From 3beeb4226e075b4f2a83619f41e1cf6ea552a417 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Wed, 15 Oct 2014 17:31:36 +0200
Subject: [PATCH] Some changes about final/stop block

---
 evmcc/Compiler.cpp | 15 +++++----------
 evmcc/Compiler.h   | 13 +++----------
 2 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/evmcc/Compiler.cpp b/evmcc/Compiler.cpp
index 5d474a0a8..cc2add6a5 100644
--- a/evmcc/Compiler.cpp
+++ b/evmcc/Compiler.cpp
@@ -24,8 +24,7 @@ namespace jit
 {
 
 Compiler::Compiler()
-	: m_finalBlock(nullptr)
-	, m_badJumpBlock(nullptr)
+	: m_badJumpBlock(nullptr)
 {
 	Type::init(llvm::getGlobalContext());
 }
@@ -125,10 +124,9 @@ void Compiler::createBasicBlocks(const bytes& bytecode)
 		basicBlocks.emplace(std::piecewise_construct, std::forward_as_tuple(beginInstIdx), std::forward_as_tuple(beginInstIdx, endInstIdx, m_mainFunc));
 	}
 
-	m_finalBlock = std::make_unique<BasicBlock>("FinalBlock", m_mainFunc);
+	m_stopBB = llvm::BasicBlock::Create(m_mainFunc->getContext(), "Stop", m_mainFunc);
 	m_badJumpBlock = std::make_unique<BasicBlock>("BadJumpBlock", m_mainFunc);
 	m_jumpTableBlock = std::make_unique<BasicBlock>("JumpTableBlock", m_mainFunc);
-	m_outOfGasBlock = std::make_unique<BasicBlock>("OutOfGas", m_mainFunc);
 
 	for (auto it = directJumpTargets.cbegin(); it != directJumpTargets.cend(); ++it)
 	{
@@ -830,8 +828,8 @@ std::unique_ptr<llvm::Module> Compiler::compile(const bytes& bytecode)
 		{
 			if (basicBlock.end() == bytecode.size())
 			{
-				//	Branch from the last regular block to the final block.
-				builder.CreateBr(m_finalBlock->llvm());
+				// Return STOP code
+				builder.CreateRet(Constant::get(ReturnCode::Stop));
 			}
 			else
 			{
@@ -848,15 +846,12 @@ std::unique_ptr<llvm::Module> Compiler::compile(const bytes& bytecode)
 	// TODO: move to separate function.
 	// Note: Right now the codegen for special blocks depends only on createBasicBlock(),
 	// not on the codegen for 'regular' blocks. But it has to be done before linkBasicBlocks().
-	builder.SetInsertPoint(m_finalBlock->llvm());
+	builder.SetInsertPoint(m_stopBB);
 	builder.CreateRet(Constant::get(ReturnCode::Stop));
 
 	builder.SetInsertPoint(m_badJumpBlock->llvm());
 	builder.CreateRet(Constant::get(ReturnCode::BadJumpDestination));
 
-	builder.SetInsertPoint(m_outOfGasBlock->llvm());
-	builder.CreateRet(Constant::get(ReturnCode::OutOfGas));
-
 	builder.SetInsertPoint(m_jumpTableBlock->llvm());
 	if (m_indirectJumpTargets.size() > 0)
 	{
diff --git a/evmcc/Compiler.h b/evmcc/Compiler.h
index 62337d2de..44eeebae4 100644
--- a/evmcc/Compiler.h
+++ b/evmcc/Compiler.h
@@ -31,7 +31,7 @@ private:
 	void linkBasicBlocks();
 
 	/**
-	 *  Maps a program counter pc to a basic block which starts at pc (if any).
+	 *  Maps a program counter pc to a basic block that starts at pc (if any).
 	 */
 	std::map<ProgramCounter, BasicBlock> basicBlocks;
 
@@ -45,13 +45,8 @@ private:
 	 */
 	std::vector<BasicBlock*> m_indirectJumpTargets;
 
-	/// Collection of basic blocks in program
-	//std::vector<BasicBlock> m_basicBlocks;
-
-	/**
-	 *  Final block for normal (non-exceptional) execution.
-	 */
-	std::unique_ptr<BasicBlock> m_finalBlock;
+	/// Stop basic block - terminates execution with STOP code (0)
+	llvm::BasicBlock* m_stopBB = nullptr;
 
 	/**
 	 *  Block with a jump table.
@@ -63,8 +58,6 @@ private:
 	 */
 	std::unique_ptr<BasicBlock> m_badJumpBlock;
 
-	std::unique_ptr<BasicBlock> m_outOfGasBlock;
-
 	/// Main program function
 	llvm::Function* m_mainFunc = nullptr;
 };