shithub: libvpx

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ref: eed1badeddcbc79e6c232194cce513774cb25a30
parent: 502ac7223328614cfd3af88764bcb866dbdba9da
author: Jingning Han <jingning@google.com>
date: Wed Apr 1 07:39:36 EDT 2015 

Optimize quantization simd implementation

This commit allows the quantizer to compare the AC coefficients to
the quantization step size to determine if further multiplication
operations are needed. It makes the quantization process 20% faster
without coding statistics change.

Change-Id: I735aaf6a9c0874c82175bb565b20e131464db64a


--- a/vp9/encoder/x86/vp9_dct_ssse3.c
+++ b/vp9/encoder/x86/vp9_dct_ssse3.c
@@ -293,7 +293,8 @@
 
   if (!skip_block) {
     __m128i eob;
-    __m128i round, quant, dequant;
+    __m128i round, quant, dequant, thr;
+    int16_t nzflag;
     {
       __m128i coeff0, coeff1;
 
@@ -368,6 +369,7 @@
 
     // AC only loop
     index = 2;
+    thr = _mm_srai_epi16(dequant, 1);
     while (n_coeffs < 0) {
       __m128i coeff0, coeff1;
       {
@@ -387,28 +389,39 @@
         qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
         qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
 
-        qcoeff0 = _mm_adds_epi16(qcoeff0, round);
-        qcoeff1 = _mm_adds_epi16(qcoeff1, round);
-        qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
-        qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
+        nzflag = _mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff0, thr)) |
+            _mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff1, thr));
 
-        // Reinsert signs
-        qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
-        qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
-        qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
-        qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
+        if (nzflag) {
+          qcoeff0 = _mm_adds_epi16(qcoeff0, round);
+          qcoeff1 = _mm_adds_epi16(qcoeff1, round);
+          qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
+          qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
 
-        _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), qcoeff0);
-        _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, qcoeff1);
+          // Reinsert signs
+          qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
+          qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
+          qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
+          qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
 
-        coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
-        coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), qcoeff0);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, qcoeff1);
 
-        _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), coeff0);
-        _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, coeff1);
+          coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
+          coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
+
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), coeff0);
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, coeff1);
+        } else {
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), zero);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, zero);
+
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), zero);
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, zero);
+        }
       }
 
-      {
+      if (nzflag) {
         // Scan for eob
         __m128i zero_coeff0, zero_coeff1;
         __m128i nzero_coeff0, nzero_coeff1;
--- a/vp9/encoder/x86/vp9_quantize_sse2.c
+++ b/vp9/encoder/x86/vp9_quantize_sse2.c
@@ -230,6 +230,8 @@
                           const int16_t* scan_ptr,
                           const int16_t* iscan_ptr) {
   __m128i zero;
+  __m128i thr;
+  int16_t nzflag;
   (void)scan_ptr;
   (void)zbin_ptr;
   (void)quant_shift_ptr;
@@ -316,6 +318,8 @@
       n_coeffs += 8 * 2;
     }
 
+    thr = _mm_srai_epi16(dequant, 1);
+
     // AC only loop
     while (n_coeffs < 0) {
       __m128i coeff0, coeff1;
@@ -335,28 +339,39 @@
         qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
         qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
 
-        qcoeff0 = _mm_adds_epi16(qcoeff0, round);
-        qcoeff1 = _mm_adds_epi16(qcoeff1, round);
-        qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
-        qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
+        nzflag = _mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff0, thr)) |
+            _mm_movemask_epi8(_mm_cmpgt_epi16(qcoeff1, thr));
 
-        // Reinsert signs
-        qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
-        qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
-        qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
-        qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
+        if (nzflag) {
+          qcoeff0 = _mm_adds_epi16(qcoeff0, round);
+          qcoeff1 = _mm_adds_epi16(qcoeff1, round);
+          qtmp0 = _mm_mulhi_epi16(qcoeff0, quant);
+          qtmp1 = _mm_mulhi_epi16(qcoeff1, quant);
 
-        _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), qcoeff0);
-        _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, qcoeff1);
+          // Reinsert signs
+          qcoeff0 = _mm_xor_si128(qtmp0, coeff0_sign);
+          qcoeff1 = _mm_xor_si128(qtmp1, coeff1_sign);
+          qcoeff0 = _mm_sub_epi16(qcoeff0, coeff0_sign);
+          qcoeff1 = _mm_sub_epi16(qcoeff1, coeff1_sign);
 
-        coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
-        coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), qcoeff0);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, qcoeff1);
 
-        _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), coeff0);
-        _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, coeff1);
+          coeff0 = _mm_mullo_epi16(qcoeff0, dequant);
+          coeff1 = _mm_mullo_epi16(qcoeff1, dequant);
+
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), coeff0);
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, coeff1);
+        } else {
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs), zero);
+          _mm_store_si128((__m128i*)(qcoeff_ptr + n_coeffs) + 1, zero);
+
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs), zero);
+          _mm_store_si128((__m128i*)(dqcoeff_ptr + n_coeffs) + 1, zero);
+        }
       }
 
-      {
+      if (nzflag) {
         // Scan for eob
         __m128i zero_coeff0, zero_coeff1;
         __m128i nzero_coeff0, nzero_coeff1;