Re: [PATCH] gengtype: Support explicit pointers in template arguments

[David Malcolm <dmalcolm at redhat dot com>]

On Mon, 2014-05-05 at 10:18 -0600, Jeff Law wrote:
> On 04/30/14 21:07, David Malcolm wrote:
> > Currently, gengtype does not support template arguments that are
> > explicitly pointers, such as:
> >    static GTY(()) vec<gimple_statement_base *> test_gimple; giving this
> > error:
> >    ../../src/gcc/gimple-expr.c:902: parse error: expected a string constant or ',', have '*' instead
> > requiring them to be typedefs.
> >
> > This patch removes this restriction, supporting up to a single pointer
> > in each template argument.
> >
> > It also adds support for inheritance, allowing:
> >    static GTY(()) vec<gimple_statement_phi *, va_gc> *test_phis;
> > where the generated gt-FOO.c file contains:
> >
> >    void
> >    gt_ggc_mx (struct gimple_statement_phi *& x)
> >    {
> >      if (x)
> >        gt_ggc_mx_gimple_statement_base ((void *) x);
> >    }
> >
> > i.e. handling the subclass by calling the marking function for the base
> > class.
> >
> > Doing so uncovered an issue within write_user_func_for_structure_ptr,
> > which would unconditionally write out a func.  This would lead to
> > gt-FOO.c containing duplicate functions e.g.:
> > gtype-desc.c:280: multiple definition of `gt_ggc_mx(gimple_statement_base*&)'
> > if more than one GTY template type referenced such a type; for example like this:
> >
> >    static GTY(()) vec<gimple, va_gc> *test_old_style_gimple;
> >    static GTY(()) vec<gimple_statement_base *, va_gc> *test_new_style_gimple;
> >
> > where "gimple" is just an alias for "gimple_statement_base *".  This
> > could be worked around by ensuring that the source tree consistently
> > uses vec<> of just one kind, but for robustness the patch also makes
> > write_user_func_for_structure_ptr idempotent, so it only writes out the
> > func once for each (struct, which-of-ggc/pch) combination.
> >
> > Motivation:
> > In the "Compile-time gimple-checking" discussion, Richi asked me to look
> > at eliminating the const_gimple typedef in favor of having "gimple" be
> > the struct, thus making the pointer to a gimple be explicit in the type:
> >    http://gcc.gnu.org/ml/gcc-patches/2014-04/msg01520.html
> > as in:
> >    http://gcc.gnu.org/ml/gcc-patches/2014-04/msg01632.html
> >> [...] And I never liked the
> >> const_ typedef variants that were introduced.  The main reason for
> >> them was probably to avoid all the churn of replacing the tree pointer
> >> typedef with a tree (non-pointer) typedef.  The mistake was to
> >> repeat that for 'gimple' ...
> >
> > I'm attempting a patch for that, but in the meantime, this patch adds
> > the needed support to gengtype.
> >
> > Successfully bootstrapped&regtested on x86_64-unknown-linux-gnu (Fedora
> > 20).
> >
> > OK for trunk?
> Basically OK.  Per the wide-int folks request, please hold off until the 
> wide-int merge is done.
> 
> If after wide-int, the only changes are trivial, then consider the patch 
> pre-approved (post the final version here so that its archived).
> 
> If after wide-int merges the changes to this patch are non-trivial, then 
> repost the RFA.
> 
> Obviously, you get to exercise some judgement as to what constitutes 
> trivial vs non-trivial.

Thanks.

The changes required after the wide-int merge were trivial.

Successfully rebootstrapped&regrtested the patch, both individually, and
followed up with v4 of the proposed gimple class patch series from:
  http://gcc.gnu.org/ml/gcc-patches/2014-05/msg00887.html
in both cases with equal testcase results compared to a control build of
r210222.

Committed to trunk as r210379; attached for reference.

Index: gcc/gengtype.c
===================================================================
--- gcc/gengtype.c	(revision 210378)
+++ gcc/gengtype.c	(revision 210379)
@@ -145,6 +145,14 @@
     s = s->u.s.base_class;
   return s;
 }
+
+static type_p
+get_ultimate_base_class (type_p s)
+{
+  while (s->u.s.base_class)
+    s = s->u.s.base_class;
+  return s;
+}
 
