Modify sample buffer size for larger displays.

src/core/SkBitmapProcShader.cpp

Index: src/core/SkBitmapProcShader.cpp
diff --git a/src/core/SkBitmapProcShader.cpp b/src/core/SkBitmapProcShader.cpp
index 5f5eb1866e4282ba2a6e6b12237d5ea5a13deb08..661db2c42499dd5d6652299f2ef89baa98288373 100644
--- a/src/core/SkBitmapProcShader.cpp
+++ b/src/core/SkBitmapProcShader.cpp
@@ -205,13 +205,23 @@ SkBitmapProcShader::BitmapProcShaderContext::~BitmapProcShaderContext() {
     fState->~SkBitmapProcState();
 }
 
-#define BUF_MAX     128
+/* Defines the buffer size for sample pixel indexes, used in the sample proc function calls.
+ * If the operation is bigger than the buffer, it's split into multiple calls. This split is bad
+ * for the performance of SIMD optimizations.
+ * A display in portrait mode, with a width of 720 pixels, requires a buffer size of at least 361
+ * to run uninterrupted in the most basic operations. (Formula: Width / 2 + 1)
+ */
+#ifdef ANDROID_LARGE_MEMORY_DEVICE

[djsollen, 2014/04/23 14:40:53]

my goal is to remove ANDROID_LARGE_MEMORY_DEVICE so I'm in agreement with Mike
that we should just go with the larger number.

[henrik.smiding, 2014/04/23 15:20:21]

Done.

+    #define BUF_MAX     541 // 1080p phone display
+#else
+    #define BUF_MAX     241 // 480p phone display
+#endif
 
 #define TEST_BUFFER_OVERRITEx
 
 #ifdef TEST_BUFFER_OVERRITE
     #define TEST_BUFFER_EXTRA   32
-    #define TEST_PATTERN    0x88888888
+    #define TEST_PATTERN        0x88888888
 #else
     #define TEST_BUFFER_EXTRA   0
 #endif
@@ -224,7 +234,9 @@ void SkBitmapProcShader::BitmapProcShaderContext::shadeSpan(int x, int y, SkPMCo
         return;
     }
 
-    uint32_t buffer[BUF_MAX + TEST_BUFFER_EXTRA];
+    // Align buffer to 16 bytes to enable more efficient SIMD optimizations.
+    uint32_t SK_ALIGN(16) buffer[BUF_MAX + TEST_BUFFER_EXTRA];
+
     SkBitmapProcState::MatrixProc   mproc = state.getMatrixProc();
     SkBitmapProcState::SampleProc32 sproc = state.getSampleProc32();
     int max = state.maxCountForBufferSize(sizeof(buffer[0]) * BUF_MAX);