is representable as an immediate, it > will check that the 64-bit sign extension of the immediate creates > the desired value (in sparc64 mode), i.e. it doesn't ignore the upper > 32 bits even if a particular instruction does not use them. >=20 > One solution is to generate negative literals for immediates if we > mean them to be sign-extended (which gcc does already for some other > instructions). The attached patch implements this, I'm not sure it > uses the best possible way to do this though, and it also needs a bit > more testing. *Ping* Someone needs to take this up with the gcc developers so it can get fixed. Kris --6c2NcOVqGQ03X4Wi Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+khjcWry0BWjoQKURAkG+AJ0aa51sc3HiTPfohFaRpMby+5yJvACfXz7g FZGA+ClAjIP2M/dQw+scez0= =Znq6 -----END PGP SIGNATURE----- --6c2NcOVqGQ03X4Wi--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030408003332.GA60864>