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1ed20a01c9
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);
47 lines
816 B
Plaintext
47 lines
816 B
Plaintext
signed : s.ub
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unsigned : s.u
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signed : s.ullb
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unsigned : s.ull
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signed : s.c
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signed : (1 ? s.ub : 1)
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unsigned : (1 ? s.u : 1)
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signed : (1 ? s.ullb : 1)
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unsigned : (1 ? s.ull : 1)
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signed : (1 ? s.c : 1)
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signed : s.ub << 1
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unsigned : s.u << 1
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signed : s.ullb << 1
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unsigned : s.ull << 1
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signed : s.c << 1
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signed : +s.ub
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unsigned : +s.u
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signed : +s.ullb
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unsigned : +s.ull
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signed : +s.c
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signed : -s.ub
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unsigned : -s.u
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signed : -s.ullb
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unsigned : -s.ull
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signed : -s.c
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signed : ~s.ub
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unsigned : ~s.u
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signed : ~s.ullb
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unsigned : ~s.ull
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signed : ~s.c
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signed : !s.ub
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signed : !s.u
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signed : !s.ullb
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signed : !s.ull
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signed : !s.c
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unsigned : +(unsigned)s.ub
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unsigned : -(unsigned)s.ub
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unsigned : ~(unsigned)s.ub
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signed : !(unsigned)s.ub
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