William Huynh 8c9863eb1e
[libc] Basic implementation of crt0 (#146863)
In order to run hermetic tests downstream (#145349), we need startup
code. This is based on the crt0 that is present in Arm Toolchain:
5446a3cbf4/arm-software/embedded/llvmlibc-support/crt0.
Note that some tests do fail due to lack of hardware setup, which will
be implemented at a later time.

Most of the CMake/structure is a copy from the existing code in both
`libc/startup/linux` and `libc/startup/gpu`. It is required to build an
object file to be linked with.

Also add header files for init/fini such that crt0 can use the provided
symbols.

---------

Co-authored-by: Michael Jones <michaelrj@google.com>
2025-07-31 12:17:17 +01:00

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//===-- Implementation file of __libc_fini_array --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "startup/baremetal/fini.h"
#include "src/__support/macros/config.h"
#include <stddef.h>
namespace LIBC_NAMESPACE_DECL {
using FiniCallback = void(void);
extern "C" void __libc_fini_array(void) {
size_t fini_array_size = __fini_array_end - __fini_array_start;
for (size_t i = fini_array_size; i > 0; --i)
reinterpret_cast<FiniCallback *>(__fini_array_start[i - 1])();
}
} // namespace LIBC_NAMESPACE_DECL