From 16e58449ab08e0eee22c5d061c3770142b55eb57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kamil=20=C5=9Aliwak?= <kamil.sliwak@codepoets.it>
Date: Tue, 28 Apr 2020 13:14:45 +0200
Subject: [PATCH] ir/Common: Add YulArity struct

---
 libsolidity/codegen/ir/Common.cpp |  8 ++++++++
 libsolidity/codegen/ir/Common.h   | 29 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/libsolidity/codegen/ir/Common.cpp b/libsolidity/codegen/ir/Common.cpp
index 8b895596a..dba6aee07 100644
--- a/libsolidity/codegen/ir/Common.cpp
+++ b/libsolidity/codegen/ir/Common.cpp
@@ -16,6 +16,7 @@
 */
 
 #include <libsolidity/codegen/ir/Common.h>
+#include <libsolidity/ast/TypeProvider.h>
 
 #include <libsolutil/CommonIO.h>
 
@@ -23,6 +24,13 @@ using namespace std;
 using namespace solidity::util;
 using namespace solidity::frontend;
 
+YulArity YulArity::fromType(FunctionType const& _functionType)
+{
+	return YulArity{
+		TupleType(_functionType.parameterTypes()).sizeOnStack(),
+		TupleType(_functionType.returnParameterTypes()).sizeOnStack()
+	};
+}
 string IRNames::function(FunctionDefinition const& _function)
 {
 	// @TODO previously, we had to distinguish creation context and runtime context,
diff --git a/libsolidity/codegen/ir/Common.h b/libsolidity/codegen/ir/Common.h
index 771dd0ab4..96e2a86ea 100644
--- a/libsolidity/codegen/ir/Common.h
+++ b/libsolidity/codegen/ir/Common.h
@@ -22,11 +22,28 @@
 
 #include <libsolidity/ast/AST.h>
 
+#include <algorithm>
 #include <string>
 
 namespace solidity::frontend
 {
 
+/**
+ * Structure that describes arity and co-arity of a Yul function, i.e. the number of its inputs and outputs.
+ */
+struct YulArity
+{
+	explicit YulArity(size_t _in, size_t _out): in(_in), out(_out) {}
+
+	static YulArity fromType(FunctionType const& _functionType);
+
+	bool operator==(YulArity const& _other) const { return in == _other.in && out == _other.out; }
+	bool operator!=(YulArity const& _other) const { return !(*this == _other); }
+
+	size_t in;  /// Number of input parameters
+	size_t out; /// Number of output parameters
+};
+
 struct IRNames
 {
 	static std::string function(FunctionDefinition const& _function);
@@ -45,3 +62,15 @@ struct IRNames
 };
 
 }
+
+// Overloading std::less() makes it possible to use YulArity as a map key. We could define operator<
+// instead but such an operator would be a bit ambiguous (e.g. YulArity{2, 2} would be be greater than
+// YulArity{1, 10} in lexicographical order but the latter has greater total number of inputs and outputs).
+template<>
+struct std::less<solidity::frontend::YulArity>
+{
+	bool operator() (solidity::frontend::YulArity const& _lhs, solidity::frontend::YulArity const& _rhs) const
+	{
+		return _lhs.in < _rhs.in || (_lhs.in == _rhs.in && _lhs.out < _rhs.out);
+	}
+};