As a side-effect, graphds_scc constructs a vector in which all
nodes in an SCC are listed consecutively. This can be useful
information, so that the patch adds an optional pass-back parameter
for it. The interface is similar to the one for graphds_dfs.
gcc/
* graphds.cc (graphds_scc): Add a pass-back parameter for the
final node order.
---
gcc/graphds.cc | 13 ++++++++++---
gcc/graphds.h | 3 ++-
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/gcc/graphds.cc b/gcc/graphds.cc
index 91a2ca5c225..2a108fd475f 100644
--- a/gcc/graphds.cc
+++ b/gcc/graphds.cc
@@ -281,7 +281,14 @@ graphds_dfs (struct graph *g, int *qs, int nq, vec<int>
*qt,
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. If SKIP_EDGE_P is not NULL, it points to a callback function.
- Edge E will be skipped if callback function returns true.
+ Edge E will be skipped if callback function returns true. If SCC_GROUPING
+ is not null, the nodes will be added to it in the following order:
+
+ - If SCC A is a direct or indirect predecessor of SCC B in the SCC dag,
+ A's nodes come before B's nodes.
+
+ - All of an SCC's nodes are listed consecutively, although the order
+ of the nodes within an SCC is not really meaningful.
After running this function, v->component is the number of the strongly
connected component for each vertex of G. Returns the number of the
@@ -289,7 +296,7 @@ graphds_dfs (struct graph *g, int *qs, int nq, vec<int> *qt,
int
graphds_scc (struct graph *g, bitmap subgraph,
- skip_edge_callback skip_edge_p)
+ skip_edge_callback skip_edge_p, vec<int> *scc_grouping)
{
int *queue = XNEWVEC (int, g->n_vertices);
vec<int> postorder = vNULL;
@@ -317,7 +324,7 @@ graphds_scc (struct graph *g, bitmap subgraph,
for (i = 0; i < nq; i++)
queue[i] = postorder[nq - i - 1];
- comp = graphds_dfs (g, queue, nq, NULL, true, subgraph, skip_edge_p);
+ comp = graphds_dfs (g, queue, nq, scc_grouping, true, subgraph, skip_edge_p);
free (queue);
postorder.release ();
diff --git a/gcc/graphds.h b/gcc/graphds.h
index c54d8767fa7..e0e4d802cbb 100644
--- a/gcc/graphds.h
+++ b/gcc/graphds.h
@@ -58,7 +58,8 @@ void identify_vertices (struct graph *, int, int);
typedef bool (*skip_edge_callback) (struct graph_edge *);
int graphds_dfs (struct graph *, int *, int,
vec<int> *, bool, bitmap, skip_edge_callback = NULL);
-int graphds_scc (struct graph *, bitmap, skip_edge_callback = NULL);
+int graphds_scc (struct graph *, bitmap, skip_edge_callback = NULL,
+ vec<int> * = NULL);
void graphds_domtree (struct graph *, int, int *, int *, int *);
typedef void (*graphds_edge_callback) (struct graph *,
struct graph_edge *, void *);
--
2.25.1
