Make function grouper idempotent.

libyul/optimiser/FunctionGrouper.cpp

@@ -33,6 +33,9 @@ using namespace dev::solidity;
 
 void FunctionGrouper::operator()(Block& _block)
 {
+	if (alreadyGrouped(_block))
+		return;
+
 	vector<Statement> reordered;
 	reordered.emplace_back(Block{_block.location, {}});
 
@@ -45,3 +48,15 @@ void FunctionGrouper::operator()(Block& _block)
 	}
 	_block.statements = std::move(reordered);
 }
+
+bool FunctionGrouper::alreadyGrouped(Block const& _block)
+{
+	if (_block.statements.empty())
+		return false;
+	if (_block.statements.front().type() != typeid(Block))
+		return false;
+	for (size_t i = 1; i < _block.statements.size(); ++i)
+		if (_block.statements.at(i).type() != typeid(FunctionDefinition))
+			return false;
+	return true;
+}

libyul/optimiser/FunctionGrouper.h

@@ -38,6 +38,9 @@ class FunctionGrouper
 {
 public:
 	void operator()(Block& _block);
+
+private:
+	bool alreadyGrouped(Block const& _block);
 };
 
 }

test/libyul/yulOptimizerTests/fullInliner/multi_fun_callback.yul

@@ -26,13 +26,11 @@
 // fullInliner
 // {
 //     {
-//         {
-//             let f_x := 100
-//             mstore(0, f_x)
-//             mstore(7, h())
-//             g(10)
-//             mstore(1, f_x)
-//         }
+//         let f_x := 100
+//         mstore(0, f_x)
+//         mstore(7, h())
+//         g(10)
+//         mstore(1, f_x)
 //     }
 //     function f(x)
 //     {

test/libyul/yulOptimizerTests/functionGrouper/already_grouped.yul

@@ -0,0 +1,17 @@
+{
+    {
+        let x := 2
+    }
+    function f() -> y { y := 8 }
+}
+// ----
+// functionGrouper
+// {
+//     {
+//         let x := 2
+//     }
+//     function f() -> y
+//     {
+//         y := 8
+//     }
+// }

test/libyul/yulOptimizerTests/functionGrouper/grouped_but_not_ordered.yul

@@ -0,0 +1,19 @@
+{
+    function f() -> y { y := 8 }
+    {
+        let x := 2
+    }
+}
+// ----
+// functionGrouper
+// {
+//     {
+//         {
+//             let x := 2
+//         }
+//     }
+//     function f() -> y
+//     {
+//         y := 8
+//     }
+// }