Overview of C Compilers

Let’s learn this concept of compilers with an example. Suppose you have been to a place where the languages you speak are completely different from each other and now you had some traveling issues and want to communicate the same with them. How? Did you need a translator right? You opt to have someone who can understand your language and translate and let the opposite person understand what you wanted to say. In the same way, we would be writing our C code in a high-level language that is a human-understandable format. How would the program understand what we have asked it to do? This is where the compiler comes into the picture. A compiler transforms and translates a high-end language to machine (low level) understandable language. The compiling process does basic translation mechanisms and also error detection. The front end compilation includes lexical, syntax, and semantic analysis. And at the back end, the compilation does the code generation and optimization. So there are many compilers in C like BDS, Clang, GCC, Interactive C, Lattice, Portable C Compiler, Visual Express, etc. Let’s get to know more about a few of them.

Explanations to C Compilers

Below are the Top Compilers of C:

1) Borland Turbo C

Turbo C is one of the basic and popular compilers for the C programming language. This was first introduced in 1987; it was popular for its small size, compilation speed, and low price. Once Turbo C++ got released in 1990, both the compilers are merged and the name Turbo C got discontinued. In 2006, Embarcadero Technologies had re-released Turbo C as freeware. Do you remember this blue screen?

2) Tiny C Compiler

The Tiny C Compiler is designed to work on slow computers with little disk space. This is an ARM processor C compiler. This compiler started its support to Windows from 2005. Some of its features are mentioned below.

Its file size is small and according to the owner of this compiler (Fabrice Bellard). The fastness of this compiler is around nine times faster than GCC. The compilation, assembling and linking of code were the main attributes considered for measuring the fastness of this compiler.
This compiler had included many compiler-specific features to boost up the optional memory, bound checker and had greater code stability.
This compiler allows automatic execution of programs during the compile-time only using command line arguments. This way, programs are executed under UNIX, using shell scripts. The latest version was released on December 2017.

3) Portable C Compiler

The Portable C Compiler (PCC) was a very early used and established compiler for the C programming language that is almost around mid-1970. This compiler had a long life span. This was prevalent during a period in such a way that many of the C compilers were based on it. The advantages of PCC depended on its capabilities and probability predictions. PCC compiler was made such that source files were machine-dependent, not all but only a few of them. It can detect syntax errors and can perform perfect validity checks. A new version of PCC was released on 10 December 2014.

4) GCC

GNU Compiler Collection is the compiler produced by the GNU Project. This supports many programming languages and it is a free software foundation under the General Public License. This compiler was first released in 1987 and it supported only C- Programming language during the start. Slowly it expanded to C++, Java, Android, and IOS. Here, each of the different language compilers has its own program that reads the code written and sends the machine code as the output. All of these have a common internal structure. When a high-level language is written, as per the language it is written, the compiler parses the code in that language and produces an abstract syntax tree. GCC uses LALR parsers, but slowly switched to recursive-descent parsers for C in 2006. Coming to the optimization part, as already known this can occur during any phase of the compilation. However, here the bulk optimizations are performed before the code generation and after the syntax, semantic analysis. Below are a few of the optimizations performed by GCC.

It can eliminate the Dead Code pieces.
It can eliminate the redundancy at the code level.
Replacement of Aggregates with respect to the scalar level.
Can perform optimizations with Arrays.

In GCC back end is specified by preprocessor macros and functions specific to a particular architecture. This code is generally built by first calling a small snippet code which is associated with each pattern and generate instructions from the instruction set. It is done using registers, offsets, and addresses that are chosen during the re-load phase. The current version of GCC is 9.2, which was released on August 12, 2019.

5) Clang

Clang; including C, is also a compiler for C++, Objective-C, and objective-C++ programming languages. This compiler uses LLVM for the back end code related compilations. This compiler has been designed to act as a replacement for the GCC by supporting many of its compilation flags and language extensions.
Clang has many contributors including Apple, Microsoft, Google, Sony, and Intel. It is open-source software. LLVM was first used by GCC for the front end compilation, but GCC had caused some problems for developers at Apple, as the source code is large and difficult to use. So, they had come up with Clang.
One of the major goals for Clang is to provide library-based architecture. It is designed to keep more information during the compilation process than GCC. This also helps to preserve the overall shape of the original code.
The error report generated by Clang during compilation is always in a detailed and specific in a machine-readable format. Clang had always aimed to reduce the over usage of memory space and increase the compilation speed as compared with GCC, and due to these qualities, it had become one of the fastest-growing used compilers during a point of time. But over a period the performance of Clang started to come down. The reports told the performance had lagged with almost large differences as compared with GCC and started to have slower performance. The most recent comparisons indicate that both the compilers had come up and increased their performance and once again creating great competition between them. Yet, GCC remains to top the list.

Conclusion

Though there are many compilers available for C, GCC stands out to be one of the best as of now. The winner declaration here lies based on durability, optimization, speed, and code/error/syntax checks. Through this, we can clearly understand that the Compiler is an important pillar to the programming languages. Without their work whatever program we write would just be garbage for the system.

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