Cycles: Fix zero-size buffer allocation with OpenCL devices

This is not really supported by OpenCL but might happen in certain
configurations. There might be some remained cases when this happens
but so far can not find any,

1 files changed, 40 insertions, 10 deletions

diff --git a/intern/cycles/device/device_opencl.cpp b/intern/cycles/device/device_opencl.cpp
index 7ab2b412f0d..4dd92c3337a 100644
--- a/intern/cycles/device/device_opencl.cpp
+++ b/intern/cycles/device/device_opencl.cpp
@@ -941,9 +941,22 @@ public:
 		else
 			mem_flag = CL_MEM_READ_WRITE;
 
-		mem.device_pointer = (device_ptr)clCreateBuffer(cxContext, mem_flag, size, mem_ptr, &ciErr);
-
-		opencl_assert_err(ciErr, "clCreateBuffer");
+		/* Zero-size allocation might be invoked by render, but not really
+		 * supported by OpenCL. Using NULL as device pointer also doesn't really
+		 * work for some reason, so for the time being we'll use special case
+		 * will null_mem buffer.
+		 */
+		if(size != 0) {
+			mem.device_pointer = (device_ptr)clCreateBuffer(cxContext,
+			                                                mem_flag,
+			                                                size,
+			                                                mem_ptr,
+			                                                &ciErr);
+			opencl_assert_err(ciErr, "clCreateBuffer");
+		}
+		else {
+			mem.device_pointer = null_mem;
+		}
 
 		stats.mem_alloc(size);
 		mem.device_size = size;
@@ -953,15 +966,31 @@ public:
 	{
 		/* this is blocking */
 		size_t size = mem.memory_size();
-		opencl_assert(clEnqueueWriteBuffer(cqCommandQueue, CL_MEM_PTR(mem.device_pointer), CL_TRUE, 0, size, (void*)mem.data_pointer, 0, NULL, NULL));
+		if(size != 0){
+			opencl_assert(clEnqueueWriteBuffer(cqCommandQueue,
+			                                   CL_MEM_PTR(mem.device_pointer),
+			                                   CL_TRUE,
+			                                   0,
+			                                   size,
+			                                   (void*)mem.data_pointer,
+			                                   0,
+			                                   NULL, NULL));
+		}
 	}
 
 	void mem_copy_from(device_memory& mem, int y, int w, int h, int elem)
 	{
 		size_t offset = elem*y*w;
 		size_t size = elem*w*h;
-
-		opencl_assert(clEnqueueReadBuffer(cqCommandQueue, CL_MEM_PTR(mem.device_pointer), CL_TRUE, offset, size, (uchar*)mem.data_pointer + offset, 0, NULL, NULL));
+		assert(size != 0);
+		opencl_assert(clEnqueueReadBuffer(cqCommandQueue,
+		                                  CL_MEM_PTR(mem.device_pointer),
+		                                  CL_TRUE,
+		                                  offset,
+		                                  size,
+		                                  (uchar*)mem.data_pointer + offset,
+		                                  0,
+		                                  NULL, NULL));
 	}
 
 	void mem_zero(device_memory& mem)
@@ -975,7 +1004,9 @@ public:
 	void mem_free(device_memory& mem)
 	{
 		if(mem.device_pointer) {
-			opencl_assert(clReleaseMemObject(CL_MEM_PTR(mem.device_pointer)));
+			if(mem.device_pointer != null_mem) {
+				opencl_assert(clReleaseMemObject(CL_MEM_PTR(mem.device_pointer)));
+			}
 			mem.device_pointer = 0;
 
 			stats.mem_free(mem.device_size);
@@ -3325,10 +3356,9 @@ protected:
 	cl_mem mem_alloc(size_t bufsize, cl_mem_flags mem_flag = CL_MEM_READ_WRITE)
 	{
 		cl_mem ptr;
+		assert(bufsize != 0);
 		ptr = clCreateBuffer(cxContext, mem_flag, bufsize, NULL, &ciErr);
-		if(opencl_error(ciErr)) {
-			assert(0);
-		}
+		opencl_assert_err(ciErr, "clCreateBuffer");
 		return ptr;
 	}
 };