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Hackery to handle ix86 "jmp constant" as a pc-relative jump to the given

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absolute address.
This commit is contained in:
Alan Modra
1999-09-13 06:45:15 +00:00
parent 9169713a19
commit 2f66722d55
4 changed files with 63 additions and 106 deletions
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5
bfd/ChangeLog
View File

@ -1,3 +1,8 @@
1999-09-13 Alan Modra <alan@spri.levels.unisa.edu.au>
* elfcode.h (write_relocs): Check for the_bfd NULL when handling
an absolute symbol in REL relocs.
Sun Sep 12 23:47:58 1999 Jeffrey A Law (law@cygnus.com)
* elf-hppa.h (elf_hppa_final_link_relocate): Handle SECREL32.

3
bfd/elfcode.h
View File

@ -871,7 +871,8 @@ write_relocs (abfd, sec, data)
last_sym_idx = n;
}
if ((*ptr->sym_ptr_ptr)->the_bfd->xvec != abfd->xvec
if ((*ptr->sym_ptr_ptr)->the_bfd != NULL
&& (*ptr->sym_ptr_ptr)->the_bfd->xvec != abfd->xvec
&& ! _bfd_elf_validate_reloc (abfd, ptr))
{
*failedp = true;

5
gas/ChangeLog
View File

@ -1,5 +1,10 @@
1999-09-13 Alan Modra <alan@spri.levels.unisa.edu.au>
* config/tc-i386.c (md_assemble): Handle "jmp/call constant" as a
pc-relative jmp/call to an absolute symbol.
(md_apply_fix3): When OBJ_ELF, don't add the values in twice for
absolute section symbols.
* config/tc-i386.c (md_assemble): Correct frag_var size. Tidy
jump handling code and comments.

