[naga] Implement atan2 in const (gfx-rs#8222)

Signed-off-by: sagudev <[email protected]>

Author: sagudev

cts_runner/test.lst

@@ -134,6 +134,8 @@ fails-if(metal) webgpu:api,operation,uncapturederror:iff_uncaptured:*
 //FAIL: webgpu:api,operation,uncapturederror:onuncapturederror_order_wrt_addEventListener
 // There are also two unimplemented SKIPs in uncapturederror not enumerated here.
 webgpu:api,validation,encoding,queries,general:occlusion_query,query_type:*
+webgpu:shader,execution,expression,call,builtin,atan2:f16:*
+webgpu:shader,execution,expression,call,builtin,atan2:f32:*
 webgpu:shader,execution,expression,call,builtin,textureSample:sampled_1d_coords:*
 webgpu:shader,execution,expression,call,builtin,textureSampleBaseClampToEdge:2d_coords:stage="c";textureType="texture_2d<f32>";*
 webgpu:shader,execution,flow_control,return:*

naga/src/proc/constant_evaluator.rs

@@ -1178,6 +1178,11 @@ impl<'a> ConstantEvaluator<'a> {
             crate::MathFunction::Atan => {
                 component_wise_float!(self, span, [arg], |e| { Ok([e.atan()]) })
             }
+            crate::MathFunction::Atan2 => {
+                component_wise_float!(self, span, [arg, arg1.unwrap()], |y, x| {
+                    Ok([y.atan2(x)])
+                })
+            }
             crate::MathFunction::Asinh => {
                 component_wise_float!(self, span, [arg], |e| { Ok([e.asinh()]) })
             }
@@ -1346,8 +1351,7 @@ impl<'a> ConstantEvaluator<'a> {
             crate::MathFunction::Cross => self.cross_product(arg, arg1.unwrap(), span),
 
             // unimplemented
-            crate::MathFunction::Atan2
-            | crate::MathFunction::Modf
+            crate::MathFunction::Modf
             | crate::MathFunction::Frexp
             | crate::MathFunction::Ldexp
             | crate::MathFunction::Dot