Johannes Sixt wrote:
> Am 3/16/2011 8:00, schrieb Jonathan Nieder:
>> +static inline uint32_t git_bswap32(uint32_t x)
>> +{
>> + uint32_t result;
>> + if (__builtin_constant_p(x))
>
> Can this predicate ever be true? Isn't it false even if the function is
> inlined?
It's true if x is a constant.
$ cat test.c
#if 0
gcc -Wall -W -O -o tryit "$0"
exec ./tryit
#else
#include <stdio.h>
#include <stdint.h>
#ifdef __GNUC__
static inline int constant(uint32_t x)
{
return __builtin_constant_p(x);
}
#else
static inline int constant(uint32_t x) { return 0; }
#endif
int main(void)
{
printf("%d\n", constant(3 + 5));
return 0;
}
#endif
$ ./test.c
1
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