Deduplicate instances caching allocator, so that we only have one instance. (#16720)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16720

I'm taking the deduplication slowly because there is something here
that is causing problems, and I want to figure out what it is.

Reviewed By: dzhulgakov

Differential Revision: D13943194

fbshipit-source-id: cbc08fee5862fdcb393b9dd5b1d2ac7250f77c4b

2 files changed, 2 insertions, 15 deletions

diff --git a/c10/cuda/CUDACachingAllocator.cpp b/c10/cuda/CUDACachingAllocator.cpp
index 75faf16741..a24df498ae 100644
--- a/c10/cuda/CUDACachingAllocator.cpp
+++ b/c10/cuda/CUDACachingAllocator.cpp
@@ -660,21 +660,14 @@ std::shared_ptr<void> getIpcDevPtr(std::string handle) {
   return sp;
 }
 
-Legacy::Legacy()
-    : _impl(new THCCachingAllocator()) {}
-
-Legacy::~Legacy() {
-  delete _impl;
-}
-
 cudaError_t
 Legacy::Alloc(void** refPtr, size_t nbytes, cudaStream_t stream) {
-  _impl->malloc(refPtr, nbytes, stream);
+  caching_allocator.malloc(refPtr, nbytes, stream);
   return cudaSuccess;
 }
 
 cudaError_t Legacy::Free(void* ptr) {
-  _impl->free(ptr);
+  caching_allocator.free(ptr);
   return cudaSuccess;
 }
 
diff --git a/c10/cuda/CUDACachingAllocator.h b/c10/cuda/CUDACachingAllocator.h
index 43082d10b1..f30036f545 100644
--- a/c10/cuda/CUDACachingAllocator.h
+++ b/c10/cuda/CUDACachingAllocator.h
@@ -47,14 +47,8 @@ struct THCCachingAllocator;
 
 class C10_CUDA_API Legacy {
  public:
-  Legacy();
-  ~Legacy();
-
   cudaError_t Alloc(void** refPtr, size_t nbytes, cudaStream_t stream);
   cudaError_t Free(void* ptr);
-
- private:
-  THCCachingAllocator* _impl;
 };
 
 } // namespace CUDACachingAllocator