[WGSL] Add support for constant multiplication

https://bugs.webkit.org/show_bug.cgi?id=262561
rdar://116413844

Reviewed by Mike Wyrzykowski.

Implement the constant function for multiplication. The function is mostly complete,
it can handle all overloads for scalars and vectors, but since we don't yet support
constant matrices I couldn't support the overloads that operate on them.

* Source/WebGPU/WGSL/ConstantFunctions.h:
(WGSL::constantMultiply):
* Source/WebGPU/WGSL/TypeCheck.cpp:
(WGSL::TypeChecker::TypeChecker):
* Source/WebGPU/WGSL/tests/valid/constants.wgsl:

Canonical link: https://commits.webkit.org/268834@main

Source/WebGPU/WGSL/ConstantFunctions.h

@@ -93,6 +93,22 @@ static ConstantValue constantMinus(const Type*, const FixedVector<ConstantValue>
     return binaryMinus();
 }
 
+static ConstantValue constantMultiply(const Type*, const FixedVector<ConstantValue>& arguments)
+{
+    ASSERT(arguments.size() == 2);
+
+    auto& lhs = arguments[0];
+    auto& rhs = arguments[1];
+
+    // FIXME: handle constant matrices
+
+    return scalarOrVector([&](const auto& left, auto& right) -> ConstantValue {
+        if (left.isInt() && right.isInt())
+            return left.toInt() * right.toInt();
+        return left.toDouble() * right.toDouble();
+    }, lhs, rhs);
+}
+
 static ConstantValue zeroValue(const Type* type)
 {
     return WTF::switchOn(*type,

Source/WebGPU/WGSL/TypeCheck.cpp

@@ -311,6 +311,7 @@ TypeChecker::TypeChecker(ShaderModule& shaderModule)
 
     m_constantFunctions.add("pow"_s, constantPow);
     m_constantFunctions.add("-"_s, constantMinus);
+    m_constantFunctions.add("*"_s, constantMultiply);
     m_constantFunctions.add("vec2"_s, constantVector2);
     m_constantFunctions.add("vec2f"_s, constantVector2);
     m_constantFunctions.add("vec2i"_s, constantVector2);

Source/WebGPU/WGSL/tests/valid/constants.wgsl

@@ -38,6 +38,16 @@ fn testArrayConstants() -> i32
     return 0;
 }
 
+fn testConstantMultiplication()
+{
+  const x1 = 2 * 2;
+  const x2 = 2 * 2.0;
+  const x3 = 2.0 * 2.0;
+  const x4 = 2.0 * vec2(2.0);
+  const x5 = vec2(2.0) * vec2(2.0);
+  const x6 = vec2(2.0) * 2.0;
+}
+
 @compute @workgroup_size(1)
 fn testVectorConstants() -> i32
 {