1 files changed, 120 insertions, 12 deletions

diff --git a/GasMeter.cpp b/GasMeter.cpp
index e5fb0e09..a8dc4dd5 100644
--- a/GasMeter.cpp
+++ b/GasMeter.cpp
@@ -20,6 +20,7 @@
  */
 
 #include "GasMeter.h"
+#include <libevmasm/KnownState.h>
 #include <libevmcore/Params.h>
 
 using namespace std;
@@ -41,55 +42,162 @@ GasMeter::GasConsumption& GasMeter::GasConsumption::operator+=(GasConsumption co
 
 GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item)
 {
-	switch (_item.type()) {
+	GasConsumption gas;
+	switch (_item.type())
+	{
 	case Push:
 	case PushTag:
-		return runGas(Instruction::PUSH1);
+	case PushData:
+	case PushString:
+	case PushSub:
+	case PushSubSize:
+	case PushProgramSize:
+		gas = runGas(Instruction::PUSH1);
+		break;
 	case Tag:
-		return runGas(Instruction::JUMPDEST);
+		gas = runGas(Instruction::JUMPDEST);
+		break;
 	case Operation:
 	{
-		GasConsumption gas = runGas(_item.instruction());
+		ExpressionClasses& classes = m_state->expressionClasses();
+		gas = runGas(_item.instruction());
 		switch (_item.instruction())
 		{
 		case Instruction::SSTORE:
-			// @todo logic can be improved
-			gas += c_sstoreSetGas;
+		{
+			ExpressionClasses::Id slot = m_state->relativeStackElement(0);
+			ExpressionClasses::Id value = m_state->relativeStackElement(-1);
+			if (classes.knownZero(value) || (
+				m_state->storageContent().count(slot) &&
+				classes.knownNonZero(m_state->storageContent().at(slot))
+			))
+				gas += c_sstoreResetGas; //@todo take refunds into account
+			else
+				gas += c_sstoreSetGas;
 			break;
+		}
 		case Instruction::SLOAD:
 			gas += c_sloadGas;
 			break;
+		case Instruction::RETURN:
+			gas += memoryGas(0, -1);
+			break;
+		case Instruction::MLOAD:
 		case Instruction::MSTORE:
+			gas += memoryGas(classes.find(eth::Instruction::ADD, {
+				m_state->relativeStackElement(0),
+				classes.find(AssemblyItem(32))
+			}));
+			break;
 		case Instruction::MSTORE8:
-		case Instruction::MLOAD:
-		case Instruction::RETURN:
+			gas += memoryGas(classes.find(eth::Instruction::ADD, {
+				m_state->relativeStackElement(0),
+				classes.find(AssemblyItem(1))
+			}));
+			break;
 		case Instruction::SHA3:
+			gas = c_sha3Gas;
+			gas += wordGas(c_sha3WordGas, m_state->relativeStackElement(-1));
+			gas += memoryGas(0, -1);
+			break;
 		case Instruction::CALLDATACOPY:
 		case Instruction::CODECOPY:
+			gas += memoryGas(0, -2);
+			gas += wordGas(c_copyGas, m_state->relativeStackElement(-2));
+			break;
 		case Instruction::EXTCODECOPY:
+			gas += memoryGas(-1, -3);
+			gas += wordGas(c_copyGas, m_state->relativeStackElement(-3));
+			break;
 		case Instruction::LOG0:
 		case Instruction::LOG1:
 		case Instruction::LOG2:
 		case Instruction::LOG3:
 		case Instruction::LOG4:
+		{
+			unsigned n = unsigned(_item.instruction()) - unsigned(Instruction::LOG0);
+			gas = c_logGas + c_logTopicGas * n;
+			gas += memoryGas(0, -1);
+			if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(-1)))
+				gas += c_logDataGas * (*value);
+			else
+				gas = GasConsumption::infinite();
+			break;
+		}
 		case Instruction::CALL:
 		case Instruction::CALLCODE:
+			gas = c_callGas;
+			if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(0)))
+				gas += (*value);
+			else
+				gas = GasConsumption::infinite();
+			if (_item.instruction() != Instruction::CALLCODE)
+				gas += c_callNewAccountGas; // We very rarely know whether the address exists.
+			if (!classes.knownZero(m_state->relativeStackElement(-2)))
+				gas += c_callValueTransferGas;
+			gas += memoryGas(-3, -4);
+			gas += memoryGas(-5, -6);
+			break;
 		case Instruction::CREATE:
+			gas = c_createGas;
+			gas += memoryGas(-1, -2);
+			break;
 		case Instruction::EXP:
-			// @todo logic can be improved
-			gas = GasConsumption::infinite();
+			gas = c_expGas;
+			if (u256 const* value = classes.knownConstant(m_state->relativeStackElement(-1)))
+				gas += c_expByteGas * (32 - (h256(*value).firstBitSet() / 8));
+			else
+				gas = GasConsumption::infinite();
 			break;
 		default:
 			break;
 		}
-		return gas;
 		break;
 	}
 	default:
+		gas = GasConsumption::infinite();
 		break;
 	}
 
-	return GasConsumption::infinite();
+	m_state->feedItem(_item);
+	return gas;
+}
+
+GasMeter::GasConsumption GasMeter::wordGas(u256 const& _multiplier, ExpressionClasses::Id _position)
+{
+	u256 const* value = m_state->expressionClasses().knownConstant(_position);
+	if (!value)
+		return GasConsumption::infinite();
+	return GasConsumption(_multiplier * ((*value + 31) / 32));
+}
+
+GasMeter::GasConsumption GasMeter::memoryGas(ExpressionClasses::Id _position)
+{
+	u256 const* value = m_state->expressionClasses().knownConstant(_position);
+	if (!value)
+		return GasConsumption::infinite();
+	if (*value < m_largestMemoryAccess)
+		return GasConsumption(u256(0));
+	u256 previous = m_largestMemoryAccess;
+	m_largestMemoryAccess = *value;
+	auto memGas = [](u256 const& pos) -> u256
+	{
+		u256 size = (pos + 31) / 32;
+		return c_memoryGas * size + size * size / c_quadCoeffDiv;
+	};
+	return memGas(*value) - memGas(previous);
+}
+
+GasMeter::GasConsumption GasMeter::memoryGas(int _stackPosOffset, int _stackPosSize)
+{
+	ExpressionClasses& classes = m_state->expressionClasses();
+	if (classes.knownZero(m_state->relativeStackElement(_stackPosSize)))
+		return GasConsumption(0);
+	else
+		return memoryGas(classes.find(eth::Instruction::ADD, {
+			m_state->relativeStackElement(_stackPosOffset),
+			m_state->relativeStackElement(_stackPosSize)
+		}));
 }
 
 GasMeter::GasConsumption GasMeter::runGas(Instruction _instruction)