Added xCONVGEMM as im2col plus a batched GEMM kernel

CHANGELOG

@@ -3,6 +3,8 @@ Development (next version)
 - Added support for shuffle instructions for NVIDIA GPUs (thanks to 'tyler-utah')
 - Fixed an issue with AMD GPUs and the new GEMMK == 1 kernel
 - Various minor fixes and enhancements
+- Added non-BLAS routines:
+  * SCONVGEMM/DCONVGEMM/HCONVGEMM (convolution as im2col followed by batched GEMM)
 
 Version 1.4.1
 - Fixed an access violation under Windows upon releasing the OpenCL program when the driver is already unloaded

doc/routines.md

@@ -93,8 +93,9 @@ In addition, some extra non-BLAS routines are also supported by CLBlast, classif
 | xHAD       | ✔ | ✔ | ✔ | ✔ | ✔ | (Hadamard product)
 | xOMATCOPY  | ✔ | ✔ | ✔ | ✔ | ✔ | (Out-of-place copying/transposing/scaling of matrices)
 | xIM2COL    | ✔ | ✔ | ✔ | ✔ | ✔ | (Image to column transform as used to express convolution as GEMM)
+| xCONVGEMM  | ✔ | ✔ | - | - | ✔ | (Experimental, implemented as im2col followed by batched GEMM)
 
-Some less commonly used BLAS routines are not yet supported yet by CLBlast. They are xROTG, xROTMG, xROT, xROTM, xTBSV, and xTPSV.
+Some less commonly used BLAS routines are not yet supported by CLBlast. They are xROTG, xROTMG, xROT, xROTM, xTBSV, and xTPSV.
 
 
 Half precision (fp16)

src/kernels/levelx/xconvgemm_part1.opencl

@@ -11,6 +11,7 @@
 // uses parameters from the direct GEMM kernel. This is the part with the loads from memory (1/2).
 // This uses "CONVGEMM_WITH_IM2COL" as a switch to select between direct convgemm or first running
 // the im2col kernel to create a 'col' temporary matrix.
+// TODO: Currently only works with 'CONVGEMM_WITH_IM2COL' set
 //
 // =================================================================================================
 

src/kernels/levelx/xconvgemm_part2.opencl

@@ -11,6 +11,7 @@
 // uses parameters from the direct GEMM kernel. This part contains the main kernel (2/2).
 // This uses "CONVGEMM_WITH_IM2COL" as a switch to select between direct convgemm or first running
 // the im2col kernel to create a 'col' temporary matrix.
+// TODO: Currently only works with 'CONVGEMM_WITH_IM2COL' set
 //
 // =================================================================================================
 

src/routines/levelx/xconvgemm.cpp

@@ -13,6 +13,7 @@
 
 #include <string>
 #include <vector>
+#include <assert.h>
 
 #include "routines/levelx/xconvgemm.hpp"
 #include "routines/levelx/xim2col.hpp"
@@ -51,6 +52,9 @@ void Xconvgemm<T>::DoConvgemm(const size_t channels, const size_t height, const
                               const Buffer<T> &kernel_buffer, const size_t kernel_offset,
                               const Buffer<T> &result_buffer, const size_t result_offset) {
 
+  // TODO: Implement single-kernel approach
+  assert(method_ == ConvGemmMethod::kWithIm2Col);
+
   // Tests for a valid batch count
   if (batch_count == 0) {
     throw BLASError(StatusCode::kInvalidBatchCount);

src/routines/levelx/xconvgemm.hpp

@@ -29,7 +29,7 @@ class Xconvgemm: public Routine {
   // Constructor
   enum class ConvGemmMethod {kWithIm2Col, kSingleKernel};
   Xconvgemm(Queue &queue, EventPointer event, const std::string &name = "CONVGEMM",
-            const ConvGemmMethod method = ConvGemmMethod::kSingleKernel);
+            const ConvGemmMethod method = ConvGemmMethod::kWithIm2Col);
 
   // Templated-precision implementation of the routine
   void DoConvgemm(const size_t channels, const size_t height, const size_t width,