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c++: Simplify process_template_parm

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Process_template_parm ends up walking the parameter list twice.
There's not need to do this.  Just rember the final node and modify
its CHAIN directly.  Also comment on why end_template_parm_list does a
pop and a push, rather than modifying the header in place.

	pt.c (process_template_parm): Don't walk the template list twice,
	remember the final node instead.
	(end_template_parm_list): Refactor.  Comment on why we do a pop
	and a push.
This commit is contained in:
Nathan Sidwell 2020-05-04 09:49:52 -07:00
parent f1621d18f5
commit 97268c374a
2 changed files with 31 additions and 21 deletions
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5
gcc/cp/ChangeLog
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@ -1,5 +1,10 @@
2020-05-04 Nathan Sidwell <nathan@acm.org>
pt.c (process_template_parm): Don't walk the template list twice,
remember the final node instead.
(end_template_parm_list): Refactor. Comment on why we do a pop
and a push.
PR c++/94827 -- don't save parms in nested requirement
* constraint.cc (tsubst_nested_requirement): TYPE directly holds
notmalized requirement.

47
gcc/cp/pt.c
View File

@ -4496,29 +4496,27 @@ tree
process_template_parm (tree list, location_t parm_loc, tree parm,
bool is_non_type, bool is_parameter_pack)
{
tree decl = 0;
int idx = 0;
gcc_assert (TREE_CODE (parm) == TREE_LIST);
tree defval = TREE_PURPOSE (parm);
tree constr = TREE_TYPE (parm);
tree prev = NULL_TREE;
int idx = 0;
if (list)
{
tree p = tree_last (list);
prev = tree_last (list);
if (p && TREE_VALUE (p) != error_mark_node)
{
p = TREE_VALUE (p);
if (TREE_CODE (p) == TYPE_DECL || TREE_CODE (p) == TEMPLATE_DECL)
idx = TEMPLATE_TYPE_IDX (TREE_TYPE (p));
else
idx = TEMPLATE_PARM_IDX (DECL_INITIAL (p));
}
tree p = TREE_VALUE (prev);
if (TREE_CODE (p) == TYPE_DECL || TREE_CODE (p) == TEMPLATE_DECL)
idx = TEMPLATE_TYPE_IDX (TREE_TYPE (p));
else if (TREE_CODE (p) == PARM_DECL)
idx = TEMPLATE_PARM_IDX (DECL_INITIAL (p));
++idx;
}
tree decl = NULL_TREE;
tree defval = TREE_PURPOSE (parm);
tree constr = TREE_TYPE (parm);
if (is_non_type)
{
parm = TREE_VALUE (parm);
@ -4616,7 +4614,12 @@ process_template_parm (tree list, location_t parm_loc, tree parm,
parm = build_tree_list (defval, parm);
TEMPLATE_PARM_CONSTRAINTS (parm) = reqs;
return chainon (list, parm);
if (prev)
TREE_CHAIN (prev) = parm;
else
list = parm;
return list;
}
/* The end of a template parameter list has been reached. Process the
@ -4627,22 +4630,24 @@ process_template_parm (tree list, location_t parm_loc, tree parm,
tree
end_template_parm_list (tree parms)
{
int nparms;
tree parm, next;
tree saved_parmlist = make_tree_vec (list_length (parms));
/* Pop the dummy parameter level and add the real one. */
/* Pop the dummy parameter level and add the real one. We do not
morph the dummy parameter in place, as it might have been
captured by a (nested) template-template-parm. */
current_template_parms = TREE_CHAIN (current_template_parms);
current_template_parms
= tree_cons (size_int (processing_template_decl),
saved_parmlist, current_template_parms);
for (parm = parms, nparms = 0; parm; parm = next, nparms++)
for (unsigned ix = 0; parms; ix++)
{
next = TREE_CHAIN (parm);
TREE_VEC_ELT (saved_parmlist, nparms) = parm;
tree parm = parms;
parms = TREE_CHAIN (parms);
TREE_CHAIN (parm) = NULL_TREE;
TREE_VEC_ELT (saved_parmlist, ix) = parm;
}
--processing_template_parmlist;