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Most compilers have at least the following compiler phases (which therefore occur at compile-time): syntax analysis, semantic analysis, and code generation.During optimization phases, constant expressions in the source code can also be evaluated at compile-time using compile-time execution, which reduces the constant expressions to a single value.
A compiler is likely to perform some or all of the following operations, often called phases: preprocessing, lexical analysis, parsing, semantic analysis (syntax-directed translation), conversion of input programs to an intermediate representation, code optimization and machine specific code generation.
The problem of compiling a self-compiling compiler has been called the chicken-or-egg problem in compiler design, and bootstrapping is a solution to this problem. [ 1 ] [ 2 ] Bootstrapping is a fairly common practice when creating a programming language .
When code generation occurs at runtime, as in just-in-time compilation (JIT), it is important that the entire process be efficient with respect to space and time. For example, when regular expressions are interpreted and used to generate code at runtime, a non-deterministic finite-state machine is often generated instead of a deterministic one, because usually the former can be created more ...
A multi-pass compiler is a type of compiler that processes the source code or abstract syntax tree of a program several times. This is in contrast to a one-pass compiler, which traverses the program only once. Each pass takes the result of the previous pass as the input, and creates an intermediate output.
One example for such a place are if statements. The guard is a quick check to determine whether the original condition is still true. If a guard fails, the execution of the trace is aborted. Since tracing is done during execution, the trace can be made to contain runtime information (e.g. type information). This information can later be used in ...
The examples above are problems in which the data-flow value is a set, e.g. the set of reaching definitions (Using a bit for a definition position in the program), or the set of live variables. These sets can be represented efficiently as bit vectors , in which each bit represents set membership of one particular element.
It splits the verification of Java bytecode in two phases: [15] Design-time – when compiling a class from source to bytecode; Runtime – when loading a class. In practice this method works by capturing knowledge that the Java compiler has of class flow and annotating the compiled method bytecodes with a synopsis of the class flow information.