rodneyxr / ffa-examples Goto Github PK

I sort of have the variable analysis part working. Another problem I am having is merging productions when there is a branch. For example:

1: $x0 = 'a';
2: $x1 = 'b';
3: $x2 = 'c';
4: $x3 = $x0;
5: $x3 = $x1;
6: if (other) {
7:    $x3 = $x2;
8: }
9: $x4 = $x3;

Usually where there is an assignment, like line 4: $x3 = $x0, I will create a new production: $x3{4} -> $x0{1}. (var_name{line #})
Same thing for line 5.

But if we look at line 9 where $x4 could be $x1 or $x2 so I am not sure how to add this production to the grammar. Currently in the live variables, $x3 has two entries for line 5 and line 7. So when line 9 comes along I have to put the line 7 value because it was the last variable added to the live variable set. But I should have some way of setting $x4 equal to both the line 5 and line 7 value.