From cfb226ba5f2562ad65450e441668d38c5f5c6fa2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Fri, 10 Oct 2014 14:12:38 +0200
Subject: [PATCH] Group gas counting into block of instructions called
 cost-block.

[#79942174]
---
 evmcc/Compiler.cpp |  3 +--
 evmcc/GasMeter.cpp | 41 ++++++++++++++++++++++++++++++++++++++++-
 evmcc/GasMeter.h   |  4 ++++
 3 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/evmcc/Compiler.cpp b/evmcc/Compiler.cpp
index 9a46313b66..0e695df06c 100644
--- a/evmcc/Compiler.cpp
+++ b/evmcc/Compiler.cpp
@@ -178,8 +178,7 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 		{
 			auto inst = static_cast<Instruction>(bytecode[currentPC]);
 
-			// Disable for now
-			//gasMeter.check(inst);
+			gasMeter.check(inst);
 
 			switch (inst)
 			{
diff --git a/evmcc/GasMeter.cpp b/evmcc/GasMeter.cpp
index 2006f319f0..a40b8cb5cc 100644
--- a/evmcc/GasMeter.cpp
+++ b/evmcc/GasMeter.cpp
@@ -49,6 +49,33 @@ uint64_t getStepCost(dev::eth::Instruction inst) // TODO: Add this function to F
 	}
 }
 
+bool isCommitTrigger(Instruction _inst)
+{
+	switch (_inst)
+	{
+	case Instruction::STOP:
+	case Instruction::CALLDATACOPY:
+	case Instruction::CODECOPY:
+	case Instruction::MLOAD:
+	case Instruction::MSTORE:
+	case Instruction::MSTORE8:
+	case Instruction::SSTORE:
+	case Instruction::JUMP:
+	case Instruction::JUMPI:
+	case Instruction::JUMPDEST:
+	case Instruction::GAS:
+	case Instruction::CREATE:
+	case Instruction::CALL:
+	case Instruction::CALLCODE:
+	case Instruction::RETURN:
+	case Instruction::SUICIDE:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 }
 
 GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
@@ -72,8 +99,20 @@ GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
 
 void GasMeter::check(Instruction _inst)
 {
+	if (!m_checkCall)
+	{
+		m_checkCall = m_builder.CreateCall(m_gasCheckFunc, m_builder.getIntN(256, 0));
+	}
+	
 	auto stepCost = getStepCost(_inst);
-	m_builder.CreateCall(m_gasCheckFunc, m_builder.getIntN(256, stepCost));
+	m_blockCost += stepCost;
+
+	auto isTrigger = isCommitTrigger(_inst);
+	if (isTrigger)
+	{
+		m_checkCall->setArgOperand(0, m_builder.getIntN(256, m_blockCost));
+		m_checkCall = nullptr;
+	}	
 }
 
 }
\ No newline at end of file
diff --git a/evmcc/GasMeter.h b/evmcc/GasMeter.h
index e2ee26a716..057391102c 100644
--- a/evmcc/GasMeter.h
+++ b/evmcc/GasMeter.h
@@ -19,7 +19,11 @@ public:
 	void check(dev::eth::Instruction _inst);
 
 private:
+	/// Cumulative gas cost of a block of instructions
+	/// @TODO Handle overflow
+	uint64_t m_blockCost = 0;
 	llvm::IRBuilder<>& m_builder;
+	llvm::CallInst* m_checkCall;
 	llvm::GlobalVariable* m_gas;
 	llvm::Function* m_gasCheckFunc;
 };