libc/src/stdlib/rand_util.h

   1 //===-- Implementation header for rand utilities ----------------*- C++ -*-===//
   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 #ifndef LLVM_LIBC_SRC_STDLIB_RAND_UTIL_H
  10 #define LLVM_LIBC_SRC_STDLIB_RAND_UTIL_H
  11
  12 #include "src/__support/GPU/utils.h"
  13 #include "src/__support/macros/attributes.h"
  14
  15 namespace LIBC_NAMESPACE {
  16
  17 #ifdef LIBC_TARGET_ARCH_IS_GPU
  18 // Implement thread local storage on the GPU using local memory. Each thread
  19 // gets its slot in the local memory array and is private to the group.
  20 // TODO: We need to implement the 'thread_local' keyword on the GPU. This is an
  21 // inefficient and incomplete stand-in until that is done.
  22 template <typename T> class ThreadLocal {
  23 private:
  24   static constexpr long MAX_THREADS = 1024;
  25   [[clang::loader_uninitialized]] static inline gpu::Local<T>
  26       storage[MAX_THREADS];
  27
  28 public:
  29   LIBC_INLINE operator T() const { return storage[gpu::get_thread_id()]; }
  30   LIBC_INLINE void operator=(const T &value) {
  31     storage[gpu::get_thread_id()] = value;
  32   }
  33 };
  34
  35 extern ThreadLocal<unsigned long> rand_next;
  36 #else
  37 extern LIBC_THREAD_LOCAL unsigned long rand_next;
  38 #endif
  39
  40 } // namespace LIBC_NAMESPACE
  41
  42 #endif // LLVM_LIBC_SRC_STDLIB_RAND_UTIL_H