Add const-eval for atanh.

This CL adds const-eval for the `atanh` operator.

Bug: tint:1581
Change-Id: I7d8989a348ad1d8ca463dae90233fd82d6faf2d9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/106849
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/transform/builtin_polyfill_test.cc

@@ -233,7 +233,7 @@ DataMap polyfillAtanh(Level level) {
 TEST_F(BuiltinPolyfillTest, ShouldRunAtanh) {
     auto* src = R"(
 fn f() {
-  atanh(1.0);
+  atanh(0.9f);
 }
 )";
 
@@ -246,7 +246,7 @@ fn f() {
 TEST_F(BuiltinPolyfillTest, Atanh_Full_f32) {
     auto* src = R"(
 fn f() {
-  let r : f32 = atanh(1234);
+  let r : f32 = atanh(0f);
 }
 )";
 
@@ -256,7 +256,7 @@ fn tint_atanh(x : f32) -> f32 {
 }
 
 fn f() {
-  let r : f32 = tint_atanh(1234);
+  let r : f32 = tint_atanh(0.0f);
 }
 )";
 
@@ -268,7 +268,7 @@ fn f() {
 TEST_F(BuiltinPolyfillTest, Atanh_Full_vec3_f32) {
     auto* src = R"(
 fn f() {
-  let r : vec3<f32> = atanh(vec3<f32>(1234));
+  let r : vec3<f32> = atanh(vec3<f32>(0f));
 }
 )";
 
@@ -278,7 +278,7 @@ fn tint_atanh(x : vec3<f32>) -> vec3<f32> {
 }
 
 fn f() {
-  let r : vec3<f32> = tint_atanh(vec3<f32>(1234));
+  let r : vec3<f32> = tint_atanh(vec3<f32>(0.0f));
 }
 )";
 
@@ -290,7 +290,7 @@ fn f() {
 TEST_F(BuiltinPolyfillTest, Atanh_Range_f32) {
     auto* src = R"(
 fn f() {
-  let r : f32 = atanh(1234);
+  let r : f32 = atanh(0f);
 }
 )";
 
@@ -300,7 +300,7 @@ fn tint_atanh(x : f32) -> f32 {
 }
 
 fn f() {
-  let r : f32 = tint_atanh(1234);
+  let r : f32 = tint_atanh(0.0f);
 }
 )";
 
@@ -312,17 +312,21 @@ fn f() {
 TEST_F(BuiltinPolyfillTest, Atanh_Range_vec3_f32) {
     auto* src = R"(
 fn f() {
-  let r : vec3<f32> = atanh(vec3<f32>(1234));
+  let r : vec3<f32> = atanh(vec3<f32>(0f));
 }
 )";
 
     auto* expect = R"(
+fn tint_atanh(x : vec3<f32>) -> vec3<f32> {
+  return select(atanh(x), vec3<f32>(0.0), (x >= vec3<f32>(1.0)));
+}
+
 fn f() {
-  let r : vec3<f32> = atanh(vec3<f32>(1234));
+  let r : vec3<f32> = tint_atanh(vec3<f32>(0.0f));
 }
 )";
 
-    auto got = Run<BuiltinPolyfill>(src, polyfillAcosh(Level::kRangeCheck));
+    auto got = Run<BuiltinPolyfill>(src, polyfillAtanh(Level::kRangeCheck));
 
     EXPECT_EQ(expect, str(got));
 }