## Mercurial > hg > CbC > CbC_gcc

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author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Fri, 17 Jul 2009 14:47:48 +0900 |

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children | 77e2b8dfacca |

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/* Graph representation and manipulation functions. Copyright (C) 2007 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "obstack.h" #include "bitmap.h" #include "vec.h" #include "vecprim.h" #include "graphds.h" /* Dumps graph G into F. */ void dump_graph (FILE *f, struct graph *g) { int i; struct graph_edge *e; for (i = 0; i < g->n_vertices; i++) { if (!g->vertices[i].pred && !g->vertices[i].succ) continue; fprintf (f, "%d (%d)\t<-", i, g->vertices[i].component); for (e = g->vertices[i].pred; e; e = e->pred_next) fprintf (f, " %d", e->src); fprintf (f, "\n"); fprintf (f, "\t->"); for (e = g->vertices[i].succ; e; e = e->succ_next) fprintf (f, " %d", e->dest); fprintf (f, "\n"); } } /* Creates a new graph with N_VERTICES vertices. */ struct graph * new_graph (int n_vertices) { struct graph *g = XNEW (struct graph); g->n_vertices = n_vertices; g->vertices = XCNEWVEC (struct vertex, n_vertices); return g; } /* Adds an edge from F to T to graph G. The new edge is returned. */ struct graph_edge * add_edge (struct graph *g, int f, int t) { struct graph_edge *e = XNEW (struct graph_edge); struct vertex *vf = &g->vertices[f], *vt = &g->vertices[t]; e->src = f; e->dest = t; e->pred_next = vt->pred; vt->pred = e; e->succ_next = vf->succ; vf->succ = e; return e; } /* Moves all the edges incident with U to V. */ void identify_vertices (struct graph *g, int v, int u) { struct vertex *vv = &g->vertices[v]; struct vertex *uu = &g->vertices[u]; struct graph_edge *e, *next; for (e = uu->succ; e; e = next) { next = e->succ_next; e->src = v; e->succ_next = vv->succ; vv->succ = e; } uu->succ = NULL; for (e = uu->pred; e; e = next) { next = e->pred_next; e->dest = v; e->pred_next = vv->pred; vv->pred = e; } uu->pred = NULL; } /* Helper function for graphds_dfs. Returns the source vertex of E, in the direction given by FORWARD. */ static inline int dfs_edge_src (struct graph_edge *e, bool forward) { return forward ? e->src : e->dest; } /* Helper function for graphds_dfs. Returns the destination vertex of E, in the direction given by FORWARD. */ static inline int dfs_edge_dest (struct graph_edge *e, bool forward) { return forward ? e->dest : e->src; } /* Helper function for graphds_dfs. Returns the first edge after E (including E), in the graph direction given by FORWARD, that belongs to SUBGRAPH. */ static inline struct graph_edge * foll_in_subgraph (struct graph_edge *e, bool forward, bitmap subgraph) { int d; if (!subgraph) return e; while (e) { d = dfs_edge_dest (e, forward); if (bitmap_bit_p (subgraph, d)) return e; e = forward ? e->succ_next : e->pred_next; } return e; } /* Helper function for graphds_dfs. Select the first edge from V in G, in the direction given by FORWARD, that belongs to SUBGRAPH. */ static inline struct graph_edge * dfs_fst_edge (struct graph *g, int v, bool forward, bitmap subgraph) { struct graph_edge *e; e = (forward ? g->vertices[v].succ : g->vertices[v].pred); return foll_in_subgraph (e, forward, subgraph); } /* Helper function for graphds_dfs. Returns the next edge after E, in the graph direction given by FORWARD, that belongs to SUBGRAPH. */ static inline struct graph_edge * dfs_next_edge (struct graph_edge *e, bool forward, bitmap subgraph) { return foll_in_subgraph (forward ? e->succ_next : e->pred_next, forward, subgraph); } /* Runs dfs search over vertices of G, from NQ vertices in queue QS. The vertices in postorder are stored into QT. If FORWARD is false, backward dfs is run. If SUBGRAPH is not NULL, it specifies the subgraph of G to run DFS on. Returns the number of the components of the graph (number of the restarts of DFS). */ int graphds_dfs (struct graph *g, int *qs, int nq, VEC (int, heap) **qt, bool forward, bitmap subgraph) { int i, tick = 0, v, comp = 0, top; struct graph_edge *e; struct graph_edge **stack = XNEWVEC (struct graph_edge *, g->n_vertices); bitmap_iterator bi; unsigned av; if (subgraph) { EXECUTE_IF_SET_IN_BITMAP (subgraph, 0, av, bi) { g->vertices[av].component = -1; g->vertices[av].post = -1; } } else { for (i = 0; i < g->n_vertices; i++) { g->vertices[i].component = -1; g->vertices[i].post = -1; } } for (i = 0; i < nq; i++) { v = qs[i]; if (g->vertices[v].post != -1) continue; g->vertices[v].component = comp++; e = dfs_fst_edge (g, v, forward, subgraph); top = 0; while (1) { while (e) { if (g->vertices[dfs_edge_dest (e, forward)].component == -1) break; e = dfs_next_edge (e, forward, subgraph); } if (!e) { if (qt) VEC_safe_push (int, heap, *qt, v); g->vertices[v].post = tick++; if (!top) break; e = stack[--top]; v = dfs_edge_src (e, forward); e = dfs_next_edge (e, forward, subgraph); continue; } stack[top++] = e; v = dfs_edge_dest (e, forward); e = dfs_fst_edge (g, v, forward, subgraph); g->vertices[v].component = comp - 1; } } free (stack); return comp; } /* Determines the strongly connected components of G, using the algorithm of Tarjan -- first determine the postorder dfs numbering in reversed graph, then run the dfs on the original graph in the order given by decreasing numbers assigned by the previous pass. If SUBGRAPH is not NULL, it specifies the subgraph of G whose strongly connected components we want to determine. After running this function, v->component is the number of the strongly connected component for each vertex of G. Returns the number of the sccs of G. */ int graphds_scc (struct graph *g, bitmap subgraph) { int *queue = XNEWVEC (int, g->n_vertices); VEC (int, heap) *postorder = NULL; int nq, i, comp; unsigned v; bitmap_iterator bi; if (subgraph) { nq = 0; EXECUTE_IF_SET_IN_BITMAP (subgraph, 0, v, bi) { queue[nq++] = v; } } else { for (i = 0; i < g->n_vertices; i++) queue[i] = i; nq = g->n_vertices; } graphds_dfs (g, queue, nq, &postorder, false, subgraph); gcc_assert (VEC_length (int, postorder) == (unsigned) nq); for (i = 0; i < nq; i++) queue[i] = VEC_index (int, postorder, nq - i - 1); comp = graphds_dfs (g, queue, nq, NULL, true, subgraph); free (queue); VEC_free (int, heap, postorder); return comp; } /* Runs CALLBACK for all edges in G. */ void for_each_edge (struct graph *g, graphds_edge_callback callback) { struct graph_edge *e; int i; for (i = 0; i < g->n_vertices; i++) for (e = g->vertices[i].succ; e; e = e->succ_next) callback (g, e); } /* Releases the memory occupied by G. */ void free_graph (struct graph *g) { struct graph_edge *e, *n; struct vertex *v; int i; for (i = 0; i < g->n_vertices; i++) { v = &g->vertices[i]; for (e = v->succ; e; e = n) { n = e->succ_next; free (e); } } free (g->vertices); free (g); } /* Returns the nearest common ancestor of X and Y in tree whose parent links are given by PARENT. MARKS is the array used to mark the vertices of the tree, and MARK is the number currently used as a mark. */ static int tree_nca (int x, int y, int *parent, int *marks, int mark) { if (x == -1 || x == y) return y; /* We climb with X and Y up the tree, marking the visited nodes. When we first arrive to a marked node, it is the common ancestor. */ marks[x] = mark; marks[y] = mark; while (1) { x = parent[x]; if (x == -1) break; if (marks[x] == mark) return x; marks[x] = mark; y = parent[y]; if (y == -1) break; if (marks[y] == mark) return y; marks[y] = mark; } /* If we reached the root with one of the vertices, continue with the other one till we reach the marked part of the tree. */ if (x == -1) { for (y = parent[y]; marks[y] != mark; y = parent[y]) continue; return y; } else { for (x = parent[x]; marks[x] != mark; x = parent[x]) continue; return x; } } /* Determines the dominance tree of G (stored in the PARENT, SON and BROTHER arrays), where the entry node is ENTRY. */ void graphds_domtree (struct graph *g, int entry, int *parent, int *son, int *brother) { VEC (int, heap) *postorder = NULL; int *marks = XCNEWVEC (int, g->n_vertices); int mark = 1, i, v, idom; bool changed = true; struct graph_edge *e; /* We use a slight modification of the standard iterative algorithm, as described in K. D. Cooper, T. J. Harvey and K. Kennedy: A Simple, Fast Dominance Algorithm sort vertices in reverse postorder foreach v dom(v) = everything dom(entry) = entry; while (anything changes) foreach v dom(v) = {v} union (intersection of dom(p) over all predecessors of v) The sets dom(v) are represented by the parent links in the current version of the dominance tree. */ for (i = 0; i < g->n_vertices; i++) { parent[i] = -1; son[i] = -1; brother[i] = -1; } graphds_dfs (g, &entry, 1, &postorder, true, NULL); gcc_assert (VEC_length (int, postorder) == (unsigned) g->n_vertices); gcc_assert (VEC_index (int, postorder, g->n_vertices - 1) == entry); while (changed) { changed = false; for (i = g->n_vertices - 2; i >= 0; i--) { v = VEC_index (int, postorder, i); idom = -1; for (e = g->vertices[v].pred; e; e = e->pred_next) { if (e->src != entry && parent[e->src] == -1) continue; idom = tree_nca (idom, e->src, parent, marks, mark++); } if (idom != parent[v]) { parent[v] = idom; changed = true; } } } free (marks); VEC_free (int, heap, postorder); for (i = 0; i < g->n_vertices; i++) if (parent[i] != -1) { brother[i] = son[parent[i]]; son[parent[i]] = i; } }