From f6eef07d37f9e23860e731f7997788aa6e928d42 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Mon, 13 Oct 2014 12:33:41 +0200
Subject: [PATCH] Use external counter for gas (external linkage global
 variable)

[#79942174]
---
 evmcc/ExecutionEngine.cpp |  4 +++-
 evmcc/Ext.cpp             |  6 ------
 evmcc/GasMeter.cpp        |  2 +-
 evmcc/Memory.cpp          |  6 ------
 evmcc/Runtime.cpp         | 12 ++++++++++--
 evmcc/Runtime.h           | 10 +++++++++-
 6 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/evmcc/ExecutionEngine.cpp b/evmcc/ExecutionEngine.cpp
index 6d9d85a4c..be45ff838 100644
--- a/evmcc/ExecutionEngine.cpp
+++ b/evmcc/ExecutionEngine.cpp
@@ -85,7 +85,8 @@ int ExecutionEngine::run(std::unique_ptr<llvm::Module> _module)
 	ext->data = calldata;
 
 	// Init runtime
-	Runtime runtime(std::move(ext));
+	uint64_t gas = 1000000;
+	Runtime runtime(gas, std::move(ext));
 
 	auto entryFunc = module->getFunction("main");
 	if (!entryFunc)
@@ -95,6 +96,7 @@ int ExecutionEngine::run(std::unique_ptr<llvm::Module> _module)
 	}
 
 	auto result = exec->runFunction(entryFunc, {});
+	gas = static_cast<decltype(gas)>(Runtime::getGas());
 	if (auto intResult = result.IntVal.getZExtValue())
 	{
 		auto index = intResult >> 32;
diff --git a/evmcc/Ext.cpp b/evmcc/Ext.cpp
index 121103354..1d309947d 100644
--- a/evmcc/Ext.cpp
+++ b/evmcc/Ext.cpp
@@ -9,12 +9,6 @@
 
 #include "Runtime.h"
 
-#ifdef _MSC_VER
-#define EXPORT __declspec(dllexport)
-#else
-#define EXPORT
-#endif
-
 using namespace llvm;
 using llvm::types::i;
 using Linkage = llvm::GlobalValue::LinkageTypes;
diff --git a/evmcc/GasMeter.cpp b/evmcc/GasMeter.cpp
index 26921dee3..fd68b9d40 100644
--- a/evmcc/GasMeter.cpp
+++ b/evmcc/GasMeter.cpp
@@ -81,7 +81,7 @@ bool isCostBlockEnd(Instruction _inst)
 GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
 	m_builder(_builder)
 {
-	m_gas = new llvm::GlobalVariable(*_module, Type::i256, false, llvm::GlobalVariable::PrivateLinkage, llvm::UndefValue::get(Type::i256), "gas");
+	m_gas = new llvm::GlobalVariable(*_module, Type::i256, false, llvm::GlobalVariable::ExternalLinkage, nullptr, "gas");
 	m_gas->setUnnamedAddr(true); // Address is not important
 
 	auto pt = m_builder.GetInsertPoint();
diff --git a/evmcc/Memory.cpp b/evmcc/Memory.cpp
index fa21237b7..8625d7b5b 100644
--- a/evmcc/Memory.cpp
+++ b/evmcc/Memory.cpp
@@ -15,12 +15,6 @@
 #include "Runtime.h"
 #include "GasMeter.h"
 
-#ifdef _MSC_VER
-	#define EXPORT __declspec(dllexport)
-#else
-	#define EXPORT
-#endif
-
 namespace evmcc
 {
 
diff --git a/evmcc/Runtime.cpp b/evmcc/Runtime.cpp
index 9d0738f05..a373d9501 100644
--- a/evmcc/Runtime.cpp
+++ b/evmcc/Runtime.cpp
@@ -6,11 +6,14 @@ namespace evmcc
 
 static Runtime* g_runtime;
 
-Runtime::Runtime(std::unique_ptr<dev::eth::ExtVMFace> _ext)
-	: m_ext(std::move(_ext))
+extern "C" { EXPORT i256 gas; }
+
+Runtime::Runtime(dev::u256 _gas, std::unique_ptr<dev::eth::ExtVMFace> _ext):
+	m_ext(std::move(_ext))
 {
 	assert(!g_runtime);
 	g_runtime = this;
+	gas = eth2llvm(_gas);
 }
 
 Runtime::~Runtime()
@@ -33,4 +36,9 @@ dev::eth::ExtVMFace& Runtime::getExt()
 	return *g_runtime->m_ext;
 }
 
+dev::u256 Runtime::getGas()
+{
+	return llvm2eth(gas);
+}
+
 }
\ No newline at end of file
diff --git a/evmcc/Runtime.h b/evmcc/Runtime.h
index 71c917b9d..547e4bcf1 100644
--- a/evmcc/Runtime.h
+++ b/evmcc/Runtime.h
@@ -7,6 +7,13 @@
 
 #include "Utils.h"
 
+
+#ifdef _MSC_VER
+	#define EXPORT __declspec(dllexport)
+#else
+	#define EXPORT
+#endif
+
 namespace evmcc
 {
 
@@ -16,7 +23,7 @@ using MemoryImpl = dev::bytes;
 class Runtime
 {
 public:
-	Runtime(std::unique_ptr<dev::eth::ExtVMFace> _ext);
+	Runtime(dev::u256 _gas, std::unique_ptr<dev::eth::ExtVMFace> _ext);
 	~Runtime();
 
 	Runtime(const Runtime&) = delete;
@@ -25,6 +32,7 @@ public:
 	static StackImpl& getStack();
 	static MemoryImpl& getMemory();
 	static dev::eth::ExtVMFace& getExt();
+	static dev::u256 getGas();
 
 private:
 	StackImpl m_stack;