Draft of Metal driver api support

dub.json

@@ -7,7 +7,12 @@
     "dependencies": {
         "derelict-cl"  : "~>3.2.0",
         "bindbc-cuda": "~>0.1.0",
-        "taggedalgebraic": "~>0.10.7"
+        "metal-d": "~>0.5.3",
+        "taggedalgebraic": "~>0.10.7",
+        "llvm_downgrader" : {
+          "repository" : "git+https://github.com/asindarov/llvm_downgrader.git",
+          "version" : "99d231c2e5fe5be2a768d573c1bca28b7a53ffab"
+        }
     },
     "configurations": [
         {
@@ -35,5 +40,12 @@
             "targetType": "executable",
             "versions": ["DComputeTestOpenCL"],
         },
-    ]
+        {
+            "name" : "test-metal",
+            "dflags": ["-mdcompute-targets=metal-400", "-version=LDC_DCompute","-oq"],
+            "dflags-ldc": ["-wi"],
+            "targetType": "executable",
+            "versions": ["DComputeTestMetal"],
+        },
+   ]
 }

source/dcompute/driver/metal/buffer.d

@@ -0,0 +1,30 @@
+module dcompute.driver.metal.buffer;
+import metal;
+import dcompute.driver.metal.program;
+import dcompute.driver.metal;
+import core.stdc.string;
+
+struct Buffer(T)
+{
+    MTLBuffer mtlBuffer;
+
+    // Host memory associated with this buffer
+    T[] hostMemory;
+
+    this(MTLBuffer _mtlBuffer, T[] array)
+    {
+        mtlBuffer = _mtlBuffer;
+        hostMemory = array;
+    }
+
+    T* contents()
+    {
+        return cast(T*) mtlBuffer.contents();
+    }
+
+    void release()
+    {
+        mtlBuffer = null;
+        hostMemory = null;
+    }
+}

source/dcompute/driver/metal/device.d

@@ -0,0 +1,44 @@
+module dcompute.driver.metal.device;
+import dcompute.driver.metal.buffer;
+import core.stdc.string;
+import metal;
+
+struct Device
+{
+    /**
+        A pointer to $(D MTLDevice). It is $(D void*) because upon storing array of $(D Device), 
+        linker look for the $(D MTLDevice) but fails to 
+        find it as it is Objective-C binding hence had to wrap it as such
+    */
+    void* raw;
+
+    @property MTLDevice mtlDevice()
+    {
+        return cast(MTLDevice) raw;
+    }
+
+    this(MTLDevice device)
+    {
+        raw = cast(void*)device;
+    }
+
+    MTLBuffer newBuffer(size_t sizeInBytes)
+    {
+        return mtlDevice.newBuffer(sizeInBytes, MTLResourceOptions.StorageModeShared);
+    }
+
+    Buffer!T makeBuffer(T)(T[] hostMemory)
+    {
+        size_t sizeInBytes = hostMemory.length * T.sizeof;
+
+        auto mtlBuffer = newBuffer(sizeInBytes);
+        auto buffer = Buffer!T(mtlBuffer, hostMemory);
+
+        if (buffer.hostMemory.ptr !is null && sizeInBytes > 0)
+        {
+            memcpy(buffer.mtlBuffer.contents(), buffer.hostMemory.ptr, sizeInBytes);
+        }
+
+        return buffer;
+    }
+}

source/dcompute/driver/metal/kernel.d

@@ -0,0 +1,12 @@
+module dcompute.driver.metal.kernel;
+import metal.library;
+
+struct Kernel(F) if (is(F==function) || is(F==void))
+{
+    MTLFunction kernelFunction;
+
+    this(MTLFunction _kernelFunction)
+    {
+        kernelFunction = _kernelFunction;
+    }
+}

