Improve basic blocks linking implementation

evmcc/BasicBlock.cpp

@@ -6,9 +6,11 @@
 namespace evmcc
 {
 
+const char* BasicBlock::NamePrefix = "Instr.";
+
 BasicBlock::BasicBlock(ProgramCounter _beginInstIdx, llvm::Function* _mainFunc):
 	m_beginInstIdx(_beginInstIdx),
-	m_llvmBB(llvm::BasicBlock::Create(_mainFunc->getContext(), {"Instr.", std::to_string(_beginInstIdx)}, _mainFunc))
+	m_llvmBB(llvm::BasicBlock::Create(_mainFunc->getContext(), {NamePrefix, std::to_string(_beginInstIdx)}, _mainFunc))
 {}
 
 }

evmcc/BasicBlock.h

@@ -13,6 +13,8 @@ class BasicBlock
 public:
 	using State = std::vector<llvm::Value*>;
 
+	static const char* NamePrefix;
+
 	explicit BasicBlock(ProgramCounter _beginInstIdx, llvm::Function* _mainFunc);
 
 	BasicBlock(const BasicBlock&) = delete;

evmcc/Compiler.cpp

@@ -797,14 +797,13 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 void Compiler::linkBasicBlocks()
 {
 	/// Helper function that finds basic block given LLVM basic block pointer
-	auto findBB = [this](llvm::BasicBlock* _llvmBB)
+	auto findBasicBlock = [this](llvm::BasicBlock* _llbb) -> BasicBlock&
 	{
-		for (auto&& bb : basicBlocks)
+		// Name is used to get basic block index (index of first instruction)
-		{
+		// TODO: If basicBlocs are still a map - multikey map can be used
-			if (bb.second.llvm() == _llvmBB)
+		auto&& idxStr = _llbb->getName().substr(sizeof(BasicBlock::NamePrefix) - 2);
-				return &bb.second;
+		auto idx = std::stoul(idxStr);
-		}
+		return basicBlocks.find(idx)->second;
-		return (BasicBlock*)nullptr;
 	};
 
 	// Link basic blocks
@@ -813,19 +812,16 @@ void Compiler::linkBasicBlocks()
 		BasicBlock& bb = p.second;
 		llvm::BasicBlock* llvmBB = bb.llvm();
 
-		size_t i = 0;
+		size_t valueIdx = 0;
-		for (auto& inst : *llvmBB)
+		auto firstNonPhi = llvmBB->getFirstNonPHI();
+		for (auto instIt = llvmBB->begin(); &*instIt != firstNonPhi; ++instIt, ++valueIdx)
 		{
-			if (auto phi = llvm::dyn_cast<llvm::PHINode>(&inst))
+			auto phi = llvm::cast<llvm::PHINode>(instIt);
+			for (auto predIt = llvm::pred_begin(llvmBB); predIt != llvm::pred_end(llvmBB); ++predIt)
 			{
-				for (auto preIt = llvm::pred_begin(llvmBB); preIt != llvm::pred_end(llvmBB); ++preIt)
+				auto& predBB = findBasicBlock(*predIt);
-				{
+				assert(valueIdx < predBB.getState().size()); // TODO: Report error
-					llvm::BasicBlock* preBB = *preIt;
+				phi->addIncoming(*(predBB.getState().rbegin() + valueIdx), predBB);
-					auto pbb = findBB(preBB);
-					assert(i < pbb->getState().size()); // TODO: Report error
-					phi->addIncoming(*(pbb->getState().rbegin() + i), preBB);
-				}
-				++i;
 			}
 		}
 	}

evmcc/Stack.cpp

@@ -23,7 +23,7 @@ llvm::Value* BBStack::pop()
 		// Create PHI node
 		auto i256Ty = llvm::Type::getIntNTy(m_block->llvm()->getContext(), 256);
 		auto llvmBB = m_block->llvm();
-		if (llvmBB->getInstList().empty())
+		if (llvmBB->empty())
 			return llvm::PHINode::Create(i256Ty, 0, {}, m_block->llvm());
 		return llvm::PHINode::Create(i256Ty, 0, {}, llvmBB->getFirstNonPHI());
 	}