support compile with cuda11 + cudnn8. test=develop (#3788)

lite/backends/cuda/cuda_utils.h

@@ -127,6 +127,10 @@ static const char* CudnnGetErrorInfo(cudnnStatus_t status) {
       return "CUDNN_STATUS_RUNTIME_IN_PROGRESS";
     case CUDNN_STATUS_RUNTIME_FP_OVERFLOW:
       return "CUDNN_STATUS_RUNTIME_FP_OVERFLOW";
+#endif
+#if CUDNN_VERSION_MIN(8, 0, 0)
+    case CUDNN_STATUS_VERSION_MISMATCH:
+      return "CUDNN_STATUS_VERSION_MISMATCH";
 #endif
   }
   return "Unknown cudnn status";

lite/backends/cuda/math/cudnn_conv.cc

@@ -161,15 +161,17 @@ bool CudnnConv2D<T, Ptype_out>::create(const operators::ConvParam& param,
                                               search_func);
 
   } else {
-    CUDNN_CHECK(
-        cudnnGetConvolutionForwardAlgorithm(this->handle_,
+    int requestedAlgoCount = 1;
+    int returnedAlgoCount;
+    CUDNN_CHECK(cudnnGetConvolutionForwardAlgorithm_v7(this->handle_,
                                                        this->input_desc_,
                                                        this->filter_desc_,
                                                        this->conv_desc_,
                                                        this->output_desc_,
-                                            this->preference_,
-                                            this->workspace_limit_bytes_,
-                                            &this->fwd_algo_));
+                                                       requestedAlgoCount,
+                                                       &returnedAlgoCount,
+                                                       &this->algo_perf_));
+    this->fwd_algo_ = this->algo_perf_.algo;
   }
   CUDNN_CHECK(
       cudnnGetConvolutionForwardWorkspaceSize(this->handle_,

lite/backends/cuda/math/cudnn_conv.h

@@ -81,6 +81,7 @@ class CudnnConv2DBase {
   cudaStream_t stream_;
   cudnnHandle_t handle_;
   cudnnConvolutionFwdAlgo_t fwd_algo_;
+  cudnnConvolutionFwdAlgoPerf_t algo_perf_;
   cudnnTensorDescriptor_t input_desc_;
   cudnnTensorDescriptor_t output_desc_;
   cudnnTensorDescriptor_t bias_desc_;
@@ -98,8 +99,6 @@ class CudnnConv2DBase {
 
   const bool use_tensor_core_ = true;
   const size_t workspace_limit_bytes_ = 4 * 1024 * 1024;
-  const cudnnConvolutionFwdPreference_t preference_ =
-      CUDNN_CONVOLUTION_FWD_PREFER_FASTEST;
 
   // For int8
   Tensor temp_tensor_;