 /* Input file handling. */
 
@@ -589,7 +597,7 @@
       /* We only accept simple template declarations (see
 	 require_template_declaration), so we only need to parse a
 	 comma-separated list of strings, implicitly assumed to
-	 be type names.  */
+	 be type names, potentially with "*" characters.  */
       char *arg = open_bracket + 1;
       char *type_id = strtok (arg, ",>");
       pair_p fields = 0;
@@ -597,8 +605,28 @@
 	{
 	  /* Create a new field for every type found inside the template
 	     parameter list.  */
-	  const char *field_name = xstrdup (type_id);
-	  type_p arg_type = resolve_typedef (field_name, pos);
+
+	  /* Support a single trailing "*" character.  */
+	  const char *star = strchr (type_id, '*');
+	  int is_ptr = (star != NULL);
+	  size_t offset_to_star = star - type_id;
+	  if (is_ptr)
+	    offset_to_star = star - type_id;
+
+	  char *field_name = xstrdup (type_id);
+
+	  type_p arg_type;
+	  if (is_ptr)
+	    {
+	      /* Strip off the first '*' character (and any subsequent text). */
+	      *(field_name + offset_to_star) = '\0';
+
+	      arg_type = find_structure (field_name, TYPE_STRUCT);
+	      arg_type = create_pointer (arg_type);
+	    }
+	  else
+	    arg_type = resolve_typedef (field_name, pos);
+
 	  fields = create_field_at (fields, arg_type, field_name, 0, pos);
 	  type_id = strtok (0, ",>");
 	}
@@ -2461,6 +2489,7 @@
   const char *reorder_note_routine;
   const char *comment;
   int skip_hooks;		/* skip hook generation if non zero */
+  enum write_types_kinds kind;
 };
 
 static void output_escaped_param (struct walk_type_data *d,
@@ -2537,7 +2566,8 @@
       size_t i;
       char *s = xstrdup (type_name);
       for (i = 0; i < strlen (s); i++)
-	if (s[i] == '<' || s[i] == '>' || s[i] == ':' || s[i] == ',')
+	if (s[i] == '<' || s[i] == '>' || s[i] == ':' || s[i] == ','
+	    || s[i] == '*')
 	  s[i] = '_';
       return s;
     }
@@ -3501,10 +3531,10 @@
 
 /* Write on OF a user-callable routine to act as an entry point for
    the marking routine for S, generated by write_func_for_structure.
-   PREFIX is the prefix to use to distinguish ggc and pch markers.  */
+   WTD distinguishes between ggc and pch markers.  */
 
 static void
-write_user_func_for_structure_ptr (outf_p of, type_p s, const char *prefix)
+write_user_func_for_structure_ptr (outf_p of, type_p s, const write_types_data *wtd)
 {
   /* Parameterized structures are not supported in user markers. There
      is no way for the marker function to know which specific type
@@ -3534,13 +3564,23 @@
 	break;
       }
 
+  DBGPRINTF ("write_user_func_for_structure_ptr: %s %s", s->u.s.tag,
+	     wtd->prefix);
+
+  /* Only write the function once. */
+  if (s->u.s.wrote_user_func_for_ptr[wtd->kind])
+    return;
+  s->u.s.wrote_user_func_for_ptr[wtd->kind] = true;
+
   oprintf (of, "\nvoid\n");
-  oprintf (of, "gt_%sx (", prefix);
+  oprintf (of, "gt_%sx (", wtd->prefix);
   write_type_decl (of, s);
   oprintf (of, " *& x)\n");
   oprintf (of, "{\n");
   oprintf (of, "  if (x)\n    ");
-  write_marker_function_name (of, alias_of ? alias_of : s, prefix);
+  write_marker_function_name (of,
+			      alias_of ? alias_of : get_ultimate_base_class (s),
+			      wtd->prefix);
   oprintf (of, " ((void *) x);\n");
   oprintf (of, "}\n");
 }
@@ -3578,7 +3618,8 @@
    which just marks the fields of T.  */
 
 static void
-write_user_marking_functions (type_p s, const char *prefix,
+write_user_marking_functions (type_p s,
+			      const write_types_data *w,
 			      struct walk_type_data *d)
 {
   gcc_assert (s->kind == TYPE_USER_STRUCT);
@@ -3590,10 +3631,10 @@
 	{
 	  type_p pointed_to_type = fld_type->u.p;
 	  if (union_or_struct_p (pointed_to_type))
-	    write_user_func_for_structure_ptr (d->of, pointed_to_type, prefix);
+	    write_user_func_for_structure_ptr (d->of, pointed_to_type, w);
 	}
       else if (union_or_struct_p (fld_type))
-	write_user_func_for_structure_body (fld_type, prefix, d);
+	write_user_func_for_structure_body (fld_type, w->prefix, d);
     }
 }
 
@@ -3791,7 +3832,7 @@
   oprintf (d.of, "}\n");
 
   if (orig_s->kind == TYPE_USER_STRUCT)
-    write_user_marking_functions (orig_s, wtd->prefix, &d);
+    write_user_marking_functions (orig_s, wtd, &d);
 }
 
 
@@ -3969,7 +4010,7 @@
 static const struct write_types_data ggc_wtd = {
   "ggc_m", NULL, "ggc_mark", "ggc_test_and_set_mark", NULL,
   "GC marker procedures.  ",
-  FALSE
+  FALSE, WTK_GGC
 };
 
 static const struct write_types_data pch_wtd = {
@@ -3976,7 +4017,7 @@
   "pch_n", "pch_p", "gt_pch_note_object", "gt_pch_note_object",
   "gt_pch_note_reorder",
   "PCH type-walking procedures.  ",
-  TRUE
+  TRUE, WTK_PCH
 };
 
