[NFC][WASM] refactor WebAssembly::parseType with StringSwitch (#90149)

Author: HerrCai0907

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTypeUtilities.cpp

@@ -18,24 +18,16 @@
 using namespace llvm;
 
 std::optional<wasm::ValType> WebAssembly::parseType(StringRef Type) {
-  // FIXME: can't use StringSwitch because wasm::ValType doesn't have a
-  // "invalid" value.
-  if (Type == "i32")
-    return wasm::ValType::I32;
-  if (Type == "i64")
-    return wasm::ValType::I64;
-  if (Type == "f32")
-    return wasm::ValType::F32;
-  if (Type == "f64")
-    return wasm::ValType::F64;
-  if (Type == "v128" || Type == "i8x16" || Type == "i16x8" || Type == "i32x4" ||
-      Type == "i64x2" || Type == "f32x4" || Type == "f64x2")
-    return wasm::ValType::V128;
-  if (Type == "funcref")
-    return wasm::ValType::FUNCREF;
-  if (Type == "externref")
-    return wasm::ValType::EXTERNREF;
-  return std::nullopt;
+  return llvm::StringSwitch<std::optional<wasm::ValType>>{Type}
+      .Case("i32", wasm::ValType::I32)
+      .Case("i64", wasm::ValType::I64)
+      .Case("f32", wasm::ValType::F32)
+      .Case("f64", wasm::ValType::F64)
+      .Cases("v128", "i8x16", "i16x8", "i32x4", "i64x2", "f32x4", "f64x2",
+             wasm::ValType::V128)
+      .Case("funcref", wasm::ValType::FUNCREF)
+      .Case("externref", wasm::ValType::EXTERNREF)
+      .Default(std::nullopt);
 }
 
 WebAssembly::BlockType WebAssembly::parseBlockType(StringRef Type) {