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Implement gcc bitfield algorithm; add -mms-bitfields

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This commit is contained in:
David Mertens 2016-11-22 16:33:12 -05:00
parent 3c68a8c6c0
commit d2e2f42382
6 changed files with 44 additions and 7 deletions
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6
libtcc.c
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@ -752,6 +752,7 @@ LIBTCCAPI TCCState *tcc_new(void)
s->alacarte_link = 1;
s->nocommon = 1;
s->warn_implicit_function_declaration = 1;
s->ms_bitfields = 0;
#ifdef CHAR_IS_UNSIGNED
s->char_is_unsigned = 1;
@ -1508,6 +1509,7 @@ enum {
TCC_OPTION_Wl,
TCC_OPTION_W,
TCC_OPTION_O,
TCC_OPTION_mms_bitfields,
TCC_OPTION_m,
TCC_OPTION_f,
TCC_OPTION_isystem,
@ -1571,6 +1573,7 @@ static const TCCOption tcc_options[] = {
{ "Wl,", TCC_OPTION_Wl, TCC_OPTION_HAS_ARG | TCC_OPTION_NOSEP },
{ "W", TCC_OPTION_W, TCC_OPTION_HAS_ARG | TCC_OPTION_NOSEP },
{ "O", TCC_OPTION_O, TCC_OPTION_HAS_ARG | TCC_OPTION_NOSEP },
{ "mms-bitfields", TCC_OPTION_mms_bitfields, 0}, /* must go before option 'm' */
{ "m", TCC_OPTION_m, TCC_OPTION_HAS_ARG },
{ "f", TCC_OPTION_f, TCC_OPTION_HAS_ARG | TCC_OPTION_NOSEP },
{ "isystem", TCC_OPTION_isystem, TCC_OPTION_HAS_ARG },
@ -1854,6 +1857,9 @@ PUB_FUNC int tcc_parse_args(TCCState *s, int argc, char **argv)
if (x > 0)
tcc_define_symbol(s, "__OPTIMIZE__", NULL);
break;
case TCC_OPTION_mms_bitfields:
s->ms_bitfields = 1;
break;
case TCC_OPTION_traditional:
case TCC_OPTION_pedantic:
case TCC_OPTION_pipe:

4
tcc-doc.texi
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@ -176,6 +176,10 @@ In a script, it gives the following header:
#!/usr/local/bin/tcc -run -L/usr/X11R6/lib -lX11
@end example
@item -mms-bitfields
Use an algorithm for bitfield alignment consistent with MSVC. Default is
gcc's algorithm.
@item -mfloat-abi (ARM only)
Select the float ABI. Possible values: @code{softfp} and @code{hard}

1
tcc.c
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@ -97,6 +97,7 @@ static void help(void)
" -o outfile set output filename\n"
" -run run compiled source\n"
" -fflag set or reset (with 'no-' prefix) 'flag' (see man page)\n"
" -mms-bitfields use bitfield alignment consistent with MSVC\n"
" -Wwarning set or reset (with 'no-' prefix) 'warning' (see man page)\n"
" -w disable all warnings\n"
" -v show version\n"

1
tcc.h
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@ -605,6 +605,7 @@ struct TCCState {
int old_struct_init_code; /* use old algorithm to init array in struct when there is no '{' used.
Liuux 2.4.26 can't find initrd when compiled with a new algorithm */
int dollars_in_identifiers; /* allows '$' char in indentifiers */
int ms_bitfields; /* if true, emulate MS algorithm for aligning bitfields */
/* warning switches */
int warn_write_strings;

30
tccgen.c
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@ -3154,7 +3154,7 @@ static void parse_attribute(AttributeDef *ad)
/* enum/struct/union declaration. u is either VT_ENUM or VT_STRUCT */
static void struct_decl(CType *type, AttributeDef *ad, int u)
{
int a, v, size, align, maxalign, c, offset, flexible;
int a, v, size, align, maxalign, c, offset, flexible, extra_bytes;
int bit_size, bit_pos, bsize, bt, lbit_pos, prevbt;
Sym *s, *ss, *ass, **ps;
AttributeDef ad1;
@ -3235,6 +3235,7 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
while (tok != '}') {
parse_btype(&btype, &ad1);
while (1) {
extra_bytes = 0;
if (flexible)
tcc_error("flexible array member '%s' not at the end of struct",
get_tok_str(v, NULL));
@ -3310,9 +3311,9 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
/* zero size: means to pad */
bit_pos = 0;
} else {
/* we do not have enough room ?
did the type change?
is it a union? */
/* if type change, union, or will overrun
* allignment slot, start at a newly
* alligned slot */
if ((bit_pos + bit_size) > bsize ||
bt != prevbt || a == TOK_UNION)
bit_pos = 0;
@ -3322,15 +3323,30 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
(bit_pos << VT_STRUCT_SHIFT) |
(bit_size << (VT_STRUCT_SHIFT + 6));
bit_pos += bit_size;
/* without ms-bitfields, allocate the
* minimum number of bytes necessary,
* adding single bytes as needed */
if (!tcc_state->ms_bitfields) {
if (lbit_pos == 0)
/* minimum bytes for new bitfield */
size = (bit_size + 7) / 8;
else {
/* enough spare bits already allocated? */
bit_size = (lbit_pos - 1) % 8 + 1 + bit_size;
if (bit_size > 8) /* doesn't fit */
extra_bytes = (bit_size - 1) / 8;
}
}
}
prevbt = bt;
} else {
bit_pos = 0;
}
if (v != 0 || (type1.t & VT_BTYPE) == VT_STRUCT) {
/* add new memory data only if starting
bit field */
if (lbit_pos == 0) {
/* add new memory data only if starting bit
field or adding bytes to existing bit field */
if (extra_bytes) c += extra_bytes;
else if (lbit_pos == 0) {
if (a == TOK_STRUCT) {
c = (c + align - 1) & -align;
offset = c;

9
tests/tcctest.c
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@ -1634,6 +1634,15 @@ void bitfield_test(void)
st2.f3 = a;
st2.f2++;
printf("%lld %lld %lld\n", st2.f1, st2.f2, st2.f3);
struct sbf3 {
int f1 : 7;
int f2 : 1;
char f3;
int f4 : 8;
int f5 : 1;
int f6 : 16;
} st3;
printf("sizeof(st3) = %d\n", sizeof(st3));
}
#ifdef __x86_64__