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Switch to SSE2 for the hottest loop.

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This commit is contained in:
Alcaro 2014-02-22 17:02:49 +01:00
parent 7d22eae00b
commit 8c3a330f5c
1 changed files with 58 additions and 28 deletions
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86
rewind.c
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@ -230,6 +230,63 @@ void state_manager_push_where(state_manager_t *state, void **data)
*data=state->nextblock;
}
#if __SSE2__
#include <emmintrin.h>
// There's no equivalent in libc, you'd think so ... std::mismatch exists, but it's not optimized at all. :(
static inline size_t find_change(const uint16_t * a, const uint16_t * b)
{
const __m128i * a128=(const __m128i*)a;
const __m128i * b128=(const __m128i*)b;
while (true)
{
__m128i v0 = _mm_loadu_si128(a128);
__m128i v1 = _mm_loadu_si128(b128);
__m128i c = _mm_cmpeq_epi32(v0, v1);
uint32_t mask = _mm_movemask_epi8(c);
if (mask != 0xffff) // Something has changed, figure out where.
{
size_t ret=(((char*)a128-(char*)a) | (__builtin_ctz(~mask))) >> 1;
return (ret | (a[ret]==b[ret]));
}
a128++;
b128++;
}
}
#else
static inline size_t find_change(const uint16_t * a, const uint16_t * b)
{
const uint16_t * a_org=a;
#ifdef NO_UNALIGNED_MEM
while ((uintptr_t)a & (sizeof(size_t)-1) && *a==*b)
{
a++;
b++;
}
if (*a==*b)
#endif
{
const size_t* a_big=(const size_t*)a;
const size_t* b_big=(const size_t*)b;
while (*a_big==*b_big)
{
a_big++;
b_big++;
}
a=(const uint16_t*)a_big;
b=(const uint16_t*)b_big;
while (*b==*a)
{
a++;
b++;
}
}
return a-a_org;
}
#endif
void state_manager_push_do(state_manager_t *state)
{
if (state->thisblock_valid)
@ -258,34 +315,7 @@ void state_manager_push_do(state_manager_t *state)
size_t num16s = state->blocksize/sizeof(uint16_t);
while (num16s)
{
const uint16_t *oldprev = old16;
#ifdef NO_UNALIGNED_MEM
while ((uintptr_t)old16 & (sizeof(size_t)-1) && *old16==*new16)
{
old16++;
new16++;
}
if (*old16==*new16)
#endif
{
const size_t *olds = (const size_t*)old16;
const size_t *news = (const size_t*)new16;
while (*olds == *news)
{
olds++;
news++;
}
old16 = (const uint16_t*)olds;
new16 = (const uint16_t*)news;
while (*old16 == *new16)
{
old16++;
new16++;
}
}
size_t skip = (old16-oldprev);
size_t skip = find_change(old16, new16);
if (skip >= num16s) break;
num16s -= skip;