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Re: RFA/types: Clean up use of field bitsize


Does anyone have a comment on this patch?  If not, I'll commit it in a
couple of days, after I'm added to the global write list.

(The type code has no specific maintainer, the debug reader and
language parts I consider obvious, and the patch is over a month old
now.)
I'm mainly wondering if we're that desperate for memory space.

I thought a data structure was added to GDB so that it could spot duplicate type info and, hence, keep its memory size down.

Andrew


Right now, we have this really disturbing comment:

/* Size of this field, in bits, or zero if not packed.
For an unpacked field, the field's type's length
says how many bytes the field occupies.
A value of -1 or -2 indicates a static field; -1 means the location
is specified by the label loc.physname; -2 means that loc.physaddr
specifies the actual address. */

Think about this for a moment. While in practice a static member is never
going to be packed, and in at least C++ can not be a bit-field, that's not
logically obvious for other languages. I don't know Ada but I wouldn't be
surprised if there were some construct which violated this assumption.

Worse, all sorts of places don't check for negative bitsize at all. It may
be that they're all safe - I didn't spend a lot of time working out problem
cases - but I have my doubts.

So, since I needed to gain a new field here anyway, and since I have no
compunctions about shrinking this field a little (packed bitfields of size
greater than a couple of words are allowed in some languages IIRC (including
GNU C maybe? Although they are not allowed in ISO C99), but they're
definitely dodgy), and since signed bitfields are not portable, I cleaned up
the construct. It turned out to be painless except for making sure symbol
readers initialized it, which was a little tedious.

This patch:
Moves 'artificial' out from 'loc' and makes it a bitfield
Creates a 'static_kind' bitfield
Makes 'bitsize' into a bitfield

The goal is to allow more kinds of fields to be marked artificial -
particularly data members. After this patch I'll submit the followup to
mark DW_AT_artificial members as artificial types.

OK?

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer

2002-09-29 Daniel Jacobowitz <drow@mvista.com>

* gdbtypes.h (struct main_type): Move artificial flag out of
loc. New member of ``struct field'' named static_kind. Reduce
overloaded meaning of bitsize.
(FIELD_ARTIFICIAL, SET_FIELD_PHYSNAME, SET_FIELD_PHYSADDR)
(TYPE_FIELD_STATIC, TYPE_FIELD_STATIC_HAS_ADDR): Likewise.
(FIELD_STATIC_KIND, TYPE_FIELD_STATIC_KIND): New macros.

* ada-lang.c (fill_in_ada_prototype): Initialize static_kind for
new fields.
(template_to_fixed_record_type, template_to_static_fixed_type)
(to_record_with_fixed_variant_part): Likewise.
* coffread.c (coff_read_struct_type, coff_read_enum_type): Likewise.
* dwarf2read.c (dwarf2_add_field, read_enumeration): Likewise.
* dwarfread.c (struct_type, enum_type): Likewise.
* hpread.c (hpread_read_enum_type)
(hpread_read_function_type, hpread_read_doc_function_type)
(hpread_read_struct_type): Likewise.
* mdebugread.c (parse_symbol): Likewise.

