GCC Middle and Back End API Reference
_elim_graph Struct Reference
Collaboration diagram for _elim_graph:

Data Fields

int size
vec< int > nodes
vec< int > edge_list
vec< source_location > edge_locus
sbitmap visited
vec< int > stack
var_map map
edge e
vec< int > const_dests
vec< treeconst_copies
vec< source_location > copy_locus

Detailed Description

   Used to hold all the components required to do SSA PHI elimination.
   The node and pred/succ list is a simple linear list of nodes and
   edges represented as pairs of nodes.

   The predecessor and successor list:  Nodes are entered in pairs, where
   [0] ->PRED, [1]->SUCC.  All the even indexes in the array represent
   predecessors, all the odd elements are successors.

   When implemented as bitmaps, very large programs SSA->Normal times were
   being dominated by clearing the interference graph.

   Typically this list of edges is extremely small since it only includes
   PHI results and uses from a single edge which have not coalesced with
   each other.  This means that no virtual PHI nodes are included, and
   empirical evidence suggests that the number of edges rarely exceed
   3, and in a bootstrap of GCC, the maximum size encountered was 7.
   This also limits the number of possible nodes that are involved to
   rarely more than 6, and in the bootstrap of gcc, the maximum number
   of nodes encountered was 12.  

Field Documentation

vec<tree> _elim_graph::const_copies
vec<int> _elim_graph::const_dests
     List of constant copies to emit.  These are pushed on in pairs.  

Referenced by insert_part_to_rtx_on_edge().

vec<source_location> _elim_graph::copy_locus
     Source locations for any constant copies.  

Referenced by insert_part_to_rtx_on_edge().

edge _elim_graph::e
     Edge being eliminated by this graph.  

Referenced by elim_unvisited_predecessor().

vec<int> _elim_graph::edge_list
      The predecessor and successor edge list.  

Referenced by delete_elim_graph(), elim_graph_size(), and insert_part_to_rtx_on_edge().

vec<source_location> _elim_graph::edge_locus
     Source locus on each edge 

Referenced by delete_elim_graph(), elim_graph_size(), and insert_part_to_rtx_on_edge().

var_map _elim_graph::map
     The variable partition map.  

Referenced by elim_unvisited_predecessor().

vec<int> _elim_graph::nodes
     List of nodes in the elimination graph.  

Referenced by clear_elim_graph(), and insert_part_to_rtx_on_edge().

int _elim_graph::size
     Size of the elimination vectors.  
vec<int> _elim_graph::stack
     Stack for visited nodes.  

Referenced by eliminate_build(), and insert_part_to_rtx_on_edge().

sbitmap _elim_graph::visited

The documentation for this struct was generated from the following file: