From a4aa2639d009d13c24961c5e8ad4a56bb767c39c Mon Sep 17 00:00:00 2001
From: hrkrshnn <webmail.hari@gmail.com>
Date: Mon, 28 Dec 2020 22:51:14 +0100
Subject: [PATCH] Replaced code for assigning scopes with the class Scoper

---
 libyul/optimiser/DataFlowAnalyzer.cpp | 50 ++++-----------------------
 libyul/optimiser/DataFlowAnalyzer.h   | 20 ++---------
 2 files changed, 10 insertions(+), 60 deletions(-)

diff --git a/libyul/optimiser/DataFlowAnalyzer.cpp b/libyul/optimiser/DataFlowAnalyzer.cpp
index b845d2722..e07436b2b 100644
--- a/libyul/optimiser/DataFlowAnalyzer.cpp
+++ b/libyul/optimiser/DataFlowAnalyzer.cpp
@@ -30,7 +30,6 @@
 
 #include <libsolutil/CommonData.h>
 
-#include <boost/range/adaptor/reversed.hpp>
 #include <boost/range/algorithm_ext/erase.hpp>
 #include <variant>
 
@@ -104,16 +103,14 @@ void DataFlowAnalyzer::operator()(Assignment& _assignment)
 
 void DataFlowAnalyzer::operator()(VariableDeclaration& _varDecl)
 {
+	if (_varDecl.value)
+		clearKnowledgeIfInvalidated(*_varDecl.value);
+
+	Scoper::operator()(_varDecl);
+
 	set<YulString> names;
 	for (auto const& var: _varDecl.variables)
 		names.emplace(var.name);
-	m_variableScopes.back().variables += names;
-
-	if (_varDecl.value)
-	{
-		clearKnowledgeIfInvalidated(*_varDecl.value);
-		visit(*_varDecl.value);
-	}
 
 	handleAssignment(names, _varDecl.value.get(), true);
 }
@@ -171,22 +168,15 @@ void DataFlowAnalyzer::operator()(FunctionDefinition& _fun)
 	swap(m_references, references);
 	swap(m_storage, storage);
 	swap(m_memory, memory);
-	pushScope(true);
 
-	for (auto const& parameter: _fun.parameters)
-		m_variableScopes.back().variables.emplace(parameter.name);
 	for (auto const& var: _fun.returnVariables)
-	{
-		m_variableScopes.back().variables.emplace(var.name);
 		handleAssignment({var.name}, nullptr, true);
-	}
-	ASTModifier::operator()(_fun);
+
+	Scoper::operator()(_fun);
 
 	// Note that the contents of return variables, storage and memory at this point
 	// might be incorrect due to the fact that the DataFlowAnalyzer ignores the ``leave``
 	// statement.
-
-	popScope();
 	swap(m_value, value);
 	swap(m_loopDepth, loopDepth);
 	swap(m_references, references);
@@ -228,14 +218,6 @@ void DataFlowAnalyzer::operator()(ForLoop& _for)
 	--m_loopDepth;
 }
 
-void DataFlowAnalyzer::operator()(Block& _block)
-{
-	size_t numScopes = m_variableScopes.size();
-	pushScope(false);
-	ASTModifier::operator()(_block);
-	popScope();
-	assertThrow(numScopes == m_variableScopes.size(), OptimizerException, "");
-}
 
 void DataFlowAnalyzer::handleAssignment(set<YulString> const& _variables, Expression* _value, bool _isDeclaration)
 {
@@ -291,11 +273,6 @@ void DataFlowAnalyzer::handleAssignment(set<YulString> const& _variables, Expres
 	}
 }
 
-void DataFlowAnalyzer::pushScope(bool _functionScope)
-{
-	m_variableScopes.emplace_back(_functionScope);
-}
-
 void DataFlowAnalyzer::popScope()
 {
 	clearValues(std::move(m_variableScopes.back().variables));
@@ -396,18 +373,6 @@ void DataFlowAnalyzer::joinKnowledgeHelper(
 		_this.eraseKey(key);
 }
 
-bool DataFlowAnalyzer::inScope(YulString _variableName) const
-{
-	for (auto const& scope: m_variableScopes | boost::adaptors::reversed)
-	{
-		if (scope.variables.count(_variableName))
-			return true;
-		if (scope.isFunction)
-			return false;
-	}
-	return false;
-}
-
 std::optional<pair<YulString, YulString>> DataFlowAnalyzer::isSimpleStore(
 	StoreLoadLocation _location,
 	ExpressionStatement const& _statement
@@ -432,4 +397,3 @@ std::optional<YulString> DataFlowAnalyzer::isSimpleLoad(
 				return key->name;
 	return {};
 }
-
diff --git a/libyul/optimiser/DataFlowAnalyzer.h b/libyul/optimiser/DataFlowAnalyzer.h
index 7a9b36a24..aa143ee53 100644
--- a/libyul/optimiser/DataFlowAnalyzer.h
+++ b/libyul/optimiser/DataFlowAnalyzer.h
@@ -23,6 +23,7 @@
 
 #pragma once
 
+#include <libyul/optimiser/Scoper.h>
 #include <libyul/optimiser/ASTWalker.h>
 #include <libyul/optimiser/KnowledgeBase.h>
 #include <libyul/YulString.h>
@@ -76,7 +77,7 @@ struct AssignedValue
  *
  * Prerequisite: Disambiguator, ForLoopInitRewriter.
  */
-class DataFlowAnalyzer: public ASTModifier
+class DataFlowAnalyzer: public Scoper
 {
 public:
 	/// @param _functionSideEffects
@@ -96,17 +97,13 @@ public:
 	void operator()(Switch& _switch) override;
 	void operator()(FunctionDefinition&) override;
 	void operator()(ForLoop&) override;
-	void operator()(Block& _block) override;
 
 protected:
 	/// Registers the assignment.
 	void handleAssignment(std::set<YulString> const& _names, Expression* _value, bool _isDeclaration);
 
-	/// Creates a new inner scope.
-	void pushScope(bool _functionScope);
-
 	/// Removes the innermost scope and clears all variables in it.
-	void popScope();
+	void popScope() override;
 
 	/// Clears information about the values assigned to the given variables,
 	/// for example at points where control flow is merged.
@@ -133,9 +130,6 @@ protected:
 		InvertibleMap<YulString, YulString> const& _olderData
 	);
 
-	/// Returns true iff the variable is in scope.
-	bool inScope(YulString _variableName) const;
-
 	enum class StoreLoadLocation {
 		Memory = 0,
 		Storage = 1,
@@ -178,17 +172,9 @@ protected:
 	/// Current nesting depth of loops.
 	size_t m_loopDepth{0};
 
-	struct Scope
-	{
-		explicit Scope(bool _isFunction): isFunction(_isFunction) {}
-		std::set<YulString> variables;
-		bool isFunction;
-	};
 	/// Special expression whose address will be used in m_value.
 	/// YulString does not need to be reset because DataFlowAnalyzer is short-lived.
 	Expression const m_zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
-	/// List of scopes.
-	std::vector<Scope> m_variableScopes;
 };
 
 }