Add transpose kernels

Makefile

@@ -34,6 +34,7 @@ all: dawnlib check-clang check-linux-vulkan lib pch
 	cd examples/gpu_puzzles && make build/gpu_puzzles
 	cd examples/hello_world && make build/hello_world
 	cd examples/matmul && make build/matmul
+	cd examples/transpose && make build/transpose
 	cd examples/physics && make build/physics
 	cd examples/render && make build/render
 
@@ -78,6 +79,7 @@ clean:
 	rm -rf examples/gpu_puzzles/build/*
 	rm -rf examples/hello_world/build/*
 	rm -rf examples/matmul/build/matmul
+	rm -rf examples/transpose/build/transpose
 	rm -rf examples/physics/build/*
 	rm -rf examples/render/build/*
 	rm -f build/gpu.h.pch
@@ -108,7 +110,7 @@ check-linux-vulkan:
 	        echo "Vulkan is installed."; \
 	        vulkaninfo; \
 	    else \
-        	echo "Vulkan is not installed. Please install Vulkan drivers to continue. On Debian / Ubuntu: sudo apt install libvulkan1 mesa-vulkan-drivers vulkan-tools"; \
+		echo "Vulkan is not installed. Please install Vulkan drivers to continue. On Debian / Ubuntu: sudo apt install libvulkan1 mesa-vulkan-drivers vulkan-tools"; \
 	        exit 1; \
 	    fi \
 	else \

examples/README.md

@@ -16,4 +16,5 @@ In order of beginning to advanced:
 | [shadertui](shadertui) | A terminal UI taker on shadertoy demonstrating runtime live reloading of WGSL. |
 | [physics](physics) | Parallel physics simulation of a double pendulum with each thread starting at a different initial condition. |
 | [matmul](matmul) | Tiled matrix multiplication. |
+| [transpose](transpose) | Tiled matrix transpose. |
 | [webgpu_from_scratch](webgpu_from_scratch) | A minimal from-scratch example of how to use WebGPU directly without this library. This is useful to understand the code internals of gpu.cpp. Note this takes a while to build as it compiles the WebGPU C API implementation. |

examples/transpose/Makefile

@@ -0,0 +1,27 @@
+CXX=clang++
+GPUCPP ?= $(PWD)/../..
+LIBDIR ?= $(GPUCPP)/third_party/lib
+LIBSPEC ?= . $(GPUCPP)/source
+NUM_JOBS?=$(shell nproc)
+CODEPATH = find . ../../utils ../../ -maxdepth 1 -type f
+TARGET=transpose
+ifeq ($(shell $(CXX) -std=c++17 -x c++ -E -include array - < /dev/null > /dev/null 2>&1 ; echo $$?),0)
+    STDLIB :=
+else
+    STDLIB := -stdlib=libc++
+endif
+FLAGS=-std=c++17 $(STDLIB) -I$(GPUCPP) -I$(GPUCPP)/third_party/headers -L$(GPUCPP)/third_party/lib run.cpp -ldl -ldawn
+
+run: ./build/$(TARGET)
+	$(LIBSPEC) && ./build/$(TARGET)
+
+# Use clang -v to see the include paths
+build/$(TARGET): run.cpp
+	mkdir -p build && $(CXX) $(FLAGS) -o ./build/$(TARGET)
+
+watch: 
+	@command -v entr >/dev/null 2>&1 || { echo >&2 "Please install entr with 'brew install entr' or 'sudo apt-get install entr'"; exit 1; }
+	mkdir -p build && $(CODEPATH) | entr -s "$(LIBSPEC) && rm -f ./build/$(TARGET) && make -j$(NUM_JOBS) ./build/$(TARGET) && ./build/$(TARGET)"
+
+clean:
+	read -r -p "This will delete the contents of build/*. Are you sure? [CTRL-C to abort] " response && rm -rf build/*

