Skip to content
Related Articles

Related Articles

Improve Article
GATE | Sudo GATE 2020 Mock II (10 January 2019) | Question 14
  • Last Updated : 07 Jan, 2020

Consider the following code segment.

x = u - t;
y = x * v;
x = y + w;
y = t - z; 

The minimum number of total variables required to convert the above code segment to static single assignment form is
(A) 6
(B) 8
(C) 9
(D) 10

Answer: (C)

Explanation: Static Single Assignment (SSA) is used for intermediate code in compiler design. In Static Single Assignment form(SSA) each assignment to a variable should be specified with distinct names. We use subscripts to distinguish each definition of variables.

In the given code segment, there are two assignments of the variable x:

x = u - t;
x = y + w; 

And three assignments of the variable y:

y = x * v;
y = t - z; 

So we use two variables x1, x2 for specifying distinct assignments of x and y1, y2 each assignment of y. So, total number of variables is 9 (x1, x2, y1, y2, t, u, v, w, z).
Static Single Assignment form(SSA) of the given code segment is:

x1 = u - t;
y1 = x1 * v;
x2 = y1 + w;
y2 = t - z; ;

Please refer below link for details

Quiz of this Question

Attention reader! Don’t stop learning now. Learn all GATE CS concepts with Free Live Classes on our youtube channel.

My Personal Notes arrow_drop_up
Recommended Articles
Page :