On Tue, 10 Oct 2023, Jakub Jelinek wrote:
> Hi!
>
> On Tue, Oct 10, 2023 at 09:30:31AM +0000, Richard Biener wrote:
> > On Mon, 9 Oct 2023, Jakub Jelinek wrote:
> > > > This makes wide_int unusable in GC structures, so for dwarf2out
> > > > which was the only place which needed it there is a new rwide_int type
> > > > (restricted wide_int) which supports only up to RWIDE_INT_MAX_ELTS limbs
> > > > inline and is trivially copyable (dwarf2out should never deal with large
> > > > _BitInt constants, those should have been lowered earlier).
> > >
> > > As discussed on IRC, the dwarf2out.{h,cc} needs are actually quite
> > > limited,
> > > it just needs to allocate new GC structures val_wide points to
> > > (constructed
> > > from some const wide_int_ref &) and needs to call operator==,
> > > get_precision, elt, get_len and get_val methods on it.
> > > Even trailing_wide_int would be overkill for that, the following just adds
> > > a new struct with precision/len and trailing val array members and
> > > implements the needed methods (only 2 of them using wide_int_ref
> > > constructed
> > > from those).
> > >
> > > Incremental patch, so far compile time tested only:
> >
> > LGTM, wonder if we can push this separately as prerequesite?
>
> Here it is as a separate independent patch. Even without the
> wide_int changing patch it should save some memory, by not always
> allocating room for 9 limbs, but say just the 2/3 or how many we actually
> need. And, another advantage is that if we really need it at some point,
> it could support even more than 9 limbs if it is created from a wide_int_ref
> with get_len () > 9.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK by me if Jason doesn't object.
Thanks,
Richard.
> 2023-10-10 Jakub Jelinek <ja...@redhat.com>
>
> * dwarf2out.h (wide_int_ptr): Remove.
> (dw_wide_int_ptr): New typedef.
> (struct dw_val_node): Change type of val_wide from wide_int_ptr
> to dw_wide_int_ptr.
> (struct dw_wide_int): New type.
> (dw_wide_int::elt): New method.
> (dw_wide_int::operator ==): Likewise.
> * dwarf2out.cc (get_full_len): Change argument type to
> const dw_wide_int & from const wide_int &. Use CEIL. Call
> get_precision method instead of calling wi::get_precision.
> (alloc_dw_wide_int): New function.
> (add_AT_wide): Change w argument type to const wide_int_ref &
> from const wide_int &. Use alloc_dw_wide_int.
> (mem_loc_descriptor, loc_descriptor): Use alloc_dw_wide_int.
> (insert_wide_int): Change val argument type to const wide_int_ref &
> from const wide_int &.
> (add_const_value_attribute): Pass rtx_mode_t temporary directly to
> add_AT_wide instead of using a temporary variable.
>
> --- gcc/dwarf2out.h.jj 2023-10-09 14:37:45.890939965 +0200
> +++ gcc/dwarf2out.h 2023-10-09 16:46:14.705816928 +0200
> @@ -30,7 +30,7 @@ typedef struct dw_cfi_node *dw_cfi_ref;
> typedef struct dw_loc_descr_node *dw_loc_descr_ref;
> typedef struct dw_loc_list_struct *dw_loc_list_ref;
> typedef struct dw_discr_list_node *dw_discr_list_ref;
> -typedef wide_int *wide_int_ptr;
> +typedef struct dw_wide_int *dw_wide_int_ptr;
>
>
> /* Call frames are described using a sequence of Call Frame
> @@ -252,7 +252,7 @@ struct GTY(()) dw_val_node {
> unsigned HOST_WIDE_INT
> GTY ((tag ("dw_val_class_unsigned_const"))) val_unsigned;
> double_int GTY ((tag ("dw_val_class_const_double"))) val_double;
> - wide_int_ptr GTY ((tag ("dw_val_class_wide_int"))) val_wide;
> + dw_wide_int_ptr GTY ((tag ("dw_val_class_wide_int"))) val_wide;
> dw_vec_const GTY ((tag ("dw_val_class_vec"))) val_vec;
> struct dw_val_die_union
> {
> @@ -313,6 +313,35 @@ struct GTY(()) dw_discr_list_node {
> int dw_discr_range;
> };
>
> +struct GTY((variable_size)) dw_wide_int {
> + unsigned int precision;
> + unsigned int len;
> + HOST_WIDE_INT val[1];
> +
> + unsigned int get_precision () const { return precision; }
> + unsigned int get_len () const { return len; }
> + const HOST_WIDE_INT *get_val () const { return val; }
> + inline HOST_WIDE_INT elt (unsigned int) const;
> + inline bool operator == (const dw_wide_int &) const;
> +};
> +
> +inline HOST_WIDE_INT
> +dw_wide_int::elt (unsigned int i) const
> +{
> + if (i < len)
> + return val[i];
