diff --git a/libc/docs/gpu/motivation.rst b/libc/docs/gpu/motivation.rst index 7e5336dbbe5d..e637d67fad75 100644 --- a/libc/docs/gpu/motivation.rst +++ b/libc/docs/gpu/motivation.rst @@ -44,7 +44,7 @@ Limitations We only implement a subset of the standard C library. The GPU does not currently support thread local variables in all cases, so variables like -``errno`` are not provided. Furthermore, the GPU under the OpenCL execution +``errno`` are atomic and global. Furthermore, the GPU under the OpenCL execution model cannot safely provide a mutex interface. This means that features like file buffering are not implemented on the GPU. We can also not easily provide threading features on the GPU due to the execution model so these will be diff --git a/libc/include/errno.h.def b/libc/include/errno.h.def index 3ffcd3fe4c72..1f7120e63bfc 100644 --- a/libc/include/errno.h.def +++ b/libc/include/errno.h.def @@ -25,8 +25,9 @@ #include "llvm-libc-macros/generic-error-number-macros.h" #endif -#if !defined(__AMDGPU__) && !defined(__NVPTX__) - +#if defined(__AMDGPU__) || defined(__NVPTX__) +extern int __llvmlibc_errno; // Not thread_local! +#else #ifdef __cplusplus extern "C" { extern thread_local int __llvmlibc_errno; @@ -34,8 +35,8 @@ extern thread_local int __llvmlibc_errno; #else extern _Thread_local int __llvmlibc_errno; #endif // __cplusplus - -#define errno __llvmlibc_errno #endif +#define errno __llvmlibc_errno + #endif // LLVM_LIBC_ERRNO_H diff --git a/libc/src/errno/libc_errno.cpp b/libc/src/errno/libc_errno.cpp index 64f9f522ca29..bd1438c22614 100644 --- a/libc/src/errno/libc_errno.cpp +++ b/libc/src/errno/libc_errno.cpp @@ -7,16 +7,21 @@ //===----------------------------------------------------------------------===// #include "libc_errno.h" +#include "src/__support/CPP/atomic.h" #ifdef LIBC_TARGET_ARCH_IS_GPU -// LIBC_THREAD_LOCAL on GPU currently does nothing. So essentially this is just +// LIBC_THREAD_LOCAL on GPU currently does nothing. So essentially this is just // a global errno for gpu to use for now. extern "C" { -LIBC_THREAD_LOCAL int __llvmlibc_gpu_errno; +LIBC_THREAD_LOCAL LIBC_NAMESPACE::cpp::Atomic __llvmlibc_errno; } -void LIBC_NAMESPACE::Errno::operator=(int a) { __llvmlibc_gpu_errno = a; } -LIBC_NAMESPACE::Errno::operator int() { return __llvmlibc_gpu_errno; } +void LIBC_NAMESPACE::Errno::operator=(int a) { + __llvmlibc_errno.store(a, cpp::MemoryOrder::RELAXED); +} +LIBC_NAMESPACE::Errno::operator int() { + return __llvmlibc_errno.load(cpp::MemoryOrder::RELAXED); +} #elif !defined(LIBC_COPT_PUBLIC_PACKAGING) // This mode is for unit testing. We just use our internal errno.