[qfcc] Add some comments

This commit is contained in:
Bill Currie 2021-06-29 09:12:57 +09:00
parent d50f2c3145
commit 0d1fad12f0

View file

@ -266,14 +266,21 @@ dag_make_children (dag_t *dag, statement_t *s,
for (i = 0; i < 3; i++) {
dagnode_t *node = dag_node (operands[i + 1]);
dagnode_t *killer = 0;
if (node && node->killed) {
// If the node has been killed, then a new node is needed
killer = node->killed;
node = 0;
}
if (!node) {
// No valid node found (either first reference to the value,
// or the value's node was killed).
node = leaf_node (dag, operands[i + 1], s->expr);
}
if (killer) {
// When an operand refers to a killed node, it must be
// evaluated AFTER the killing node has been evaluated.
set_add (node->edges, killer->number);
}
children[i] = node;