Introduce the concept of builtin functions.

libyul/Dialect.h

@@ -0,0 +1,82 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * Yul dialect.
+ */
+
+#pragma once
+
+#include <libyul/YulString.h>
+
+#include <memory>
+
+namespace yul
+{
+
+class YulString;
+using Type = YulString;
+
+enum class AsmFlavour
+{
+	Loose,  // no types, EVM instructions as function, jumps and direct stack manipulations
+	Strict, // no types, EVM instructions as functions, but no jumps and no direct stack manipulations
+	Yul     // same as Strict mode with types
+};
+
+struct BuiltinFunction
+{
+	YulString name;
+	std::vector<Type> parameters;
+	std::vector<Type> returns;
+	bool movable;
+};
+
+/**
+ * Class to query for builtin functions and their semantics.
+ */
+struct Builtins
+{
+	virtual ~Builtins() = default;
+	/// @returns the builtin function of the given name or a nullptr if it is not a builtin function.
+	virtual BuiltinFunction const* query(YulString /*_name*/) const { return nullptr; }
+};
+
+struct Dialect
+{
+	AsmFlavour flavour = AsmFlavour::Loose;
+	std::shared_ptr<Builtins> builtins;
+
+	Dialect(AsmFlavour _flavour, std::shared_ptr<Builtins> _builtins):
+		flavour(_flavour), builtins(std::move(_builtins))
+	{}
+	static Dialect looseAssemblyForEVM()
+	{
+		return Dialect{AsmFlavour::Loose, std::make_shared<Builtins>()};
+	}
+	static Dialect strictAssemblyForEVM()
+	{
+		// The EVM instructions will be moved to builtins at some point.
+		return Dialect{AsmFlavour::Strict, std::make_shared<Builtins>()};
+	}
+	static Dialect yul()
+	{
+		// Will have to add builtins later.
+		return Dialect{AsmFlavour::Yul, std::make_shared<Builtins>()};
+	}
+};
+
+}