It gets input from code optimization phase and produces the target code or object code as result.Code generation is the final phase of a compiler.O Removal of unwanted temporary variables. O Collapsing of repeated expression into temporary string. O Calculation of constants in expressions and terms. O Deduction and removal of dead code (unreachable code). To improve the code generation, the optimization involves.During the code optimization, the result of the program is not affected.This phase reduces the redundant code and attempts to improve the intermediate code so that faster-running machine code will result.It can be done by reducing the number of lines of code for a program.It results in faster running machine code.Code optimization phase gets the intermediate code as input and produces optimized intermediate code as output.It should be easy to translate into target program.Id 1 = t 3 Properties of intermediate code Most commonly used form is the three address code. Intermediate code generation produces intermediate representations for the source program which are of the following forms:.Type information is gathered and stored in symbol table or in syntax tree.It checks for the semantic consistency.Semantic analysis is the third phase of compiler.Syntax tree is a compressed representation of the parse tree in which the operators appear as interior nodes and the operands of the operator are the children of the node for that operator.A parse tree describes the syntactic structure of the input.Parser converts the tokens produced by lexical analyzer into a tree like representation called parse tree.Syntax analysis is the second phase of compiler which is also called as parsing.Once a token is generated the corresponding entry is made in the symbol table.It is the structure that must be matched by strings. Pattern: Pattern describes the rule that the lexemes of a token takes.Lexeme: Lexeme is instance of a token i.e., group of characters forming a token.Token: Token is a sequence of characters that represent lexical unit, which matches with the pattern, such as keywords, operators, identifiers etc.Source program is scanned to read the stream of characters and those characters are grouped to form a sequence called lexemes which produces token as output.Lexical analysis is the first phase of compiler which is also termed as scanning.The different phases of compiler are as follows:Īll of the aforementioned phases involve the following tasks: Static type checking is complex when a language enables a memory cell to save values of multiple types at various times during execution.The design of compiler can be decomposed into several phases, each of which converts one form of source program into another. Static type checking likely to influence declarations, data control structures, and supplies for independent compilation of subprograms. In languages without declarations, there is no static type checking is possible. Many languages like APL and SNOBOL4, because of their dynamic type binding, enable only dynamic type checking. There are the following disadvantages of static type checking which are as follows −
There is no requirement of type tags on data objects at runtime.Ī consequential gain in the adaptability of storage use. It is used to checking all execution paths. The early detection of errors at compile time. There are the following advantages of static type checking which are as follows − The required data for static type checking is generally supported in part by declarations that the programmer supports and in part by different language structures. Using the rules of a type system, a compiler can infer from the source text that a function f will be applied to an operand a of the right type, each time the expression f (a) is evaluated. Therefore, static type checking involves examining the program text, usually during translation. It is more to identify errors at compile time than at runtime because the previous correction is generally less expensive. If all binding of variables to type is static in a language, then type checking can virtually continually be completed statistically. Similarly, the operands for addition and assignment can be evaluated. Here b should be of a type that allows multiplication by an integer. It can illustrate the concept of type checking considers the following statement. A type error is the application of an operator to an operand of an improper type. This automatic conversion is known as coercion.
A compatible type is one that is legal for the operator or is enabled under language rules to be implicitly modified by compiler-generated code to a legal type. Type checking is the activity of providing that the operands of an operator are of compatible types.
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