[libc][NFC] Ensure internal implementation is in __llvm_libc namespace

[abrachet]

Summary

In preparation for D76818.

[MaskRay]

Can we just remove the namespace?

[PaulkaToast]

In D76967#1947500, @MaskRay wrote:

Can we just remove the namespace?

What do you mean? Remove this particular namespace, or namespaces in general?

[MaskRay]

In D76967#1947510, @PaulkaToast wrote:

In D76967#1947500, @MaskRay wrote:

Can we just remove the namespace?

What do you mean? Remove this particular namespace, or namespaces in general?

Delete all occurrences of __llvm_libc.

[sivachandra]

In D76967#1947520, @MaskRay wrote:

Delete all occurrences of __llvm_libc.

We made a decision to start with this, so we will stick with it unless we find some absolutely no go situation.

[sivachandra]

In D76967#1947538, @sivachandra wrote:

In D76967#1947520, @MaskRay wrote:

Delete all occurrences of __llvm_libc.

We made a decision to start with this, so we will stick with it unless we find some absolutely no go situation.

BTW, some of the reasons have been outlined in previous patches and discussions. For example, being able to mix with other libc implementations. There are possibly other ways to do it. Decision on using namespaces as a solution has already been made so we will stick with it.

[gchatelet]

libc/src/string/memory_utils/memcpy_utils.h

23

Thx!

libc/src/signal/linux/__restore.cpp

 //===----------------- Linux implementation of __restore_rt ---------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // This file is implemented seperately from sigaction.cpp so that we can
 // strongly control the options this file is compiled with. __restore_rt cannot
 // make any stack allocations so we must ensure this.
 
 #include "config/linux/syscall.h"
 #include "include/sys/syscall.h"
 
+namespace __llvm_libc {
+
 extern "C" void __restore_rt()
     __attribute__((no_sanitize("thread", "memory", "undefined", "fuzzer"),
                    hidden));
 
 extern "C" void __restore_rt() { __llvm_libc::syscall(SYS_rt_sigreturn); }
+
+} // namespace __llvm_libc

libc/src/string/memory_utils/memcpy_utils.h

 // __builtin_memcpy_inline guarantees to never call external functions.
 // Unfortunately it is not widely available.
 #if defined(__clang__) && __has_builtin(__builtin_memcpy_inline)
 #define USE_BUILTIN_MEMCPY_INLINE
 #elif defined(__GNUC__)
 #define USE_BUILTIN_MEMCPY
 #endif
 
+namespace __llvm_libc {
+
 // This is useful for testing.
 #if defined(LLVM_LIBC_MEMCPY_MONITOR)
 extern "C" void LLVM_LIBC_MEMCPY_MONITOR(char *__restrict,
                                          const char *__restrict, size_t);
 #endif
 
-namespace __llvm_libc {
-
 // Copies `kBlockSize` bytes from `src` to `dst`.
 template <size_t kBlockSize>
 static void Copy(char *__restrict dst, const char *__restrict src) {
 #if defined(LLVM_LIBC_MEMCPY_MONITOR)
   LLVM_LIBC_MEMCPY_MONITOR(dst, src, kBlockSize);
 #elif defined(USE_BUILTIN_MEMCPY_INLINE)
   __builtin_memcpy_inline(dst, src, kBlockSize);
 #elif defined(USE_BUILTIN_MEMCPY)

libc/src/threads/linux/thread_utils.h

 //===-- Linux specific definitions for threads implementations. --*- C++ -*===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H
 #define LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H
 
 #include "thread_start_args.h"
 
 #include <stdatomic.h>
 #include <stdint.h>
 
+namespace __llvm_libc {
+
 // The futex data has to be exactly 4 bytes long. However, we use a uint type
 // here as we do not want to use `_Atomic uint32_t` as the _Atomic keyword which
 // is C only. The header stdatomic.h does not define an atomic type
 // corresponding to `uint32_t` or to something which is exaclty 4 bytes wide.
 using FutexData = atomic_uint;
 
 // We use a tri-state mutex because we want to avoid making syscalls
 // as much as possible. In `mtx_unlock` a syscall to wake waiting threads is
 // made only if the mutex status is `MutexStatus::Waiting`.
 enum MutexStatus : uint32_t { MS_Free, MS_Locked, MS_Waiting };
 
 static_assert(sizeof(atomic_uint) == 4,
               "Size of the `atomic_uint` type is not 4 bytes on your platform. "
               "The implementation of the standard threads library for linux "
               "requires that size of `atomic_uint` be 4 bytes.");
 
 struct ThreadParams {
   static constexpr uintptr_t DefaultStackSize = 1 << 16; // 64 KB
   static constexpr uint32_t ClearTIDValue = 0xABCD1234;
 };
 
+} // namespace __llvm_libc
+
 #endif // LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H