examples/transpose/run.cpp

@@ -0,0 +1,241 @@
+#include <array>
+#include <chrono>
+#include <future>
+#include <random>
+#include <cstdlib>
+
+#include "gpu.h" // createContext, createTensor, createKernel, dispatchKernel,
+                 // wait, resetCommandBuffer, toCPU
+
+#include "llmc/reference_impls.h" // for CPU reference implementation
+#include "utils/array_utils.h"    // show, isclose, randn, randint
+#include "utils/logging.h"        // LOG
+#include "experimental/wgsl.h"    // loopUnrolling
+
+using namespace gpu;
+
+// This implements the tranpose kernels in https://developer.nvidia.com/blog/efficient-matrix-transpose-cuda-cc .
+
+static const char *kShaderTranspose1 = R"(
+@group(0) @binding(0) var<storage, read_write> A: array<{{precision}}>;
+@group(0) @binding(1) var<storage, read_write> B: array<{{precision}}>;
+@compute @workgroup_size({{workgroupSize}})
+fn main(
+    @builtin(global_invocation_id) globalID : vec3<u32>) {
+    let bRow: u32 = globalID.x;
+    let bCol: u32 = globalID.y;
+    B[bRow * {{M}} + bCol] = A[bCol * {{N}} + bRow];
+}
+)";
+
+inline KernelCode createTranspose1(const char *shaderTemplate,
+				   const size_t M, const size_t N,
+                                   const Shape &workgroupSize = {256, 1, 1},
+                                   NumType precision = kf32) {
+  std::string codeString(shaderTemplate);
+  replaceAll(codeString, {{"{{workgroupSize}}", toString(workgroupSize)},
+                          {"{{precision}}", toString(precision)},
+                          {"{{M}}", toString(M)},
+                          {"{{N}}", toString(N)}});
+  return {codeString, workgroupSize};
+}
+
+// Shared memory cache-blocking
+static const char *kShaderTranspose2 = R"(
+@group(0) @binding(0) var<storage, read_write> A: array<{{precision}}>;
+@group(0) @binding(1) var<storage, read_write> B: array<{{precision}}>;
+var<workgroup> tile: array<{{precision}}, {{BN}} * {{BM}}>;
+@compute @workgroup_size({{workgroupSize}})
+fn main(
+  @builtin(local_invocation_id) localID : vec3<u32>,
+  @builtin(workgroup_id) groupID: vec3<u32>) {
+    let bRow: u32 = groupID.x * {{BN}};
+    let bCol: u32 = groupID.y * {{BM}};
+
+    let aPtr = bCol * {{N}} + bRow;
+    let bPtr = bRow * {{M}} + bCol;
+    let numThread: u32 = ({{BM}} * {{BN}}) / ({{TM}} * {{TN}});
+
+    for (var resIdxM: u32 = 0; resIdxM < {{TM}}; resIdxM++) {
+      for (var resIdxN: u32 = 0; resIdxN < {{TN}}; resIdxN++) {
+        let idx: u32 = localID.x + numThread * (resIdxN + {{TN}} * resIdxM);
+        let loadRow: u32 = idx / {{BN}};
+        let loadCol: u32 = idx % {{BN}};
+        tile[loadCol * {{BN}} + loadRow] = A[aPtr + loadRow * {{N}} + loadCol];
+      }
+    }
+
+    workgroupBarrier();
+
+    for (var resIdxN: u32 = 0; resIdxN < {{TN}}; resIdxN++) {
+      for (var resIdxM: u32 = 0; resIdxM < {{TM}}; resIdxM++) {
+        let idx: u32 = localID.x + numThread * (resIdxM + {{TM}} * resIdxN);
+        let loadRow: u32 = idx / {{BM}};
+        let loadCol: u32 = idx % {{BM}};
+        B[bPtr + loadRow * {{M}} + loadCol] = tile[loadRow * {{BM}} + loadCol];
+      }
+    }
+}
+)";
+
+inline KernelCode createTranspose2(const char *shaderTemplate,
+				   const size_t M, const size_t N,
+				   const size_t BM, const size_t BN,
+                                   const size_t TM, const size_t TN,
+                                   const Shape &workgroupSize = {256, 1, 1},
+                                   NumType precision = kf32) {
+  assert(BM % TM == 0);
+  assert(BN % TN == 0);
+  assert(M % BM == 0);
+  assert(N % BN == 0);
+  std::string codeString(shaderTemplate);
+  replaceAll(codeString, {{"{{workgroupSize}}", toString(workgroupSize)},
+                          {"{{precision}}", toString(precision)},
+                          {"{{M}}", toString(M)},
+                          {"{{N}}", toString(N)},
+                          {"{{BM}}", toString(BM)},
+                          {"{{BN}}", toString(BN)},
+                          {"{{TM}}", toString(TM)},
+                          {"{{TN}}", toString(TN)}
+                          });
+  std::string unrolledCode = codeString ;// loopUnrolling(codeString);
+  return {unrolledCode, workgroupSize};
+}
+
+void initData(size_t M, size_t N, std::unique_ptr<float[]> &inputPtr) {
+  std::mt19937 gen(314159);
+  randn(inputPtr.get(), M * N, gen);
+  LOG(kDefLog, kInfo, "%s", show<float>(inputPtr.get(), M, N, "Input").c_str());
+}
+
+Kernel selectTranspose(Context &ctx, int version,
+                       const Bindings</* input, output */ 2> &bindings,
+                       size_t M, size_t N) {
+  Kernel kernel;
+  if (version == 1) {
