1 //===-- Implementation of crt for nvptx -----------------------------------===// 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 DataEnvironment app; 21 22 // FIXME: Factor this out into common logic so we don't need to stub it here. 23 void teardown_main_tls() {} 24 25 extern "C" { 26 // Nvidia's 'nvlink' linker does not provide these symbols. We instead need 27 // to manually create them and update the globals in the loader implememtation. 28 uintptr_t *__init_array_start [[gnu::visibility("protected")]]; 29 uintptr_t *__init_array_end [[gnu::visibility("protected")]]; 30 uintptr_t *__fini_array_start [[gnu::visibility("protected")]]; 31 uintptr_t *__fini_array_end [[gnu::visibility("protected")]]; 32 } 33 34 // Nvidia requires that the signature of the function pointers match. This means 35 // we cannot support the extended constructor arguments. 36 using InitCallback = void(void); 37 using FiniCallback = void(void); 38 39 static void call_init_array_callbacks(int, char **, char **) { 40 size_t init_array_size = __init_array_end - __init_array_start; 41 for (size_t i = 0; i < init_array_size; ++i) 42 reinterpret_cast<InitCallback *>(__init_array_start[i])(); 43 } 44 45 static void call_fini_array_callbacks() { 46 size_t fini_array_size = __fini_array_end - __fini_array_start; 47 for (size_t i = fini_array_size; i > 0; --i) 48 reinterpret_cast<FiniCallback *>(__fini_array_start[i - 1])(); 49 } 50 51 } // namespace LIBC_NAMESPACE_DECL 52 53 extern "C" [[gnu::visibility("protected"), clang::nvptx_kernel]] void 54 _begin(int argc, char **argv, char **env) { 55 __atomic_store_n(&LIBC_NAMESPACE::app.env_ptr, 56 reinterpret_cast<uintptr_t *>(env), __ATOMIC_RELAXED); 57 58 // We want the fini array callbacks to be run after other atexit 59 // callbacks are run. So, we register them before running the init 60 // array callbacks as they can potentially register their own atexit 61 // callbacks. 62 LIBC_NAMESPACE::atexit(&LIBC_NAMESPACE::call_fini_array_callbacks); 63 LIBC_NAMESPACE::call_init_array_callbacks(argc, argv, env); 64 } 65 66 extern "C" [[gnu::visibility("protected"), clang::nvptx_kernel]] void 67 _start(int argc, char **argv, char **envp, int *ret) { 68 // Invoke the 'main' function with every active thread that the user launched 69 // the _start kernel with. 70 __atomic_fetch_or(ret, main(argc, argv, envp), __ATOMIC_RELAXED); 71 } 72 73 extern "C" [[gnu::visibility("protected"), clang::nvptx_kernel]] void 74 _end(int retval) { 75 // To finis the execution we invoke all the callbacks registered via 'atexit' 76 // and then exit with the appropriate return value. 77 LIBC_NAMESPACE::exit(retval); 78 } 79