From b697f76ff655da234de74458f735c6c60ca4a611 Mon Sep 17 00:00:00 2001
From: Natalie Chouinard <chouinard@google.com>
Date: Tue, 28 Jul 2026 11:59:10 -0400
Subject: [PATCH] Add chained swizzle assignment tests

Add validation and execution tests for chained swizzles on the LHS of an
assignment. These are valid with the swizzle_assignment language feature
as long as the final indices actually assigned are free from duplicate
targets.

Bug: crbug.com/539634915
---
 .../statement/swizzle_assignment.spec.ts      | 20 ++++++++++++
 .../statement/swizzle_assignment.spec.ts      | 31 +++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/src/webgpu/shader/execution/statement/swizzle_assignment.spec.ts b/src/webgpu/shader/execution/statement/swizzle_assignment.spec.ts
index fef0a734b8bd..26e4e3159cc2 100644
--- a/src/webgpu/shader/execution/statement/swizzle_assignment.spec.ts
+++ b/src/webgpu/shader/execution/statement/swizzle_assignment.spec.ts
@@ -297,6 +297,26 @@ const kSwizzleAssignmentCases: Record<string, SwizzleAssignmentCase> = {
     rhs: 'true',
     expected: [1, 0],
   },
+  // v = vec3u(1, 2, 3)
+  // v.xyy.xy = vec2u(4, 5);
+  vec3u_chained_dup_lhs_pass: {
+    elemType: 'u32',
+    vecSize: 3,
+    initial: [1, 2, 3],
+    swizzle: 'xyy.xy',
+    rhs: 'vec2u(4, 5)',
+    expected: [4, 5, 3],
+  },
+  // v = vec2f(1.0, 2.0)
+  // v.xx.x = 5.0;
+  vec2f_chained_dup_lhs_pass: {
+    elemType: 'f32',
+    vecSize: 2,
+    initial: [1.0, 2.0],
+    swizzle: 'xx.x',
+    rhs: '5.0f',
+    expected: [5.0, 2.0],
+  },
 };
 
 g.test('swizzle_assignment_vars')
diff --git a/src/webgpu/shader/validation/statement/swizzle_assignment.spec.ts b/src/webgpu/shader/validation/statement/swizzle_assignment.spec.ts
index fcc4e2478090..163e243639b3 100644
--- a/src/webgpu/shader/validation/statement/swizzle_assignment.spec.ts
+++ b/src/webgpu/shader/validation/statement/swizzle_assignment.spec.ts
@@ -3,6 +3,7 @@ Validation tests for swizzle assignments.
 `;
 
 import { makeTestGroup } from '../../../../common/framework/test_group.js';
+import { keysOf } from '../../../../common/util/data_tables.js';
 import { ShaderValidationTest } from '../shader_validation_test.js';
 
 export const g = makeTestGroup(ShaderValidationTest);
@@ -213,3 +214,33 @@ fn main() {
 
     t.expectCompileResult(expected, code);
   });
+
+const kChainedSwizzleCases = {
+  // Valid cases:
+  xy_y: { chain: 'xy.y', size: 1, pass: true }, // y
+  xx_x: { chain: 'xx.x', size: 1, pass: true }, // x
+  xyy_xy: { chain: 'xyy.xy', size: 2, pass: true }, // xy
+  xxyy_zxy_xy: { chain: 'xxyy.zxy.xy', size: 2, pass: true }, // yx
+  // Invalid cases:
+  xxyy_xy: { chain: 'xxyy.xy', size: 2, pass: false }, // xx
+  xyy_yy: { chain: 'xyy.yy', size: 2, pass: false }, // yy
+  xxyy_zxy_yz: { chain: 'xxyy.zxy.yz', size: 2, pass: false }, // xx
+  zy_xyx: { chain: 'zy.xyx', size: 3, pass: false }, // zyz
+};
+
+g.test('chained_swizzle')
+  .desc('Validate chained swizzles on the LHS of an assignment')
+  .params(u => u.combine('case', keysOf(kChainedSwizzleCases)))
+  .fn(t => {
+    const { chain, size, pass } = kChainedSwizzleCases[t.params.case];
+    const rhs = size === 1 ? '1.0' : `vec${size}f(1.0)`;
+    const code = `
+@fragment
+fn main() {
+  var v = vec4f();
+  v.${chain} = ${rhs};
+}
+`;
+    const expected = pass && t.hasLanguageFeature('swizzle_assignment');
+    t.expectCompileResult(expected, code);
+  });