Functional gas estimator.

ASTPrinter.cpp

@@ -33,7 +33,7 @@ namespace solidity
 ASTPrinter::ASTPrinter(
 	ASTNode const& _ast,
 	string const& _source,
-	StructuralGasEstimator::ASTGasConsumption const& _gasCosts
+	GasEstimator::ASTGasConsumption const& _gasCosts
 ): m_indentation(0), m_source(_source), m_ast(&_ast), m_gasCosts(_gasCosts)
 {
 }

ASTPrinter.h

@@ -24,7 +24,7 @@
 
 #include <ostream>
 #include <libsolidity/ASTVisitor.h>
-#include <libsolidity/StructuralGasEstimator.h>
+#include <libsolidity/GasEstimator.h>
 
 namespace dev
 {
@@ -42,7 +42,7 @@ public:
 	ASTPrinter(
 		ASTNode const& _ast,
 		std::string const& _source = std::string(),
-		StructuralGasEstimator::ASTGasConsumption const& _gasCosts = StructuralGasEstimator::ASTGasConsumption()
+		GasEstimator::ASTGasConsumption const& _gasCosts = GasEstimator::ASTGasConsumption()
 	);
 	/// Output the string representation of the AST to _stream.
 	void print(std::ostream& _stream);
@@ -133,7 +133,7 @@ private:
 	int m_indentation;
 	std::string m_source;
 	ASTNode const* m_ast;
-	StructuralGasEstimator::ASTGasConsumption m_gasCosts;
+	GasEstimator::ASTGasConsumption m_gasCosts;
 	std::ostream* m_ostream;
 };
 

GasEstimator.cpp

@@ -20,12 +20,14 @@
  * Gas consumption estimator working alongside the AST.
  */
 
-#include "StructuralGasEstimator.h"
+#include "GasEstimator.h"
 #include <map>
 #include <functional>
 #include <memory>
+#include <libdevcore/SHA3.h>
 #include <libevmasm/ControlFlowGraph.h>
 #include <libevmasm/KnownState.h>
+#include <libevmasm/PathGasMeter.h>
 #include <libsolidity/AST.h>
 #include <libsolidity/ASTVisitor.h>
 
@@ -34,13 +36,13 @@ using namespace dev;
 using namespace dev::eth;
 using namespace dev::solidity;
 
-StructuralGasEstimator::ASTGasConsumptionSelfAccumulated StructuralGasEstimator::performEstimation(
+GasEstimator::ASTGasConsumptionSelfAccumulated GasEstimator::structuralEstimation(
 	AssemblyItems const& _items,
 	vector<ASTNode const*> const& _ast
 )
 {
 	solAssert(std::count(_ast.begin(), _ast.end(), nullptr) == 0, "");
-	map<SourceLocation, GasMeter::GasConsumption> particularCosts;
+	map<SourceLocation, GasConsumption> particularCosts;
 
 	ControlFlowGraph cfg(_items);
 	for (BasicBlock const& block: cfg.optimisedBlocks())
@@ -72,7 +74,7 @@ StructuralGasEstimator::ASTGasConsumptionSelfAccumulated StructuralGasEstimator:
 	return gasCosts;
 }
 
-map<ASTNode const*, GasMeter::GasConsumption> StructuralGasEstimator::breakToStatementLevel(
+map<ASTNode const*, GasMeter::GasConsumption> GasEstimator::breakToStatementLevel(
 	ASTGasConsumptionSelfAccumulated const& _gasCosts,
 	vector<ASTNode const*> const& _roots
 )
@@ -99,7 +101,7 @@ map<ASTNode const*, GasMeter::GasConsumption> StructuralGasEstimator::breakToSta
 	// we use the location of a node if
 	//  - its statement depth is 0 or
 	//  - its statement depth is undefined but the parent's statement depth is at least 1
-	map<ASTNode const*, GasMeter::GasConsumption> gasCosts;
+	map<ASTNode const*, GasConsumption> gasCosts;
 	auto onNodeSecondPass = [&](ASTNode const& _node)
 	{
 		return statementDepth.count(&_node);
@@ -121,7 +123,28 @@ map<ASTNode const*, GasMeter::GasConsumption> StructuralGasEstimator::breakToSta
 	return gasCosts;
 }
 
