* [PATCH] c++: use auto_vec in cp_parser_template_argument_list
@ 2021-11-09 16:02 Patrick Palka
2021-11-09 16:59 ` Jason Merrill
0 siblings, 1 reply; 5+ messages in thread
From: Patrick Palka @ 2021-11-09 16:02 UTC (permalink / raw)
To: gcc-patches
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
gcc/cp/ChangeLog:
* parser.c (cp_parser_template_argument_list): Use auto_vec
instead of manual memory management.
---
gcc/cp/parser.c | 35 ++++++++---------------------------
1 file changed, 8 insertions(+), 27 deletions(-)
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 32de97b08bd..8823399529e 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser,
static tree
cp_parser_template_argument_list (cp_parser* parser)
{
- tree fixed_args[10];
- unsigned n_args = 0;
- unsigned alloced = 10;
- tree *arg_ary = fixed_args;
- tree vec;
bool saved_in_template_argument_list_p;
bool saved_ice_p;
bool saved_non_ice_p;
@@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser* parser)
parser->non_integral_constant_expression_p = false;
/* Parse the arguments. */
+ auto_vec<tree, 10> args;
do
{
- tree argument;
-
- if (n_args)
+ if (!args.is_empty ())
/* Consume the comma. */
cp_lexer_consume_token (parser->lexer);
/* Parse the template-argument. */
- argument = cp_parser_template_argument (parser);
+ tree argument = cp_parser_template_argument (parser);
/* If the next token is an ellipsis, we're expanding a template
argument pack. */
@@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser* parser)
argument = make_pack_expansion (argument);
}
- if (n_args == alloced)
- {
- alloced *= 2;
-
- if (arg_ary == fixed_args)
- {
- arg_ary = XNEWVEC (tree, alloced);
- memcpy (arg_ary, fixed_args, sizeof (tree) * n_args);
- }
- else
- arg_ary = XRESIZEVEC (tree, arg_ary, alloced);
- }
- arg_ary[n_args++] = argument;
+ args.safe_push (argument);
}
while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA));
- vec = make_tree_vec (n_args);
+ int n_args = args.length ();
+ tree vec = make_tree_vec (n_args);
- while (n_args--)
- TREE_VEC_ELT (vec, n_args) = arg_ary[n_args];
+ for (int i = 0; i < n_args; i++)
+ TREE_VEC_ELT (vec, i) = args[i];
- if (arg_ary != fixed_args)
- free (arg_ary);
parser->non_integral_constant_expression_p = saved_non_ice_p;
parser->integral_constant_expression_p = saved_ice_p;
parser->in_template_argument_list_p = saved_in_template_argument_list_p;
--
2.34.0.rc1.14.g88d915a634
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: use auto_vec in cp_parser_template_argument_list
2021-11-09 16:02 [PATCH] c++: use auto_vec in cp_parser_template_argument_list Patrick Palka
@ 2021-11-09 16:59 ` Jason Merrill
2021-11-09 18:42 ` Patrick Palka
0 siblings, 1 reply; 5+ messages in thread
From: Jason Merrill @ 2021-11-09 16:59 UTC (permalink / raw)
To: Patrick Palka, gcc-patches
On 11/9/21 11:02, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
OK, though I wonder about using releasing_vec instead of auto_vec;
reusing a previously allocated vec vs. building one on the stack.
> gcc/cp/ChangeLog:
>
> * parser.c (cp_parser_template_argument_list): Use auto_vec
> instead of manual memory management.