156
gas/config/tc-i386.c
View File

@ -2085,6 +2085,16 @@ md_assemble (line)
i.imm_operands = 0;
}
if ((i.tm.opcode_modifier & (Jump | JumpByte | JumpDword))
&& i.disps[0]->X_op == O_constant)
{
/* Convert "jmp constant" (and "call constant") to a jump (call) to
the absolute address given by the constant. Since ix86 jumps and
calls are pc relative, we need to generate a reloc. */
i.disps[0]->X_add_symbol = &abs_symbol;
i.disps[0]->X_op = O_symbol;
}
/* We are ready to output the insn. */
{
register char *p;
@ -2115,77 +2125,28 @@ md_assemble (line)
if (i.prefixes != 0 && !intel_syntax)
as_warn (_("skipping prefixes on this instruction"));
if (i.disps[0]->X_op == O_constant)
{
long n = (long) i.disps[0]->X_add_number;
if (fits_in_signed_byte (n))
{
insn_size += 2;
p = frag_more (2);
p[0] = i.tm.base_opcode;
p[1] = n;
}
else
{
/* Use 16-bit jumps only for 16-bit code,
because text segments are limited to 64K anyway;
Use 32-bit jumps for 32-bit code, because they're faster,
and a 16-bit jump will clear the top 16 bits of %eip. */
if (code16 && !fits_in_signed_word (n))
{
as_bad (_("16-bit jump out of range"));
return;
}
if (i.tm.base_opcode == JUMP_PC_RELATIVE)
{ /* pace */
/* unconditional jump */
insn_size += prefix + 1 + size;
p = frag_more (prefix + 1 + size);
if (prefix)
*p++ = DATA_PREFIX_OPCODE;
*p++ = (char) 0xe9;
md_number_to_chars (p, (valueT) n, size);
}
else
{
/* conditional jump */
insn_size += prefix + 2 + size;
p = frag_more (prefix + 2 + size);
if (prefix)
*p++ = DATA_PREFIX_OPCODE;
*p++ = TWO_BYTE_OPCODE_ESCAPE;
*p++ = i.tm.base_opcode + 0x10;
md_number_to_chars (p, (valueT) n, size);
}
}
}
else
{
/* It's a symbol; End frag & setup for relax.
Make sure there is enough room in this frag for the largest
instruction we may generate in md_convert_frag. This is 2
bytes for the opcode and room for the prefix and largest
displacement. */
frag_grow (prefix + 2 + size);
insn_size += prefix + 1;
/* Prefix and 1 opcode byte go in fr_fix. */
p = frag_more (prefix + 1);
if (prefix)
*p++ = DATA_PREFIX_OPCODE;
*p = i.tm.base_opcode;
/* 1 possible extra opcode + displacement go in fr_var */
frag_var (rs_machine_dependent,
1 + size,
1,
((unsigned char) *p == JUMP_PC_RELATIVE
? ENCODE_RELAX_STATE (UNCOND_JUMP, SMALL) | code16
: ENCODE_RELAX_STATE (COND_JUMP, SMALL) | code16),
i.disps[0]->X_add_symbol,
i.disps[0]->X_add_number,
p);
}
/* It's always a symbol; End frag & setup for relax.
Make sure there is enough room in this frag for the largest
instruction we may generate in md_convert_frag. This is 2
bytes for the opcode and room for the prefix and largest
displacement. */
frag_grow (prefix + 2 + size);
insn_size += prefix + 1;
/* Prefix and 1 opcode byte go in fr_fix. */
p = frag_more (prefix + 1);
if (prefix)
*p++ = DATA_PREFIX_OPCODE;
*p = i.tm.base_opcode;
/* 1 possible extra opcode + displacement go in fr_var. */
frag_var (rs_machine_dependent,
1 + size,
1,
((unsigned char) *p == JUMP_PC_RELATIVE
? ENCODE_RELAX_STATE (UNCOND_JUMP, SMALL) | code16
: ENCODE_RELAX_STATE (COND_JUMP, SMALL) | code16),
i.disps[0]->X_add_symbol,
i.disps[0]->X_add_number,
p);
}
else if (i.tm.opcode_modifier & (JumpByte | JumpDword))
{
@ -2240,28 +2201,8 @@ md_assemble (line)
}
*p++ = i.tm.base_opcode & 0xff;
if (i.disps[0]->X_op == O_constant)
{
long n = (long) i.disps[0]->X_add_number;
if (size == 1 && !fits_in_signed_byte (n))
{
as_bad (_("`%s' only takes byte displacement; %ld shortened to %d"),
i.tm.name, n, *p);
}
else if (size == 2 && !fits_in_signed_word (n))
{
as_bad (_("16-bit jump out of range"));
return;
}
md_number_to_chars (p, (valueT) n, size);
}
else
{
fix_new_exp (frag_now, p - frag_now->fr_literal, size,
i.disps[0], 1, reloc (size, 1, i.disp_reloc[0]));
}
fix_new_exp (frag_now, p - frag_now->fr_literal, size,
i.disps[0], 1, reloc (size, 1, i.disp_reloc[0]));
}
else if (i.tm.opcode_modifier & JumpInterSegment)
{
@ -3912,19 +3853,24 @@ md_apply_fix3 (fixP, valp, seg)
value += fixP->fx_where + fixP->fx_frag->fr_address;
#endif
#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
if (OUTPUT_FLAVOR == bfd_target_elf_flavour
&& (S_GET_SEGMENT (fixP->fx_addsy) == seg
|| symbol_section_p (fixP->fx_addsy))
&& ! S_IS_EXTERNAL (fixP->fx_addsy)
&& ! S_IS_WEAK (fixP->fx_addsy)
&& S_IS_DEFINED (fixP->fx_addsy)
&& ! S_IS_COMMON (fixP->fx_addsy))
if (OUTPUT_FLAVOR == bfd_target_elf_flavour)
{
/* Yes, we add the values in twice. This is because
bfd_perform_relocation subtracts them out again. I think
bfd_perform_relocation is broken, but I don't dare change
it. FIXME. */
value += fixP->fx_where + fixP->fx_frag->fr_address;
segT fseg = S_GET_SEGMENT (fixP->fx_addsy);
if ((fseg == seg
|| (symbol_section_p (fixP->fx_addsy)
&& fseg != absolute_section))
&& ! S_IS_EXTERNAL (fixP->fx_addsy)
&& ! S_IS_WEAK (fixP->fx_addsy)
&& S_IS_DEFINED (fixP->fx_addsy)
&& ! S_IS_COMMON (fixP->fx_addsy))
{
/* Yes, we add the values in twice. This is because
bfd_perform_relocation subtracts them out again. I think
bfd_perform_relocation is broken, but I don't dare change
it. FIXME. */
value += fixP->fx_where + fixP->fx_frag->fr_address;
}
}
#endif
#if defined (OBJ_COFF) && defined (TE_PE)