Update on "bump pt core pin to 0718"

Differential Revision: [D78579692](https://our.internmc.facebook.com/intern/diff/D78579692/)

[ghstack-poisoned]

Author: Gasoonjia

runtime/core/portable_type/c10/torch/headeronly/macros/Export.h

@@ -1,5 +1,12 @@
 #pragma once
 
+#ifndef C10_MACROS_EXPORT_H_
+#define C10_MACROS_EXPORT_H_
+
+#ifndef C10_USING_CUSTOM_GENERATED_MACROS
+#include <torch/headeronly/macros/cmake_macros.h>
+#endif // C10_USING_CUSTOM_GENERATED_MACROS
+
 /* Header file to define the common scaffolding for exported symbols.
  *
  * Export is by itself a quite tricky situation to deal with, and if you are
@@ -85,3 +92,62 @@
 #else
 #define C10_API C10_IMPORT
 #endif
+
+// This one is being used by libtorch.so
+#ifdef CAFFE2_BUILD_MAIN_LIB
+#define TORCH_API C10_EXPORT
+#else
+#define TORCH_API C10_IMPORT
+#endif
+
+// You may be wondering why we have TORCH_CUDA_CPP_API and TORCH_CUDA_CU_API
+// belonging to the same library instead of just one TORCH_CUDA_API. Well, it
+// can indeed just be one TORCH_CUDA_API (and used to be)! TORCH_CUDA_CPP_API
+// and TORCH_CUDA_CU_API are artifacts of when we needed a split build to
+// avoid relocation marker linking errors. The context is as follows:
+//
+// Once upon a time, there _was_ only TORCH_CUDA_API. All was happy until we
+// tried to compile PyTorch for CUDA 11.1, which ran into relocation marker
+// issues when linking big binaries.
+// (https://github.com/pytorch/pytorch/issues/39968) We had two choices:
+//    (1) Stop supporting so many GPU architectures
+//    (2) Do something else
+// We chose #2 and decided to split the behemoth that was torch_cuda into two
+// smaller libraries, one with most of the core kernel functions (torch_cuda_cu)
+// and the other that had..well..everything else (torch_cuda_cpp). The idea was
+// this: instead of linking our static libraries (like the hefty
+// libcudnn_static.a) with another huge library, torch_cuda, and run into pesky
+// relocation marker issues, we could link our static libraries to a smaller
+// part of torch_cuda (torch_cuda_cpp) and avoid the issues.
+
+// libtorch_cuda.so (where torch_cuda_cu and torch_cuda_cpp are a part of the
+// same api)
+#ifdef TORCH_CUDA_BUILD_MAIN_LIB
+#define TORCH_CUDA_CPP_API C10_EXPORT
+#define TORCH_CUDA_CU_API C10_EXPORT
+#else
+#define TORCH_CUDA_CPP_API C10_IMPORT
+#define TORCH_CUDA_CU_API C10_IMPORT
+#endif
+
+#if defined(TORCH_HIP_BUILD_MAIN_LIB)
+#define TORCH_HIP_CPP_API C10_EXPORT
+#define TORCH_HIP_API C10_EXPORT
+#else
+#define TORCH_HIP_CPP_API C10_IMPORT
+#define TORCH_HIP_API C10_IMPORT
+#endif
+
+#if defined(TORCH_XPU_BUILD_MAIN_LIB)
+#define TORCH_XPU_API C10_EXPORT
+#else
+#define TORCH_XPU_API C10_IMPORT
+#endif
+
+// Enums only need to be exported on windows for non-CUDA files
+#if defined(_WIN32) && defined(__CUDACC__)
+#define C10_API_ENUM C10_API
+#else
+#define C10_API_ENUM
+#endif
+#endif // C10_MACROS_EXPORT_H_