From f34340d4c1c89ad92d8bbf88881f3b73aa0ab564 Mon Sep 17 00:00:00 2001
From: artur-zawlocki <artur.zawlocki@gmail.com>
Date: Fri, 3 Oct 2014 11:30:15 +0200
Subject: [PATCH] - fixes for RETURN and STOP - codegen for SLT, SGT, EQ and
 NEG

---
 evmcc/Compiler.cpp         | 83 +++++++++++++++++++++++++++++---------
 evmcc/bytecode/return1.evm |  1 +
 evmcc/lll/return1.lll      |  6 +++
 3 files changed, 71 insertions(+), 19 deletions(-)
 create mode 100644 evmcc/bytecode/return1.evm
 create mode 100644 evmcc/lll/return1.lll

diff --git a/evmcc/Compiler.cpp b/evmcc/Compiler.cpp
index 4b22c0241..796db093e 100644
--- a/evmcc/Compiler.cpp
+++ b/evmcc/Compiler.cpp
@@ -61,6 +61,7 @@ llvm::BasicBlock* Compiler::getOrCreateBasicBlockAtPC(ProgramCounter pc)
 void Compiler::createBasicBlocks(const dev::bytes& bytecode)
 {
 	getOrCreateBasicBlockAtPC(0);
+	getOrCreateBasicBlockAtPC(bytecode.size());
 
 	for (auto curr = bytecode.cbegin(); curr != bytecode.cend(); ++curr)
 	{
@@ -147,6 +148,18 @@ void Compiler::createBasicBlocks(const dev::bytes& bytecode)
 			std::exit(1);
 		}
 
+		case Instruction::RETURN:
+		case Instruction::STOP:
+		{
+			// Create a basic block starting at the following instruction.
+			if (curr + 1 < bytecode.cend())
+			{
+				ProgramCounter nextPC = (curr + 1 - bytecode.cbegin());
+				getOrCreateBasicBlockAtPC(nextPC);
+			}
+			break;
+		}
+
 		default:
 			break;
 		}
@@ -178,12 +191,9 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 	auto memory = Memory(builder, module.get());
 	auto ext = Ext(builder, module.get());
 
-	auto userRet = false;
-	auto finished = false;
-
 	BasicBlock* currentBlock = entryBlock;
 
-	for (auto pc = bytecode.cbegin(); pc != bytecode.cend() && !finished; ++pc)
+	for (auto pc = bytecode.cbegin(); pc != bytecode.cend(); ++pc)
 	{
 		using dev::eth::Instruction;
 
@@ -286,6 +296,15 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 			break;
 		}
 
+		case Instruction::NEG:
+		{
+			auto top = stack.pop();
+			auto zero = ConstantInt::get(Types.word256, 0);
+			auto res = builder.CreateSub(zero, top);
+			stack.push(res);
+			break;
+		}
+
 		case Instruction::LT:
 		{
 			auto lhs = stack.pop();
@@ -306,6 +325,36 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 			break;
 		}
 
+		case Instruction::SLT:
+		{
+			auto lhs = stack.pop();
+			auto rhs = stack.pop();
+			auto res1 = builder.CreateICmpSLT(lhs, rhs);
+			auto res256 = builder.CreateZExt(res1, Types.word256);
+			stack.push(res256);
+			break;
+		}
+
+		case Instruction::SGT:
+		{
+			auto lhs = stack.pop();
+			auto rhs = stack.pop();
+			auto res1 = builder.CreateICmpSGT(lhs, rhs);
+			auto res256 = builder.CreateZExt(res1, Types.word256);
+			stack.push(res256);
+			break;
+		}
+
+		case Instruction::EQ:
+		{
+			auto lhs = stack.pop();
+			auto rhs = stack.pop();
+			auto res1 = builder.CreateICmpEQ(lhs, rhs);
+			auto res256 = builder.CreateZExt(res1, Types.word256);
+			stack.push(res256);
+			break;
+		}
+
 		case Instruction::NOT:
 		{
 			auto top = stack.pop();
@@ -682,36 +731,32 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 			ret = builder.CreateOr(ret, size);
 
 			builder.CreateRet(ret);
-			finished = true;
-			userRet = true;
+			currentBlock = nullptr;
 			break;
 		}
 
 		case Instruction::STOP:
 		{
-			finished = true;
+			builder.CreateRet(builder.getInt64(0));
+			currentBlock = nullptr;
 			break;
 		}
 
 		}
 	}
 
-	// Generate final basic block (may be jumped to).
+	// Generate the final basic block.
 	auto finalPC = bytecode.size();
 	auto it = basicBlocks.find(finalPC);
-	if (it != basicBlocks.end())
-	{
-		auto finalBlock = it->second;
+	assert(it != basicBlocks.end());
+	auto finalBlock = it->second;
 
-		if (currentBlock != nullptr)
-			builder.CreateBr(finalBlock);
-
-		mainFunc->getBasicBlockList().push_back(finalBlock);
-		builder.SetInsertPoint(finalBlock);
-	}
+	if (currentBlock != nullptr)
+		builder.CreateBr(finalBlock);
 
-	if (!userRet)
-		builder.CreateRet(builder.getInt64(0));
+	mainFunc->getBasicBlockList().push_back(finalBlock);
+	builder.SetInsertPoint(finalBlock);
+	builder.CreateRet(builder.getInt64(0));
 
 	return module;
 }
diff --git a/evmcc/bytecode/return1.evm b/evmcc/bytecode/return1.evm
new file mode 100644
index 000000000..8092cb007
--- /dev/null
+++ b/evmcc/bytecode/return1.evm
@@ -0,0 +1 @@
+600160805460006080530b601b59600160005460206000f2602a58602760005460206000f26002608054
diff --git a/evmcc/lll/return1.lll b/evmcc/lll/return1.lll
new file mode 100644
index 000000000..159d15ca3
--- /dev/null
+++ b/evmcc/lll/return1.lll
@@ -0,0 +1,6 @@
+;; code should return 39
+;; i should remain 1
+{
+  [i] 1
+  ( if (> @i 0) { (return 39) [i] 2 } (return 1) )
+}
\ No newline at end of file