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host-utils: Use __int128_t for mul[us]64

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Replace some x86_64 specific inline assembly with something that
all 64-bit hosts ought to optimize well.  At worst this becomes
a call to the gcc __multi3 routine, which is no worse than our
implementation in util/host-utils.c.

With gcc 4.7, we get identical code generation for x86_64.  We
now get native multiplication on ia64 and s390x hosts.  With minor
improvements to gcc we can get it for ppc64 as well.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Richard Henderson 2013-02-16 12:46:59 -08:00 • committed by Blue Swirl
parent be96bd3fbf
commit f540166b7d
3 changed files with 30 additions and 11 deletions
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4
util/host-utils.c
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@ -30,7 +30,7 @@
//#define DEBUG_MULDIV
/* Long integer helpers */
#if !defined(__x86_64__)
#ifndef CONFIG_INT128
static void add128 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
{
*plow += a;
@ -102,4 +102,4 @@ void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b)
a, b, *phigh, *plow);
#endif
}
#endif /* !defined(__x86_64__) */
#endif /* !CONFIG_INT128 */