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x86/Intel: issue diagnostics for redundant segment override prefixes 

While we shouldn't outright reject such (as was wrongly done by commit
4d36230d59 ("x86: Update segment register check in Intel syntax"), as
MASM accepts them even silently, issue (by default) a warning for such
questionable constructs.
This commit is contained in:
Jan Beulich 2017-11-30 11:46:26 +01:00 committed by Jan Beulich
parent e21440ba62
commit fd4e034759
6 changed files with 64 additions and 7 deletions
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12
gas/ChangeLog
View File

@ -1,3 +1,15 @@
2017-11-29 Jan Beulich <jbeulich@suse.com>
PR gas/21874
* config/tc-i386-intel.c (i386_intel_simplify): Chain together
multiple segment override expressions.
(i386_intel_operand): Issue diagnostic for redundant segment
overrides.
* testsuite/gas/i386/intelok.e: New.
* testsuite/gas/i386/intelok.d: Reference intelok.e.
* testsuite/gas/i386/inval-seg.s: Add redundant override checks.
* testsuite/gas/i386/inval-seg.l: Adjust expectations.
2017-11-29 Jim Wilson <jimw@sifive.com>
Palmer Dabbelt <palmer@sifive.com>

29
gas/config/tc-i386-intel.c
View File

@ -413,7 +413,19 @@ static int i386_intel_simplify (expressionS *e)
intel_state.index))
return 0;
if (!intel_state.in_offset)
intel_state.seg = e->X_add_symbol;
{
if (!intel_state.seg)
intel_state.seg = e->X_add_symbol;
else
{
expressionS exp;
exp.X_op = O_full_ptr;
exp.X_add_symbol = e->X_add_symbol;
exp.X_op_symbol = intel_state.seg;
intel_state.seg = make_expr_symbol (&exp);
}
}
i386_intel_fold (e, e->X_op_symbol);
break;
@ -956,10 +968,12 @@ i386_intel_operand (char *operand_string, int got_a_float)
if (intel_state.seg)
{
for (;;)
for (ret = check_none; ; ret = operand_check)
{
expP = symbol_get_value_expression (intel_state.seg);
if (expP->X_op != O_full_ptr)
if (expP->X_op != O_full_ptr
|| symbol_get_value_expression (expP->X_op_symbol)->X_op
!= O_register)
break;
intel_state.seg = expP->X_add_symbol;
}
@ -974,6 +988,15 @@ i386_intel_operand (char *operand_string, int got_a_float)
as_bad (_("invalid use of register"));
return 0;
}
switch (ret)
{
case check_error:
as_bad (_("redundant segment overrides"));
return 0;
case check_warning:
as_warn (_("redundant segment overrides"));
break;
}
switch (i386_regtab[expP->X_add_number].reg_num)
{
case 0: i.seg[i.mem_operands] = &es; break;

1
gas/testsuite/gas/i386/intelok.d
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@ -1,6 +1,7 @@
#as: -J --divide
#objdump: -dwMintel
#name: i386 intel-ok
#stderr: intelok.e
.*: +file format .*

2
gas/testsuite/gas/i386/intelok.e Normal file
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@ -0,0 +1,2 @@
.*: Assembler messages:
.*:153: Warning: redundant segment overrides

20
gas/testsuite/gas/i386/inval-seg.l
View File

@ -1,10 +1,22 @@
.*: Assembler messages:
.*:3: Error: .*
.*:4: Error: .*
.*:7: Error: .*
.*:8: Error: .*
.*:9: Error: .*
.*:10: Error: .*
.*:11: Error: .*
GAS LISTING .*
1 [ ]* .text
2 [ ]*# All the following should be illegal
3 [ ]* movl %ds,\(%eax\)
4 [ ]* movl \(%eax\),%ds
[ ]*[1-9][0-9]*[ ]*\.text
[ ]*[1-9][0-9]*[ ]*# All the following should be illegal
[ ]*[1-9][0-9]*[ ]*movl %ds,\(%eax\)
[ ]*[1-9][0-9]*[ ]*movl \(%eax\),%ds
[ ]*[1-9][0-9]*[ ]*
[ ]*[1-9][0-9]*[ ]*\.intel_syntax noprefix
[ ]*[1-9][0-9]*[ ]*mov eax, es:foo:\[eax\]
[ ]*[1-9][0-9]*[ ]*mov eax, es:fs:foo:\[eax\]
[ ]*[1-9][0-9]*[ ]*mov eax, fs:foo:bar:\[eax\]
[ ]*[1-9][0-9]*[ ]*mov eax, fs:foo:gs:\[eax\]
[ ]*[1-9][0-9]*[ ]*mov eax, bar:gs:\[eax\]

7
gas/testsuite/gas/i386/inval-seg.s
View File

@ -2,3 +2,10 @@
# All the following should be illegal
movl %ds,(%eax)
movl (%eax),%ds
.intel_syntax noprefix
mov eax, es:foo:[eax]
mov eax, es:fs:foo:[eax]
mov eax, fs:foo:bar:[eax]
mov eax, fs:foo:gs:[eax]
mov eax, bar:gs:[eax]