source/dcompute/driver/metal/package.d

@@ -0,0 +1,26 @@
+module dcompute.driver.metal;
+import ldc.dcompute;
+import std.range;
+import std.meta;
+import std.traits;
+
+public import dcompute.driver.metal.buffer;
+public import dcompute.driver.metal.device;
+public import dcompute.driver.metal.kernel;
+public import dcompute.driver.metal.platform;
+public import dcompute.driver.metal.program;
+public import dcompute.driver.metal.queue;
+
+
+template HostArgsOf(F)
+{
+    template toBuffer(T)
+    {
+        static if (is(T: Pointer!(n,U), uint n, U))
+            alias toBuffer = Buffer!U;
+        else
+            alias toBuffer = T;
+    }
+
+    alias HostArgsOf = staticMap!(toBuffer, Parameters!F);
+}

source/dcompute/driver/metal/platform.d

@@ -0,0 +1,26 @@
+module dcompute.driver.metal.platform;
+
+import dcompute.driver.metal.device;
+import metal.device;
+
+struct Platform
+{
+    static Device[] getDevices()
+    {
+        auto mtlDevices = MTLCopyAllDevices();
+        auto devices = new Device[mtlDevices.length];
+
+        for(int i=0;i < mtlDevices.length;i ++)
+        {
+            devices[i] = Device(mtlDevices[i]);
+        }
+
+        return devices;
+    }
+
+    static Device getDefaultDevice()
+    {
+        auto device = Device(MTLCreateSystemDefaultDevice());
+        return device;
+    }
+}

source/dcompute/driver/metal/program.d

@@ -0,0 +1,114 @@
+module dcompute.driver.metal.program;
+import dcompute.driver.metal.device;
+import dcompute.driver.metal.kernel;
+import objc;
+import foundation;
+import core.stdc.stdio;
+import std.string;
+import std.path;
+import metal.library;
+import metal.device;
+import llvm_downgrader.lib;
+import std.process;
+import std.typecons: Nullable, nullable;
+struct Program
+{
+    MTLLibrary metalLibrary;
+
+    Kernel!void getKernelByName(immutable(char)* name)
+    {
+        auto kName = fromStringz(name);
+
+        auto kNameInNSString = NSString.create(kName);
+
+        auto kernelFunction = metalLibrary.newFunctionWithName(kNameInNSString);
+
+        if (kernelFunction is null)
+        {
+            printf("Error: Could not find kernel function %s in library.\n", name);
+            assert(0);
+        }
+
+        return Kernel!void(kernelFunction);
+    }
+
+    Kernel!(typeof(k)) getKernel(alias k)()
+    {
+        return cast(typeof(return)) getKernelByName(k.mangleof.ptr);
+    }
+
+    static Program fromFile(Device device, string path)
+    {
+        auto downgraded_llvm_bitcode_path = downgrade_llvm_bitcode(path);
+
+        if (downgraded_llvm_bitcode_path.isNull) {
+            printf("Error occured while downgrading given air\n");
+        }
+
+        auto compiled_metallib_path = metallib_as(downgraded_llvm_bitcode_path.get());
+
+        if (compiled_metallib_path.isNull) {
+            printf("Error occured while compiling the downgraded air to metallib binary\n");
+        }
+
+        NSError error;
+        auto nsPath = NSString.create(absolutePath(compiled_metallib_path.get()));
+
+        auto library = device.mtlDevice.newLibrary(NSURL.fromPath(nsPath), error);
+
+        if (library is null)
+        {
+            printf("Error loading .metallib: %s\n", error.localizedDescription().ptr);
+            assert(0);
+        }
+
+        return Program(library);
+    }
+
+    static Nullable!string metallib_as(string air_bit_code_path) {
+        string absInputPath = absolutePath(air_bit_code_path);
+
+        string absOutputPath = absInputPath.setExtension("metallib");
+
+        auto result = execute([
+                "xcrun",
+                "-sdk", "macosx",
+                "metallib",
+                absInputPath,
+                "-o", absOutputPath
+            ]);
+
+        if (result.status != 0) {
+            printf("Apple metallib tool failed:\n%s\n", result.output.ptr);
+            return Nullable!string.init;
+        }
+
+        return nullable(absOutputPath);
+    }
+
+    static Nullable!string downgrade_llvm_bitcode(string air_bit_code_path) {
+        string absInputPath = absolutePath(air_bit_code_path);
+        string absOutputPath = absInputPath.setExtension("bc");
+        return llvm_downgrade( (string downgrader) {
+
+            auto result = execute([
+                downgrader,
+                "-o",  absOutputPath,
+                absInputPath,
+                "--bitcode-version=14.0"
+            ]);
+
+            if (result.status != 0) {
+                return Nullable!string.init;
+            }
+
+            return nullable(absOutputPath);
+        } );
+    }
+    __gshared static Program globalProgram;
+
+    void unload()
+    {
+        metalLibrary = null;
+    }
+}

