Static Single Assignment

Question

Definition of Static Single Assignment

Static single-assignment form arranges for every value computed by a program to have a unique assignment (aka, “definition”)

but 

p3 = a - b

q4 = p3 * c

p4 = u * v

q5 = p4 + q4 

is an valid example of SSA

Now, tell me a,b,c,u,v are not assigned or previously recognized

Then how this is a valid example of SSA?

for ref see here

Comments

mam,

a,b,c,u,v if previously not recognized then how you can use it?

therefore need not to specially mention that they are recognized, by default we can assume they are recognized.

Answer 1

1. Each assignment to a temporary is given a unique name
2. All of the uses reached by that assignment are renamed

because of this. we are giving unique name to p as p3 as a-b is temporary assigned to p3.

now, p3 is used and q renamed as q4.

Comments

no,I am telling why a,b are not stored in separate temporary variable?

like t1=1, t2=b

like that

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Read definition you have written, every value computed to have a unique assignment. we are giving temporary variable to the value computed. They variable b are already a variable so why we need again to give them

Answer 2

a,b,c,u,v are loaded initially into temporary variables. So extra temporary variables are required for them.