fix smoothstep execution: only compute valid cases when const (#3901)

For const cases, low < high is required
See gpuweb/gpuweb#4616

Bug: crbug.com/351378281

src/webgpu/shader/execution/expression/call/builtin/smoothstep.spec.ts

@@ -7,18 +7,30 @@ T is S or vecN<S>
 Returns the smooth Hermite interpolation between 0 and 1.
 Component-wise when T is a vector.
 For scalar T, the result is t * t * (3.0 - 2.0 * t), where t = clamp((x - low) / (high - low), 0.0, 1.0).
+
+If low >= high:
+* It is a shader-creation error if low and high are const-expressions.
+* It is a pipeline-creation error if low and high are override-expressions.
 `;
 
 import { makeTestGroup } from '../../../../../../common/framework/test_group.js';
 import { GPUTest } from '../../../../../gpu_test.js';
-import { Type } from '../../../../../util/conversion.js';
+import { ScalarValue, Type, Value } from '../../../../../util/conversion.js';
+import { Case } from '../../case.js';
 import { allInputSources, onlyConstInputSource, run } from '../../expression.js';
 
 import { abstractFloatBuiltin, builtin } from './builtin.js';
 import { d } from './smoothstep.cache.js';
 
 export const g = makeTestGroup(GPUTest);
 
+// Returns true if `c` is valid for a const evaluation of smoothstep.
+function validForConst(c: Case): boolean {
+  const low = (c.input as Value[])[0] as ScalarValue;
+  const high = (c.input as Value[])[1] as ScalarValue;
+  return low.value < high.value;
+}
+
 g.test('abstract_float')
   .specURL('https://www.w3.org/TR/WGSL/#float-builtin-functions')
   .desc(`abstract float tests`)
@@ -28,7 +40,7 @@ g.test('abstract_float')
       .combine('vectorize', [undefined, 2, 3, 4] as const)
   )
   .fn(async t => {
-    const cases = await d.get('abstract_const');
+    const cases = (await d.get('abstract_const')).filter(c => validForConst(c));
     await run(
       t,
       abstractFloatBuiltin('smoothstep'),
@@ -47,7 +59,15 @@ g.test('f32')
   )
   .fn(async t => {
     const cases = await d.get(t.params.inputSource === 'const' ? 'f32_const' : 'f32_non_const');
-    await run(t, builtin('smoothstep'), [Type.f32, Type.f32, Type.f32], Type.f32, t.params, cases);
+    const validCases = cases.filter(c => t.params.inputSource !== 'const' || validForConst(c));
+    await run(
+      t,
+      builtin('smoothstep'),
+      [Type.f32, Type.f32, Type.f32],
+      Type.f32,
+      t.params,
+      validCases
+    );
   });
 
 g.test('f16')
@@ -61,5 +81,13 @@ g.test('f16')
   })
   .fn(async t => {
     const cases = await d.get(t.params.inputSource === 'const' ? 'f16_const' : 'f16_non_const');
-    await run(t, builtin('smoothstep'), [Type.f16, Type.f16, Type.f16], Type.f16, t.params, cases);
+    const validCases = cases.filter(c => t.params.inputSource !== 'const' || validForConst(c));
+    await run(
+      t,
+      builtin('smoothstep'),
+      [Type.f16, Type.f16, Type.f16],
+      Type.f16,
+      t.params,
+      validCases
+    );
   });

src/webgpu/shader/validation/expression/call/builtin/smoothstep.spec.ts

@@ -80,6 +80,8 @@ g.test('partial_eval_errors')
       .beginSubcases()
       .expand('low', u => [0, 10])
       .expand('high', u => [0, 10])
+      // in_shader: Is the function call statically accessed by the entry point?
+      .combine('in_shader', [false, true] as const)
   )
   .beforeAllSubcases(t => {
     if (scalarTypeOf(kValuesTypes[t.params.type]) === Type.f16) {
@@ -129,7 +131,10 @@ fn foo() {
     const shader_error =
       error && t.params.lowStage === 'constant' && t.params.highStage === 'constant';
     const pipeline_error =
-      error && t.params.lowStage !== 'runtime' && t.params.highStage !== 'runtime';
+      t.params.in_shader &&
+      error &&
+      t.params.lowStage !== 'runtime' &&
+      t.params.highStage !== 'runtime';
     t.expectCompileResult(!shader_error, wgsl);
     if (!shader_error) {
       const constants: Record<string, number> = {};
@@ -140,7 +145,7 @@ fn foo() {
         code: wgsl,
         constants,
         reference: ['o_low', 'o_high'],
-        statements: ['foo();'],
+        statements: t.params.in_shader ? ['foo();'] : [],
       });
     }
   });