Messages in this thread |  | | From | Denis Vlasenko <> | | Subject | Re: Some functions are not inlined by gcc 3.2, resulting code is ugly | | Date | Sun, 3 Nov 2002 22:23:01 -0200 |
| |
On 3 November 2002 13:23, Martin J. Bligh wrote: > > Here is the cure: force_inline will guarantee inlining. > > > > To use _only_ with functions which meant to be almost > > optimized away to nothing but are large and gcc might decide > > they are _too_ large for inlining. > > So aside from the ugliness of code, which one actually runs faster?
This can *never* run faster non-inlined because it is called with n being compile time constant:
static inline void * __constant_memcpy(void * to, const void * from, size_t n) { switch (n) { case 0: return to; case 1: *(unsigned char *)to = *(const unsigned char *)from; return to; case 2: *(unsigned short *)to = *(const unsigned short *)from; return to; case 3: *(unsigned short *)to = *(const unsigned short *)from; *(2+(unsigned char *)to) = *(2+(const unsigned char *)from); return to; case 4: *(unsigned long *)to = *(const unsigned long *)from; return to; case 6: /* for Ethernet addresses */ *(unsigned long *)to = *(const unsigned long *)from; *(2+(unsigned short *)to) = *(2+(const unsigned short *)from); return to; case 8: *(unsigned long *)to = *(const unsigned long *)from; *(1+(unsigned long *)to) = *(1+(const unsigned long *)from); return to; case 12: *(unsigned long *)to = *(const unsigned long *)from; *(1+(unsigned long *)to) = *(1+(const unsigned long *)from); *(2+(unsigned long *)to) = *(2+(const unsigned long *)from); return to; case 16: *(unsigned long *)to = *(const unsigned long *)from; *(1+(unsigned long *)to) = *(1+(const unsigned long *)from); *(2+(unsigned long *)to) = *(2+(const unsigned long *)from); *(3+(unsigned long *)to) = *(3+(const unsigned long *)from); return to; case 20: *(unsigned long *)to = *(const unsigned long *)from; *(1+(unsigned long *)to) = *(1+(const unsigned long *)from); *(2+(unsigned long *)to) = *(2+(const unsigned long *)from); *(3+(unsigned long *)to) = *(3+(const unsigned long *)from); *(4+(unsigned long *)to) = *(4+(const unsigned long *)from); return to; } #define COMMON(x) \ __asm__ __volatile__( \ "rep ; movsl" \ x \ : "=&c" (d0), "=&D" (d1), "=&S" (d2) \ : "0" (n/4),"1" ((long) to),"2" ((long) from) \ : "memory"); { int d0, d1, d2; switch (n % 4) { case 0: COMMON(""); return to; case 1: COMMON("\n\tmovsb"); return to; case 2: COMMON("\n\tmovsw"); return to; default: COMMON("\n\tmovsw\n\tmovsb"); return to; } } -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |