apple metal support

arraymancer.nimble

@@ -219,6 +219,11 @@ task test_opencl, "Run all OpenCL backend tests":
   switches.add " -d:blas=cblas" # Archlinux, comment out on Debian/Ubuntu
   test "tests_opencl", switches, split = false, "cpp"
 
+task test_metal, "Run all Metal backend tests":
+  var switches = " -d:metal"
+  switches.add " -d:blas=cblas" # Archlinux, comment out on Debian/Ubuntu
+  test "tests_metal", switches, split = false
+
 # task test_deprecated, "Run all tests on deprecated procs":
 #  test "tests_cpu_deprecated"
 

src/arraymancer/tensor.nim

@@ -81,3 +81,7 @@ when defined(cuda) or defined(nimdoc) or defined(nimsuggest):
 when defined(opencl) or defined(nimdoc) or defined(nimsuggest):
   import ./tensor/tensor_opencl
   export tensor_opencl
+
+when defined(metal) or defined(nimdoc) or defined(nimsuggest):
+  import ./tensor/tensor_metal
+  export tensor_metal

src/arraymancer/tensor/backend/global_config.nim

@@ -32,6 +32,10 @@ const CUDA_HOF_BPG*: cint = 256     # should be (grid-stride+threadsPerBlock-1)
 const OMP_FOR_THRESHOLD* = 1000    # Tensor number of elements threshold before using OpenMP multithreading
 const OMP_MAX_REDUCE_BLOCKS* = 8   # Max number of expected OpenMP threads (used in reduce)
 
+# Metal-specific configuration
+const METAL_THREADGROUP_SIZE* = 256  # Default threadgroup size for Metal kernels
+const METAL_BUFFER_POOL_MAX_SIZE* = 1024 * 1024 * 1024  # 1GB max buffer pool size
+
 # Full procesor optimization (AVX, AVX2, ARM neon, ... if applicable)
 when defined(native):
   {.passC: "-march=native".}

src/arraymancer/tensor/backend/metal.nim

@@ -0,0 +1,29 @@
+# Copyright 2017 the Arraymancer contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+## Metal backend for Arraymancer
+## Provides GPU acceleration on macOS using Apple's Metal framework
+
+when defined(metal):
+  import  ../data_structure,
+          ./metal/metal_buffer,
+          ./metal/metal_backend
+
+  export  metal_buffer,
+          metal_backend
+
+  # Re-export types for convenience
+  export MetalBuffer, MetalBufferPool
+  export MTLDevice, MTLCommandQueue, MTLCommandBuffer, MTLBuffer
+  export MetalContext, metalContext, initMetalContext, isMetalAvailable