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Reduce unsharing in constexpr call evaluation.

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* constexpr.c (unshare_constructor): Only unshare if T is itself a
	CONSTRUCTOR.
	(cxx_eval_call_expression): Don't call it on the result here.

From-SVN: r272126
This commit is contained in:
Jason Merrill 2019-06-10 15:32:30 -04:00 committed by Jason Merrill
parent 3c961dc755
commit 9b9eb42a41
2 changed files with 26 additions and 17 deletions
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4
gcc/cp/ChangeLog
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@ -1,5 +1,9 @@
2019-06-10 Jason Merrill <jason@redhat.com>
* constexpr.c (unshare_constructor): Only unshare if T is itself a
CONSTRUCTOR.
(cxx_eval_call_expression): Don't call it on the result here.
Reduce constexpr_call memory consumption.
* constexpr.c (cxx_bind_parameters_in_call): Use TREE_VEC rather
than TREE_LIST.

39
gcc/cp/constexpr.c
View File

@ -1321,27 +1321,32 @@ adjust_temp_type (tree type, tree temp)
return cp_fold_convert (type, temp);
}
/* Callback for walk_tree used by unshare_constructor. */
/* If T is a CONSTRUCTOR, return an unshared copy of T and any
sub-CONSTRUCTORs. Otherwise return T.
static tree
find_constructor (tree *tp, int *walk_subtrees, void *)
{
if (TYPE_P (*tp))
*walk_subtrees = 0;
if (TREE_CODE (*tp) == CONSTRUCTOR)
return *tp;
return NULL_TREE;
}
/* If T is a CONSTRUCTOR or an expression that has a CONSTRUCTOR node as a
subexpression, return an unshared copy of T. Otherwise return T. */
We use this whenever we initialize an object as a whole, whether it's a
parameter, a local variable, or a subobject, so that subsequent
modifications don't affect other places where it was used. */
tree
unshare_constructor (tree t)
{
tree ctor = walk_tree (&t, find_constructor, NULL, NULL);
if (ctor != NULL_TREE)
return unshare_expr (t);
if (!t || TREE_CODE (t) != CONSTRUCTOR)
return t;
auto_vec <tree*, 4> ptrs;
ptrs.safe_push (&t);
while (!ptrs.is_empty ())
{
tree *p = ptrs.pop ();
tree n = copy_node (*p);
CONSTRUCTOR_ELTS (n) = vec_safe_copy (CONSTRUCTOR_ELTS (*p));
*p = n;
vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (n);
constructor_elt *ce;
for (HOST_WIDE_INT i = 0; vec_safe_iterate (v, i, &ce); ++i)
if (TREE_CODE (ce->value) == CONSTRUCTOR)
ptrs.safe_push (&ce->value);
}
return t;
}
@ -1898,7 +1903,7 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
clear_no_implicit_zero (result);
pop_cx_call_context ();
return unshare_constructor (result);
return result;
}
/* FIXME speed this up, it's taking 16% of compile time on sieve testcase. */