Fix for undefined format for 6 dim tensor (#38553)

* 6 dims fix

* removed limitations of max dims

paddle/fluid/platform/mkldnn_helper.h

@@ -269,9 +269,13 @@ inline dnnl::memory::format_tag GetMKLDNNFormat(dnnl::memory::desc mem_desc) {
     if (inner_nblks == 0) {
       if (strides[0] >= strides[1] && strides[1] >= strides[2] &&
           strides[2] >= strides[3] && strides[3] >= strides[4]) {
-        return dnnl::memory::format_tag::ncdhw;
-      } else {
-        return dnnl::memory::format_tag::ndhwc;
+        return dnnl::memory::format_tag::abcde;
+      } else if (strides[0] >= strides[2] && strides[2] >= strides[1] &&
+                 strides[1] >= strides[3] && strides[3] >= strides[4]) {
+        return dnnl::memory::format_tag::acbde;
+      } else if (strides[0] >= strides[2] && strides[2] >= strides[3] &&
+                 strides[3] >= strides[4] && strides[4] >= strides[1]) {
+        return dnnl::memory::format_tag::acdeb;
       }
     } else if (inner_nblks == 1) {
       if (inner_blks[0] == 8 && inner_idxs[0] == 0) {
@@ -310,6 +314,10 @@ inline dnnl::memory::format_tag GetMKLDNNFormat(dnnl::memory::desc mem_desc) {
           strides[2] >= strides[3] && strides[3] >= strides[4] &&
           strides[4] >= strides[5]) {
         return dnnl::memory::format_tag::abcdef;
+      } else if (strides[0] >= strides[2] && strides[2] >= strides[1] &&
+                 strides[1] >= strides[3] && strides[3] >= strides[4] &&
+                 strides[4] >= strides[5]) {
+        return dnnl::memory::format_tag::acbdef;
       }
     }
   }
@@ -397,7 +405,9 @@ inline MKLDNNMemoryFormat MKLDNNFormatForSize(size_t dims_size,
       return MKLDNNMemoryFormat::ndhwc;
     }
   } else if (dims_size == 6) {
-    return MKLDNNMemoryFormat::abcdef;
+    if (data_format == MKLDNNMemoryFormat::nchw) {
+      return MKLDNNMemoryFormat::abcdef;
+    }
   }
   return data_format;
 }