[patch 4/8] Simplify handling of scalar types

[Zack Weinberg <zackw at panix dot com>]

TYPE_SCALARs save their declared types as strings, but the only
thing this is used for is deciding whether to substitute TYPE_STRING
for an array or pointer type in adjust_field_type.  So replace it with
a boolean.  Also, rearrange data flow a little so that yylex passes
back a string rather than a type_p for the SCALAR terminal (after the
next patch, yylex will deal only in strings).

In case anyone is wondering, scalar_char and scalar_nonchar are fully
initialized at runtime rather than in their definitions because there is
no way in C90 to initialize any member of a union but the first.  We
wouldn't gain anything by it anyway - they can't be const because their
pointer_to fields may get filled out at some point.

	* gengtype.h (struct type): Replace 'sc' with boolean, scalar_is_char.
	(string_type): Don't declare.
	(do_scalar_typedef): Declare.
	(create_scalar_type): Update prototype.
	* gengtype.c (string_type): Make static.
	(scalar_nonchar, scalar_char): New.
	(do_scalar_typedef): Export.  Always use scalar_nonchar for the type.
	(resolve_typedef): Use scalar_nonchar for error recovery.
	(create_scalar_type): Remove name_len field.  Return scalar_char
	or scalar_nonchar as appropriate.
	(adjust_field_type): Look at scalar_is_char boolean to decide whether
	to use string_type.
	(throughout): Use scalar_nonchar instead of calling create_scalar_type,
	whenever possible.
	(main): Initialize scalar_char and scalar_nonchar before calling
	gen_rtx_next.
	* gengtype-lex.l: Adjust for removal of second argument to
	create_scalar_type.  Use yylval.s instead of yylval.t when
	returning SCALAR.
	* gengtype-yacc.y: Type of SCALAR is string.  Call
	create_scalar_type from type:SCALAR rule.  Adjust for removal of
	second argument to create_scalar_type.

Index: S-vn-gtsmall/gcc/gengtype.c
===================================================================
--- S-vn-gtsmall.orig/gcc/gengtype.c	2007-03-17 16:08:39.000000000 -0700
+++ S-vn-gtsmall/gcc/gengtype.c	2007-03-17 16:08:44.000000000 -0700
@@ -78,8 +78,18 @@
 
 /* The one and only TYPE_STRING.  */
 
-struct type string_type = {
-  TYPE_STRING, NULL, NULL, GC_USED, {0}
+static struct type string_type = {
+  TYPE_STRING, 0, 0, GC_USED, {0}
+};
+
+/* The two and only TYPE_SCALARs.  Their u.scalar_is_char flags are
+   set to appropriate values at the beginning of main.  */
+
+static struct type scalar_nonchar = {
+  TYPE_SCALAR, 0, 0, GC_USED, {0}
+};
+static struct type scalar_char = {
+  TYPE_SCALAR, 0, 0, GC_USED, {0}
 };
 
 /* Lists of various things.  */
@@ -89,7 +99,6 @@
 static type_p param_structs;
 static pair_p variables;
 
-static void do_scalar_typedef (const char *, struct fileloc *);
 static type_p find_param_structure
   (type_p t, type_p param[NUM_PARAM]);
 static type_p adjust_field_tree_exp (type_p t, options_p opt);
@@ -121,12 +130,14 @@
   typedefs = p;
 }
 
-/* Define S as a typename of a scalar.  */
+/* Define S as a typename of a scalar.  Cannot be used to define
+   typedefs of 'char'.  Note: is also used for pointer-to-function
+   typedefs (which are therefore not treated as pointers).  */
 
-static void
+void
 do_scalar_typedef (const char *s, struct fileloc *pos)
 {
-  do_typedef (s, create_scalar_type (s, strlen (s)), pos);
+  do_typedef (s, &scalar_nonchar, pos);
 }
 
 /* Return the type previously defined for S.  Use POS to report errors.  */
@@ -139,7 +150,7 @@
     if (strcmp (p->name, s) == 0)
       return p->type;
   error_at_line (pos, "unidentified type `%s'", s);
-  return create_scalar_type ("char", 4);
+  return &scalar_nonchar;  /* treat as "int" */
 }
 
 /* Create and return a new structure with tag NAME (or a union iff
@@ -269,12 +280,12 @@
 /* Return a scalar type with name NAME.  */
 
 type_p
-create_scalar_type (const char *name, size_t name_len)
+create_scalar_type (const char *name)
 {
-  type_p r = XCNEW (struct type);
-  r->kind = TYPE_SCALAR;
-  r->u.sc = (char *) xmemdup (name, name_len, name_len + 1);
-  return r;
+  if (!strcmp (name, "char") || !strcmp (name, "unsigned char"))
+    return &scalar_char;
+  else
+    return &scalar_nonchar;
 }
 
