Explain the phases of a compiler.
The phases of a compiler are:
- Lexical Analysis: Breaks the source code into a stream of tokens.
- Syntax Analysis: Parses the token stream to create a syntax tree.
- Semantic Analysis: Checks the syntax tree for semantic errors.
- Intermediate Code Generation: Generates an intermediate representation of the source code.
- Code Optimization: Optimizes the intermediate code to improve performance.
- Code Generation: Generates the target machine code.
How does lexical analysis differ from syntax analysis?
Lexical Analysis: The first phase of a compiler, it converts the source code into a stream of tokens. It is concerned with the structure of words.
Syntax Analysis: The second phase of a compiler, it takes the token stream from the lexical analyzer and builds a syntax tree. It is concerned with the grammatical structure of the code.
What is intermediate code generation?
Intermediate code generation is the phase of a compiler that translates the source code into an intermediate representation. This intermediate code is a machine-independent representation of the source code that is easy to optimize and translate into the target machine code.
How do symbol tables help in compilation?
A symbol table is a data structure used by a language translator such as a compiler or interpreter, where each identifier in a program's source code is associated with information relating to its declaration or appearance in the source. It is used to store information about the identifiers, such as their type, scope, and location.
Explain different error-handling techniques in compilers.
Some common error-handling techniques in compilers include:
- Panic Mode: The compiler discards input symbols one at a time until a synchronizing token is found.
- Phrase-level Recovery: The compiler performs local correction on the remaining input to allow the rest of the program to be parsed.
- Error Productions: The compiler is augmented with error productions that generate erroneous constructs.
- Global Correction: The compiler tries to find the smallest set of changes to make the program valid.
What is register allocation and why is it important?
Register allocation is the process of assigning a large number of target program variables onto a small number of CPU registers. It is important because accessing data from registers is much faster than accessing it from memory, so effective register allocation can significantly improve the performance of the generated code.
How do modern compilers optimize code execution?
Modern compilers use a variety of techniques to optimize code execution, including:
- Constant Folding: Evaluating constant expressions at compile time.
- Dead Code Elimination: Removing code that does not affect the program's results.
- Loop Optimization: Applying techniques like loop unrolling and code motion to make loops run faster.