Deprecate Memory::require(size) function. Risk of unsigned integer overflow.

libevmjit/Compiler.cpp

@@ -785,12 +785,9 @@ void Compiler::compileBasicBlock(BasicBlock& basicBlock, bytesConstRef bytecode,
 
 			gasMeter.commitCostBlock(gas);
 
-			// Require memory for the max of in and out buffers
+			// Require memory for in and out buffers
-			auto inSizeReq = m_builder.CreateAdd(inOff, inSize, "inSizeReq");
+			memory.require(outOff, outSize);	// Out buffer first as we guess it will be after the in one
-			auto outSizeReq = m_builder.CreateAdd(outOff, outSize, "outSizeReq");
+			memory.require(inOff, inSize);
-			auto cmp = m_builder.CreateICmpUGT(inSizeReq, outSizeReq);
-			auto sizeReq = m_builder.CreateSelect(cmp, inSizeReq, outSizeReq, "sizeReq");
-			memory.require(sizeReq);
 
 			auto receiveAddress = codeAddress;
 			if (inst == Instruction::CALLCODE)

libevmjit/Memory.cpp

@@ -171,7 +171,7 @@ void Memory::require(llvm::Value* _size)
 
 void Memory::require(llvm::Value* _offset, llvm::Value* _size)
 {
-	auto sizeRequired = m_builder.CreateAdd(_offset, _size, "sizeRequired");
+	auto sizeRequired = m_builder.CreateNUWAdd(_offset, _size, "sizeRequired");
 	require(sizeRequired);
 }
 

libevmjit/Memory.h

@@ -24,9 +24,6 @@ public:
 	void copyBytes(llvm::Value* _srcPtr, llvm::Value* _srcSize, llvm::Value* _srcIndex,
 				   llvm::Value* _destMemIdx, llvm::Value* _byteCount);
 
-	/// Requires this amount of memory. And counts gas fee for that memory.
-	void require(llvm::Value* _size);
-
 	/// Requires the amount of memory to for data defined by offset and size. And counts gas fee for that memory.
 	void require(llvm::Value* _offset, llvm::Value* _size);
 
@@ -36,7 +33,9 @@ private:
 	llvm::Function* createFunc(bool _isStore, llvm::Type* _type, GasMeter& _gasMeter);
 	llvm::Function* createRequireFunc(GasMeter& _gasMeter, RuntimeManager& _runtimeManager);
 
-private:
+	/// Requires this amount of memory. And counts gas fee for that memory.
+	void require(llvm::Value* _size);
+
 	llvm::GlobalVariable* m_data;
 	llvm::GlobalVariable* m_size;