Merge pull request #5919 from qingqing01/roi_pooling

Fix bug in RoI pooling.

paddle/gserver/layers/ROIPoolLayer.cpp

@@ -13,6 +13,7 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #include "ROIPoolLayer.h"
+#include <cfloat>
 
 namespace paddle {
 
@@ -126,10 +127,8 @@ void ROIPoolLayer::forward(PassType passType) {
 
           bool isEmpty = (hend <= hstart) || (wend <= wstart);
           size_t poolIndex = ph * pooledWidth_ + pw;
-          if (isEmpty) {
-            outputData[poolIndex] = 0;
+          outputData[poolIndex] = isEmpty ? 0 : -FLT_MAX;
           argmaxData[poolIndex] = -1;
-          }
 
           for (size_t h = hstart; h < hend; ++h) {
             for (size_t w = wstart; w < wend; ++w) {