From 5a15a4a6bd44252dec9081e30e4181aa56ed667c Mon Sep 17 00:00:00 2001
From: hrkrshnn <webmail.hari@gmail.com>
Date: Thu, 26 Nov 2020 20:10:05 +0100
Subject: [PATCH] Fix a bug in NameSimplifier.

A new name created by NameSimplifier could also be created by NameDispenser, since the knowledge of
the new name was not stored in NameSimplifier.
---
 Changelog.md                        |  2 ++
 libyul/optimiser/NameSimplifier.cpp | 30 +++++++++++++----------------
 libyul/optimiser/NameSimplifier.h   |  8 ++------
 3 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index 0851a79d2..90f20f4ba 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -12,6 +12,8 @@ Compiler Features:
 
 Bugfixes:
  * SMTChecker: Fix internal compiler error when doing bitwise compound assignment with string literals.
+ * Yul Optimizer: Fix a bug in NameSimplifier where a new name created by NameSimplifier could also be created by NameDispenser.
+ * Yul Optimizer: Removed NameSimplifier from optimization steps available to users.
 
 ### 0.7.5 (2020-11-18)
 
diff --git a/libyul/optimiser/NameSimplifier.cpp b/libyul/optimiser/NameSimplifier.cpp
index 2e1bb822a..9054a9c39 100644
--- a/libyul/optimiser/NameSimplifier.cpp
+++ b/libyul/optimiser/NameSimplifier.cpp
@@ -19,6 +19,8 @@
 #include <libyul/optimiser/NameCollector.h>
 #include <libyul/AsmData.h>
 #include <libyul/Dialect.h>
+#include <libyul/YulString.h>
+#include <libyul/optimiser/NameDispenser.h>
 #include <libyul/optimiser/OptimizerUtilities.h>
 
 #include <libsolutil/CommonData.h>
@@ -28,19 +30,13 @@
 using namespace solidity::yul;
 using namespace std;
 
-NameSimplifier::NameSimplifier(
-	OptimiserStepContext& _context,
-	Block const& _ast
-):
-	m_context(_context),
-	m_usedNames(_context.reservedIdentifiers)
+NameSimplifier::NameSimplifier(OptimiserStepContext& _context, Block const& _ast):
+	m_context(_context)
 {
-	for (YulString name: m_usedNames)
+	for (YulString name: _context.reservedIdentifiers)
 		m_translations[name] = name;
 
-	set<YulString> allNames = NameCollector(_ast).names();
-	m_usedNames += allNames;
-	for (YulString name: allNames)
+	for (YulString const& name: NameCollector(_ast).names())
 		findSimplification(name);
 }
 
@@ -77,7 +73,7 @@ void NameSimplifier::operator()(FunctionCall& _funCall)
 	ASTModifier::operator()(_funCall);
 }
 
-void NameSimplifier::findSimplification(YulString _name)
+void NameSimplifier::findSimplification(YulString const& _name)
 {
 	if (m_translations.count(_name))
 		return;
@@ -98,19 +94,19 @@ void NameSimplifier::findSimplification(YulString _name)
 		{regex("index_access_t_array"), "index_access"},
 		{regex("[0-9]*_$"), ""}
 	};
+
 	for (auto const& [pattern, substitute]: replacements)
 	{
 		string candidate = regex_replace(name, pattern, substitute);
-		if (
-			!isRestrictedIdentifier(m_context.dialect, YulString(candidate)) &&
-			!m_usedNames.count(YulString(candidate))
-		)
+		if (!m_context.dispenser.illegalName(YulString(candidate)))
 			name = candidate;
 	}
+
 	if (name != _name.str())
 	{
-		m_usedNames.insert(YulString(name));
-		m_translations[_name] = YulString(name);
+		YulString newName{name};
+		m_context.dispenser.markUsed(newName);
+		m_translations[_name] = move(newName);
 	}
 }
 
diff --git a/libyul/optimiser/NameSimplifier.h b/libyul/optimiser/NameSimplifier.h
index 924e734f9..593a3bf5c 100644
--- a/libyul/optimiser/NameSimplifier.h
+++ b/libyul/optimiser/NameSimplifier.h
@@ -57,19 +57,15 @@ public:
 	void operator()(FunctionDefinition& _funDef) override;
 
 private:
-	NameSimplifier(
-		OptimiserStepContext& _context,
-		Block const& _ast
-	);
+	NameSimplifier(OptimiserStepContext& _context, Block const& _ast);
 
 	/// Tries to rename a list of variables.
 	void renameVariables(std::vector<TypedName>& _variables);
 
-	void findSimplification(YulString _name);
+	void findSimplification(YulString const& _name);
 	void translate(YulString& _name);
 
 	OptimiserStepContext& m_context;
-	std::set<YulString> m_usedNames;
 	std::map<YulString, YulString> m_translations;
 };