Do not overwrite allowMSizeOptimization

libyul/optimiser/UnusedPruner.cpp

@@ -119,15 +119,13 @@ void UnusedPruner::operator()(Block& _block)
 void UnusedPruner::runUntilStabilised(
 	Dialect const& _dialect,
 	Block& _ast,
-	bool _allowMSizeOptization,
+	bool _allowMSizeOptimization,
 	set<YulString> const& _externallyUsedFunctions
 )
 {
-	_allowMSizeOptization = !SideEffectsCollector(_dialect, _ast).containsMSize();
-
 	while (true)
 	{
-		UnusedPruner pruner(_dialect, _ast, _allowMSizeOptization, _externallyUsedFunctions);
+		UnusedPruner pruner(_dialect, _ast, _allowMSizeOptimization, _externallyUsedFunctions);
 		pruner(_ast);
 		if (!pruner.shouldRunAgain())
 			return;

libyul/optimiser/UnusedPruner.h

@@ -34,6 +34,11 @@ struct Dialect;
  * Optimisation stage that removes unused variables and functions and also
  * removes side-effect-free expression statements.
  *
+ * If msize is used, we cannot remove any statements that access memory.
+ * Because of that, the Unused Pruner should only be invoked on full ASTs,
+ * such that it can check for the presence of msize itself, or
+ * the `_allowMSizeOptimization` needs to be passed.
+ *
  * Note that this does not remove circular references.
  *
  * Prerequisite: Disambiguator
@@ -64,7 +69,7 @@ public:
 	static void runUntilStabilised(
 		Dialect const& _dialect,
 		Block& _ast,
-		bool _allowMSizeOptization,
+		bool _allowMSizeOptimization,
 		std::set<YulString> const& _externallyUsedFunctions = {}
 	);