> ---
> gcc/cp/parser.c | 35 ++++++++---------------------------
> 1 file changed, 8 insertions(+), 27 deletions(-)
>
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 32de97b08bd..8823399529e 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser,
> static tree
> cp_parser_template_argument_list (cp_parser* parser)
> {
> - tree fixed_args[10];
> - unsigned n_args = 0;
> - unsigned alloced = 10;
> - tree *arg_ary = fixed_args;
> - tree vec;
> bool saved_in_template_argument_list_p;
> bool saved_ice_p;
> bool saved_non_ice_p;
> @@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser* parser)
> parser->non_integral_constant_expression_p = false;
>
> /* Parse the arguments. */
> + auto_vec<tree, 10> args;
> do
> {
> - tree argument;
> -
> - if (n_args)
> + if (!args.is_empty ())
> /* Consume the comma. */
> cp_lexer_consume_token (parser->lexer);
>
> /* Parse the template-argument. */
> - argument = cp_parser_template_argument (parser);
> + tree argument = cp_parser_template_argument (parser);
>
> /* If the next token is an ellipsis, we're expanding a template
> argument pack. */
> @@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser* parser)
> argument = make_pack_expansion (argument);
> }
>
> - if (n_args == alloced)
> - {
> - alloced *= 2;
> -
> - if (arg_ary == fixed_args)
> - {
> - arg_ary = XNEWVEC (tree, alloced);
> - memcpy (arg_ary, fixed_args, sizeof (tree) * n_args);
> - }
> - else
> - arg_ary = XRESIZEVEC (tree, arg_ary, alloced);
> - }
> - arg_ary[n_args++] = argument;
> + args.safe_push (argument);
> }
> while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA));
>
> - vec = make_tree_vec (n_args);
> + int n_args = args.length ();
> + tree vec = make_tree_vec (n_args);
>
> - while (n_args--)
> - TREE_VEC_ELT (vec, n_args) = arg_ary[n_args];
> + for (int i = 0; i < n_args; i++)
> + TREE_VEC_ELT (vec, i) = args[i];
>
> - if (arg_ary != fixed_args)
> - free (arg_ary);
> parser->non_integral_constant_expression_p = saved_non_ice_p;
> parser->integral_constant_expression_p = saved_ice_p;
> parser->in_template_argument_list_p = saved_in_template_argument_list_p;
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: use auto_vec in cp_parser_template_argument_list
2021-11-09 16:59 ` Jason Merrill
@ 2021-11-09 18:42 ` Patrick Palka
2021-11-10 5:16 ` Jason Merrill
0 siblings, 1 reply; 5+ messages in thread
From: Patrick Palka @ 2021-11-09 18:42 UTC (permalink / raw)
To: Jason Merrill; +Cc: Patrick Palka, gcc-patches
On Tue, 9 Nov 2021, Jason Merrill wrote:
> On 11/9/21 11:02, Patrick Palka wrote:
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
>
> OK, though I wonder about using releasing_vec instead of auto_vec; reusing a
> previously allocated vec vs. building one on the stack.
Thanks a lot. And hmm, I think using reusing a previously allocated vec
here would be tricky since cp_parser_template_argument_list can be
called recursively, and so only the outermost call would be able to
benefit from reuse unless we perhaps maintain a freelist of such vecs
IIUC. Seems like that would complicate the code enough to not be worth
it.
> > gcc/cp/ChangeLog:
> >
> > * parser.c (cp_parser_template_argument_list): Use auto_vec
> > instead of manual memory management.
> > ---
> > gcc/cp/parser.c | 35 ++++++++---------------------------
> > 1 file changed, 8 insertions(+), 27 deletions(-)
> >
> > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> > index 32de97b08bd..8823399529e 100644
> > --- a/gcc/cp/parser.c
> > +++ b/gcc/cp/parser.c
> > @@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser,
> > static tree
> > cp_parser_template_argument_list (cp_parser* parser)
> > {
> > - tree fixed_args[10];
> > - unsigned n_args = 0;
> > - unsigned alloced = 10;
> > - tree *arg_ary = fixed_args;
> > - tree vec;
> > bool saved_in_template_argument_list_p;
> > bool saved_ice_p;
> > bool saved_non_ice_p;
> > @@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser*
> > parser)
> > parser->non_integral_constant_expression_p = false;
> > /* Parse the arguments. */
> > + auto_vec<tree, 10> args;
> > do
> > {
> > - tree argument;
> > -
> > - if (n_args)
> > + if (!args.is_empty ())
> > /* Consume the comma. */
> > cp_lexer_consume_token (parser->lexer);
> > /* Parse the template-argument. */
> > - argument = cp_parser_template_argument (parser);
> > + tree argument = cp_parser_template_argument (parser);
> > /* If the next token is an ellipsis, we're expanding a template
> > argument pack. */
> > @@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser*
> > parser)
> > argument = make_pack_expansion (argument);
> > }
> > - if (n_args == alloced)
> > - {
> > - alloced *= 2;
> > -
> > - if (arg_ary == fixed_args)
> > - {
> > - arg_ary = XNEWVEC (tree, alloced);
> > - memcpy (arg_ary, fixed_args, sizeof (tree) * n_args);
> > - }
> > - else
> > - arg_ary = XRESIZEVEC (tree, arg_ary, alloced);
> > - }
> > - arg_ary[n_args++] = argument;
> > + args.safe_push (argument);
> > }
> > while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA));
> > - vec = make_tree_vec (n_args);
> > + int n_args = args.length ();
> > + tree vec = make_tree_vec (n_args);
> > - while (n_args--)
> > - TREE_VEC_ELT (vec, n_args) = arg_ary[n_args];
> > + for (int i = 0; i < n_args; i++)
> > + TREE_VEC_ELT (vec, i) = args[i];
> > - if (arg_ary != fixed_args)
> > - free (arg_ary);
> > parser->non_integral_constant_expression_p = saved_non_ice_p;
> > parser->integral_constant_expression_p = saved_ice_p;
> > parser->in_template_argument_list_p = saved_in_template_argument_list_p;
> >
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: use auto_vec in cp_parser_template_argument_list
2021-11-09 18:42 ` Patrick Palka
@ 2021-11-10 5:16 ` Jason Merrill
2021-11-10 17:13 ` Patrick Palka
0 siblings, 1 reply; 5+ messages in thread
From: Jason Merrill @ 2021-11-10 5:16 UTC (permalink / raw)
To: Patrick Palka; +Cc: gcc-patches
On 11/9/21 13:42, Patrick Palka wrote:
> On Tue, 9 Nov 2021, Jason Merrill wrote:
>
>> On 11/9/21 11:02, Patrick Palka wrote:
>>> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
>>
>> OK, though I wonder about using releasing_vec instead of auto_vec; reusing a
>> previously allocated vec vs. building one on the stack.
