Method delDef

chapter21/src/main/java/com/seaofnodes/simple/node/Node.java:194–202

(int idx)

        unlock();
        while( nIns() > n ) {
            Node old_def = _inputs.pop();
            if( old_def != null &&     // If it exists and
                old_def.delUse(this) ) // If we removed the last use, the old def is now dead
                old_def.kill();        // Kill old def
        }
    }

    /**
     * Kill a Node with no <em>uses</em>, by setting all of its <em>defs</em>
     * to null.  This may recursively kill more Nodes, and is basically dead
     * code elimination.
     */