Index: ada-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/ada-lang.c,v
retrieving revision 1.9
diff -u -p -r1.9 ada-lang.c
--- ada-lang.c 8 Sep 2002 17:43:26 -0000 1.9
+++ ada-lang.c 30 Sep 2002 00:43:30 -0000
@@ -4189,6 +4189,7 @@ fill_in_ada_prototype (struct symbol *fu
case LOC_REGPARM_ADDR:
TYPE_FIELD_BITPOS (ftype, nargs) = nargs;
TYPE_FIELD_BITSIZE (ftype, nargs) = 0;
+ TYPE_FIELD_STATIC_KIND (ftype, nargs) = 0;
TYPE_FIELD_TYPE (ftype, nargs) =
lookup_pointer_type (check_typedef (SYMBOL_TYPE (sym)));
TYPE_FIELD_NAME (ftype, nargs) = SYMBOL_NAME (sym);
@@ -4202,6 +4203,7 @@ fill_in_ada_prototype (struct symbol *fu
case LOC_BASEREG_ARG:
TYPE_FIELD_BITPOS (ftype, nargs) = nargs;
TYPE_FIELD_BITSIZE (ftype, nargs) = 0;
+ TYPE_FIELD_STATIC_KIND (ftype, nargs) = 0;
TYPE_FIELD_TYPE (ftype, nargs) = check_typedef (SYMBOL_TYPE (sym));
TYPE_FIELD_NAME (ftype, nargs) = SYMBOL_NAME (sym);
nargs += 1;
@@ -6046,6 +6048,7 @@ template_to_fixed_record_type (struct ty
* rediscover why we needed field_offset and fix it properly. */
TYPE_FIELD_BITPOS (rtype, f) = off;
TYPE_FIELD_BITSIZE (rtype, f) = 0;
+ TYPE_FIELD_STATIC_KIND (rtype, f) = 0;
if (ada_is_variant_part (type, f))
{
@@ -6149,6 +6152,7 @@ template_to_static_fixed_type (struct ty
{
TYPE_FIELD_BITPOS (type, f) = 0;
TYPE_FIELD_BITSIZE (type, f) = 0;
+ TYPE_FIELD_STATIC_KIND (type, f) = 0;
if (is_dynamic_field (templ_type, f))
{
@@ -6218,6 +6222,7 @@ to_record_with_fixed_variant_part (struc
TYPE_FIELD_TYPE (rtype, nfields - 1) = branch_type;
TYPE_FIELD_NAME (rtype, nfields - 1) = "S";
TYPE_FIELD_BITSIZE (rtype, nfields - 1) = 0;
+ TYPE_FIELD_STATIC_KIND (rtype, nfields - 1) = 0;
TYPE_LENGTH (rtype) += TYPE_LENGTH (branch_type);
-TYPE_LENGTH (TYPE_FIELD_TYPE (type, nfields - 1));
}
Index: coffread.c
===================================================================
RCS file: /cvs/src/src/gdb/coffread.c,v
retrieving revision 1.29
diff -u -p -r1.29 coffread.c
--- coffread.c 22 Aug 2002 05:50:11 -0000 1.29
+++ coffread.c 30 Sep 2002 00:43:30 -0000
@@ -1997,6 +1997,7 @@ coff_read_struct_type (int index, int le
FIELD_TYPE (list->field) = decode_type (ms, ms->c_type, &sub_aux);
FIELD_BITPOS (list->field) = 8 * ms->c_value;
FIELD_BITSIZE (list->field) = 0;
+ FIELD_STATIC_KIND (list->field) = 0;
nfields++;
break;
@@ -2015,6 +2016,7 @@ coff_read_struct_type (int index, int le
FIELD_TYPE (list->field) = decode_type (ms, ms->c_type, &sub_aux);
FIELD_BITPOS (list->field) = ms->c_value;
FIELD_BITSIZE (list->field) = sub_aux.x_sym.x_misc.x_lnsz.x_size;
+ FIELD_STATIC_KIND (list->field) = 0;
nfields++;
break;
@@ -2135,6 +2137,7 @@ coff_read_enum_type (int index, int leng
if (SYMBOL_VALUE (xsym) < 0)
unsigned_enum = 0;
TYPE_FIELD_BITSIZE (type, n) = 0;
+ TYPE_FIELD_STATIC_KIND (type, n) = 0;
}
if (syms == osyms)
break;
