Properly enable S32_D16_filter_DX_SSE2 optimization.

Currently, the S32_D16_filter_DX_SSE2 optimization is only used in
configurations where the maximum SSE level is SSE2.
This patch enables it for higher levels, as well as fixing a color
conversion bug when the subpixels are converted into RGB565 format.
Also, refactored the function a bit, to make future modifications
less error-prone.

Author: henrik.smiding@intel.com

Signed-off-by: Henrik Smiding <henrik.smiding@intel.com>

Committed: http://code.google.com/p/skia/source/detail?r=14333

R=reed@google.com, mtklein@google.com, tomhudson@google.com, djsollen@google.com, joakim.landberg@intel.com

Author: henrik.smiding@intel.com

Review URL: https://codereview.chromium.org/239453010

git-svn-id: http://skia.googlecode.com/svn/trunk@14403 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/opts/SkBitmapProcState_opts_SSE2.cpp b/src/opts/SkBitmapProcState_opts_SSE2.cpp
index 0b07997..54a2f2d 100644
--- a/src/opts/SkBitmapProcState_opts_SSE2.cpp
+++ b/src/opts/SkBitmapProcState_opts_SSE2.cpp
@@ -9,6 +9,7 @@
 
 #include <emmintrin.h>
 #include "SkBitmapProcState_opts_SSE2.h"
+#include "SkColorPriv.h"
 #include "SkPaint.h"
 #include "SkUtils.h"
 
@@ -639,8 +640,8 @@
  *  It combines S32_opaque_D32_filter_DX_SSE2 and SkPixel32ToPixel16
  */
 void S32_D16_filter_DX_SSE2(const SkBitmapProcState& s,
-                                   const uint32_t* xy,
-                                   int count, uint16_t* colors) {
+                            const uint32_t* xy,
+                            int count, uint16_t* colors) {
     SkASSERT(count > 0 && colors != NULL);
     SkASSERT(s.fFilterLevel != SkPaint::kNone_FilterLevel);
     SkASSERT(s.fBitmap->config() == SkBitmap::kARGB_8888_Config);
@@ -744,23 +745,6 @@
         // Extract low int and store.
         dstColor = _mm_cvtsi128_si32(sum);
 
-        //*colors++ = SkPixel32ToPixel16(dstColor);
-        // below is much faster than the above. It's tested for Android benchmark--Softweg
-        __m128i _m_temp1 = _mm_set1_epi32(dstColor);
-        __m128i _m_temp2 = _mm_srli_epi32(_m_temp1, 3);
-
-        unsigned int r32 = _mm_cvtsi128_si32(_m_temp2);
-        unsigned r = (r32 & ((1<<5) -1)) << 11;
-
-        _m_temp2 = _mm_srli_epi32(_m_temp2, 7);
-        unsigned int g32 = _mm_cvtsi128_si32(_m_temp2);
-        unsigned g = (g32 & ((1<<6) -1)) << 5;
-
-        _m_temp2 = _mm_srli_epi32(_m_temp2, 9);
-        unsigned int b32 = _mm_cvtsi128_si32(_m_temp2);
-        unsigned b = (b32 & ((1<<5) -1));
-
-        *colors++ = r | g | b;
-
+        *colors++ = SkPixel32ToPixel16(dstColor);
     } while (--count > 0);
 }
diff --git a/src/opts/opts_check_SSE2.cpp b/src/opts/opts_check_SSE2.cpp
index 5adfb6b..6c684c2 100644
--- a/src/opts/opts_check_SSE2.cpp
+++ b/src/opts/opts_check_SSE2.cpp
@@ -133,46 +133,54 @@
 }
 
 void SkBitmapProcState::platformProcs() {
-    if (cachedHasSSSE3()) {
-        if (fSampleProc32 == S32_opaque_D32_filter_DX) {
-            fSampleProc32 = S32_opaque_D32_filter_DX_SSSE3;
-        } else if (fSampleProc32 == S32_alpha_D32_filter_DX) {
-            fSampleProc32 = S32_alpha_D32_filter_DX_SSSE3;
-        }
+    /* Every optimization in the function requires at least SSE2 */
+    if (!cachedHasSSE2()) {
+        return;
+    }
 
