Eliminate dead instructions replaced in AP arithmetic lowering.

evmjit/libevmjit/Optimizer.cpp

@@ -54,27 +54,32 @@ bool LowerEVMPass::runOnBasicBlock(llvm::BasicBlock& _bb)
 {
 	auto modified = false;
 	auto module = _bb.getParent()->getParent();
-	for (auto&& inst : _bb)
-	{
-		if (inst.getOpcode() == llvm::Instruction::Mul)
+	for (auto it = _bb.begin(); it != _bb.end(); )
 	{
+		auto& inst = *it++;
+		llvm::Function* func = nullptr;
 		if (inst.getType() == Type::Word)
 		{
-				auto call = llvm::CallInst::Create(Arith256::getMulFunc(*module), {inst.getOperand(0), inst.getOperand(1)}, "", &inst);
-				inst.replaceAllUsesWith(call);
-				modified = true;
+			switch (inst.getOpcode())
+			{
+			case llvm::Instruction::Mul:
+				func = Arith256::getMulFunc(*module);
+				break;
+
+			case llvm::Instruction::UDiv:
+				func = Arith256::getUDiv256Func(*module);
+				break;
 			}
 		}
-		else if (inst.getOpcode() == llvm::Instruction::UDiv)
-		{
-			if (inst.getType() == Type::Word)
+
+		if (func)
 		{
-				auto call = llvm::CallInst::Create(Arith256::getUDiv256Func(*module), {inst.getOperand(0), inst.getOperand(1)}, "", &inst);
+			auto call = llvm::CallInst::Create(func, {inst.getOperand(0), inst.getOperand(1)}, "", &inst);
 			inst.replaceAllUsesWith(call);
+			inst.eraseFromParent();
 			modified = true;
 		}
 	}
-	}
 	return modified;
 }
 
@@ -90,7 +95,6 @@ bool prepare(llvm::Module& _module)
 	auto pm = llvm::legacy::PassManager{};
 	pm.add(llvm::createDeadCodeEliminationPass());
 	pm.add(new LowerEVMPass{});
-	pm.add(llvm::createDeadInstEliminationPass()); // Remove leftovers
 	return pm.run(_module);
 }