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.66
diff -u -p -r1.66 dwarf2read.c
--- dwarf2read.c 3 Sep 2002 17:32:11 -0000 1.66
+++ dwarf2read.c 30 Sep 2002 00:43:33 -0000
@@ -2055,6 +2055,8 @@ dwarf2_add_field (struct field_info *fip
/* Get type of field. */
fp->type = die_type (die, objfile, cu_header);
+ FIELD_STATIC_KIND (*fp) = 0;
+
/* Get bit size of field (zero if none). */
attr = dwarf_attr (die, DW_AT_bit_size);
if (attr)
@@ -2163,6 +2165,7 @@ dwarf2_add_field (struct field_info *fip
FIELD_BITPOS (*fp) = (decode_locdesc (DW_BLOCK (attr), objfile, cu_header)
* bits_per_byte);
FIELD_BITSIZE (*fp) = 0;
+ FIELD_STATIC_KIND (*fp) = 0;
FIELD_TYPE (*fp) = die_type (die, objfile, cu_header);
FIELD_NAME (*fp) = type_name_no_tag (fp->type);
fip->nbaseclasses++;
@@ -2667,6 +2670,7 @@ read_enumeration (struct die_info *die, FIELD_TYPE (fields[num_fields]) = NULL;
FIELD_BITPOS (fields[num_fields]) = SYMBOL_VALUE (sym);
FIELD_BITSIZE (fields[num_fields]) = 0;
+ FIELD_STATIC_KIND (fields[num_fields]) = 0;
num_fields++;
}
Index: dwarfread.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarfread.c,v
retrieving revision 1.14
diff -u -p -r1.14 dwarfread.c
--- dwarfread.c 1 Aug 2002 17:18:32 -0000 1.14
+++ dwarfread.c 30 Sep 2002 00:43:33 -0000
@@ -1027,6 +1027,7 @@ struct_type (struct dieinfo *dip, char *
&objfile->type_obstack);
FIELD_TYPE (list->field) = decode_die_type (&mbr);
FIELD_BITPOS (list->field) = 8 * locval (&mbr);
+ FIELD_STATIC_KIND (list->field) = 0;
/* Handle bit fields. */
FIELD_BITSIZE (list->field) = mbr.at_bit_size;
if (BITS_BIG_ENDIAN)
@@ -1694,6 +1695,7 @@ enum_type (struct dieinfo *dip, struct o
list = new;
FIELD_TYPE (list->field) = NULL;
FIELD_BITSIZE (list->field) = 0;
+ FIELD_STATIC_KIND (list->field) = 0;
FIELD_BITPOS (list->field) =
target_to_host (scan, TARGET_FT_LONG_SIZE (objfile), GET_SIGNED,
objfile);
Index: gdbtypes.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbtypes.h,v
retrieving revision 1.36
diff -u -p -r1.36 gdbtypes.h
--- gdbtypes.h 14 Sep 2002 02:09:39 -0000 1.36
+++ gdbtypes.h 30 Sep 2002 00:43:34 -0000
@@ -381,22 +381,25 @@ struct main_type
CORE_ADDR physaddr;
char *physname;
-
- /* For a function or member type, this is 1 if the argument is marked
- artificial. Artificial arguments should not be shown to the
- user. */
- int artificial;
}
loc;
+ /* For a function or member type, this is 1 if the argument is marked
+ artificial. Artificial arguments should not be shown to the
+ user. */
+ unsigned int artificial : 1;
+
+ /* This flag is zero for non-static fields, 1 for fields whose location
+ is specified by the label loc.physname, and 2 for fields whose location
+ is specified by loc.physaddr. */
+
+ unsigned int static_kind : 2;
+
/* Size of this field, in bits, or zero if not packed.
For an unpacked field, the field's type's length
