Re: [PATCH] dwarf2out: Stop using wide_int in GC structures
On Tue, 10 Oct 2023, Jakub Jelinek wrote:
> Hi!
>
> On Tue, Oct 10, 2023 at 09:30:31AM +, 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
>
> * 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.jj2023-10-09 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
[PATCH] dwarf2out: Stop using wide_int in GC structures
Hi!
On Tue, Oct 10, 2023 at 09:30:31AM +, 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?
2023-10-10 Jakub Jelinek
* 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.cc2023-10-09 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)
-
