A translation is an input/output mapping. Generally three types of translation scheme are used -
- Three Address Statements
- Quadruples &
- Triples
Three Address Statements : Three address statements are a sequence of statements.
Typically, the general form A : B op C, where A, & C are either programmer defined names. Constants or compiler - generated temporary names. Op stands for any operator, such as a fixed or floating -point arithmatic operator or a logical operator on Boolean -valued data. Three address statements usually contain three addresses, two for the operands & one for the result.
Example : Let us consider the expression A : = -B*(C+D).
We get the following three-address code from the expression :
T1 : = -B
T2 : = C+D
T3 : = T1+T2
A : = T3
Quardruples : Quadruples representation the three - address code by using four fields
These are -
OP, ARG1, ARG2 & RESULT.
Implementation of quadruples : Let us consider the following three - address code :
T1 : = -B
T2 : = C+D
T3 : = T1+T2
A : = T3
These statement are represented by quadruples as shown in fig . (a)
| SL NO | OP | ARG1 | ARG2 | RESULT |
|---|---|---|---|---|
| (0) | Uminus | B | - | T1 |
| (1) | + | C | D | T2 |
| (2) | * | T1 | T2 | T3 |
| (3) | := | T3 | - | A |
Fig. (a) quadruple representation of three -address statements.
Triple : Triple representation the three address code by using three fields.
These are -
OP, ARG1, ARG2.
So, we use parenthesized number to represent pointer into the triple
structure.while symbol-table pointers are represented by names
themselves.
Implementation of quadruples : Let us consider the following three - address code :
T1 : = -B
T2 : = C+D
T3 : = T1+T2
A : = T3
These statement are represented by quadruples as shown in fig . (a)
| SL NO | OP | ARG1 | ARG2 |
|---|---|---|---|
| (0) | Uminus | B | - |
| (1) | + | C | D |
| (2) | * | (0) | (1) |
| (3) | := | A | (2) |
Fig. (b) triple representation of three -address statements.
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