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PR c++/70462 - unnecessary base ctor variant with final.

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As pointed out in the PR, we don't need base 'tor variants for a final
class, since it can never be a base.  I tried also dropping complete
variants for abstract classes, but that runs into ABI compatibility problems
with older releases that refer to those symbols.

	* optimize.c (populate_clone_array): Skip base variant if
	CLASSTYPE_FINAL.
	(maybe_clone_body): We don't need an alias if we are only defining
	one clone.

From-SVN: r272669
This commit is contained in:
Jason Merrill 2019-06-26 00:56:07 -04:00 • committed by Jason Merrill
parent e21b52afe9
commit 09039e9c72
3 changed files with 23 additions and 4 deletions
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6
gcc/cp/ChangeLog
View file

@ -1,5 +1,11 @@
2019-06-25 Jason Merrill <jason@redhat.com>
PR c++/70462 - unnecessary base ctor variant with final.
* optimize.c (populate_clone_array): Skip base variant if
CLASSTYPE_FINAL.
(maybe_clone_body): We don't need an alias if we are only defining
one clone.
* class.c (resolves_to_fixed_type_p): Check CLASSTYPE_FINAL.
2019-06-25 Jakub Jelinek <jakub@redhat.com>

12
gcc/cp/optimize.c
View file

@ -247,15 +247,19 @@ populate_clone_array (tree fn, tree *fns)
fns[1] = NULL_TREE;
fns[2] = NULL_TREE;
/* Look for the complete destructor which may be used to build the
delete destructor. */
tree ctx = DECL_CONTEXT (fn);
FOR_EACH_CLONE (clone, fn)
if (DECL_NAME (clone) == complete_dtor_identifier
|| DECL_NAME (clone) == complete_ctor_identifier)
fns[1] = clone;
else if (DECL_NAME (clone) == base_dtor_identifier
|| DECL_NAME (clone) == base_ctor_identifier)
fns[0] = clone;
{
/* We don't need to define the base variants for a final class. */
if (!CLASSTYPE_FINAL (ctx))
fns[0] = clone;
}
else if (DECL_NAME (clone) == deleting_dtor_identifier)
fns[2] = clone;
else
@ -480,7 +484,7 @@ maybe_clone_body (tree fn)
/* Remember if we can't have multiple clones for some reason. We need to
check this before we remap local static initializers in clone_body. */
if (!tree_versionable_function_p (fn))
if (!tree_versionable_function_p (fn) && fns[0] && fns[1])
need_alias = true;
/* We know that any clones immediately follow FN in the TYPE_FIELDS

9
gcc/testsuite/g++.dg/other/final8.C Normal file
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@ -0,0 +1,9 @@
// { dg-do compile { target c++11 } }
// { dg-final { scan-assembler-not "_ZN1BC2Ev" } }
// { dg-final { scan-assembler-not "_ZN1BD2Ev" } }
struct A { int i; A(); virtual ~A() = 0; };
struct B final: public virtual A { int j; B(); ~B(); };
B::B() {}
B::~B() {}