From 7b9d4956a52c2e8794ac44d44bb44c9b561652af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Thu, 8 Jan 2015 11:10:10 +0100
Subject: [PATCH] BLOCKHASH instruction

---
 libevmjit-cpp/Env.cpp  | 5 +++++
 libevmjit/Compiler.cpp | 8 ++++++++
 libevmjit/Ext.cpp      | 9 +++++++++
 libevmjit/Ext.h        | 2 ++
 4 files changed, 24 insertions(+)

diff --git a/libevmjit-cpp/Env.cpp b/libevmjit-cpp/Env.cpp
index 4112774eed..9fa15735ef 100644
--- a/libevmjit-cpp/Env.cpp
+++ b/libevmjit-cpp/Env.cpp
@@ -42,6 +42,11 @@ extern "C"
 		*o_value = eth2llvm(u);
 	}
 
+	EXPORT void env_blockhash(ExtVMFace* _env, i256* _number, h256* o_hash)
+	{
+		*o_hash = _env->prevhash(llvm2eth(*_number));
+	}
+
 	EXPORT void env_create(ExtVMFace* _env, i256* io_gas, i256* _endowment, byte* _initBeg, uint64_t _initSize, h256* o_address)
 	{
 		auto endowment = llvm2eth(*_endowment);
diff --git a/libevmjit/Compiler.cpp b/libevmjit/Compiler.cpp
index 6f256a5712..7733321aaa 100644
--- a/libevmjit/Compiler.cpp
+++ b/libevmjit/Compiler.cpp
@@ -645,6 +645,14 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 			break;
 		}
 
+		case Instruction::BLOCKHASH:
+		{
+			auto number = stack.pop();
+			auto hash = _ext.blockhash(number);
+			stack.push(hash);
+			break;
+		}
+
 		case Instruction::BALANCE:
 		{
 			auto address = stack.pop();
diff --git a/libevmjit/Ext.cpp b/libevmjit/Ext.cpp
index f2db32137c..c30b0a1e38 100644
--- a/libevmjit/Ext.cpp
+++ b/libevmjit/Ext.cpp
@@ -45,6 +45,7 @@ std::array<FuncDesc, sizeOf<EnvFunc>::value> const& getEnvFuncDescs()
 		FuncDesc{"env_create", getFunctionType(Type::Void, {Type::EnvPtr, Type::WordPtr, Type::WordPtr, Type::BytePtr, Type::Size, Type::WordPtr})},
 		FuncDesc{"env_call", getFunctionType(Type::Bool, {Type::EnvPtr, Type::WordPtr, Type::WordPtr, Type::WordPtr, Type::BytePtr, Type::Size, Type::BytePtr, Type::Size, Type::WordPtr})},
 		FuncDesc{"env_log", getFunctionType(Type::Void, {Type::EnvPtr, Type::BytePtr, Type::Size, Type::WordPtr, Type::WordPtr, Type::WordPtr, Type::WordPtr})},
+		FuncDesc{"env_blockhash", getFunctionType(Type::Void, {Type::EnvPtr, Type::WordPtr, Type::WordPtr})},
 		FuncDesc{"env_getExtCode", getFunctionType(Type::BytePtr, {Type::EnvPtr, Type::WordPtr, Type::Size->getPointerTo()})},
 		FuncDesc{"ext_calldataload", getFunctionType(Type::Void, {Type::RuntimeDataPtr, Type::WordPtr, Type::WordPtr})},
 	}};
@@ -117,6 +118,14 @@ llvm::Value* Ext::balance(llvm::Value* _address)
 	return m_builder.CreateLoad(ret);
 }
 
+llvm::Value* Ext::blockhash(llvm::Value* _number)
+{
+	auto hash = getArgAlloca();
+	createCall(EnvFunc::blockhash, {getRuntimeManager().getEnvPtr(), byPtr(_number), hash});
+	hash =  m_builder.CreateLoad(hash);
+	return Endianness::toNative(getBuilder(), hash);
+}
+
 llvm::Value* Ext::create(llvm::Value*& _gas, llvm::Value* _endowment, llvm::Value* _initOff, llvm::Value* _initSize)
 {
 	auto gas = byPtr(_gas);
diff --git a/libevmjit/Ext.h b/libevmjit/Ext.h
index 9a9b3548ac..2850be072b 100644
--- a/libevmjit/Ext.h
+++ b/libevmjit/Ext.h
@@ -33,6 +33,7 @@ enum class EnvFunc
 	create,
 	call,
 	log,
+	blockhash,
 	getExtCode,
 	calldataload,  // Helper function, not client Env interface
 
@@ -51,6 +52,7 @@ public:
 	llvm::Value* calldataload(llvm::Value* _index);
 	llvm::Value* create(llvm::Value*& _gas, llvm::Value* _endowment, llvm::Value* _initOff, llvm::Value* _initSize);
 	llvm::Value* call(llvm::Value*& _gas, llvm::Value* _receiveAddress, llvm::Value* _value, llvm::Value* _inOff, llvm::Value* _inSize, llvm::Value* _outOff, llvm::Value* _outSize, llvm::Value* _codeAddress);
+	llvm::Value* blockhash(llvm::Value* _number);
 
 	llvm::Value* sha3(llvm::Value* _inOff, llvm::Value* _inSize);
 	MemoryRef getExtCode(llvm::Value* _addr);