Smoothstep validation changes : No compiler error for anything except…

… low == high (for const/override) (#4082)

* Update smoothstep validation to only fail on low/high equal

* Change to triple equals

---------

Co-authored-by: Peter McNeeley <[email protected]>

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

@@ -51,8 +51,8 @@ Validates that constant evaluation and override evaluation of ${builtin}() rejec
   .fn(t => {
     const type = kValuesTypes[t.params.type];
 
-    // We expect to fail if low >= high.
-    const expectedResult = t.params.value1 < t.params.value2;
+    // We expect to fail if low == high.
+    const expectedResult = t.params.value1 !== t.params.value2;
 
     validateConstOrOverrideBuiltinEval(
       t,
@@ -66,7 +66,7 @@ Validates that constant evaluation and override evaluation of ${builtin}() rejec
 const kStages = [...kConstantAndOverrideStages, 'runtime'] as const;
 
 g.test('partial_eval_errors')
-  .desc('Validates that low < high')
+  .desc('Validates that low != high')
   .params(u =>
     u
       .combine('lowStage', kStages)
@@ -127,7 +127,7 @@ fn foo() {
   let tmp = smoothstep(${lowArg}, ${highArg}, x);
 }`;
 
-    const error = t.params.low >= t.params.high;
+    const error = t.params.low === t.params.high;
     const shader_error =
       error && t.params.lowStage === 'constant' && t.params.highStage === 'constant';
     const pipeline_error =
@@ -349,7 +349,7 @@ g.test('early_eval_errors')
     validateConstOrOverrideBuiltinEval(
       t,
       builtin,
-      /* expectedResult */ t.params.low < t.params.high,
+      /* expectedResult */ t.params.low !== t.params.high,
       [f32(t.params.low), f32(t.params.high), f32(0)],
       t.params.stage
     );