901266dad3
The GPU has a different execution model to standard `_start` implementations. On the GPU, all threads are active at the start of a kernel. In order to correctly intitialize and call the constructors we want single threaded semantics. Previously, this was done using a makeshift global barrier with atomics. However, it should be easier to simply put the portions of the code that must be single threaded in separate kernels and then call those with only one thread. Generally, mixing global state between kernel launches makes optimizations more difficult, similarly to calling a function outside of the TU, but for testing it is better to be correct. Depends on D149527 D148943 Reviewed By: JonChesterfield Differential Revision: https://reviews.llvm.org/D149581
98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
//===-- Generic device loader interface -----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_UTILS_GPU_LOADER_LOADER_H
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#define LLVM_LIBC_UTILS_GPU_LOADER_LOADER_H
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#include <cstdint>
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#include <cstring>
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#include <stddef.h>
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/// Generic launch parameters for configuration the number of blocks / threads.
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struct LaunchParameters {
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uint32_t num_threads_x;
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uint32_t num_threads_y;
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uint32_t num_threads_z;
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uint32_t num_blocks_x;
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uint32_t num_blocks_y;
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uint32_t num_blocks_z;
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};
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/// The arguments to the '_begin' kernel.
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struct begin_args_t {
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int argc;
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void *argv;
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void *envp;
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void *inbox;
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void *outbox;
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void *buffer;
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};
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/// The arguments to the '_start' kernel.
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struct start_args_t {
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int argc;
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void *argv;
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void *envp;
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void *ret;
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};
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/// The arguments to the '_end' kernel.
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struct end_args_t {
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int argc;
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};
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/// Generic interface to load the \p image and launch execution of the _start
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/// kernel on the target device. Copies \p argc and \p argv to the device.
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/// Returns the final value of the `main` function on the device.
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int load(int argc, char **argv, char **evnp, void *image, size_t size,
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const LaunchParameters ¶ms);
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/// Return \p V aligned "upwards" according to \p Align.
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template <typename V, typename A> inline V align_up(V val, A align) {
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return ((val + V(align) - 1) / V(align)) * V(align);
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}
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/// Copy the system's argument vector to GPU memory allocated using \p alloc.
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template <typename Allocator>
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void *copy_argument_vector(int argc, char **argv, Allocator alloc) {
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size_t argv_size = sizeof(char *) * (argc + 1);
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size_t str_size = 0;
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for (int i = 0; i < argc; ++i)
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str_size += strlen(argv[i]) + 1;
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// We allocate enough space for a null terminated array and all the strings.
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void *dev_argv = alloc(argv_size + str_size);
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if (!dev_argv)
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return nullptr;
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// Store the strings linerally in the same memory buffer.
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void *dev_str = reinterpret_cast<uint8_t *>(dev_argv) + argv_size;
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for (int i = 0; i < argc; ++i) {
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size_t size = strlen(argv[i]) + 1;
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std::memcpy(dev_str, argv[i], size);
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static_cast<void **>(dev_argv)[i] = dev_str;
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dev_str = reinterpret_cast<uint8_t *>(dev_str) + size;
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}
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// Ensure the vector is null terminated.
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reinterpret_cast<void **>(dev_argv)[argv_size] = nullptr;
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return dev_argv;
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};
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/// Copy the system's environment to GPU memory allocated using \p alloc.
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template <typename Allocator>
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void *copy_environment(char **envp, Allocator alloc) {
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int envc = 0;
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for (char **env = envp; *env != 0; ++env)
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++envc;
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return copy_argument_vector(envc, envp, alloc);
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};
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#endif
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