check overlapping indices of scatterElements

src/lib/validate-input.js

@@ -653,12 +653,26 @@ export function validateScatterElementsParams(input, indices, updates, {axis = 0
         `The axis ${axis} should be an unsigned integer in the interval [0, ${inputRank}).`);
   }
   const axisSize = input.shape[axis];
+  const updatedLocationDict = {};
   for (let i = 0; i < sizeOfShape(indices.shape); ++i) {
-    const index = indices.getValueByIndex(i);
+    let index = indices.getValueByIndex(i);
     if (!Number.isInteger(index) || index < -axisSize || index >= axisSize) {
       throw new Error(`Invalid indices value - it should be an integer in the interval ` +
       `[${-axisSize}, ${axisSize - 1}]`);
     }
+    const indicesLocation = indices.locationFromIndex(i);
+    const originOutputLocation =
+        [...indicesLocation.slice(0, axis), index, ...indicesLocation.slice(axis + 1)];
+    index = index < 0 ? index + input.shape[axis] : index;
+    const outputLocation =
+        [...indicesLocation.slice(0, axis), index, ...indicesLocation.slice(axis + 1)];
+    const locationString = outputLocation.toString();
+    if (Object.hasOwn(updatedLocationDict, locationString)) {
+      throw new Error(`Invalid indices, [${originOutputLocation}] and ` +
+        `[${updatedLocationDict[locationString]}] point to the same output location.`);
+    } else {
+      updatedLocationDict[locationString] = originOutputLocation;
+    }
   }
 }
 

test/scatter_elements_test.js

@@ -121,4 +121,26 @@ describe('test scatterElements', function() {
     };
     testScatterElements(input, indices, updates, expected, {axis: 1});
   });
+
+  it('scatterElements throws error with overlapping indices', function() {
+    const input = {
+      shape: [1, 5],
+      data: [1, 2, 3, 4, 5],
+    };
+    const indices = {
+      shape: [1, 2],
+      data: [3, -2],
+    };
+    const updates = {
+      shape: [1, 2],
+      data: [1.1, 2.1],
+    };
+    const expected = {
+      shape: [1, 5],
+      data: [1, 2, 3, 2.1, 5],
+    };
+    utils.expectThrowError(() => {
+      testScatterElements(input, indices, updates, expected, {axis: 1});
+    }, 'Invalid indices, [0,-2] and [0,3] point to the same output location.');
+  });
 });

test/utils.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const assert = chai.assert;
+const expect = chai.expect;
 
 /**
  * Get bitwise of the given value.
@@ -40,6 +41,10 @@ assert.isAlmostEqualUlp = function(a, b, nulp, message) {
   }
 };
 
+export function expectThrowError(errorFunc, message) {
+  expect(errorFunc).to.throw(message);
+}
+
 export function checkValue(tensor, expected, nulp = 0) {
   assert.isTrue(tensor.size === expected.length);
   for (let i = 0; i < expected.length; ++i) {