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x86-64: special case LEA when determining signedness of displacement

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LEA behavior without a 64-bit destination is independent of address size
- in particular LEA with 32-bit addressing and 64-bit destination is the
same as LEA with 64-bit addressing and 32-bit destination. IOW checking
merely i.prefix[ADDR_PREFIX] is insufficient. This also means wrong
relocation types (R_X86_64_32S when R_X86_64_32 is needed) were used so
far in such cases.

Note that in one case in build_modrm_byte() the 64-bit check came too
early altogether, and hence gets dropped in favor of the one included in
the new helper. This is benign to non-64-bit code from all I can tell,
but the failure to clear disp16 could have been a latent problem.
This commit is contained in:
Jan Beulich
2021-04-23 09:18:06 +02:00
parent cce08655c6
commit a9aabc23ef
2 changed files with 24 additions and 8 deletions
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7
gas/ChangeLog
View File

@ -1,3 +1,10 @@
2021-04-23 Jan Beulich <jbeulich@suse.com>
* config/tc-i386.c (want_disp32): New.
(md_assemble): Use it.
(optimize_disp): Likewise.
(build_modrm_byte): Likewise.
2021-04-23 Jan Beulich <jbeulich@suse.com> 2021-04-23 Jan Beulich <jbeulich@suse.com>
* config/tc-i386.c (i386_finalize_displacement): Move Disp32S * config/tc-i386.c (i386_finalize_displacement): Move Disp32S

25
gas/config/tc-i386.c
View File

@ -3555,6 +3555,16 @@ tc_i386_fix_adjustable (fixS *fixP ATTRIBUTE_UNUSED)
return 1; return 1;
} }
static INLINE bool
want_disp32 (const insn_template *t)
{
return flag_code != CODE_64BIT
|| i.prefix[ADDR_PREFIX]
|| (t->base_opcode == 0x8d
&& t->opcode_modifier.opcodespace == SPACE_BASE
&& !i.types[1].bitfield.qword);
}
static int static int
intel_float_operand (const char *mnemonic) intel_float_operand (const char *mnemonic)
{ {
@ -4740,7 +4750,7 @@ md_assemble (char *line)
if (i.imm_operands) if (i.imm_operands)
optimize_imm (); optimize_imm ();
if (i.disp_operands && flag_code == CODE_64BIT && !i.prefix[ADDR_PREFIX]) if (i.disp_operands && !want_disp32 (current_templates->start))
{ {
for (j = 0; j < i.operands; ++j) for (j = 0; j < i.operands; ++j)
{ {
@ -5748,7 +5758,7 @@ optimize_disp (void)
#ifdef BFD64 #ifdef BFD64
else if (flag_code == CODE_64BIT) else if (flag_code == CODE_64BIT)
{ {
if (i.prefix[ADDR_PREFIX] if (want_disp32 (current_templates->start)
&& fits_in_unsigned_long (op_disp)) && fits_in_unsigned_long (op_disp))
i.types[op].bitfield.disp32 = 1; i.types[op].bitfield.disp32 = 1;
@ -8108,7 +8118,7 @@ build_modrm_byte (void)
i.types[op].bitfield.disp8 = 0; i.types[op].bitfield.disp8 = 0;
i.types[op].bitfield.disp16 = 0; i.types[op].bitfield.disp16 = 0;
i.types[op].bitfield.disp64 = 0; i.types[op].bitfield.disp64 = 0;
if (flag_code != CODE_64BIT || i.prefix[ADDR_PREFIX]) if (want_disp32 (&i.tm))
{ {
/* Must be 32 bit */ /* Must be 32 bit */
i.types[op].bitfield.disp32 = 1; i.types[op].bitfield.disp32 = 1;
@ -8159,7 +8169,7 @@ build_modrm_byte (void)
i.rm.regmem = ESCAPE_TO_TWO_BYTE_ADDRESSING; i.rm.regmem = ESCAPE_TO_TWO_BYTE_ADDRESSING;
i.sib.base = NO_BASE_REGISTER; i.sib.base = NO_BASE_REGISTER;
i.sib.index = NO_INDEX_REGISTER; i.sib.index = NO_INDEX_REGISTER;
newdisp = (!i.prefix[ADDR_PREFIX] ? disp32s : disp32); newdisp = (want_disp32(&i.tm) ? disp32 : disp32s);
} }
else if ((flag_code == CODE_16BIT) else if ((flag_code == CODE_16BIT)
^ (i.prefix[ADDR_PREFIX] != 0)) ^ (i.prefix[ADDR_PREFIX] != 0))
@ -8188,7 +8198,7 @@ build_modrm_byte (void)
i.types[op].bitfield.disp8 = 0; i.types[op].bitfield.disp8 = 0;
i.types[op].bitfield.disp16 = 0; i.types[op].bitfield.disp16 = 0;
i.types[op].bitfield.disp64 = 0; i.types[op].bitfield.disp64 = 0;
if (flag_code != CODE_64BIT || i.prefix[ADDR_PREFIX]) if (want_disp32 (&i.tm))
{ {
/* Must be 32 bit */ /* Must be 32 bit */
i.types[op].bitfield.disp32 = 1; i.types[op].bitfield.disp32 = 1;
@ -8263,12 +8273,11 @@ build_modrm_byte (void)
} }
else /* i.base_reg and 32/64 bit mode */ else /* i.base_reg and 32/64 bit mode */
{ {
if (flag_code == CODE_64BIT if (operand_type_check (i.types[op], disp))
&& operand_type_check (i.types[op], disp))
{ {
i.types[op].bitfield.disp16 = 0; i.types[op].bitfield.disp16 = 0;
i.types[op].bitfield.disp64 = 0; i.types[op].bitfield.disp64 = 0;
if (i.prefix[ADDR_PREFIX] == 0) if (!want_disp32 (&i.tm))
{ {
i.types[op].bitfield.disp32 = 0; i.types[op].bitfield.disp32 = 0;
i.types[op].bitfield.disp32s = 1; i.types[op].bitfield.disp32s = 1;