Welcome to Coding Ninjas; Today, we are going to discuss a type of compiler called cross compiler. In this article, we will discuss what cross compiler is, why to use it, working of the cross compiler with an example. And We will also discuss the pros and cons of cross-compilers.
Before directly reading the cross compiler, you should read about the compiler; click here.
If you want to see what compilers do practically in a programming language, you should read various types of compilers for C++ here.
What is Cross Compiler?
A cross-compiler is a type of compiler that allows you to write code one platform at a time, and an executable code can be generated for another platform. The cross-compiler can be used to write and test the code on the development system before deploying it to the target hardware.
Let’s understand this by an example:
If a developer wants to develop software for the x86 architecture machine by doing the development in an ARM-based device. In this scenario, Cross Compiler can be used to generate the x86 machine-compatible code on the ARM-based device. Now the generated code can be transferred to the x86 architecture machine for testing and deployment.
Why use Cross Compiler
Here are several reasons to use a cross-compiler:
- Efficient Development: Cross-compilers can be used to develop software efficiently because a developer can code on a development system, and that can be transferred into the target machine.
- Cost Cutting: Using the cross compiler, Developers do not need a high-end system (or system for which the software is being developed). This can affect the cost drastically.
- Code Quality: Cross Compiler helps in improving the code quality as all the analysis and code optimizations are done by the compiler, which is better than the human-typed code.
- Security: The cross compiler can help in improving the security as a developer is writing code on the development machine, so the important directories and files are not exposed to the target machine.
How does cross-compilation work?
Cross-compilation involves the process of compiling code on one system (the host) to create executable code that can run on a different system (the target). It works as follows:
- Source Code Preparation: Developers write code on the host using specific languages and libraries
- Compiler Selection: Choose a cross-compiler for the target's architecture
- Compilation: Cross-compiler translates source code into target-compatible machine code
- Linking: Link compiled code with target libraries for proper interaction
- Executable Generation: Cross-compiler produces binary for the target system
- Deployment: Transfer binary to target through various means
- Execution: Run binary on the target system for the intended application
Working of Cross Compiler
In order to understand the working of the cross compiler, we need to understand the concept of bootstrapping. Bootstrapping is the main process that is involved in the working of the cross-compiler.
Bootstrapping is a process by which a particular language is used to translate a more complicated program, which in turn may handle an even more compilated program. Theoretically, T-Diagram is a diagram used for the representation of cross compiler. Here’s an example of a T-Diagram:
If a developer is writing a code ‘S’ on a development system and ‘I’ is the language that will convert or translate the ‘S’ code to ‘T’ target language code.
Types of Cross Compiler
- Source-to-Source Cross Compiler: This type of compiler is used for embedded systems; a source code is written in a high-level language such as C++, and the compiler translates this high-level language source code to lower-level language such as Assembly. Source-to-Soirce Cross Compiler is also known as Transpilers.
- Binary Cross Compiler: As the name suggests, binary is a binary code consisting of 0’s and 1’s. This type of compiler translates the source code of high-level language such as C++ to Binary Code.
- Virtual Machine Cross Compiler: This type of compiler translates or generates a code that can be run on a virtual machine. This compiler generates a bytecode that can be executed on the target virtual machine.
- Emulation-Based Cross Compiler: This type of compiler translates a source code of high-level language into the source code of machine code, and this machine code can be executed on the target platform’s emulator.
- Cross Compilers for Embedded Systems: These types of cross compilers can be used in embedded systems that generate the binary code. The binary code generated by these compilers is generally used with libraries and tools that are made for embedded systems.
- Cross Compilers for Mobile Devices: These types of cross compilers can be used in mobile devices such as smartphones and tablets. These compilers also generate a binary code that is generally used with libraries and tools that are made for mobile devices.
What are the phases of the compiler?
A compiler operates through several phases:
- Lexical Analysis: In this phase, the source code is broken down into tokens or lexemes, which are the smallest meaningful units of the language
- Syntax Analysis (Parsing): The parser checks if the code adheres to the grammar rules of the programming language. It creates a parse tree to represent the code's syntactic structure
- Semantic Analysis: This phase ensures the code's meaning is correct in terms of the language's semantics. It involves type-checking and generating an abstract syntax tree (AST)
- Intermediate Code Generation: If the language has an intermediate representation, the compiler generates code in that form. This makes optimization and targeting different architectures easier
- Code Optimization: The compiler optimizes the code to make it more efficient, often by rearranging instructions or eliminating redundancies
- Code Generation: The actual machine code or assembly code is generated based on the optimized code and the target architecture's instruction set
- Symbol Table Management: The symbol table keeps track of variables, functions, and other symbols used in the code. It's essential for linking and code generation
- Error Handling: Throughout the process, the compiler identifies and reports errors to the programmer, helping them correct their code.
How compiler is different from a cross-compiler?
A compiler translates source code into machine code for the same platform it runs on. However, a cross-compiler translates code on one platform (host) into code for a different platform (target). There are several key differences between them:
- A compiler targets the same platform as the host, while a cross-compiler targets a different platform
- Compilers are used for regular development. On the other hand, cross-compilers are used when developing for platforms with different architectures or operating systems
- A compiler runs on the same machine where it's used. While a cross-compiler runs on one system but generates code for another
- Code generated by a compiler stays on the host machine, but cross-compiled code is deployed to the target machine
- GCC is a compiler that generates machine code for the host platform. Android developers use a cross-compiler to create apps for various device architectures
- Cross-compilers are more complex as they need to understand and generate code for different architectures and environments.
Pros of Cross Compiler
- Developers do not need to write code again for the different target machines, as the cross-compiler will take care of it.
- Cross compiler speeds up the development process as developers don’t need to write and test the code.
- The cross-compiler also does code optimization while transferring the code from the development system to the target machine.
- The developer’s time and effort will be saved If a cross-compiler is used.
Cons of Cross Compiler
- Developers may face problems, and can be challenging while debugging the code as the code is generated by the cross-compiler.
- Setting up and configuring the cross-compiler can be complex If the targeted machine is different from the development machine.
- The compilation process in the cross-compiler can be slower than the native compiler, especially for large software.
Frequently Asked Questions
Is cross-compiler process hard?
The complexity of the cross-compiler process varies based on factors like target architecture and compatibility. It can be challenging due to handling different platforms and dependencies, but with proper tools and knowledge, it becomes manageable.
What are cross-compiled apps?
Cross-compiled apps are software designed on one platform but meant to run on another. They enable developers to create software for different platforms without needing separate development setups for each. This is useful in embedded systems and mobile apps.
How cross-compiler is different from native-compiler?
Native Compilers are used to compile the developer’s code which generates an executable file that can only be run on the same architecture systems. On the other hand, an Executable file generated by the cross-compiler can also be used by a different architecture system.
A cross compiler is a type of compiler that allows you to write code one platform at a time, and an executable code can be generated for another platform. In this article, we discussed what a cross compiler is, how it works, and why a cross-compiler is used. We also discussed the pros and cons of the cross compiler.
A better understanding of the compilers will boost your preparation for your goal. So I will recommend reading about compilers and compilers for C++ here because theory and practicality are both pieces of knowledge that matter.
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