source/dcompute/driver/metal/queue.d

@@ -0,0 +1,105 @@
+module dcompute.driver.metal.queue;
+import dcompute.driver.metal.buffer;
+
+import dcompute.driver.metal;
+import dcompute.driver.metal.device;
+import dcompute.driver.metal.program;
+import metal;
+import metal.argument;
+import metal.types;
+import core.stdc.stdio;
+import objc;
+import foundation;
+
+struct Queue
+{
+    Device device;
+    MTLCommandQueue commandQueue;
+    MTLCommandBuffer lastActiveBuffer;
+
+    // TODO(asadbek): explore options to make the use of async execution with events
+    this (Device _device /*bool async*/)
+    {
+        device = _device;
+        commandQueue = device.mtlDevice.newCommandQueue();
+    }
+
+    auto enqueue(alias k)(uint[3] _grid, uint[3] _block)
+    {
+        static struct Call
+        {
+            Queue* q;
+            uint[3] grid, block;
+
+            this(Queue* _q, uint[3] _grid, uint[3] _block)
+            {
+                q = _q;
+                grid = _grid;
+                block = _block;
+            }
+
+            void opCall(HostArgsOf!(typeof(k)) args)
+            {
+                NSError error;
+
+                auto kernel = Program.globalProgram.getKernel!k();
+
+                auto pipelineState = q.device.mtlDevice.newComputePipelineStateWithFunction(
+                    kernel.kernelFunction,
+                    MTLPipelineOption.None,
+                    null,
+                    error
+                );
+
+                if (pipelineState is null)
+                {
+                    printf("Error: Backend compilation failed: %s\n", error.localizedDescription().ptr);
+                    assert(0);
+                }
+
+                auto commandBuffer = q.commandQueue.commandBuffer();
+
+                auto computeEncoder = commandBuffer.computeCommandEncoder();
+
+                computeEncoder.setComputePipelineState(pipelineState);
+
+                foreach (i, arg; args)
+                {
+                    static if (is(typeof(arg): Buffer!U, U))
+                    {
+                        computeEncoder.setBuffer(arg.mtlBuffer, 0, i);
+                    } else static if (__traits(isScalar, typeof(arg)))
+                    {
+                        computeEncoder.setBytes(&arg, typeof(arg).sizeof, i);
+                    }
+                    else 
+                    {
+                        static assert(0, "Unsupported argument type for Metal kernel dispatch!");
+                    }
+                }
+
+                auto threadgroupsPerGrid = MTLSize(grid[0], grid[1], grid[2]);
+
+                auto threadsPerThreadgroup = MTLSize(block[0], block[1], block[2]);
+
+                computeEncoder.dispatchThreads(threadgroupsPerGrid, threadsPerThreadgroup);
+
+                computeEncoder.endEncoding();
+                commandBuffer.commit();
+
+                q.lastActiveBuffer = commandBuffer;
+            }
+        }
+
+        return Call(&this, _grid, _block);
+    }
+
+    void finish() {
+        if (lastActiveBuffer !is null) { 
+            lastActiveBuffer.waitUntilCompleted();
+            lastActiveBuffer.release();
+
+            lastActiveBuffer = null;
+        }
+    }
+}