Found 146 Articles for Compiler Design

Control statements are the statements that change the flow of execution of statements.Consider the GrammarS → if E then S1        |if E then S1 else S2         |while E do S1In this grammar, E is the Boolean expression depending upon which S1 or S2 will be executed.Following representation shows the order of execution of an instruction of if-then, ifthen-else, & while do.𝐒 → 𝐢𝐟 𝐄 𝐭𝐡𝐞𝐧 𝐒𝟏E.CODE & S.CODE are a sequence of statements which generate three address code.E.TRUE is the label to which control flow if E is true.E.FALSE is the label to which ... Read More

Control statements are the statements that change the flow of execution of statements. For example, If, If-else, Switch-Case, while-do statements. In programming languages, Boolean expressions are used toAlter the flow of control− Boolean expressions are used as conditional expressions in a statement that alter the flow of control. The value of such Boolean expression is implicit in a position reached in a program. For example, if (E) S, the expression E should be true if statement S is reached.Compute logical values− A Boolean expression can define true or false values. Such Boolean expressions can be computed in parallel to arithmetic ... Read More

Boolean means True or False. It can also be represented by 1 or 0.Boolean Expression is the expression that returns true or false. Boolean Expression can be represented in two ways−Conditional ExpressionsFor example, If a > b{     cout Y)A = B + CSolution(1) If A < B goto(4)(2) If X > Y goto(4)(3) goto(6)(4) T = B + C(5) A = TExample3− Write three address code for a > b 𝐀𝐍𝐃 c < d 𝐀𝐍𝐃 e < f.Solution(1) If a > b goto(4)(2) t1 = 0(3) goto(5)(4) t1 = 1(5) If c < d goto(8)(6) t2 = 0(7) goto(9)(8) t2 = 1(9) If e < f goto(12)(10) t3 = 0(11) goto(13)(12) t3 = 1(13) t4 = t1 𝐀𝐍𝐃 t2(14) t5 = t4 𝐀𝐍𝐃 t3

Assignment statements consist of an expression. It involves only integer variables.Abstract Translation SchemeConsider the grammar, which consists of an assignment statement.S → id = EE → E + EE → E ∗ EE → −EE → (E)E → idHere Translation of E can have two attributes −𝐄. 𝐏𝐋𝐀𝐂𝐄− It tells about the name that will hold the value of the expression.𝐄. 𝐂𝐎𝐃𝐄− It represents a sequence of three address statements evaluating the expression E in grammar represents an Assignment statement. E. CODE represents the three address codes of the statement. CODE for non-terminals on the left is the concatenation of ... Read More

SolutionFirst of all this statement will be converted into Three Address Code as−t1 = a + bt2 = −t1t3 = c + dt4 = t2 ∗ t3t5 = t1 + ct6 = t4 − t5QuadrupleLocationOperatorarg 1arg 2Result(0)+abt1(1)−t1t2(2)+cdt3(3)∗t2t3t4(4)+t1ct5(5)−t4t5t6                                                                                            TripleLocationOperatorarg 1arg 2(0)+ab(1)−(0)(2)+cd(3)∗(1)(2)(4)+(0)c(5)−(3)(4)Array RepresentationQuadruple is a structure that contains atmost four fields, i.e., operator, Argument 1, Argument 2, ... Read More

There are three implementations used for three address code statements which are as follows −QuadruplesTriplesIndirect TriplesQuadruplesQuadruple is a structure that contains atmost four fields, i.e., operator, Argument 1, Argument 2, and Result.OperatorArgument 1Argument 2ResultFor a statement a = b + c, Quadruple Representation places + in the operator field, a in the Argument 1 field, b in Argument 2, and c in Result field.For example− Consider the Statementa = b + c * dFirst, convert this statement into Three Address code∴ Three Address code will bet1 = c ∗ dt2 = b + t1a = t2.After construction of the Three ... Read More

The three-address code is a sequence of statements of the form A−=B op C, where A, B, C are either programmer-defined names, constants, or compiler-generated temporary names, the op represents an operator that can be constant or floatingpoint arithmetic operators or a Boolean valued data or a logical operator. The reason for the name “three address code” is that each statement generally includes three addresses, two for the operands, and one for the result.In the three-address code, atmost three addresses are define any statement. Two addresses for operand & one for the result.Hence, op is an operator.An only a single ... Read More

Parse TreeParse tree is a hierarchical structure that defines the derivation of the grammar to yield input strings. In parsing, the string is derived using the start symbol. The root of the parse tree is that start symbol. It is the graphical description of symbols that can be terminals or non-terminals. Parse tree follows the precedence of operators. The deepest sub-tree traversed first. Therefore, the operator in the parent node has less precedence over the operator in the sub-tree.A Parse Tree for a CFG G = (V, Σ, P, S) is a tree satisfying the following conditions −Root has the ... Read More

Tree in which each leaf node describes an operand & each interior node an operator. The syntax tree is shortened form of the Parse Tree.Example1 − Draw Syntax Tree for the string a + b ∗ c − d.Rules for constructing a syntax treeEach node in a syntax tree can be executed as data with multiple fields. In the node for an operator, one field recognizes the operator and the remaining field includes a pointer to the nodes for the operands. The operator is known as the label of the node. The following functions are used to create the nodes ... Read More

The translation of the source code into the object code for the target machine, a compiler can produce a middle-level language code, which is referred to as intermediate code or intermediate text. There are three types of intermediate code representation are as follows −Postfix NotationIn postfix notation, the operator comes after an operand, i.e., the operator follows an operand.ExamplePostfix Notation for the expression (a+b) * (c+d) is ab + cd +*Postfix Notation for the expression (a*b) - (c+d) is ab* + cd + - .Syntax TreeA tree in which each leaf node describes an operand & each interior node an ... Read More