- says how many bytes the field occupies.
- A value of -1 or -2 indicates a static field; -1 means the location
- is specified by the label loc.physname; -2 means that loc.physaddr
- specifies the actual address. */
+ says how many bytes the field occupies. */
- int bitsize;
+ unsigned int bitsize : 29;
/* In a struct or union type, type of this field.
In a function or member type, type of this argument.
@@ -793,14 +796,15 @@ extern void allocate_cplus_struct_type (
#define FIELD_TYPE(thisfld) ((thisfld).type)
#define FIELD_NAME(thisfld) ((thisfld).name)
#define FIELD_BITPOS(thisfld) ((thisfld).loc.bitpos)
-#define FIELD_ARTIFICIAL(thisfld) ((thisfld).loc.artificial)
+#define FIELD_ARTIFICIAL(thisfld) ((thisfld).artificial)
#define FIELD_BITSIZE(thisfld) ((thisfld).bitsize)
+#define FIELD_STATIC_KIND(thisfld) ((thisfld).static_kind)
#define FIELD_PHYSNAME(thisfld) ((thisfld).loc.physname)
#define FIELD_PHYSADDR(thisfld) ((thisfld).loc.physaddr)
#define SET_FIELD_PHYSNAME(thisfld, name) \
- ((thisfld).bitsize = -1, FIELD_PHYSNAME(thisfld) = (name))
+ ((thisfld).static_kind = 1, FIELD_PHYSNAME(thisfld) = (name))
#define SET_FIELD_PHYSADDR(thisfld, name) \
- ((thisfld).bitsize = -2, FIELD_PHYSADDR(thisfld) = (name))
+ ((thisfld).static_kind = 2, FIELD_PHYSADDR(thisfld) = (name))
#define TYPE_FIELD(thistype, n) TYPE_MAIN_TYPE(thistype)->fields[n]
#define TYPE_FIELD_TYPE(thistype, n) FIELD_TYPE(TYPE_FIELD(thistype, n))
#define TYPE_FIELD_NAME(thistype, n) FIELD_NAME(TYPE_FIELD(thistype, n))
@@ -840,8 +844,9 @@ extern void allocate_cplus_struct_type (
(TYPE_CPLUS_SPECIFIC(thistype)->virtual_field_bits == NULL ? 0 \
: B_TST(TYPE_CPLUS_SPECIFIC(thistype)->virtual_field_bits, (n)))
-#define TYPE_FIELD_STATIC(thistype, n) (TYPE_MAIN_TYPE (thistype)->fields[n].bitsize < 0)
-#define TYPE_FIELD_STATIC_HAS_ADDR(thistype, n) (TYPE_MAIN_TYPE (thistype)->fields[n].bitsize == -2)
+#define TYPE_FIELD_STATIC(thistype, n) (TYPE_MAIN_TYPE (thistype)->fields[n].static_kind != 0)
+#define TYPE_FIELD_STATIC_KIND(thistype, n) TYPE_MAIN_TYPE (thistype)->fields[n].static_kind
+#define TYPE_FIELD_STATIC_HAS_ADDR(thistype, n) (TYPE_MAIN_TYPE (thistype)->fields[n].static_kind == 2)
#define TYPE_FIELD_STATIC_PHYSNAME(thistype, n) FIELD_PHYSNAME(TYPE_FIELD(thistype, n))
#define TYPE_FIELD_STATIC_PHYSADDR(thistype, n) FIELD_PHYSADDR(TYPE_FIELD(thistype, n))
Index: hpread.c
===================================================================
RCS file: /cvs/src/src/gdb/hpread.c,v
retrieving revision 1.22
diff -u -p -r1.22 hpread.c
--- hpread.c 4 Aug 2002 19:11:12 -0000 1.22
+++ hpread.c 30 Sep 2002 00:43:35 -0000
@@ -3186,6 +3186,7 @@ hpread_read_enum_type (dnttpointer hp_ty
TYPE_FIELD_NAME (type, n) = SYMBOL_NAME (xsym);
TYPE_FIELD_BITPOS (type, n) = SYMBOL_VALUE (xsym);
TYPE_FIELD_BITSIZE (type, n) = 0;