 /* Return a pointer to T.  */
@@ -499,7 +510,7 @@
   bitmap_tp = create_pointer (find_structure ("bitmap_element_def", 0));
   basic_block_tp = create_pointer (find_structure ("basic_block_def", 0));
   constant_tp = create_pointer (find_structure ("constant_descriptor_rtx", 0));
-  scalar_tp = create_scalar_type ("rtunion scalar", 14);
+  scalar_tp = &scalar_nonchar;  /* rtunion int */
 
   {
     pair_p note_flds = NULL;
@@ -796,13 +807,11 @@
   if (! length_p
       && pointer_p
       && t->u.p->kind == TYPE_SCALAR
-      && (strcmp (t->u.p->u.sc, "char") == 0
-	  || strcmp (t->u.p->u.sc, "unsigned char") == 0))
+      && t->u.p->u.scalar_is_char)
     return &string_type;
   if (t->kind == TYPE_ARRAY && t->u.a.p->kind == TYPE_POINTER
       && t->u.a.p->u.p->kind == TYPE_SCALAR
-      && (strcmp (t->u.a.p->u.p->u.sc, "char") == 0
-	  || strcmp (t->u.a.p->u.p->u.sc, "unsigned char") == 0))
+      && t->u.a.p->u.p->u.scalar_is_char)
     return create_array (&string_type, t->u.a.len);
 
   return t;
@@ -3015,7 +3024,7 @@
 
   if (is_scalar)
     {
-      t = create_scalar_type (typename, strlen (typename));
+      t = create_scalar_type (typename);
       o = 0;
     }
   else
@@ -3034,7 +3043,7 @@
   fields = f;
 
   f = XNEW (struct pair);
-  f->type = adjust_field_type (create_scalar_type ("unsigned", 8), 0);
+  f->type = adjust_field_type (create_scalar_type ("unsigned"), 0);
   f->name = "alloc";
   f->opt = 0;
   f->line = *pos;
@@ -3042,7 +3051,7 @@
   fields = f;
 
   f = XNEW (struct pair);
-  f->type = adjust_field_type (create_scalar_type ("unsigned", 8), 0);
+  f->type = adjust_field_type (create_scalar_type ("unsigned"), 0);
   f->name = "num";
   f->opt = 0;
   f->line = *pos;
@@ -3083,10 +3092,13 @@
   static struct fileloc pos = { __FILE__, __LINE__ };
   unsigned j;
 
-  gen_rtx_next ();
-
   srcdir_len = strlen (srcdir);
 
+  scalar_char.u.scalar_is_char = true;
+  scalar_nonchar.u.scalar_is_char = false;
+
+  gen_rtx_next ();
+
   do_scalar_typedef ("CUMULATIVE_ARGS", &pos);
   do_scalar_typedef ("REAL_VALUE_TYPE", &pos);
   do_scalar_typedef ("double_int", &pos);
@@ -3101,9 +3113,7 @@
 
   do_typedef ("PTR", create_pointer (resolve_typedef ("void", &pos)), &pos);
 
-  do_typedef ("HARD_REG_SET", create_array (
-	      create_scalar_type ("unsigned long", strlen ("unsigned long")),
-	      "2"), &pos);
+  do_typedef ("HARD_REG_SET", create_array (&scalar_nonchar, "2"), &pos);
 
   for (i = 0; i < NUM_GT_FILES; i++)
     {
Index: S-vn-gtsmall/gcc/gengtype.h
===================================================================
--- S-vn-gtsmall.orig/gcc/gengtype.h	2007-03-17 16:08:39.000000000 -0700
+++ S-vn-gtsmall/gcc/gengtype.h	2007-03-17 16:08:44.000000000 -0700
@@ -90,7 +90,7 @@
       lang_bitmap bitmap;
       type_p lang_struct;
     } s;
-    char *sc;
+    bool scalar_is_char;
     struct {
       type_p p;
       const char *len;
@@ -112,9 +112,6 @@
   || (x)->kind == TYPE_STRUCT 			\
   || (x)->kind == TYPE_LANG_STRUCT)
 
-/* The one and only TYPE_STRING.  */
-extern struct type string_type;
-
 /* Variables used to communicate between the lexer and the parser.  */
 extern int lexer_toplevel_done;
 extern struct fileloc lexer_line;
@@ -132,12 +129,13 @@
 
