Address review feedback

Author: andykaylor

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -1178,6 +1178,7 @@ def CIR_SwitchOp : CIR_Op<"switch", [
 //===----------------------------------------------------------------------===//
 
 def CIR_IsConstantOp : CIR_Op<"is_constant", [Pure]> {
+  let summary = "Test for manifest compile-time constant";
   let description = [{
     Returns `true` if the argument is known to be a manifest compile-time
     constant otherwise returns `false`. If the argument is a constant expression

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -577,8 +577,8 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
 
     mlir::Value result = cir::IsConstantOp::create(
         builder, getLoc(e->getSourceRange()), argValue);
-    if (result.getType() != resultType)
-      result = builder.createBoolToInt(result, resultType);
+    // IsConstantOp returns a bool, but __builtin_constant_p returns an int.
+    result = builder.createBoolToInt(result, resultType);
     return RValue::get(result);
   }
   case Builtin::BI__builtin_dynamic_object_size: