Re: show size of stack needed by functions

[Sebastian]

Attached is a patch with some experiments of mine.

On Tue, 10 May 2016 01:17:37 +0200
Eric Botcazou <ebotca...@adacore.com> wrote:

> > Wishes:
> > - Add stack-usage in output of -fdump-ipa-cgraph, so that you don't need to
> > relate information from two input files at all. I guess this is not
> > trivial. Or is it?  
> 
> It's not difficult, but there is a conflict between them because 
> -fstack-usage 
> is designed to be conservatively correct while -fdump-ipa-cgraph is not (it 
> does not dump the full callgraph).

This is what I tried first (see attached patch). Doesn't seem to work. I get 
only outputs of "no su" and "no func".
So at the point in time when the callgraph dump happens, there is no 
stack-usage data attached to the "function" structures?

Can you elaborate on the conflict you mentioned?
Under which circumstances are there missing functions in the cgraph?
For my example AVR program, all identifiers appearing in the stack-usage output 
also appeared in the cgraph output.


On Mon, 9 May 2016 23:47:10 +0200
Sebastian <sebastianspublicaddr...@googlemail.com> wrote:

> - In -fstack-usage, use the same unique identifiers as in -fdump-ipa-cgraph.

This is what I tried next (see attached patch).
Currently, I just add another column with the cgraph identifier. Assuming the 
patch will go into SVN eventually, do you think I should replace the existing 
identifier instead? What would be less trouble for existing tools that parse 
the output?

With just changing the output of the identifier, still some functions are 
missing.
But for all of them I've got something like this:
        References: SYMBOL/ORDER (alias)
which then is in stack-usage. So no problem.


Summary:
With the unique identifiers from cgraph node->asm_name() / node->order patched 
into stack-usage, cgraph and stack-usage are consistent for my example program.
I wonder what I should change (output format, anything else?) before it's fit 
for SVN.


Sebastian
diff -aur gcc-5.3.0/gcc/cgraph.c ../gcc-5.3.0/gcc/cgraph.c
--- gcc-5.3.0/gcc/cgraph.c	2015-06-17 09:42:39.000000000 +0200
+++ ../gcc-5.3.0/gcc/cgraph.c	2016-05-16 21:27:58.351356039 +0200
@@ -2061,6 +2061,28 @@
       fprintf (f, "\n");
     }
   
+  if (flag_stack_usage_info)
+  {
+      function *func = get_fun();
+      if(func && func->su)
+      {
+        fprintf (f, "\n  stack-usage: %d", func->su->static_stack_size);
+      }
+      else if(func)
+      {
+        fprintf (f, "\n  stack-usage: no su");
+      }
+      else
+      {
+        fprintf (f, "\n  stack-usage: no func");
+      }
+  }
+  else
+  {
+        fprintf (f, "\n  stack-usage: disabled");
+  }
+  fprintf (f, "\n");
+
   fprintf (f, "  Called by: ");
 
   for (edge = callers; edge; edge = edge->next_caller)
@@ -2110,6 +2132,7 @@
     fprintf (f, "  Is instrumented version.\n");
   else if (instrumented_version)
     fprintf (f, "  Has instrumented version.\n");
+    
 }
 
 /* Dump call graph node NODE to stderr.  */
diff -aur gcc-5.3.0/gcc/toplev.c ../gcc-5.3.0/gcc/toplev.c
--- gcc-5.3.0/gcc/toplev.c	2015-07-10 14:33:28.000000000 +0200
+++ ../gcc-5.3.0/gcc/toplev.c	2016-05-18 21:18:38.603461168 +0200
@@ -1122,15 +1122,28 @@
 	}
 
       fprintf (stack_usage_file,
-	       "%s:%d:%d:%s\t"HOST_WIDE_INT_PRINT_DEC"\t%s\n",
+	       "%s:%d:%d:%s\t"HOST_WIDE_INT_PRINT_DEC"\t%s",
 	       lbasename (loc.file),
 	       loc.line,
 	       loc.column,
 	       name,
 	       stack_usage,
 	       stack_usage_kind_str[stack_usage_kind]);
+      cgraph_node *node = cgraph_node::get (current_function_decl);
+      if(node)
+      {
+        // cfun->funcdef_no is different than node->order in some cases.
+        fprintf (stack_usage_file, "\t%s/%i\n",
+          xstrdup_for_dump (node->asm_name ()),
+          node->order);
+      }
+      else
+      {
+        fprintf (stack_usage_file, "\n");
+      }
     }
 
+
   if (warn_stack_usage >= 0)
     {
       const location_t loc = DECL_SOURCE_LOCATION (current_function_decl);