assembler error in XFree86 snapshot

Kris Kennaway kris at
Mon Apr 7 17:33:34 PDT 2003

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:
> > 
> > cc -c -O -pipe  -ansi -Dasm=__asm -Wall -Wpointer-arith -Wundef    -I/usr/tmp/XFree86-4-libraries-devel/work/xc -I/usr/tmp/XFree86-4-libraries-devel/work/xc/exports/include   -DCSRG_BASED  -DFUNCPROTO=15 -DNARROWPROTO -DXTHREADS  -D_REENTRANT -D_THREAD_SAFE -DXUSE_MTSAFE_API -DXNO_MTSAFE_PWDAPI    -DMALLOC_0_RETURNS_NULL   XRes.c
> > {standard input}: Assembler messages:
> > {standard input}:667: Error: relocation overflow
> > *** Error code 1
> > 
> > line 667 of the .s file is:
> > 
> > > .LL86:
> > >         umul    %o0, 4294967295, %o0
> 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.
> 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.
> 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.


Someone needs to take this up with the gcc developers so it can get fixed.

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