code fix (#13365)

Bai Yifan · qingqing01 · commit e69d9c845b30 · 2018-09-12T20:49:22.000-05:00
diff --git a/paddle/fluid/operators/softmax_with_cross_entropy_op.cu b/paddle/fluid/operators/softmax_with_cross_entropy_op.cu
@@ -31,7 +31,8 @@ __global__ void CrossEntropyGrad(T* logit_grad, const int64_t* labels,
   for (int i = blockIdx.x * blockDim.x + threadIdx.x; i < batch_size;
        i += blockDim.x * gridDim.x) {
     int idx = i * class_num + labels[i];
-    logit_grad[idx] -= static_cast<T>(1.);
+    logit_grad[idx] -=
+        ignore_index == labels[i] ? static_cast<T>(0.) : static_cast<T>(1.);
   }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -31,7 +31,8 @@ __global__ void CrossEntropyGrad(T* logit_grad, const int64_t* labels,`
`31`	`31`	`for (int i = blockIdx.x * blockDim.x + threadIdx.x; i < batch_size;`
`32`	`32`	`i += blockDim.x * gridDim.x) {`
`33`	`33`	`int idx = i * class_num + labels[i];`
`34`		`- logit_grad[idx] -= static_cast<T>(1.);`
	`34`	`+ logit_grad[idx] -=`
	`35`	`+ ignore_index == labels[i] ? static_cast<T>(0.) : static_cast<T>(1.);`
`35`	`36`	`}`
`36`	`37`	`}`
`37`	`38`