Static single variable

Question

Comments

refer this- https://gateoverflow.in/227604/static-single-variable

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7 is correct only

Answer 1

Ans is 7

This can be converted to SSA as

a1 = b + c

c1 = a1 + x

d1 = b + c1

b1 = a1 + x

so total count of variables is 7

Comments

shouldn't the answer be 5 as the b+c,a1+x is repeated

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No, if variable is repeated on LHS then it is replaced with new variable.

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according to ME solution the answer is 6, the are using DAG as there solution.

Answer 2

Static single assignment means assignment to register can be done only one time-

a(temp3) = b(temp1) + c(temp2);

c(temp5) = a + x(temp4);

d(temp6) = b + c;

b(temp7) = a + x;

total 7 variables are required.

Comments

temp5 and temp7 are same. Do they need separate register allocation?

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@MiNiPanda,Shouldn't be assignment of each variable unique? In SSA every definition gets its own version.

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but answer given is 6