These three questions are closely inter-related making them impossible to answer individually and, regardless of appearances, are not the modern version of the chicken and the egg! To answer this, we need to look back to the beginnings of computer science. It was in when Grace Hopper , one of the most influential contributors to informatics, wrote the first compiler: the A-0 system.
She to whom we owe the Word bug from the famous Mark I anecdote put together subroutines, used over the years, into machine language and on a tape associated to a numeric code. The A-0 system could translate mathematical symbolic codes to machine language, using said codes, by searching through the tape for the corresponding subroutines.
Although this corresponds more to the idea of a linker or loader, the A-0 system is considered to be the first ever compiler. Initially, this was done manually: someone had to actually convert instructions, which existed in a language totally alien to a computer such as mathematical symbols , into binary.
As computing evolved and became more and more complex, instructions were entered in an assembler and directly mapped to machine language instructions, to be directly executed by a processor. A very simple compiler can be written from an assembler and machine code.
Once you have a software that is able to translate something into binary instructions, you can use the original compiler to write a more sophisticated one then use a second further refined one to write a third and so on.
This iterative process of making a tool from a simpler version is known as bootstrapping. The something could be instructions written in the same programming language the compiler uses, creating new self-hosting.
These source codes must be converted into machine language and here comes the role of compilers and interpreters. Differences between Interpreter and Compiler Interpreter translates just one statement of the program at a time into machine code. Compiler scans the entire program and translates the whole of it into machine code at once. An interpreter takes very less time to analyze the source code.
However, the overall time to execute the process is much slower. A compiler takes a lot of time to analyze the source code. However, the overall time taken to execute the process is much faster. An interpreter does not generate an intermediary code. Hence, an interpreter is highly efficient in terms of its memory.
A compiler always generates an intermediary object code. It will need further linking. The compiler process goes through lexical, syntax, and semantic analysis at the front end and code generation and optimization at the back-end. In this Compiler Design tutorial , you will learn. In single pass Compiler source code directly transforms into machine code. For example, Pascal language. The Two pass compiler method also simplifies the retargeting process. It also allows multiple front ends.
The multipass compiler processes the source code or syntax tree of a program several times. It divided a large program into multiple small programs and process them. It develops multiple intermediate codes. All of these multipass take the output of the previous phase as an input. So it requires less memory.
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