>
> Thanks a lot. And hmm, I think using reusing a previously allocated vec
> here would be tricky since cp_parser_template_argument_list can be
> called recursively, and so only the outermost call would be able to
> benefit from reuse unless we perhaps maintain a freelist of such vecs
> IIUC.
We do maintain such a freelist, in make_tree_vector/release_tree_vector,
which releasing_vec is a wrapper class for.
> Seems like that would complicate the code enough to not be worth
> it.
>
>>> gcc/cp/ChangeLog:
>>>
>>> * parser.c (cp_parser_template_argument_list): Use auto_vec
>>> instead of manual memory management.
>>> ---
>>> gcc/cp/parser.c | 35 ++++++++---------------------------
>>> 1 file changed, 8 insertions(+), 27 deletions(-)
>>>
>>> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
>>> index 32de97b08bd..8823399529e 100644
>>> --- a/gcc/cp/parser.c
>>> +++ b/gcc/cp/parser.c
>>> @@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser,
>>> static tree
>>> cp_parser_template_argument_list (cp_parser* parser)
>>> {
>>> - tree fixed_args[10];
>>> - unsigned n_args = 0;
>>> - unsigned alloced = 10;
>>> - tree *arg_ary = fixed_args;
>>> - tree vec;
>>> bool saved_in_template_argument_list_p;
>>> bool saved_ice_p;
>>> bool saved_non_ice_p;
>>> @@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser*
>>> parser)
>>> parser->non_integral_constant_expression_p = false;
>>> /* Parse the arguments. */
>>> + auto_vec<tree, 10> args;
>>> do
>>> {
>>> - tree argument;
>>> -
>>> - if (n_args)
>>> + if (!args.is_empty ())
>>> /* Consume the comma. */
>>> cp_lexer_consume_token (parser->lexer);
>>> /* Parse the template-argument. */
>>> - argument = cp_parser_template_argument (parser);
>>> + tree argument = cp_parser_template_argument (parser);
>>> /* If the next token is an ellipsis, we're expanding a template
>>> argument pack. */
>>> @@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser*
>>> parser)
>>> argument = make_pack_expansion (argument);
>>> }
>>> - if (n_args == alloced)
>>> - {
>>> - alloced *= 2;
>>> -
>>> - if (arg_ary == fixed_args)
>>> - {
>>> - arg_ary = XNEWVEC (tree, alloced);
>>> - memcpy (arg_ary, fixed_args, sizeof (tree) * n_args);
>>> - }
>>> - else
>>> - arg_ary = XRESIZEVEC (tree, arg_ary, alloced);
>>> - }
>>> - arg_ary[n_args++] = argument;
>>> + args.safe_push (argument);
>>> }
>>> while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA));
>>> - vec = make_tree_vec (n_args);
>>> + int n_args = args.length ();
>>> + tree vec = make_tree_vec (n_args);
>>> - while (n_args--)
>>> - TREE_VEC_ELT (vec, n_args) = arg_ary[n_args];
>>> + for (int i = 0; i < n_args; i++)
>>> + TREE_VEC_ELT (vec, i) = args[i];
>>> - if (arg_ary != fixed_args)
>>> - free (arg_ary);
>>> parser->non_integral_constant_expression_p = saved_non_ice_p;
>>> parser->integral_constant_expression_p = saved_ice_p;
>>> parser->in_template_argument_list_p = saved_in_template_argument_list_p;
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: use auto_vec in cp_parser_template_argument_list
2021-11-10 5:16 ` Jason Merrill
@ 2021-11-10 17:13 ` Patrick Palka
0 siblings, 0 replies; 5+ messages in thread
From: Patrick Palka @ 2021-11-10 17:13 UTC (permalink / raw)
To: Jason Merrill; +Cc: GCC Patches
On Wed, Nov 10, 2021 at 12:16 AM Jason Merrill <jason@redhat.com> wrote:
>
> On 11/9/21 13:42, Patrick Palka wrote:
> > On Tue, 9 Nov 2021, Jason Merrill wrote:
> >
> >> On 11/9/21 11:02, Patrick Palka wrote:
> >>> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
> >>
> >> OK, though I wonder about using releasing_vec instead of auto_vec; reusing a
> >> previously allocated vec vs. building one on the stack.