 /* Write out the local pointer-walking routines.  */
Index: gcc/gengtype.h
===================================================================
--- gcc/gengtype.h	(revision 210378)
+++ gcc/gengtype.h	(revision 210379)
@@ -127,8 +127,16 @@
 extern type_p param_structs;
 extern pair_p variables;
 
+/* An enum for distinguishing GGC vs PCH.  */
 
+enum write_types_kinds
+{
+  WTK_GGC,
+  WTK_PCH,
 
+  NUM_WTK
+};
+
 /* Discrimating kind of types we can understand.  */
 
 enum typekind {
@@ -302,6 +310,10 @@
       type_p first_subclass;
       /* The next in that list.  */
       type_p next_sibling_class;
+
+      /* Have we already written ggc/pch user func for ptr to this?
+	 (in write_user_func_for_structure_ptr).  */
+      bool wrote_user_func_for_ptr[NUM_WTK];
     } s;
 
     /* when TYPE_SCALAR: */
Index: gcc/ChangeLog
===================================================================
--- gcc/ChangeLog	(revision 210378)
+++ gcc/ChangeLog	(revision 210379)
@@ -1,3 +1,32 @@
+2014-05-13  David Malcolm  <dmalcolm@redhat.com>
+
+	* gengtype-parse.c (require3): Eliminate in favor of...
+	(require4): New.
+	(require_template_declaration): Update to support optional single *
+	on a type.
+
+	* gengtype.c (get_ultimate_base_class): Add a non-const overload.
+	(create_user_defined_type): Handle a single level of explicit
+	pointerness within template arguments.
+	(struct write_types_data): Add field "kind".
+	(filter_type_name): Handle "*" character.
+	(write_user_func_for_structure_ptr): Require a write_types_data
+	rather than just a prefix string, so that we can look up the kind
+	of the wtd and use it as an index into wrote_user_func_for_ptr,
+	ensuring that such functions are written at most once.  Support
+	subclasses by invoking the marking function of the ultimate base
+	class.
+	(write_user_func_for_structure_body): Require a write_types_data
+	rather than just a prefix string, so that we can pass this to
+	write_user_func_for_structure_ptr.
+	(write_func_for_structure): Likewise.
+	(ggc_wtd): Add initializer of new "kind" field.
+	(pch_wtd): Likewise.
+
+	* gengtype.h (enum write_types_kinds): New.
+	(struct type): Add field wrote_user_func_for_ptr to the "s"
+	union member.
+
 2014-05-13  Richard Sandiford  <r.sandiford@uk.ibm.com>
 
 	* fold-const.c (optimize_bit_field_compare): Use wi:: operations
Index: gcc/gengtype-parse.c
===================================================================
--- gcc/gengtype-parse.c	(revision 210378)
+++ gcc/gengtype-parse.c	(revision 210379)
@@ -197,18 +197,19 @@
   return v;
 }
 
-/* If the next token does not have one of the codes T1, T2 or T3, report a
+/* If the next token does not have one of the codes T1, T2, T3 or T4, report a
    parse error; otherwise return the token's value.  */
 static const char *
-require3 (int t1, int t2, int t3)
+require4 (int t1, int t2, int t3, int t4)
 {
   int u = token ();
   const char *v = advance ();
-  if (u != t1 && u != t2 && u != t3)
+  if (u != t1 && u != t2 && u != t3 && u != t4)
     {
-      parse_error ("expected %s, %s or %s, have %s",
+      parse_error ("expected %s, %s, %s or %s, have %s",
 		   print_token (t1, 0), print_token (t2, 0),
-		   print_token (t3, 0), print_token (u, v));
+		   print_token (t3, 0), print_token (t4, 0),
+		   print_token (u, v));
       return 0;
     }
   return v;
@@ -245,7 +246,9 @@
 
 /* The caller has detected a template declaration that starts
    with TMPL_NAME.  Parse up to the closing '>'.  This recognizes
-   simple template declarations of the form ID<ID1,ID2,...,IDn>.
+   simple template declarations of the form ID<ID1,ID2,...,IDn>,
+   potentially with a single level of indirection e.g.
+     ID<ID1 *, ID2, ID3 *, ..., IDn>.
    It does not try to parse anything more sophisticated than that.
 
    Returns the template declaration string "ID<ID1,ID2,...,IDn>".  */
@@ -254,6 +257,7 @@
 require_template_declaration (const char *tmpl_name)
 {
   char *str;
+  int num_indirections = 0;
 
   /* Recognize the opening '<'.  */
   require ('<');
@@ -294,9 +298,21 @@
 	  depth -= 1;
 	  continue;
 	}
-      const char *id = require3 (SCALAR, ID, ',');
+      const char *id = require4 (SCALAR, ID, '*', ',');
       if (id == NULL)
-	id = ",";
+	{
+	  if (T.code == '*')
+	    {
+	      id = "*";
+	      if (num_indirections++)
+		parse_error ("only one level of indirection is supported"
+			     " in template arguments");
+	    }
+	  else
+	    id = ",";
+	}
+      else
+	num_indirections = 0;
       str = concat (str, id, (char *) 0);
     }
   return str;