The 'errno' value is most likely not useful on the GPU and it prevents
us from providing certain functions on the GPU that depend on it, like
`atoi`. This patch makes the necessary changes to support `errno` by
simple replacing it with a consumer class.
Supporting `errno` on the GPU is possible in some aspects. The first
approach would be to use a buffer of shared memory that has enough space
for all threads. Another option would be to change code generation to
support `thread_local` using `address_space(5)` memory allocated at
kernel launch. The former could look like the following, which could be
implemented in a later patch:
```
template <typename T>
using SharedBuffer = T[gpu::MAX_THREADS] [[clang::address_space(3)]];
template <typename T> struct ErrnoSetter {
constexpr ErrnoSetter(SharedBuffer<T> &storage) : storage(storage) {}
SharedBuffer<T> &storage;
void operator=(const T &val) { storage[gpu::get_thread_id()] = val; }
};
static SharedBuffer<int> thread_local_buffer [[clang::loader_uninitialized]];
ErrnoSetter<int> __llvmlibc_internal_errno(thread_local_buffer);
```
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D149107
Summary:
Made all header files consistent based of this documentation: https://llvm.org/docs/CodingStandards.html#file-headers.
And did the same for all source files top of file comments.
Reviewers: sivachandra, abrachet
Reviewed By: sivachandra, abrachet
Subscribers: MaskRay, tschuett, libc-commits
Tags: #libc-project
Differential Revision: https://reviews.llvm.org/D77533
