Count gas cost for SSTORE instruction

[#79942174]

evmcc/Compiler.cpp

@@ -609,6 +609,7 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 			{
 				auto index = stack.pop();
 				auto value = stack.pop();
+				gasMeter.countSStore(ext, index, value);
 				ext.setStore(index, value);
 				break;
 			}

evmcc/GasMeter.cpp

@@ -9,6 +9,7 @@
 
 #include "Type.h"
 #include "Utils.h"
+#include "Ext.h"
 
 namespace evmcc
 {
@@ -100,12 +101,34 @@ void GasMeter::count(Instruction _inst)
 		m_checkCall = m_builder.CreateCall(m_gasCheckFunc, llvm::UndefValue::get(Type::i256));
 	}
 	
-	m_blockCost += getStepCost(_inst);
+	if (_inst != Instruction::SSTORE) // Handle cost of SSTORE separately in countSStore()
+		m_blockCost += getStepCost(_inst);
 
 	if (isCostBlockEnd(_inst))
 		commitCostBlock();
 }
 
+void GasMeter::countSStore(Ext& _ext, llvm::Value* _index, llvm::Value* _newValue)
+{
+	assert(!m_checkCall); // Everything should've been commited before
+
+	static const auto sstoreCost = static_cast<uint64_t>(c_sstoreGas);
+
+	// [ADD] if oldValue == 0 and newValue != 0  =>  2*cost
+	// [DEL] if oldValue != 0 and newValue == 0  =>  0
+
+	auto oldValue = _ext.store(_index);
+	auto oldValueIsZero = m_builder.CreateICmpEQ(oldValue, Constant::get(0), "oldValueIsZero");
+	auto newValueIsZero = m_builder.CreateICmpEQ(_newValue, Constant::get(0), "newValueIsZero");
+	auto oldValueIsntZero = m_builder.CreateICmpNE(oldValue, Constant::get(0), "oldValueIsntZero");
+	auto newValueIsntZero = m_builder.CreateICmpNE(_newValue, Constant::get(0), "newValueIsntZero");
+	auto isAdd = m_builder.CreateAnd(oldValueIsZero, newValueIsntZero, "isAdd");
+	auto isDel = m_builder.CreateAnd(oldValueIsntZero, newValueIsZero, "isDel");
+	auto cost = m_builder.CreateSelect(isAdd, Constant::get(2 * sstoreCost), Constant::get(sstoreCost), "cost");
+	cost = m_builder.CreateSelect(isDel, Constant::get(0), cost, "cost");
+	m_builder.CreateCall(m_gasCheckFunc, cost);
+}
+
 void GasMeter::giveBack(llvm::Value* _gas)
 {
 	llvm::Value* gasCounter = m_builder.CreateLoad(m_gas, "gas");

evmcc/GasMeter.h

@@ -19,6 +19,9 @@ public:
 	/// Count step cost of instruction
 	void count(dev::eth::Instruction _inst);
 
+	/// Calculate & count gas cost for SSTORE instruction
+	void countSStore(class Ext& _ext, llvm::Value* _index, llvm::Value* _newValue);
+
 	/// Finalize cost-block by checking gas needed for the block before the block
 	/// @param _additionalCost adds additional cost to cost-block before commit
 	void commitCostBlock(llvm::Value* _additionalCost = nullptr);