Ensure that tf.exp() ops up-cast 'int32' types to Float. (#107)

Author: nkreeger

src/nodejs_kernel_backend.ts

@@ -416,7 +416,8 @@ export class NodeJSKernelBackend implements KernelBackend {
   }
 
   exp<T extends Tensor>(x: T): T {
-    return this.executeSingleInput('Exp', x) as T;
+    const xTensor = x.dtype === 'int32' ? x.toFloat() : x;
+    return this.executeSingleInput('Exp', xTensor) as T;
   }
 
   log<T extends Tensor>(x: T): T {

src/nodejs_kernel_backend_test.ts

@@ -37,3 +37,9 @@ describe('delayed upload', () => {
     expect(softmaxLogits.get(2)).toEqual(data[2]);
   });
 });
+
+describe('type casting', () => {
+  it('exp support int32', () => {
+    tf.exp(tf.scalar(2, 'int32'));
+  });
+});