[Bug gas/4572] division doesn't work on solaris/x86

[Michael dot Abshoff at googlemail dot com]

------- Additional Comments From Michael dot Abshoff at googlemail dot com  
2008-07-14 17:52 -------
(In reply to comment #4)
> Subject: Re:  division doesn't work on solaris/x86
> 
> Hi Clint,

[My first journey into the world of binutils, so please be gentle :)]

Hi Clint, Alan, Nick,

> > You are saying there is no way to do division in integer expressions with 
> > gas on
> > solaris, even though it works on all other OSes?  Isn't that less than 
> > ideal?
> 
> Actually Alan was saying that you should look at the assembler source 
> file gas/app.c and see how you can modify it to interpret "\/" as a 
> division operator and not a comment.
> 
> Cheers
>    Nick
> 

I hit the problem Clint reported when building his project (ATLAS 3.8.1+Errata
applied specifically) on Solaris 10/Intel with compiled from vanilla sources
binutils 2.18. The solution is exposed when looking at gas/config/tc-i386.c: 

[quote]
#if (defined (TE_I386AIX)                               \
     || ((defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)) \
         && !defined (TE_GNU)                           \
         && !defined (TE_LINUX)                         \
         && !defined (TE_NETWARE)                       \
         && !defined (TE_FreeBSD)                       \
         && !defined (TE_NetBSD)))
/* This array holds the chars that always start a comment.  If the
   pre-processor is disabled, these aren't very useful.  The option
   --divide will remove '/' from this list.  */
const char *i386_comment_chars = "#/"; [Remove the "/" here ]
#define SVR4_COMMENT_CHARS 1
#define PREFIX_SEPARATOR '\\'

#else
const char *i386_comment_chars = "#";
#define PREFIX_SEPARATOR '/'
#endif
[end quote]

There are two solutions:

 a) Brute force, i.e. remove "/" as indicated above

or

 b) add '-Wa,--divide' to the CFLAGS of ATLAS as suggested by the comments in
the source code

(a) worked on my Solaris 10 box, i.e. it build ATLAS and the rest of Sage, but
(b) seems like a much better solution since most people don't build their custom
binutils ;). I have not tried it yet, but on Solaris 10 on Intel (b) ought to
work universally since Sun's version of gas is from binutils 2.15 and the issue
you hit was allegedly introduced between 2.13 and 2.15 - see

http://osdir.com/ml/gnu.binutils.bugs/2005-02/msg00054.html

for that statement I have not verified. I attempted to build binutils 2.13 and
2.14 on Solaris 10 and it did not work, so this workaround (b) ought to work on
all Intel Solaris 10 boxen. Since I could not get any gcc to build using Sun's
as it also seems pretty save to me, but caution ought to be applied.

Clint: I will file a bug report against ATLAS in case you do not respond to this
ticket in the next couple days.

Cheers,

Michael


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=4572

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