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Added SSE2 variants for Average2/3/4

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The predictors based on Average2 are tad slower.

Following is the performance data for these predictors normalized to
number of instruction cycles (as per valgrind) per operation:
- Predictor6 & Predictor7 now takes 15 instruction cycles compared to 11
  instruction cycles for the C version.
- Predictor8 & Predictor9 now takes 15 instruction cycles compared to 12
  instruction cycles for the C version.

The predictors based on Average4 is faster and Average3 is tad slower:
- Predictor10 (Average4) now takes 23 instruction cycles compared to 25
  instruction cycles for the C version.
- Predictor5 (Average3) now takes 20 instruction cycles compared to 18
  instruction cycles for the C version.

Maybe SSE2 version of Average2 can be improved further. Otherwise, we can
remove the SSE2 version and always fallback to the C version.

Change-Id: I388b2871919985bc28faaad37c1d4beeb20ba029
This commit is contained in:
Vikas Arora 2014-04-03 17:07:35 +00:00 committed by James Zern
parent b3a616b356
commit 6d6865f0db
1 changed files with 44 additions and 4 deletions
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48
src/dsp/lossless_sse2.c
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@ -76,8 +76,44 @@ static WEBP_INLINE uint32_t Select(uint32_t a, uint32_t b, uint32_t c) {
return (pa_minus_pb <= 0) ? a : b;
}
#if 0
// TODO(skal): optimize these to SSE2 too.
static WEBP_INLINE __m128i Average2_128i(uint32_t a0, uint32_t a1) {
const __m128i zero = _mm_setzero_si128();
const __m128i A0 = _mm_unpacklo_epi8(_mm_cvtsi32_si128(a0), zero);
const __m128i A1 = _mm_unpacklo_epi8(_mm_cvtsi32_si128(a1), zero);
const __m128i sum = _mm_add_epi16(A1, A0);
const __m128i avg = _mm_srli_epi16(sum, 1);
return avg;
}
static WEBP_INLINE uint32_t Average2(uint32_t a0, uint32_t a1) {
const __m128i avg = Average2_128i(a0, a1);
const __m128i A2 = _mm_packus_epi16(avg, avg);
const uint32_t output = _mm_cvtsi128_si32(A2);
return output;
}
static WEBP_INLINE uint32_t Average3(uint32_t a0, uint32_t a1, uint32_t a2) {
const __m128i zero = _mm_setzero_si128();
const __m128i avg1 = Average2_128i(a0, a2);
const __m128i A1 = _mm_unpacklo_epi8(_mm_cvtsi32_si128(a1), zero);
const __m128i sum = _mm_add_epi16(avg1, A1);
const __m128i avg2 = _mm_srli_epi16(sum, 1);
const __m128i A2 = _mm_packus_epi16(avg2, avg2);
const uint32_t output = _mm_cvtsi128_si32(A2);
return output;
}
static WEBP_INLINE uint32_t Average4(uint32_t a0, uint32_t a1,
uint32_t a2, uint32_t a3) {
const __m128i avg1 = Average2_128i(a0, a1);
const __m128i avg2 = Average2_128i(a2, a3);
const __m128i sum = _mm_add_epi16(avg2, avg1);
const __m128i avg3 = _mm_srli_epi16(sum, 1);
const __m128i A0 = _mm_packus_epi16(avg3, avg3);
const uint32_t output = _mm_cvtsi128_si32(A0);
return output;
}
static uint32_t Predictor5(uint32_t left, const uint32_t* const top) {
const uint32_t pred = Average3(left, top[0], top[1]);
return pred;
@ -104,8 +140,6 @@ static uint32_t Predictor10(uint32_t left, const uint32_t* const top) {
const uint32_t pred = Average4(left, top[-1], top[0], top[1]);
return pred;
}
#endif
static uint32_t Predictor11(uint32_t left, const uint32_t* const top) {
const uint32_t pred = Select(top[0], left, top[-1]);
return pred;
@ -473,6 +507,12 @@ extern void VP8LDspInitSSE2(void);
void VP8LDspInitSSE2(void) {
#if defined(WEBP_USE_SSE2)
VP8LPredictors[5] = Predictor5;
VP8LPredictors[6] = Predictor6;
VP8LPredictors[7] = Predictor7;
VP8LPredictors[8] = Predictor8;
VP8LPredictors[9] = Predictor9;
VP8LPredictors[10] = Predictor10;
VP8LPredictors[11] = Predictor11;
VP8LPredictors[12] = Predictor12;
VP8LPredictors[13] = Predictor13;