+    Shape wgSize = {16, 16, 1};
+    LOG(kDefLog, kInfo, "wgSize: %s", toString(wgSize).c_str());
+    KernelCode transpose =
+        createTranspose1(kShaderTranspose1, M, N, /*wgsize*/ wgSize); // The shape of input == M x N
+    kernel = createKernel(ctx, transpose, bindings,
+                          /*nWorkgroups*/ cdiv({N, M, 1}, wgSize)); // The shape of output == N x M
+  } else if (version == 2) {
+    static constexpr size_t BM = 64;
+    static constexpr size_t BK = 16;
+    static constexpr size_t BN = 64;
+    static constexpr size_t TM = BM / BK;
+    static constexpr size_t TN = BN / BK;
+    Shape wgSize = {(BM / TM) * (BN / TN), 1, 1}; // This is the same as BK * BK.
+    Shape nWorkgroups = {cdiv(N, BN), cdiv(M, BM), 1};
+    LOG(kDefLog, kInfo, "M: %d, N: %d", M, N);
+    LOG(kDefLog, kInfo, "BM: %d, BK: %d, BN: %d, TM: %d, TN: %d", BM, BK, BN, TM, TN);
+    LOG(kDefLog, kInfo, "wgSize: ( %s )", toString(wgSize).c_str());
+    LOG(kDefLog, kInfo, "nWorkgroups: ( %s )", toString(nWorkgroups).c_str());
+    KernelCode transpose = createTranspose2(kShaderTranspose2, M, N, BM, BN, TM, TN,
+					    /*wgSize*/ wgSize,
+					    kf32);
+    kernel = createKernel(ctx, transpose, bindings,
+                          /*nWorkgroups*/ nWorkgroups);
+  } else if (version == 0) {
+    LOG(kDefLog, kInfo, "Skip Creating Kernel", M, N);
+  }
+  return kernel;
+}
+
+void runTest(int version, size_t M, size_t N,
+             std::unique_ptr<float[]> &inputPtr,
+             std::unique_ptr<float[]> &outputPtr) {
+  bool isCPU = version == 0;
+
+  // Allocate GPU buffers and copy data
+  Context ctx = createContext();
+  Tensor input = createTensor(ctx, Shape{M, N}, kf32, inputPtr.get());
+  Tensor output = createTensor(ctx, Shape{N, M}, kf32);
+
+  constexpr size_t nIter = 50;
+
+  // Initialize Kernel and bind GPU buffers
+  LOG(kDefLog, kInfo, "Creating Kernel");
+  Kernel kernel = selectTranspose(ctx, version, {input, output}, M, N);
+
+  // Dispatch kernel execution
+  LOG(kDefLog, kInfo, "Dispatching Kernel version %d, %d iterations ...",
+      version, nIter);
+
+  // pre-allocate promises and futures for async dispatch
+  // TODO(avh): implement a pooling mechanism for promises/futures in gpu.h
+  std::array<std::promise<void>, nIter> promises;
+  std::array<std::future<void>, nIter> futures;
+  for (int i = 0; i < nIter; i++) {
+    futures[i] = promises[i].get_future();
+  }
+
+  // Dispatch kernel nIter times
+  auto start = std::chrono::high_resolution_clock::now();
+  for (int i = 0; i < nIter; i++) {
+    if (!isCPU) {
+      dispatchKernel(ctx, kernel, promises[i]);
+      wait(ctx, futures[i]);
+      resetCommandBuffer(ctx.device, kernel);
+    } else {
+      transpose(inputPtr.get(), outputPtr.get(), M, N);
+    }
+  }
+  auto end = std::chrono::high_resolution_clock::now();
+
+  // Report performance.
+  // Use microsecond for more accurate time measurement
+  auto duration =
+      std::chrono::duration_cast<std::chrono::microseconds>(end - start);
+  float gbps = sizeof(float) * M * N /
+               (static_cast<double>(duration.count()) / 1000000.0) /
+               1000000000.0 * static_cast<float>(nIter);
+
+  LOG(kDefLog, kInfo, "Copying result to CPU");
+  if (!isCPU) {
+    toCPU(ctx, output, outputPtr.get(), M * N * sizeof(float));
+  }
+  LOG(kDefLog, kInfo, "%s",
+      show<float>(outputPtr.get(), N, M, "Output").c_str());
+
+  LOG(kDefLog, kInfo, "\n\n===================================================================="
+      "============\nExecution Time: (M = %d, N = %d) x %d iterations "
+      ":\n%.3f "
+      "milliseconds / dispatch ~ %.2f "
+      "GB/s\n================================================================"
+      "================\n\n",
+      M, N, nIter, duration.count() / static_cast<double>(nIter) / 1000.0 /* us -> ms */, gbps);
+}
+
+int main() {
+  char* version_str = getenv("TEST_VERSION");
+  int version = version_str == NULL ? 2 : atoi(version_str);
+    // 0 == cpu
+    // 1 == naive transpose
+    // 2 == tiling with shared memory
+
+  size_t M, N;  // Matrix dimensions
+  static constexpr int kTestSize = 2;
+  if constexpr (kTestSize == 0) {
+    // Tiny test
+    M = 16;
+    N = 32;
+  } else if constexpr (kTestSize == 1) {
+    // Small test
+    M = 256;
+    N = 512;
+  } else {
+    // Large test
+    M = 4096;
+    N = 2 * 4096;
+  }
+
+  std::unique_ptr<float[]> inputPtr = std::make_unique<float[]>(M * N);
+  std::unique_ptr<float[]> outputPtr = std::make_unique<float[]>(N * M);
+
+  initData(M, N, inputPtr);
+  runTest(version, M, N, inputPtr, outputPtr);
+
+  LOG(kDefLog, kInfo, "Done.");
+  return 0;
+}