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Optimize VP8SetResidualCoeffs.

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Brings down WebP lossy encoding timings by 5%

Change-Id: Ia4a2fab0a887aaaf7841ce6d9ee16270d3e15489
This commit is contained in:
skal
2014-06-03 06:44:04 +02:00
parent ac591cf22e
commit 6679f8996f
6 changed files with 107 additions and 44 deletions
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29
src/dsp/enc_sse2.c
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@ -17,7 +17,9 @@
#include <stdlib.h> // for abs()
#include <emmintrin.h>
#include "../enc/cost.h"
#include "../enc/vp8enci.h"
#include "../utils/utils.h"
//------------------------------------------------------------------------------
// Quite useful macro for debugging. Left here for convenience.
@ -929,6 +931,33 @@ static int QuantizeBlockWHT(int16_t in[16], int16_t out[16],
return DoQuantizeBlock(in, out, 0, &mtx->sharpen_[0], mtx);
}
// Forward declaration.
void VP8SetResidualCoeffsSSE2(const int16_t* const coeffs,
VP8Residual* const res);
void VP8SetResidualCoeffsSSE2(const int16_t* const coeffs,
VP8Residual* const res) {
const __m128i c0 = _mm_loadu_si128((const __m128i*)coeffs);
const __m128i c1 = _mm_loadu_si128((const __m128i*)(coeffs + 8));
// Use SSE to compare 8 values with a single instruction.
const __m128i zero = _mm_setzero_si128();
const __m128i m0 = _mm_cmpeq_epi16(c0, zero);
const __m128i m1 = _mm_cmpeq_epi16(c1, zero);
// Get the comparison results as a bitmask, consisting of two times 16 bits:
// two identical bits for each result. Concatenate both bitmasks to get a
// single 32 bit value. Negate the mask to get the position of entries that
// are not equal to zero. Finally, mask out least significant bits according
// to res->first.
const uint32_t mask =
~((_mm_movemask_epi8(m1) << 16) | _mm_movemask_epi8(m0)) &
-(1U << (res->first << 1));
// The position of the most significant non-zero bit indicates the position of
// the last non-zero value. Divide the result by two because __movemask_epi8
// operates on 8 bit values instead of 16 bit values.
res->last = mask ? (BitsLog2Floor(mask) >> 1) : -1;
res->coeffs = coeffs;
}
#endif // WEBP_USE_SSE2
//------------------------------------------------------------------------------

36
src/dsp/lossless.h
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@ -19,6 +19,7 @@
#include "../webp/decode.h"
#include "../enc/histogram.h"
#include "../utils/utils.h"
#ifdef __cplusplus
extern "C" {
@ -169,41 +170,6 @@ extern VP8LHistogramAddFunc VP8LHistogramAdd;
// -----------------------------------------------------------------------------
// PrefixEncode()
// use GNU builtins where available.
#if defined(__GNUC__) && \
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
return 31 ^ __builtin_clz(n);
}
#elif defined(_MSC_VER) && _MSC_VER > 1310 && \
(defined(_M_X64) || defined(_M_IX86))
#include <intrin.h>
#pragma intrinsic(_BitScanReverse)
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
unsigned long first_set_bit;
_BitScanReverse(&first_set_bit, n);
return first_set_bit;
}
#else
// Returns (int)floor(log2(n)). n must be > 0.
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
int log = 0;
uint32_t value = n;
int i;
for (i = 4; i >= 0; --i) {
const int shift = (1 << i);
const uint32_t x = value >> shift;
if (x != 0) {
value = x;
log += shift;
}
}
return log;
}
#endif
static WEBP_INLINE int VP8LBitsLog2Ceiling(uint32_t n) {
const int log_floor = BitsLog2Floor(n);
if (n == (n & ~(n - 1))) // zero or a power of two.