Data flow equations to determine value dependencies

Question

I need to define the data-flow analysis equations to determine the value dependencies of an statement.

For example:

a = 9 
b = a + 7
c = b * 2

the value of c depends on the value of a.

I'm sure this is a well known problem in data flow analysis, can any one point to the equations solving this? Static Single Assignment (SSA) form can be used.

Answer 1

Well, it seems that this can be reduced to the Reaching Definition problem, who's equations are:

$REACH_{in}(S) = \bigcup_{p \in pred(S)} REACH_{out}(p)$

$REACH_{out}(S) = GEN(S) \cup (REACH_{in}(S) - KILL(S))$

$GEN[d: y \rightarrow f(x_1, .., x_n)] = {d}$

$KILL[d: y \rightarrow f(x_1, .., x_n)] =DEFS(y) - {d}$