Merge pull request #6437 from ethereum/add-scoped-vars

Reference only those variables that are in scope.

test/tools/ossfuzz/protoToYul.cpp

@@ -69,10 +69,10 @@ void ProtoConverter::visit(Literal const& _x)
 	}
 }
 
-// We only reference x_0...x_9 that are I/O params of hardcoded function "foo"
+// Reference any index in [0, m_numLiveVars-1] or [0, m_numLiveVars)
 void ProtoConverter::visit(VarRef const& _x)
 {
-	m_output  << "x_" << (static_cast<uint32_t>(_x.varnum()) % 10);
+	m_output  << "x_" << (static_cast<uint32_t>(_x.varnum()) % m_numLiveVars);
 }
 
 void ProtoConverter::visit(Expression const& _x)
@@ -175,17 +175,19 @@ void ProtoConverter::visit(BinaryOp const& _x)
 	m_output << ")";
 }
 
-// New var numbering starts from x_10 until x_16
+// New var numbering starts from x_10
 void ProtoConverter::visit(VarDecl const& _x)
 {
-	m_output << "let x_" << ((_x.id() % 7) + 10) << " := ";
+	m_output << "let x_" << m_numLiveVars << " := ";
 	visit(_x.expr());
+	m_numVarsPerScope.top()++;
+	m_numLiveVars++;
 	m_output << "\n";
 }
 
 void ProtoConverter::visit(TypedVarDecl const& _x)
 {
-	m_output << "let x_" << ((_x.id() % 7) + 10);
+	m_output << "let x_" << m_numLiveVars;
 	switch (_x.type())
 	{
 		case TypedVarDecl::BOOL:
@@ -244,6 +246,8 @@ void ProtoConverter::visit(TypedVarDecl const& _x)
 			m_output << " : u256\n";
 			break;
 	}
+	m_numVarsPerScope.top()++;
+	m_numLiveVars++;
 }
 
 void ProtoConverter::visit(UnaryOp const& _x)
@@ -303,8 +307,12 @@ void ProtoConverter::visit(StoreFunc const& _x)
 
 void ProtoConverter::visit(ForStmt const& _x)
 {
-	m_output << "for { let i := 0 } lt(i, 0x100) { i := add(i, 0x20) } ";
+	std::string loopVarName("i_" + std::to_string(m_numNestedForLoops++));
+	m_output << "for { let " << loopVarName << " := 0 } "
+		<< "lt(" << loopVarName << ", 0x60) "
+		<< "{ " << loopVarName << " := add(" << loopVarName << ", 0x20) } ";
 	visit(_x.for_body());
+	--m_numNestedForLoops;
 }
 
 void ProtoConverter::visit(CaseStmt const& _x)
@@ -366,10 +374,13 @@ void ProtoConverter::visit(Block const& _x)
 {
 	if (_x.statements_size() > 0)
 	{
+		m_numVarsPerScope.push(0);
 		m_output << "{\n";
 		for (auto const& st: _x.statements())
 			visit(st);
 		m_output << "}\n";
+		m_numLiveVars -= m_numVarsPerScope.top();
+		m_numVarsPerScope.pop();
 	}
 	else
 		m_output << "{}\n";
@@ -399,4 +410,4 @@ string ProtoConverter::protoToYul(const uint8_t* _data, size_t _size)
 	if (!message.ParsePartialFromArray(_data, _size))
 		return "#error invalid proto\n";
 	return functionToString(message);
-}
+}

test/tools/ossfuzz/protoToYul.h

@@ -20,6 +20,7 @@
 #include <string>
 #include <ostream>
 #include <sstream>
+#include <stack>
 
 #include <test/tools/ossfuzz/yulProto.pb.h>
 
@@ -32,6 +33,15 @@ namespace yul_fuzzer
 class ProtoConverter
 {
 public:
+	ProtoConverter()
+	{
+		// The hard-coded function template foo has 10 parameters that are already "live"
+		m_numLiveVars = 10;
+		m_numVarsPerScope.push(m_numLiveVars);
+		m_numNestedForLoops = 0;
+	}
+	ProtoConverter(ProtoConverter const&) = delete;
+	ProtoConverter(ProtoConverter&&) = delete;
 	std::string functionToString(Function const& _input);
 	std::string protoToYul(uint8_t const* _data, size_t _size);
 
@@ -59,7 +69,10 @@ private:
 	std::string createAlphaNum(std::string const& _strBytes) const;
 
 	std::ostringstream m_output;
+	std::stack<uint8_t> m_numVarsPerScope;
+	int32_t m_numLiveVars;
+	int32_t m_numNestedForLoops;
 };
 }
 }
-}
+}

test/tools/ossfuzz/yulProto.proto

@@ -18,8 +18,7 @@
 syntax = "proto2";
 
 message VarDecl {
-  required int32 id = 1;
-  required Expression expr = 2;
+  required Expression expr = 1;
 }
 
 message TypedVarDecl {

test/tools/ossfuzz/yulProtoFuzzer.cpp

@@ -63,4 +63,4 @@ DEFINE_PROTO_FUZZER(Function const& _input)
 
 	// Optimize
 	stack.optimize();
-}
+}

test/tools/ossfuzz/yulProto_diff_ossfuzz.cpp

@@ -96,4 +96,4 @@ DEFINE_PROTO_FUZZER(Function const& _input)
 	bool isTraceEq = (os1.str() == os2.str());
 	yulAssert(isTraceEq, "Interpreted traces for optimized and unoptimized code differ.");
 	return;
-}
+}