#include <tree-ssa-sccvn.h>

Collaboration diagram for vn_avail:

Data Fields
vn_avail *	next

int	location

int	leader

struct vn_ssa_aux *	next_undo

Detailed Description

Instead of having a local availability lattice for each basic-block
and availability at X defined as union of the local availabilities
at X and its dominators we're turning this upside down and track
availability per value given values are usually made available at very
few points.
So we have a chain of LOCATION, LEADER entries where LOCATION is
specifying the basic-block LEADER is made available for VALUE.
We prepend to this chain in RPO order thus for iteration we can simply
remove the last entries.
LOCATION is the basic-block index and LEADER is its SSA name version.