 /* Constructor routines for types.  */
 extern void do_typedef (const char *s, type_p t, struct fileloc *pos);
+extern void do_scalar_typedef (const char *s, struct fileloc *pos);
 extern type_p resolve_typedef (const char *s, struct fileloc *pos);
 extern type_p new_structure (const char *name, int isunion,
 			     struct fileloc *pos, pair_p fields,
 			     options_p o);
 extern type_p find_structure (const char *s, int isunion);
-extern type_p create_scalar_type (const char *name, size_t name_len);
+extern type_p create_scalar_type (const char *name);
 extern type_p create_pointer (type_p t);
 extern type_p create_array (type_p t, const char *len);
 extern options_p create_option (options_p, const char *name, const void *info);
Index: S-vn-gtsmall/gcc/gengtype-lex.l
===================================================================
--- S-vn-gtsmall.orig/gcc/gengtype-lex.l	2007-03-17 16:08:39.000000000 -0700
+++ S-vn-gtsmall/gcc/gengtype-lex.l	2007-03-17 16:08:44.000000000 -0700
@@ -95,7 +95,6 @@
 
   char *namestart;
   size_t namelen;
-  struct type *t;
   char *typestart;
   size_t typelen;
 
@@ -112,9 +111,10 @@
        ISSPACE (typestart[typelen-1]);
        typelen--)
     ;
+  typestart[typelen] = '\0';
 
-  t = create_scalar_type (typestart, typelen);
-  do_typedef ((const char *) xmemdup (namestart, namelen, namelen+1), t,
+  do_typedef ((const char *) xmemdup (namestart, namelen, namelen+1),
+  	      create_scalar_type (typestart),
 	      &lexer_line);
   update_lineno (yytext, yyleng);
 }
@@ -122,7 +122,6 @@
 [^[:alnum:]_]typedef{WS}{ID}{WS}{ID}{WS}"(" {
   char *namestart;
   size_t namelen;
-  struct type *t;
 
   for (namestart = yytext + yyleng - 2; ISSPACE (*namestart); namestart--)
     ;
@@ -130,16 +129,14 @@
     ;
   namestart -= namelen - 1;
 
-  t = create_scalar_type ("function type", sizeof ("function type")-1);
-  do_typedef ((const char *) xmemdup (namestart, namelen, namelen+1), t,
-	      &lexer_line);
+  do_scalar_typedef ((const char *) xmemdup (namestart, namelen, namelen+1),
+  		     &lexer_line);
   update_lineno (yytext, yyleng);
 }
 
 [^[:alnum:]_]typedef{WS}{ID}{WS}?"*"?{WS}?"("{WS}?"*"{WS}?{ID}{WS}?")"{WS}?"(" {
   char *namestart;
   size_t namelen;
-  struct type *t;
 
   for (namestart = yytext + yyleng - 2; !ISIDNUM (*namestart); namestart--)
     ;
@@ -147,9 +144,8 @@
     ;
   namestart -= namelen - 1;
 
-  t = create_scalar_type ("function type", sizeof ("function type")-1);
-  do_typedef ((const char *) xmemdup (namestart, namelen, namelen+1), t,
-	      &lexer_line);
+  do_scalar_typedef ((const char *) xmemdup (namestart, namelen, namelen+1),
+  		     &lexer_line);
   update_lineno (yytext, yyleng);
 }
 
@@ -264,7 +260,7 @@
   for (len = yyleng; ISSPACE (yytext[len-1]); len--)
     ;
 
-  yylval.t = create_scalar_type (yytext, len);
+  yylval.s = (const char *) xmemdup (yytext, len, len+1);
   update_lineno (yytext, yyleng);
   return SCALAR;
 }
Index: S-vn-gtsmall/gcc/gengtype-yacc.y
===================================================================
--- S-vn-gtsmall.orig/gcc/gengtype-yacc.y	2007-03-17 16:08:39.000000000 -0700
+++ S-vn-gtsmall/gcc/gengtype-yacc.y	2007-03-17 16:08:44.000000000 -0700
@@ -47,7 +47,7 @@
 %token NESTED_PTR
 %token <s>PARAM_IS
 %token NUM
-%token <t>SCALAR
+%token <s>SCALAR
 %token <s>ID
 %token <s>STRING
 %token <s>ARRAY
@@ -158,7 +158,7 @@
 	     ;
 
 type: SCALAR
-         { $$ = $1; }
+         { $$ = create_scalar_type ($1); }
       | ID
          { $$ = resolve_typedef ($1, &lexer_line); }
       | VEC_TOKEN '(' ID ',' ID ')'
@@ -175,9 +175,9 @@
       | UNION ID
          { $$ = find_structure ($2, 1); }
       | ENUM ID
-         { $$ = create_scalar_type ($2, strlen ($2)); }
+         { $$ = create_scalar_type ($2); }
       | ENUM ID '{' enum_items '}'
-         { $$ = create_scalar_type ($2, strlen ($2)); }
+         { $$ = create_scalar_type ($2); }
       ;
 
 enum_items: /* empty */

--