From b1454433b27124badece507b3f3aae822de8d83d Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Sat, 3 Nov 2018 16:04:42 +0100
Subject: Remove variables that go out of scope from data structure.

---
 libyul/optimiser/RedundantAssignEliminator.cpp | 32 ++++++++++++++++++--------
 libyul/optimiser/RedundantAssignEliminator.h   |  7 ++++++
 2 files changed, 29 insertions(+), 10 deletions(-)

(limited to 'libyul')

diff --git a/libyul/optimiser/RedundantAssignEliminator.cpp b/libyul/optimiser/RedundantAssignEliminator.cpp
index df6c4e4e..b7217074 100644
--- a/libyul/optimiser/RedundantAssignEliminator.cpp
+++ b/libyul/optimiser/RedundantAssignEliminator.cpp
@@ -96,9 +96,15 @@ void RedundantAssignEliminator::operator()(FunctionDefinition const& _functionDe
 	(*this)(_functionDefinition.body);
 
 	for (auto const& param: _functionDefinition.parameters)
+	{
 		changeUndecidedTo(param.name, State::Unused);
+		finalize(param.name);
+	}
 	for (auto const& retParam: _functionDefinition.returnVariables)
+	{
 		changeUndecidedTo(retParam.name, State::Used);
+		finalize(retParam.name);
+	}
 }
 
 void RedundantAssignEliminator::operator()(ForLoop const& _forLoop)
@@ -150,16 +156,7 @@ void RedundantAssignEliminator::run(Block& _ast)
 	RedundantAssignEliminator rae;
 	rae(_ast);
 
-	std::set<Assignment const*> assignmentsToRemove;
-	for (auto const& variables: rae.m_assignments)
-		for (auto const& assignment: variables.second)
-		{
-			assertThrow(assignment.second != State::Undecided, OptimizerException, "");
-			if (assignment.second == State::Unused && MovableChecker{*assignment.first->value}.movable())
-				assignmentsToRemove.emplace(assignment.first);
-		}
-
-	AssignmentRemover remover{assignmentsToRemove};
+	AssignmentRemover remover{rae.m_assignmentsToRemove};
 	remover(_ast);
 }
 
@@ -192,6 +189,8 @@ void joinMap(std::map<K, V>& _a, std::map<K, V>&& _b, F _conflictSolver)
 
 void RedundantAssignEliminator::join(RedundantAssignEliminator& _other)
 {
+	m_assignmentsToRemove.insert(begin(_other.m_assignmentsToRemove), end(_other.m_assignmentsToRemove));
+
 	joinMap(m_assignments, std::move(_other.m_assignments), [](
 		map<Assignment const*, State>& _assignmentHere,
 		map<Assignment const*, State>&& _assignmentThere
@@ -208,6 +207,19 @@ void RedundantAssignEliminator::changeUndecidedTo(YulString _variable, Redundant
 			assignment.second = _newState;
 }
 
+void RedundantAssignEliminator::finalize(YulString _variable)
+{
+	for (auto& assignment: m_assignments[_variable])
+	{
+		assertThrow(assignment.second != State::Undecided, OptimizerException, "");
+		if (assignment.second == State{State::Unused} && MovableChecker{*assignment.first->value}.movable())
+			// TODO the only point where we actually need this
+			// to be a set is for the for loop
+			m_assignmentsToRemove.insert(assignment.first);
+	}
+	m_assignments.erase(_variable);
+}
+
 void AssignmentRemover::operator()(Block& _block)
 {
 	boost::range::remove_erase_if(_block.statements, [=](Statement const& _statement) -> bool {
diff --git a/libyul/optimiser/RedundantAssignEliminator.h b/libyul/optimiser/RedundantAssignEliminator.h
index a9c6a8f7..76106aae 100644
--- a/libyul/optimiser/RedundantAssignEliminator.h
+++ b/libyul/optimiser/RedundantAssignEliminator.h
@@ -149,8 +149,12 @@ private:
 		}
 		~BlockScope()
 		{
+			// This should actually store all declared variables
+			// into a different mapping
 			for (auto const& var: m_rae.m_declaredVariables)
 				m_rae.changeUndecidedTo(var, State::Unused);
+			for (auto const& var: m_rae.m_declaredVariables)
+				m_rae.finalize(var);
 			swap(m_rae.m_declaredVariables, m_outerDeclaredVariables);
 		}
 
@@ -164,10 +168,13 @@ private:
 	/// Will destroy @a _other.
 	void join(RedundantAssignEliminator& _other);
 	void changeUndecidedTo(YulString _variable, State _newState);
+	void finalize(YulString _variable);
 
 	std::set<YulString> m_declaredVariables;
 	// TODO check that this does not cause nondeterminism!
+	// This could also be a pseudo-map from state to assignment.
 	std::map<YulString, std::map<Assignment const*, State>> m_assignments;
+	std::set<Assignment const*> m_assignmentsToRemove;
 };
 
 class AssignmentRemover: public ASTModifier
-- 
cgit