-set<ASTNode const*> StructuralGasEstimator::finestNodesAtLocation(
+GasEstimator::GasConsumption GasEstimator::functionalEstimation(
+	AssemblyItems const& _items,
+	string const& _signature
+)
+{
+	auto state = make_shared<KnownState>();
+
+	ExpressionClasses& classes = state->expressionClasses();
+	using Id = ExpressionClasses::Id;
+	using Ids = vector<Id>;
+	Id hashValue = classes.find(u256(FixedHash<4>::Arith(FixedHash<4>(dev::sha3(_signature)))));
+	Id calldata = classes.find(eth::Instruction::CALLDATALOAD, Ids{classes.find(u256(0))});
+	classes.forceEqual(hashValue, eth::Instruction::DIV, Ids{
+		calldata,
+		classes.find(u256(1) << (8 * 28))
+	});
+
+	PathGasMeter meter(_items);
+	return meter.estimateMax(0, state);
+}
+
+set<ASTNode const*> GasEstimator::finestNodesAtLocation(
 	vector<ASTNode const*> const& _roots
 )
 {
@@ -140,4 +163,3 @@ set<ASTNode const*> StructuralGasEstimator::finestNodesAtLocation(
 		root->accept(visitor);
 	return nodes;
 }
-

GasEstimator.h

@@ -34,17 +34,18 @@ namespace dev
 namespace solidity
 {
 
-class StructuralGasEstimator
+struct GasEstimator
 {
 public:
-	using ASTGasConsumption = std::map<ASTNode const*, eth::GasMeter::GasConsumption>;
+	using GasConsumption = eth::GasMeter::GasConsumption;
+	using ASTGasConsumption = std::map<ASTNode const*, GasConsumption>;
 	using ASTGasConsumptionSelfAccumulated =
-		std::map<ASTNode const*, std::array<eth::GasMeter::GasConsumption, 2>>;
+		std::map<ASTNode const*, std::array<GasConsumption, 2>>;
 
 	/// Estimates the gas consumption for every assembly item in the given assembly and stores
 	/// it by source location.
 	/// @returns a mapping from each AST node to a pair of its particular and syntactically accumulated gas costs.
-	ASTGasConsumptionSelfAccumulated performEstimation(
+	static ASTGasConsumptionSelfAccumulated structuralEstimation(
 		eth::AssemblyItems const& _items,
 		std::vector<ASTNode const*> const& _ast
 	);
@@ -52,14 +53,21 @@ public:
 	/// the following source locations are part of the mapping:
 	/// 1. source locations of statements that do not contain other statements
 	/// 2. maximal source locations that do not overlap locations coming from the first rule
-	ASTGasConsumption breakToStatementLevel(
+	static ASTGasConsumption breakToStatementLevel(
 		ASTGasConsumptionSelfAccumulated const& _gasCosts,
 		std::vector<ASTNode const*> const& _roots
 	);
 
+	/// @returns the estimated gas consumption by the (public or external) function with the
+	/// given signature. If no signature is given, estimates the maximum gas usage.
+	static GasConsumption functionalEstimation(
+		eth::AssemblyItems const& _items,
+		std::string const& _signature = ""
+	);
+
 private:
 	/// @returns the set of AST nodes which are the finest nodes at their location.
-	std::set<ASTNode const*> finestNodesAtLocation(std::vector<ASTNode const*> const& _roots);
+	static std::set<ASTNode const*> finestNodesAtLocation(std::vector<ASTNode const*> const& _roots);
 };
 
 }