The document discusses three address code generation, which is an intermediate machine-independent code used in optimizing compilers, consisting of statements like x = y op z. It outlines various types of three address statements, including assignment, unconditional jumps, conditional jumps, and procedure calls, among others. Additionally, it features examples of code generation and references for further reading on the topic.

1. Three Adress Code
Generation
Presented by:
Rabin BK

2. CONTENTS
01
02
03
INTRODUCTION
TYPES
EXAMPLE
04 REFERENCES

3. INTRODUCTION
● An intermediate code (machine independent code) used by the optimizing
compilers
● A sequence of statements of the general form x = y op z
● where x, y, z are names, constants
● op stands for any operator (such as fixed or floating point arithmetic
operator or a logical operator on boolean valued data)
● Eliminates the need of a new full compiler for every unique machine by
keeping the analysis portion same for all the compilers.
● Assumes to have unlimited number of memory storage (register) to
generate code

4. TYPES OF 3 ADDRESS STATEMENTS
● Assignment statements
– Having the form x := y op z
– op --> binary arithmetic or logical operation
● Assignment Instructions
– Having the form x := op y
– op --> unary operation (unary plus, unary minus shift etc)
● Copy statements
● Having the form x := y

5. TYPES OF 3 ADDRESS STATEMENTS CONTD...
● Unconditional (Jump goto L)
– The three address statement with label L is the next to be executed
● Conditional Jumps (such as if x relop y goto L)
– applies a relational operator (<,>,<=,>=) to x and y
– if (condition satisfied) { execute the statement with label L } else {
execute the statement following, if x relop y goto L }

6. TYPES OF 3 ADDRESS STATEMENTS CONTD...
● param x and call p, n
– Used for procedure calls and return y(represents returned value)
– generated as a part of the three address code for call of the
procedure p(x1,x2,x3,....xn) where n are the number of variables
being sent to the procedure
param x1
param x2
.
.
param xn
call p,n

7. TYPES OF 3 ADDRESS STATEMENTS CONTD...
● Indexed copy instructions
x = y[i]
x[i] = y
● Address and pointer assignments
x = &y
x = *y
*x = y

8. EXAMPLE
if (a < b + c)
a = a - c;
c = b * c;
_t1 = b + c;
_t2 = a < _t1;
If Z _t2 Goto _L0;
_t3 = a - c;
a = _t3;
_L0: _t4 = b * c;
c = _t4;
int foo(int a, int b){
return a + b;
}
void main() {
int c;
int d;
foo(c, d);
}
foo:
BeginFunc 4;
_t0 = a + b;
Return _t0;
EndFunc;
main:
BeginFunc 12;
PushParam d;
PushParam c;
_t1 = LCall _foo;
PopParams 8;
EndFunc;
Number of bytes
for a function
Stack operation

9. REFERENCES
● https://web.stanford.edu/class/archive/cs/cs143/cs143.1128/handouts/24
0%20TAC%20Examples.pdf
● https://web.stanford.edu/class/archive/cs/cs143/cs143.1128/lectures/13/S
lides13.pdf
● https://www.tutorialspoint.com/compiler_design/compiler_design_interme
diate_code_generations.htm
● https://www.javatpoint.com/three-address-code
● http://cic.puj.edu.co/wiki/lib/exe/fetch.php?media=materias:compi:comp_
sesion21_aux1.pdf

10. QUERIES