> + wide_int_ref ref = wi::storage_ref (val, len, precision);
> + return wi::sign_mask (ref);
> +}
> +
> +inline bool
> +dw_wide_int::operator == (const dw_wide_int &o) const
> +{
> + wide_int_ref ref1 = wi::storage_ref (val, len, precision);
> + wide_int_ref ref2 = wi::storage_ref (o.val, o.len, o.precision);
> + return ref1 == ref2;
> +}
> +
> /* Interface from dwarf2out.cc to dwarf2cfi.cc. */
> extern struct dw_loc_descr_node *build_cfa_loc
> (dw_cfa_location *, poly_int64);
> --- gcc/dwarf2out.cc.jj 2023-10-09 14:37:45.894939909 +0200
> +++ gcc/dwarf2out.cc 2023-10-09 16:48:24.565014459 +0200
> @@ -397,11 +397,9 @@ dump_struct_debug (tree type, enum debug
> of the number. */
>
> static unsigned int
> -get_full_len (const wide_int &op)
> +get_full_len (const dw_wide_int &op)
> {
> - int prec = wi::get_precision (op);
> - return ((prec + HOST_BITS_PER_WIDE_INT - 1)
> - / HOST_BITS_PER_WIDE_INT);
> + return CEIL (op.get_precision (), HOST_BITS_PER_WIDE_INT);
> }
>
> static bool
> @@ -3900,7 +3898,7 @@ static void add_data_member_location_att
> struct vlr_context *);
> static bool add_const_value_attribute (dw_die_ref, machine_mode, rtx);
> static void insert_int (HOST_WIDE_INT, unsigned, unsigned char *);
> -static void insert_wide_int (const wide_int &, unsigned char *, int);
> +static void insert_wide_int (const wide_int_ref &, unsigned char *, int);
> static unsigned insert_float (const_rtx, unsigned char *);
> static rtx rtl_for_decl_location (tree);
> static bool add_location_or_const_value_attribute (dw_die_ref, tree, bool);
> @@ -4594,19 +4592,31 @@ AT_unsigned (dw_attr_node *a)
> return a->dw_attr_val.v.val_unsigned;
> }
>
> +dw_wide_int *
> +alloc_dw_wide_int (const wide_int_ref &w)
> +{
> + dw_wide_int *p
> + = (dw_wide_int *) ggc_internal_alloc (sizeof (dw_wide_int)
> + + ((w.get_len () - 1)
> + * sizeof (HOST_WIDE_INT)));
> + p->precision = w.get_precision ();
> + p->len = w.get_len ();
> + memcpy (p->val, w.get_val (), p->len * sizeof (HOST_WIDE_INT));
> + return p;
> +}
> +
> /* Add an unsigned wide integer attribute value to a DIE. */
>
> static inline void
> add_AT_wide (dw_die_ref die, enum dwarf_attribute attr_kind,
> - const wide_int& w)
> + const wide_int_ref &w)
> {
> dw_attr_node attr;
>
> attr.dw_attr = attr_kind;
> attr.dw_attr_val.val_class = dw_val_class_wide_int;
> attr.dw_attr_val.val_entry = NULL;
> - attr.dw_attr_val.v.val_wide = ggc_alloc<wide_int> ();
> - *attr.dw_attr_val.v.val_wide = w;
> + attr.dw_attr_val.v.val_wide = alloc_dw_wide_int (w);
> add_dwarf_attr (die, &attr);
> }
>
> @@ -16714,8 +16724,8 @@ mem_loc_descriptor (rtx rtl, machine_mod
> mem_loc_result->dw_loc_oprnd1.v.val_die_ref.external = 0;
> mem_loc_result->dw_loc_oprnd2.val_class
> = dw_val_class_wide_int;
> - mem_loc_result->dw_loc_oprnd2.v.val_wide = ggc_alloc<wide_int> ();
> - *mem_loc_result->dw_loc_oprnd2.v.val_wide = rtx_mode_t (rtl, mode);
> + mem_loc_result->dw_loc_oprnd2.v.val_wide
> + = alloc_dw_wide_int (rtx_mode_t (rtl, mode));
> }
> break;
>
> @@ -17288,8 +17298,8 @@ loc_descriptor (rtx rtl, machine_mode mo
> loc_result = new_loc_descr (DW_OP_implicit_value,
> GET_MODE_SIZE (int_mode), 0);
> loc_result->dw_loc_oprnd2.val_class = dw_val_class_wide_int;
> - loc_result->dw_loc_oprnd2.v.val_wide = ggc_alloc<wide_int> ();
> - *loc_result->dw_loc_oprnd2.v.val_wide = rtx_mode_t (rtl, int_mode);
> + loc_result->dw_loc_oprnd2.v.val_wide
> + = alloc_dw_wide_int (rtx_mode_t (rtl, int_mode));
> }
> break;
>
> @@ -20189,7 +20199,7 @@ extract_int (const unsigned char *src, u
> /* Writes wide_int values to dw_vec_const array. */
>
> static void
> -insert_wide_int (const wide_int &val, unsigned char *dest, int elt_size)
> +insert_wide_int (const wide_int_ref &val, unsigned char *dest, int elt_size)
> {
> int i;
>
> @@ -20274,8 +20284,7 @@ add_const_value_attribute (dw_die_ref di
> && (GET_MODE_PRECISION (int_mode)
> & (HOST_BITS_PER_WIDE_INT - 1)) == 0)
> {
> - wide_int w = rtx_mode_t (rtl, int_mode);
> - add_AT_wide (die, DW_AT_const_value, w);
> + add_AT_wide (die, DW_AT_const_value, rtx_mode_t (rtl, int_mode));
> return true;
> }
> return false;
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
