my first version of
get_be32() was a macro that did this:
#define SHA_SRC(t) \
({ unsigned char *__d = (unsigned char *)&data[t]; \
(__d[0]<< 24) | (__d[1]<< 16) | (__d[2]<< 8) | (__d[3]<< 0); })
With such a construct, gcc would always allocate a register to hold __d
and then dereference that with an offset from 0 to 3. Whereas:
#define SHA_SRC(t) \
({ unsigned char *__d = (unsigned char *)data; \
(__d[(t)*4 + 0]<< 24) | (__d[(t)*4 + 1]<< 16) | \
(__d[(t)*4 + 2]<< 8) | (__d[(t)*4 + 3]<< 0); })
does produce optimal assembly as only the register holding the data
pointer is dereferenced with the absolute byte offset. I suspect your
usage of inline functions has the same effect as the first SHA_SRC
definition above.
Yes, that's what happens.
Paolo
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