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/*******************************************************
* Create ascii pattern to match in order to find
* alignment at compile time
*******************************************************/
// Compile this program and match
// the produced executable against:
// INT64_ALIGNMENT=<code>
// VOIDP_ALIGNMENT=<code>
// DOUBLE_ALIGNMENT=<code>
//
// to get the alignment used by the (cross)compiler.
//
// <code> is the alignment as an ascii digit.
#include <stdint.h>
#if defined(__GNUC__) || defined(__clang__)
#define ALIGNOF(type) (__alignof(type) + 48) // Ascii '1' for 1, '4' for 4, '8' for 8
#else
#define ALIGNOF(type) (sizeof(type) + 48) // Safe fallback
#endif
int prevent_optimization(unsigned char*p, int size) {
unsigned char *d;
int i;
//Prevent optimizer from eliminating the constants in main()
unsigned char dummy[24]; /* var is not allowed */
d = dummy;
for (i = 0; i < size; ++i) {
*d++ = *p++;
}
return dummy[size-1];
}
#define int64_pat_sz 18
#define voidp_pat_sz 18
#define double_pat_sz 19
int main() {
static const unsigned char int64_alignment[int64_pat_sz] = {
'I', 'N','T','6','4','_','A','L','I','G','N','M','E','N','T','=',
ALIGNOF(int64_t), 0x0
};
static const unsigned char voidp_alignment[voidp_pat_sz] = {
'V', 'O','I','D','P','_','A','L','I','G','N','M','E','N','T','=',
ALIGNOF(void*), 0x0
};
static const unsigned char double_alignment[double_pat_sz] = {
'D', 'O','U','B','L','E','_','A','L','I','G','N','M','E','N','T','=',
ALIGNOF(double), 0x0
};
//Not used, prevent optimization
return prevent_optimization((unsigned char*)int64_alignment, int64_pat_sz) +
prevent_optimization((unsigned char*)voidp_alignment, voidp_pat_sz) +
prevent_optimization((unsigned char*)double_alignment, double_pat_sz);
}
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