From 54e4ef657c41a5bb794ebd2a34932cae16a8507b Mon Sep 17 00:00:00 2001
From: Ilya Lavrenov <ilya.lavrenov@itseez.com>
Date: Fri, 27 Jun 2014 14:03:05 +0400
Subject: [PATCH] optimized cv::transpose inplace

---
 modules/core/src/matrix.cpp          | 16 ++++++++++++----
 modules/core/src/opencl/transpose.cl | 20 +++++++++++++-------
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/modules/core/src/matrix.cpp b/modules/core/src/matrix.cpp
index c27c96107..f199cb253 100644
--- a/modules/core/src/matrix.cpp
+++ b/modules/core/src/matrix.cpp
@@ -2973,8 +2973,10 @@ static inline int divUp(int a, int b)
 
 static bool ocl_transpose( InputArray _src, OutputArray _dst )
 {
+    const ocl::Device & dev = ocl::Device::getDefault();
     const int TILE_DIM = 32, BLOCK_ROWS = 8;
-    int type = _src.type(), cn = CV_MAT_CN(type), depth = CV_MAT_DEPTH(type);
+    int type = _src.type(), cn = CV_MAT_CN(type), depth = CV_MAT_DEPTH(type),
+        rowsPerWI = dev.isIntel() ? 4 : 1;
 
     UMat src = _src.getUMat();
     _dst.create(src.cols, src.rows, type);
@@ -2990,9 +2992,9 @@ static bool ocl_transpose( InputArray _src, OutputArray _dst )
     }
 
     ocl::Kernel k(kernelName.c_str(), ocl::core::transpose_oclsrc,
-                  format("-D T=%s -D T1=%s -D cn=%d -D TILE_DIM=%d -D BLOCK_ROWS=%d",
+                  format("-D T=%s -D T1=%s -D cn=%d -D TILE_DIM=%d -D BLOCK_ROWS=%d -D rowsPerWI=%d",
                          ocl::memopTypeToStr(type), ocl::memopTypeToStr(depth),
-                         cn, TILE_DIM, BLOCK_ROWS));
+                         cn, TILE_DIM, BLOCK_ROWS, rowsPerWI));
     if (k.empty())
         return false;
 
@@ -3003,7 +3005,13 @@ static bool ocl_transpose( InputArray _src, OutputArray _dst )
                ocl::KernelArg::WriteOnlyNoSize(dst));
 
     size_t localsize[2]  = { TILE_DIM, BLOCK_ROWS };
-    size_t globalsize[2] = { src.cols, inplace ? src.rows : divUp(src.rows, TILE_DIM) * BLOCK_ROWS };
+    size_t globalsize[2] = { src.cols, inplace ? (src.rows + rowsPerWI - 1) / rowsPerWI : (divUp(src.rows, TILE_DIM) * BLOCK_ROWS) };
+
+    if (inplace && dev.isIntel())
+    {
+        localsize[0] = 16;
+        localsize[1] = dev.maxWorkGroupSize() / localsize[0];
+    }
 
     return k.run(2, globalsize, localsize, false);
 }
diff --git a/modules/core/src/opencl/transpose.cl b/modules/core/src/opencl/transpose.cl
index d56e49909..cad3616b5 100644
--- a/modules/core/src/opencl/transpose.cl
+++ b/modules/core/src/opencl/transpose.cl
@@ -117,18 +117,24 @@ __kernel void transpose(__global const uchar * srcptr, int src_step, int src_off
 __kernel void transpose_inplace(__global uchar * srcptr, int src_step, int src_offset, int src_rows)
 {
     int x = get_global_id(0);
-    int y = get_global_id(1);
+    int y = get_global_id(1) * rowsPerWI;
 
-    if (y < src_rows && x < y)
+    if (x < y + rowsPerWI)
     {
         int src_index = mad24(y, src_step, mad24(x, TSIZE, src_offset));
         int dst_index = mad24(x, src_step, mad24(y, TSIZE, src_offset));
+        T tmp;
 
-        __global const uchar * src = srcptr + src_index;
-        __global uchar * dst = srcptr + dst_index;
+        #pragma unroll
+        for (int i = 0; i < rowsPerWI; ++i, ++y, src_index += src_step, dst_index += TSIZE)
+            if (y < src_rows && x < y)
+            {
+                __global uchar * src = srcptr + src_index;
+                __global uchar * dst = srcptr + dst_index;
 
-        T tmp = loadpix(dst);
-        storepix(loadpix(src), dst);
-        storepix(tmp, src);
+                tmp = loadpix(dst);
+                storepix(loadpix(src), dst);
+                storepix(tmp, src);
+            }
     }
 }