+ TYPE_FIELD_STATIC_KIND (type, n) = 0;
}
if (syms == osyms)
break;
@@ -3347,6 +3348,7 @@ hpread_read_function_type (dnttpointer h
TYPE_FIELD_TYPE (type, n) = SYMBOL_TYPE (xsym);
TYPE_FIELD_ARTIFICIAL (type, n) = 0;
TYPE_FIELD_BITSIZE (type, n) = 0;
+ TYPE_FIELD_STATIC_KIND (type, n) = 0;
}
}
/* Mark it as having been processed */
@@ -3520,6 +3522,7 @@ hpread_read_doc_function_type (dnttpoint
TYPE_FIELD_TYPE (type, n) = SYMBOL_TYPE (xsym);
TYPE_FIELD_ARTIFICIAL (type, n) = 0;
TYPE_FIELD_BITSIZE (type, n) = 0;
+ TYPE_FIELD_STATIC_KIND (type, n) = 0;
}
}
@@ -3704,6 +3707,7 @@ hpread_read_struct_type (dnttpointer hp_
list = new;
FIELD_BITSIZE (list->field) = 0;
+ FIELD_STATIC_KIND (list->field) = 0;
/* The "classname" field is actually a DNTT pointer to the base class */
baseclass = hpread_type_lookup (parentp->dinheritance.classname,
@@ -4101,6 +4105,7 @@ hpread_read_struct_type (dnttpointer hp_
list->field.name = VT (objfile) + fn_fieldp->dsvar.name;
FIELD_BITPOS (list->field) = 0; /* FIXME is this always true? */
FIELD_BITSIZE (list->field) = 0; /* use length from type */
+ FIELD_STATIC_KIND (list->field) = 0;
memtype = hpread_type_lookup (fn_fieldp->dsvar.type, objfile);
list->field.type = memtype;
list->attributes = 0;
@@ -4120,6 +4125,7 @@ hpread_read_struct_type (dnttpointer hp_
list->field.name = VT (objfile) + fn_fieldp->ddvar.name;
FIELD_BITPOS (list->field) = 0; /* FIXME is this always true? */
FIELD_BITSIZE (list->field) = 0; /* use length from type */
+ FIELD_STATIC_KIND (list->field) = 0;
memtype = hpread_type_lookup (fn_fieldp->ddvar.type, objfile);
list->field.type = memtype;
list->attributes = 0;
@@ -4168,6 +4174,7 @@ hpread_read_struct_type (dnttpointer hp_
/* A FIELD by itself (without a GENFIELD) can also be a static member */
+ FIELD_STATIC_KIND (list->field) = 0;
if (fieldp->dfield.staticmem)
{
FIELD_BITPOS (list->field) = -1;
Index: mdebugread.c
===================================================================
RCS file: /cvs/src/src/gdb/mdebugread.c,v
retrieving revision 1.29
diff -u -p -r1.29 mdebugread.c
--- mdebugread.c 18 Sep 2002 20:47:39 -0000 1.29
+++ mdebugread.c 30 Sep 2002 00:43:36 -0000
@@ -1092,6 +1092,7 @@ parse_symbol (SYMR *sh, union aux_ext *a
FIELD_TYPE (*f) = t;
FIELD_NAME (*f) = debug_info->ss + cur_fdr->issBase + tsym.iss;
FIELD_BITSIZE (*f) = 0;
+ FIELD_STATIC_KIND (*f) = 0;
enum_sym = ((struct symbol *)
obstack_alloc (&current_objfile->symbol_obstack,
@@ -1284,6 +1285,7 @@ parse_symbol (SYMR *sh, union aux_ext *a
bitsize = 0;
FIELD_TYPE (*f) = parse_type (cur_fd, ax, sh->index, &bitsize, bigend, name);
FIELD_BITSIZE (*f) = bitsize;
+ FIELD_STATIC_KIND (*f) = 0;
break;
case stIndirect: /* forward declaration on Irix5 */


-- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer


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