[gimplefe] The symbol table for declarations

Hi,
The following patch is a basic attempt to build a symbol table that
stores the names of all the declarations made in the input file.

   next_token = gl_consume_token (parser->lexer);
@@ -981,6 +1027,7 @@
   gimple_parser *parser = ggc_alloc_cleared_gimple_parser ();
   line_table = parser->line_table = ggc_alloc_cleared_line_maps ();
   parser->ident_hash = ident_hash;
+
   linemap_init (parser->line_table);
   parser->lexer = gl_init (parser, fname);

@@ -1403,6 +1450,9 @@
   if (parser->lexer->filename == NULL)
     return;

+  gimple_symtab =
+    htab_create_ggc (1021, gimple_symtab_entry_hash,
+		     gimple_symtab_eq_hash, NULL);
   gl_lex (parser->lexer);
   gp_parse (parser);
   gp_finish (parser);

The changelog is as follows:

2011-10-11  Sandeep Soni  <soni.sandeepb@gmail.com>

	* parser.c : Include hashtab.h.
	(struct gimple_symtab_entry_def): New.
	(gimple_symtab): New. The symbol table.
	(gimple_symtab_entry_hash): New.
	(gimple_symtab_eq_hash): New.
	(gp_parse_var_decl): Build the declaration and put it in the symbol
	table.
	(gimple_main): Creates the symbol table

>>>>> "Sandeep" == Sandeep Soni <soni.sandeepb@gmail.com> writes:

Sandeep> The following patch is a basic attempt to build a symbol table that
Sandeep> stores the names of all the declarations made in the input file.

I don't know anything about gimplefe, but unless you have complicated
needs, it is more usual to just put a symbol's value directly into the
identifier node.  The C front end is a good example of this.

Tom

On Tue, Oct 11, 2011 at 09:42, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Sandeep" == Sandeep Soni <soni.sandeepb@gmail.com> writes:
>
> Sandeep> The following patch is a basic attempt to build a symbol table that
> Sandeep> stores the names of all the declarations made in the input file.
>
> I don't know anything about gimplefe, but unless you have complicated
> needs, it is more usual to just put a symbol's value directly into the
> identifier node.  The C front end is a good example of this.

Granted, but a central symbol table simplifies processing like
generating gimple output.  The gimple FE will want to emit a text file
with transformed gimple.


Diego.

On 11-10-10 17:47 , Sandeep Soni wrote:
> Hi,
> The following patch is a basic attempt to build a symbol table that
> stores the names of all the declarations made in the input file.
>
> Index: gcc/gimple/parser.c
> ===================================================================
> --- gcc/gimple/parser.c	(revision 174754)
> +++ gcc/gimple/parser.c	(working copy)
> @@ -28,6 +28,7 @@
>   #include "tree.h"
>   #include "gimple.h"
>   #include "parser.h"
> +#include "hashtab.h"
>   #include "ggc.h"
>
>   /* The GIMPLE parser.  Note: do not use this variable directly.  It is
> @@ -44,6 +45,43 @@
>   /* EOF token.  */
>   static gimple_token gl_eof_token = { CPP_EOF, 0, 0, 0 };
>
> +/* The GIMPLE symbol table entry.  */
> +
> +struct GTY (()) gimple_symtab_entry_def
> +{
> +  /* Variable that is declared.  */
> +  tree decl;
> +
> +};

No blank line before '};'

Add 'typedef struct gimple_symtab_entry_def gimple_symtab_entry;' to 
shorten declarations.

> +
> +/* Gimple symbol table.  */
> +static htab_t gimple_symtab;
> +
> +/* Return the hash value of the declaration name of a gimple_symtab_entry_def
> +   object pointed by ENTRY.  */
> +
> +static hashval_t
> +gimple_symtab_entry_hash (const void *entry)
> +{
> +  const struct gimple_symtab_entry_def *base =
> +    (const struct gimple_symtab_entry_def *)entry;
> +  return IDENTIFIER_HASH_VALUE (DECL_NAME(base->decl));

Space after DECL_NAME.

> +}
> +
> +/* Returns non-zero if ENTRY1 and ENTRY2 points to gimple_symtab_entry_def

s/points/point/

> +   objects corresponding to the same declaration.  */
> +
> +static int
> +gimple_symtab_eq_hash (const void *entry1, const void *entry2)
> +{
> +  const struct gimple_symtab_entry_def *p1 =
> +    (const struct gimple_symtab_entry_def *)entry1;
> +  const struct gimple_symtab_entry_def *p2 =
> +    (const struct gimple_symtab_entry_def *)entry2;
> +
> +  return DECL_NAME(p1->decl) == DECL_NAME(p2->decl);

Space after DECL_NAME.

> +}
> +
>   /* Return the string representation of token TOKEN.  */
>
>   static const char *
> @@ -807,6 +845,7 @@
>       }
>   }
>
> +
>   /* The Declaration section within a .gimple file can consist of
>      a) Declaration of variables.
>      b) Declaration of functions.
> @@ -870,11 +909,17 @@
>   static void
>   gp_parse_var_decl (gimple_parser *parser)
>   {
> -  const gimple_token *next_token;
> +  const gimple_token *next_token, *name_token;
> +  const char* name;

s/char* /char */

>     enum tree_code code ;
> +  struct gimple_symtab_entry_def e;
>
>     gl_consume_expected_token (parser->lexer, CPP_LESS);
> -  gl_consume_expected_token (parser->lexer, CPP_NAME);
> +  name_token = gl_consume_expected_token (parser->lexer, CPP_NAME);
> +  name = gl_token_as_text (name_token);
> +  e.decl =
> +  build_decl (UNKNOWN_LOCATION, VAR_DECL, get_identifier(name),
> void_type_node);

No need to use UNKNOWN_LOCATION.  Get the location for E.DECL from 
name_token.location.

Additionally, before building the decl, you should make sure that the 
symbol table does not already have it.  So, instead of looking up with a 
DECL, you should look it up using IDENTIFIER_NODEs.  There are two 
approaches you can use:

1- Add an identifier field to gimple_symtab_entry_def.  Use that field 
for hash table lookups (in this code you'd then fill E.ID with NAME_TOKEN).

2- Use a pointer_map_t and a VEC().  With this approach, you use a 
pointer map to map identifier nodes to unsigned integers.  These 
integers are the index into the VEC() array where the corresponding decl 
is stored.

In this case, I think #1 is the simplest approach.

> +  htab_find_slot (gimple_symtab,&e, INSERT);

This looks wrong.  Where are you actually filling in the slot?  You need 
to check the returned slot, if it's empty, you fill it in with E.DECL. 
See other uses of htab_*.

>     gl_consume_expected_token (parser->lexer, CPP_COMMA);
>
>     next_token = gl_consume_token (parser->lexer);
> @@ -981,6 +1027,7 @@
>     gimple_parser *parser = ggc_alloc_cleared_gimple_parser ();
>     line_table = parser->line_table = ggc_alloc_cleared_line_maps ();
>     parser->ident_hash = ident_hash;
> +
>     linemap_init (parser->line_table);
>     parser->lexer = gl_init (parser, fname);
>
> @@ -1403,6 +1450,9 @@
>     if (parser->lexer->filename == NULL)
>       return;
>
> +  gimple_symtab =
> +    htab_create_ggc (1021, gimple_symtab_entry_hash,
> +		     gimple_symtab_eq_hash, NULL);

Do you need to indent it this way?  Seems to me that the call to 
htab_create_ggc can fit in the line above.


Diego.