Andrew Haley wrote:
Tom St Denis wrote:
#define SQRADDSC(i, j) \
asm( \
" mullw %0,%3,%4 \n\t" \
" mulhwu %1,%3,%4 \n\t" \
" xor %2,%2,%2 \n\t" \
:"=r"(sc0), "=r"(sc1), "=r"(sc2): "r"(i),"r"(j) : "%cc");
#endif
This isn't a bug: look for "earlyclobber" in the documentation.
Adding =&r worked, however ... (this is the part where I complain
perhaps needlessly :-) )
This doesn't make sense. In the subsequent line "mulhwu ..." I
specifically asked for %3,%4 which is i and j respectively. Yet,
without early clobber it gives me sc0. To me that sounds like a bug.
Maybe it's not the way the inline asm is "meant" to be used, but to
someone who reads the code it's not obvious that %3 no longer means i.
Semantically it's as if I used "%1,%0,%4" as the operands for the 2nd line.
Either way, thank you for pointing me in the right direction.
Tom