> >
> > Thanks a lot. And hmm, I think using reusing a previously allocated vec
> > here would be tricky since cp_parser_template_argument_list can be
> > called recursively, and so only the outermost call would be able to
> > benefit from reuse unless we perhaps maintain a freelist of such vecs
> > IIUC.
>
> We do maintain such a freelist, in make_tree_vector/release_tree_vector,
> which releasing_vec is a wrapper class for.
Oops sorry, I had totally forgotten about that aspect of
make/release_tree_vector. Hmm, so given that a template argument list
is very likely to be very small, whereas a vector obtained from the
freelist can have an arbitrary large capacity (depending on what it
stored for its previous users), it seems more overall resourceful to
use a stack-allocated auto_vec here IMHO.
>
> > Seems like that would complicate the code enough to not be worth
> > it.
> >
> >>> gcc/cp/ChangeLog:
> >>>
> >>> * parser.c (cp_parser_template_argument_list): Use auto_vec
> >>> instead of manual memory management.
> >>> ---
> >>> gcc/cp/parser.c | 35 ++++++++---------------------------
> >>> 1 file changed, 8 insertions(+), 27 deletions(-)
> >>>
> >>> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> >>> index 32de97b08bd..8823399529e 100644
> >>> --- a/gcc/cp/parser.c
> >>> +++ b/gcc/cp/parser.c
> >>> @@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser,
> >>> static tree
> >>> cp_parser_template_argument_list (cp_parser* parser)
> >>> {
> >>> - tree fixed_args[10];
> >>> - unsigned n_args = 0;
> >>> - unsigned alloced = 10;
> >>> - tree *arg_ary = fixed_args;
> >>> - tree vec;
> >>> bool saved_in_template_argument_list_p;
> >>> bool saved_ice_p;
> >>> bool saved_non_ice_p;
> >>> @@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser*
> >>> parser)
> >>> parser->non_integral_constant_expression_p = false;
> >>> /* Parse the arguments. */
> >>> + auto_vec<tree, 10> args;
> >>> do
> >>> {
> >>> - tree argument;
> >>> -
> >>> - if (n_args)
> >>> + if (!args.is_empty ())
> >>> /* Consume the comma. */
> >>> cp_lexer_consume_token (parser->lexer);
> >>> /* Parse the template-argument. */
> >>> - argument = cp_parser_template_argument (parser);
> >>> + tree argument = cp_parser_template_argument (parser);
> >>> /* If the next token is an ellipsis, we're expanding a template
> >>> argument pack. */
> >>> @@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser*
> >>> parser)
> >>> argument = make_pack_expansion (argument);
> >>> }
> >>> - if (n_args == alloced)
> >>> - {
> >>> - alloced *= 2;
> >>> -
> >>> - if (arg_ary == fixed_args)
> >>> - {
> >>> - arg_ary = XNEWVEC (tree, alloced);
> >>> - memcpy (arg_ary, fixed_args, sizeof (tree) * n_args);
> >>> - }
> >>> - else
> >>> - arg_ary = XRESIZEVEC (tree, arg_ary, alloced);
> >>> - }
> >>> - arg_ary[n_args++] = argument;
> >>> + args.safe_push (argument);
> >>> }
> >>> while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA));
> >>> - vec = make_tree_vec (n_args);
> >>> + int n_args = args.length ();
> >>> + tree vec = make_tree_vec (n_args);
> >>> - while (n_args--)
> >>> - TREE_VEC_ELT (vec, n_args) = arg_ary[n_args];
> >>> + for (int i = 0; i < n_args; i++)
> >>> + TREE_VEC_ELT (vec, i) = args[i];
> >>> - if (arg_ary != fixed_args)
> >>> - free (arg_ary);
> >>> parser->non_integral_constant_expression_p = saved_non_ice_p;
> >>> parser->integral_constant_expression_p = saved_ice_p;
> >>> parser->in_template_argument_list_p = saved_in_template_argument_list_p;
> >>>
> >>
> >>
> >
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-11-09 16:02 [PATCH] c++: use auto_vec in cp_parser_template_argument_list Patrick Palka
2021-11-09 16:59 ` Jason Merrill
2021-11-09 18:42 ` Patrick Palka
2021-11-10 5:16 ` Jason Merrill
2021-11-10 17:13 ` Patrick Palka
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