[PATCH] Add dotfn

[Tom de Vries <Tom_deVries at mentor dot com>]

Hi,

this patch adds a debug function dotfn and a convenience macro DOTFN 
similar to dot-fn in gdbhooks.py.

It can be used to have the compiler:
- dump a control flow graph, or
- pop up a control flow graph window
at specific moments in the compilation flow, for debugging purposes.

Bootstrapped and reg-tested on x86_64.

Used for debugging PR81192.

OK for trunk?

Thanks,
- Tom

Add dotfn

2017-06-30  Tom de Vries  <tom@codesourcery.com>

	* graph.c (get_graph_file_name): New function, factored out of ...
	(open_graph_file): ... here.
	(dotfn): New function.
	* graph.h (dotfn): Declare.
	(DOTFN): New macro.

---
 gcc/graph.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 gcc/graph.h |  7 +++++++
 2 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/gcc/graph.c b/gcc/graph.c
index 9261732..e6d3f2e 100644
--- a/gcc/graph.c
+++ b/gcc/graph.c
@@ -37,23 +37,45 @@ along with GCC; see the file COPYING3.  If not see
    ignore that recommendation...  */
 static const char *const graph_ext = ".dot";
 
+/* Return filename for dumping our graph to.  If NUM, use *NUM in the file name
+   and increase *NUM.  */
+
+static char *
+get_graph_file_name (const char *base, unsigned int *num = NULL)
+{
+  size_t namelen = strlen (base);
+  size_t extlen = strlen (graph_ext);
+  size_t numlen = num ? 11 : 0;
+  size_t len = namelen + extlen + numlen + 1;
+  char *buf = XNEWVEC (char, len);
+
+  char *pos = buf;
+  memcpy (pos, base, namelen);
+  pos += namelen;
+  if (num)
+    {
+      pos += snprintf (pos, numlen, ".%u", *num);
+      ++*num;
+    }
+  memcpy (pos, graph_ext, extlen + 1);
+
+  return buf;
+}
+
 /* Open a file with MODE for dumping our graph to.
    Return the file pointer.  */
 static FILE *
 open_graph_file (const char *base, const char *mode)
 {
-  size_t namelen = strlen (base);
-  size_t extlen = strlen (graph_ext) + 1;
-  char *buf = XALLOCAVEC (char, namelen + extlen);
+  char *buf = get_graph_file_name (base);
   FILE *fp;
 
-  memcpy (buf, base, namelen);
-  memcpy (buf + namelen, graph_ext, extlen);
-
   fp = fopen (buf, mode);
   if (fp == NULL)
     fatal_error (input_location, "can%'t open %s: %m", buf);
 
+  XDELETEVEC (buf);
+
   return fp;
 }
 
@@ -354,3 +376,37 @@ finish_graph_dump_file (const char *base)
   end_graph_dump (fp);
   fclose (fp);
 }
+
+/* Dump graph into file '<base>.dot', or if COUNTER is defined
+   '<base>.<*COUNTER>.dot'.  If POPUP, show the graph in a popup window.  */
+
+void DEBUG_FUNCTION
+dotfn (const char *base, unsigned int *counter, bool popup)
+{
+  char *name = get_graph_file_name (base, counter);
+
+  FILE *fp = fopen (name, "w");
+  if (fp != NULL)
+    {
+      start_graph_dump (fp, "<debug>");
+      print_graph_cfg (fp, cfun, dump_flags);
+      end_graph_dump (fp);
+      fclose (fp);
+
+      if (popup)
+	{
+	  char prog[] = "dot";
+	  char arg1[] = "-Tx11";
+	  char *const cmd[] = { prog, arg1, name , NULL };
+	  struct pex_obj *pex = pex_init (0, prog, NULL);
+	  int err;
+	  pex_run (pex, PEX_LAST | PEX_SEARCH, prog, cmd, NULL, NULL, &err);
+
+	  int status;
+	  pex_get_status (pex, 1, &status);
+	  pex_free (pex);
+	}
+    }
+
+  XDELETEVEC (name);
+}
diff --git a/gcc/graph.h b/gcc/graph.h
index 4db253f..168b60c 100644
--- a/gcc/graph.h
+++ b/gcc/graph.h
@@ -24,4 +24,11 @@ extern void print_graph_cfg (const char *, struct function *);
 extern void clean_graph_dump_file (const char *);
 extern void finish_graph_dump_file (const char *);
 
+extern void dotfn (const char *base, unsigned int *counter, bool popup);
+#define DOTFN(base, popup)			\
+  {						\
+    static unsigned int counter = 0;		\
+    dotfn (base, &counter, popup);		\
+  }
+
 #endif /* ! GCC_GRAPH_H */