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* config/tc-mips.c (mips_validate_fix): New function.

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* config/tc-mips.h (TC_VALIDATE_FIX): Define.
(mips_validate_fix): Declare.
This commit is contained in:
Alexandre Oliva 2003-03-12 23:07:38 +00:00
parent d17b874b6c
commit 45f8dfe8f6
3 changed files with 94 additions and 0 deletions
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6
gas/ChangeLog
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@ -1,3 +1,9 @@
2003-03-12 Alexandre Oliva <aoliva@redhat.com>
* config/tc-mips.c (mips_validate_fix): New function.
* config/tc-mips.h (TC_VALIDATE_FIX): Define.
(mips_validate_fix): Declare.
2003-03-12 Alexandre Oliva <aoliva@redhat.com>
* Reverted 2003-03-02's patch.

79
gas/config/tc-mips.c
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@ -11026,6 +11026,85 @@ mips_force_relocation (fixp)
|| fixp->fx_r_type == BFD_RELOC_PCREL_LO16));
}
/* This hook is called before a fix is simplified. We don't really
decide whether to skip a fix here. Rather, we turn global symbols
used as branch targets into local symbols, such that they undergo
simplification. We can only do this if the symbol is defined and
it is in the same section as the branch. If this doesn't hold, we
emit a better error message than just saying the relocation is not
valid for the selected object format.
FIXP is the fix-up we're going to try to simplify, SEG is the
segment in which the fix up occurs. The return value should be
non-zero to indicate the fix-up is valid for further
simplifications. */
int
mips_validate_fix (fixP, seg)
struct fix *fixP;
asection *seg;
{
/* There's a lot of discussion on whether it should be possible to
use R_MIPS_PC16 to represent branch relocations. The outcome
seems to be that it can, but gas/bfd are very broken in creating
RELA relocations for this, so for now we only accept branches to
symbols in the same section. Anything else is of dubious value,
since there's no guarantee that at link time the symbol would be
in range. Even for branches to local symbols this is arguably
wrong, since it we assume the symbol is not going to be
overridden, which should be possible per ELF library semantics,
but then, there isn't a dynamic relocation that could be used to
this effect, and the target would likely be out of range as well.
Unfortunately, it seems that there is too much code out there
that relies on branches to symbols that are global to be resolved
as if they were local, like the IRIX tools do, so we do it as
well, but with a warning so that people are reminded to fix their
code. If we ever get back to using R_MIPS_PC16 for branch
targets, this entire block should go away (and probably the
whole function). */
if (fixP->fx_r_type == BFD_RELOC_16_PCREL_S2
&& (((OUTPUT_FLAVOR == bfd_target_ecoff_flavour
|| OUTPUT_FLAVOR == bfd_target_elf_flavour)
&& mips_pic != EMBEDDED_PIC)
|| bfd_reloc_type_lookup (stdoutput, BFD_RELOC_16_PCREL_S2) == NULL)
&& fixP->fx_addsy)
{
if (! S_IS_DEFINED (fixP->fx_addsy))
{
as_bad_where (fixP->fx_file, fixP->fx_line,
_("Cannot branch to undefined symbol."));
/* Avoid any further errors about this fixup. */
fixP->fx_done = 1;
}
else if (S_GET_SEGMENT (fixP->fx_addsy) != seg)
{
as_bad_where (fixP->fx_file, fixP->fx_line,
_("Cannot branch to symbol in another section."));
fixP->fx_done = 1;
}
else if (S_IS_EXTERNAL (fixP->fx_addsy))
{
symbolS *sym = fixP->fx_addsy;
as_warn_where (fixP->fx_file, fixP->fx_line,
_("Pretending global symbol used as branch target is local."));
fixP->fx_addsy = symbol_create (S_GET_NAME (sym),
S_GET_SEGMENT (sym),
S_GET_VALUE (sym),
symbol_get_frag (sym));
copy_symbol_attributes (fixP->fx_addsy, sym);
S_CLEAR_EXTERNAL (fixP->fx_addsy);
assert (symbol_resolved_p (sym));
symbol_mark_resolved (fixP->fx_addsy);
}
}
return 1;
}
#ifdef OBJ_ELF
static int
mips_need_elf_addend_fixup (fixP)

9
gas/config/tc-mips.h
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@ -140,6 +140,15 @@ extern int mips_fix_adjustable PARAMS ((struct fix *));
#define TC_FORCE_RELOCATION(FIX) mips_force_relocation (FIX)
extern int mips_force_relocation PARAMS ((struct fix *));
/* We use this to turn branches to global symbols into branches to
local symbols, so that they can be simplified. */
#define TC_VALIDATE_FIX(fixp, this_segment, skip_label) \
do \
if (! mips_validate_fix ((fixp), (this_segment))) \
goto skip_label; \
while (0)
extern int mips_validate_fix PARAMS ((struct fix *, asection *));
/* Register mask variables. These are set by the MIPS assembly code
and used by ECOFF and possibly other object file formats. */
extern unsigned long mips_gprmask;