Cuda updates

Summary:
Updates to:
- enable cuda kernel launches on any GPU (not just the default)
- cuda and contiguous checks for all kernels
- checks to ensure all tensors are on the same device
- error reporting in the cuda kernels
- cuda tests now run on a random device not just the default

Reviewed By: jcjohnson, gkioxari

Differential Revision: D21215280

fbshipit-source-id: 1bedc9fe6c35e9e920bdc4d78ed12865b1005519

pytorch3d/csrc/utils/pytorch3d_cutils.h

@@ -3,9 +3,9 @@
 #pragma once
 #include <torch/extension.h>
 
-#define CHECK_CUDA(x) AT_ASSERTM(x.is_cuda(), #x "must be a CUDA tensor.")
+#define CHECK_CUDA(x) TORCH_CHECK(x.is_cuda(), #x "must be a CUDA tensor.")
 #define CHECK_CONTIGUOUS(x) \
-  AT_ASSERTM(x.is_contiguous(), #x "must be contiguous.")
+  TORCH_CHECK(x.is_contiguous(), #x "must be contiguous.")
 #define CHECK_CONTIGUOUS_CUDA(x) \
   CHECK_CUDA(x);                 \
   CHECK_CONTIGUOUS(x)