libc/startup/gpu/amdgpu/start.cpp

   1 //===-- Implementation of crt for amdgpu ----------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "config/gpu/app.h"
  10 #include "src/__support/GPU/utils.h"
  11 #include "src/__support/RPC/rpc_client.h"
  12 #include "src/__support/macros/config.h"
  13 #include "src/stdlib/atexit.h"
  14 #include "src/stdlib/exit.h"
  15
  16 extern "C" int main(int argc, char **argv, char **envp);
  17
  18 namespace LIBC_NAMESPACE_DECL {
  19
  20 // FIXME: Factor this out into common logic so we don't need to stub it here.
  21 void teardown_main_tls() {}
  22
  23 DataEnvironment app;
  24
  25 extern "C" uintptr_t __init_array_start[];
  26 extern "C" uintptr_t __init_array_end[];
  27 extern "C" uintptr_t __fini_array_start[];
  28 extern "C" uintptr_t __fini_array_end[];
  29
  30 using InitCallback = void(int, char **, char **);
  31 using FiniCallback = void(void);
  32
  33 static void call_init_array_callbacks(int argc, char **argv, char **env) {
  34   size_t init_array_size = __init_array_end - __init_array_start;
  35   for (size_t i = 0; i < init_array_size; ++i)
  36     reinterpret_cast<InitCallback *>(__init_array_start[i])(argc, argv, env);
  37 }
  38
  39 static void call_fini_array_callbacks() {
  40   size_t fini_array_size = __fini_array_end - __fini_array_start;
  41   for (size_t i = fini_array_size; i > 0; --i)
  42     reinterpret_cast<FiniCallback *>(__fini_array_start[i - 1])();
  43 }
  44
  45 } // namespace LIBC_NAMESPACE_DECL
  46
  47 extern "C" [[gnu::visibility("protected"), clang::amdgpu_kernel,
  48              clang::amdgpu_flat_work_group_size(1, 1),
  49              clang::amdgpu_max_num_work_groups(1)]] void
  50 _begin(int argc, char **argv, char **env) {
  51   __atomic_store_n(&LIBC_NAMESPACE::app.env_ptr,
  52                    reinterpret_cast<uintptr_t *>(env), __ATOMIC_RELAXED);
  53   // We want the fini array callbacks to be run after other atexit
  54   // callbacks are run. So, we register them before running the init
  55   // array callbacks as they can potentially register their own atexit
  56   // callbacks.
  57   LIBC_NAMESPACE::atexit(&LIBC_NAMESPACE::call_fini_array_callbacks);
  58   LIBC_NAMESPACE::call_init_array_callbacks(argc, argv, env);
  59 }
  60
  61 extern "C" [[gnu::visibility("protected"), clang::amdgpu_kernel]] void
  62 _start(int argc, char **argv, char **envp, int *ret) {
  63   // Invoke the 'main' function with every active thread that the user launched
  64   // the _start kernel with.
  65   __atomic_fetch_or(ret, main(argc, argv, envp), __ATOMIC_RELAXED);
  66 }
  67
  68 extern "C" [[gnu::visibility("protected"), clang::amdgpu_kernel,
  69              clang::amdgpu_flat_work_group_size(1, 1),
  70              clang::amdgpu_max_num_work_groups(1)]] void
  71 _end(int retval) {
  72   // Only a single thread should call `exit` here, the rest should gracefully
  73   // return from the kernel. This is so only one thread calls the destructors
  74   // registred with 'atexit' above.
  75   LIBC_NAMESPACE::exit(retval);
  76 }