New Patch to fix MIPS -mno-shared with multi-got...

[David Daney <ddaney at avtrex dot com>]

Richard Sandiford wrote:
> David Daney <ddaney@avtrex.com> writes:
>
> > The main question being:  Use _gp or __gnu_local_gp ?
> >
> > The pros of using _gp are that Thiemo's plan to magically rename _gp
> > would be binary compatible.
> >
> > The pros of using __gnu_local_gp are that existing code using _gp
> > outside of .cpload would continue to work.
> >
> > I am inclined to use _gp as it does not create a gnu specific ABI
> > extension, but I am apprehensive about what will happen when I try to
> > build glibc.
>
>
> Well, I think Thiemo was suggesting that the assembler use _gp.N
> instead of _gp, so that would need a GNU-specific extension as well.
>
> Other arguments in favour of __gnu_local_gp:
>
>   - What -mno-shared does is already a GNU-specific ABI extension,
>     in that no existing MIPS tools do it as far as I'm aware.  So in
>     a way, it seems natural to use a GNU-specific extension for the
>     symbol as well.
>
>   - -mno-shared isn't implied by other options.  You have to ask for
>     it explicitly.  It seems reasonable to ask that you only use
>     -mno-shared with a linker that would support it.
>
>   - Simply adding a "__gnu_local_gp = _gp;" assignment to a linker
>     script would make it work with existing linkers.
>
> FWIW, I like your patch (but I can't approve it).  One very minor
> nit though:
>
>
> > !   ex.X_add_symbol = symbol_find_or_make (in_shared ? "_gp_disp" : "__gnu_local_gp");
>
>
> ...watch the long lines.

Done.

Attached is what I hope is the final version of the patch.  I had to 
bzip2 it because the testcase is a bit large.

Comments from Richard Sandiford and Daniel Jacobowitz convinced me that 
we should use "__gnu_local_gp" as the symbol referenced in the 
-mno-shared .cpload optimization.

Tested on i686-linux -> mipsel-linux cross with make -k check no 
regressions found.

bfd ChangeLog:
2005-03-04  David Daney <ddaney@avtrex.com>

	* elfxx-mips.c (mips_elf_calculate_relocation): Handle special
	'__gnu_local_gp' symbol used by gas -mno-shared.

gas ChangeLog:
2005-03-04  David Daney <ddaney@avtrex.com>

	* config/tc-mips.c (macro_build_lui): Use '__gnu_local_gp' instead
	of '_gp' for -mno-shared optimization.
	(s_cpload): Ditto.
	(s_abicalls): Document it in the comment.
	(md_show_usage): Document the -mno-shared option.


gas/testsuite ChangeLog:
2005-03-04  David Daney <ddaney@avtrex.com>

	* gas/mips/elf-rel23b.d: Use '__gnu_local_gp' instead
	of '_gp' for -mno-shared optimization.
	* gas/mips/elf-rel25a.d: Ditto.

ld/testsuite ChangeLog:
2005-03-04  David Daney <ddaney@avtrex.com>

	* ld-mips-elf/multi-got-no-shared{-1.s, -2.s, .d}: New test.
	* ld-mips-elf/mips-elf.exp: Run it.

If O.K.  I can try to commit as it appears that I have CVS write access 
(although never tested with binutils).

David Daney.

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