[PATCH GCC][01/06]New interface returning all adjacent vertices in graph

[PATCH GCC][01/06]New interface returning all adjacent vertices in graph

[Bin Cheng]

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Hi,
This simple patch adds new interface returning adjacent vertices for a vertex in graph.
Bootstrap and test in series.  Is it OK?

Thanks,
bin
2017-08-10  Bin Cheng  <bin.cheng@arm.com>

	* graphds.c (adjacent_vertices): New function.
	* graphds.h (adjacent_vertices): New declaration.

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From d84e4dd5b840d5f34a619a0f89e502fccf24326f Mon Sep 17 00:00:00 2001
From: Bin Cheng <binche01@e108451-lin.cambridge.arm.com>
Date: Tue, 13 Jun 2017 15:51:54 +0100
Subject: [PATCH 1/6] graphds-adjacent_vertices-20170801.txt

---
 gcc/graphds.c | 19 +++++++++++++++++++
 gcc/graphds.h |  1 +
 2 files changed, 20 insertions(+)

diff --git a/gcc/graphds.c b/gcc/graphds.c
index 2951349..5618074 100644
--- a/gcc/graphds.c
+++ b/gcc/graphds.c
@@ -338,6 +338,25 @@ for_each_edge (struct graph *g, graphds_edge_callback callback, void *data)
       callback (g, e, data);
 }
 
+/* Given graph G, record V's adjacent vertices in ADJ and return if ADJ
+   isn't NULL.  */
+
+void
+adjacent_vertices (struct graph *g, int v, vec<int> *adj)
+{
+  struct graph_edge *e;
+
+  if (!adj)
+    return;
+
+  e = dfs_fst_edge (g, v, true, NULL, NULL);
+  while (e != NULL)
+    {
+      adj->safe_push (e->dest);
+      e = dfs_next_edge (e, true, NULL, NULL);
+    }
+}
+
 /* Releases the memory occupied by G.  */
 
 void
diff --git a/gcc/graphds.h b/gcc/graphds.h
index 9f9fc10..86172a2 100644
--- a/gcc/graphds.h
+++ b/gcc/graphds.h
@@ -63,6 +63,7 @@ void graphds_domtree (struct graph *, int, int *, int *, int *);
 typedef void (*graphds_edge_callback) (struct graph *,
 				       struct graph_edge *, void *);
 void for_each_edge (struct graph *, graphds_edge_callback, void *);
+void adjacent_vertices (struct graph *, int, vec<int> *);
 void free_graph (struct graph *g);
 
 #endif /* GCC_GRAPHDS_H */
-- 
1.9.1

Re: [PATCH GCC][01/06]New interface returning all adjacent vertices in graph

[Richard Biener]

On Mon, Aug 14, 2017 at 11:19 AM, Bin Cheng <Bin.Cheng@arm.com> wrote:
> Hi,
> This simple patch adds new interface returning adjacent vertices for a vertex in graph.
> Bootstrap and test in series.  Is it OK?

The comment of the function doesn't match its implementation.  Why did
you choose
to use the dfs helpers instead of (more clearly IMHO) using

 e = v->succ;
 while (e)
   {
     adj->safe_push (e->dest);
     e = e->succ_next;

given you do not expose the direction as arggument to adjacent_vertices?  Btw,
is this "adjacent" a term understood in the context of (directed) graphs?

Richard.

> Thanks,
> bin
> 2017-08-10  Bin Cheng  <bin.cheng@arm.com>
>
>         * graphds.c (adjacent_vertices): New function.
>         * graphds.h (adjacent_vertices): New declaration.