-        if (fSampleProc32 == S32_opaque_D32_filter_DXDY) {
-            fSampleProc32 = S32_opaque_D32_filter_DXDY_SSSE3;
-        } else if (fSampleProc32 == S32_alpha_D32_filter_DXDY) {
-            fSampleProc32 = S32_alpha_D32_filter_DXDY_SSSE3;
-        }
-    } else if (cachedHasSSE2()) {
-        if (fSampleProc32 == S32_opaque_D32_filter_DX) {
+    /* Check fSampleProc32 */
+    if (fSampleProc32 == S32_opaque_D32_filter_DX) {
+        if (cachedHasSSSE3()) {
+            fSampleProc32 = S32_opaque_D32_filter_DX_SSSE3;
+        } else {
             fSampleProc32 = S32_opaque_D32_filter_DX_SSE2;
-        } else if (fSampleProc32 == S32_alpha_D32_filter_DX) {
+        }
+    } else if (fSampleProc32 == S32_opaque_D32_filter_DXDY) {
+        if (cachedHasSSSE3()) {
+            fSampleProc32 = S32_opaque_D32_filter_DXDY_SSSE3;
+        }
+    } else if (fSampleProc32 == S32_alpha_D32_filter_DX) {
+        if (cachedHasSSSE3()) {
+            fSampleProc32 = S32_alpha_D32_filter_DX_SSSE3;
+        } else {
             fSampleProc32 = S32_alpha_D32_filter_DX_SSE2;
         }
-
-        if (fSampleProc16 == S32_D16_filter_DX) {
-            fSampleProc16 = S32_D16_filter_DX_SSE2;
+    } else if (fSampleProc32 == S32_alpha_D32_filter_DXDY) {
+        if (cachedHasSSSE3()) {
+            fSampleProc32 = S32_alpha_D32_filter_DXDY_SSSE3;
         }
     }
 
-    if (cachedHasSSSE3() || cachedHasSSE2()) {
-        if (fMatrixProc == ClampX_ClampY_filter_scale) {
-            fMatrixProc = ClampX_ClampY_filter_scale_SSE2;
-        } else if (fMatrixProc == ClampX_ClampY_nofilter_scale) {
-            fMatrixProc = ClampX_ClampY_nofilter_scale_SSE2;
-        }
+    /* Check fSampleProc16 */
+    if (fSampleProc16 == S32_D16_filter_DX) {
+        fSampleProc16 = S32_D16_filter_DX_SSE2;
+    }
 
-        if (fMatrixProc == ClampX_ClampY_filter_affine) {
-            fMatrixProc = ClampX_ClampY_filter_affine_SSE2;
-        } else if (fMatrixProc == ClampX_ClampY_nofilter_affine) {
-            fMatrixProc = ClampX_ClampY_nofilter_affine_SSE2;
-        }
-        if (c_hqfilter_sse) {
-            if (fShaderProc32 == highQualityFilter32) {
-                fShaderProc32 = highQualityFilter_SSE2;
-            }
+    /* Check fMatrixProc */
+    if (fMatrixProc == ClampX_ClampY_filter_scale) {
+        fMatrixProc = ClampX_ClampY_filter_scale_SSE2;
+    } else if (fMatrixProc == ClampX_ClampY_nofilter_scale) {
+        fMatrixProc = ClampX_ClampY_nofilter_scale_SSE2;
+    } else if (fMatrixProc == ClampX_ClampY_filter_affine) {
+        fMatrixProc = ClampX_ClampY_filter_affine_SSE2;
+    } else if (fMatrixProc == ClampX_ClampY_nofilter_affine) {
+        fMatrixProc = ClampX_ClampY_nofilter_affine_SSE2;
+    }
+
+    /* Check fShaderProc32 */
+    if (c_hqfilter_sse) {
+        if (fShaderProc32 == highQualityFilter32) {
+            fShaderProc32 = highQualityFilter_SSE2;
         }
     }
 }