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| author | grischka <grischka> | 2017-05-09 18:36:24 +0200 |
|---|---|---|
| committer | grischka <grischka> | 2017-05-09 18:36:24 +0200 |
| commit | 1ed20a01c962ea15b4f4486a9ec17160313e3314 (patch) | |
| tree | 70613b17b8ba864270301b887d9f9f0e12de6e94 /tccgen.c | |
| parent | d242706f3b739bcb00de1d970a01a319db6ad77d (diff) | |
| download | tinycc-1ed20a01c962ea15b4f4486a9ec17160313e3314.tar.gz tinycc-1ed20a01c962ea15b4f4486a9ec17160313e3314.tar.bz2 | |
bitfields: promote to signed int
For integer promotion with for example arithmetics or
expr_cond (x ? y : z), integral types need to be promoted
to signed if they fit.
According to latest standards, this also applies to bit-field
types taking into account their specific width.
In tcc, VT_BITFIELD set means width < original type width
Field-widths between 33 and 63 are promoted to signed long long
accordingly.
struct { unsigned long long ullb:35; } s = { 1 };
#define X (s.ullb - 2)
int main (void)
{
long long Y = X;
printf("%d %016llx %016llx\n", X < 0, -X, -Y);
return 0;
}
Results:
GCC 4.7 : 0 0000000000000001 FFFFFFF800000001
MSVC : 1 0000000000000001 0000000000000001
TCC : 1 0000000000000001 0000000000000001
Also, gcc would promote long long bitfields of size < 32
to int as well. Example:
struct { unsigned long long x:20; } t = { 123 };
/* with gcc: */ printf("%d %d\n", t.x, 456);
/* with tcc: */ printf("%lld %d\n", t.x, 456);
Diffstat (limited to 'tccgen.c')
| -rw-r--r-- | tccgen.c | 18 |
1 files changed, 9 insertions, 9 deletions
@@ -2086,23 +2086,23 @@ redo: goto std_op; } else if (op == TOK_SHR || op == TOK_SAR || op == TOK_SHL) { t = bt1 == VT_LLONG ? VT_LLONG : VT_INT; - if ((t1 & (VT_BTYPE | VT_UNSIGNED)) == (t | VT_UNSIGNED)) + if ((t1 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (t | VT_UNSIGNED)) t |= VT_UNSIGNED; goto std_op; } else if (bt1 == VT_LLONG || bt2 == VT_LLONG) { /* cast to biggest op */ t = VT_LLONG; /* convert to unsigned if it does not fit in a long long */ - if ((t1 & (VT_BTYPE | VT_UNSIGNED)) == (VT_LLONG | VT_UNSIGNED) || - (t2 & (VT_BTYPE | VT_UNSIGNED)) == (VT_LLONG | VT_UNSIGNED)) + if ((t1 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_LLONG | VT_UNSIGNED) || + (t2 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_LLONG | VT_UNSIGNED)) t |= VT_UNSIGNED; goto std_op; } else { /* integer operations */ t = VT_INT; /* convert to unsigned if it does not fit in an integer */ - if ((t1 & (VT_BTYPE | VT_UNSIGNED)) == (VT_INT | VT_UNSIGNED) || - (t2 & (VT_BTYPE | VT_UNSIGNED)) == (VT_INT | VT_UNSIGNED)) + if ((t1 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_INT | VT_UNSIGNED) || + (t2 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_INT | VT_UNSIGNED)) t |= VT_UNSIGNED; std_op: /* XXX: currently, some unsigned operations are explicit, so @@ -5198,8 +5198,8 @@ static void expr_cond(void) /* cast to biggest op */ type.t = VT_LLONG; /* convert to unsigned if it does not fit in a long long */ - if ((t1 & (VT_BTYPE | VT_UNSIGNED)) == (VT_LLONG | VT_UNSIGNED) || - (t2 & (VT_BTYPE | VT_UNSIGNED)) == (VT_LLONG | VT_UNSIGNED)) + if ((t1 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_LLONG | VT_UNSIGNED) || + (t2 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_LLONG | VT_UNSIGNED)) type.t |= VT_UNSIGNED; } else if (bt1 == VT_PTR || bt2 == VT_PTR) { /* If one is a null ptr constant the result type @@ -5225,8 +5225,8 @@ static void expr_cond(void) /* integer operations */ type.t = VT_INT; /* convert to unsigned if it does not fit in an integer */ - if ((t1 & (VT_BTYPE | VT_UNSIGNED)) == (VT_INT | VT_UNSIGNED) || - (t2 & (VT_BTYPE | VT_UNSIGNED)) == (VT_INT | VT_UNSIGNED)) + if ((t1 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_INT | VT_UNSIGNED) || + (t2 & (VT_BTYPE | VT_UNSIGNED | VT_BITFIELD)) == (VT_INT | VT_UNSIGNED)) type.t |= VT_UNSIGNED; } /* keep structs lvalue by transforming `(expr ? a : b)` to `*(expr ? &a : &b)` so |