Hi,
On 27/06/19 23:19, Jason Merrill wrote:
Ah, thanks. Then perhaps we want to change the CLASSTYPE_FINAL in
build_over_call to resolves_to_fixed_type_p (arg), to also handle the
other reasons we might know the dynamic type of the argument, and
remove the related code from build_new_method_call_1?
You could avoid needing to move the conditional lower by comparing
DECL_CONTEXT (fn) and BINFO_TYPE (cand->conversion_path) rather than
parmtype and TREE_TYPE (converted_arg).
Sorry for late replying, a few days off.
Anyway, great, it looks like we are reaching a nice synthesis. I must
admit that until yesterday I hadn't noticed that Fabien dealt precisely
with using declarations in order to fix c++/11750, thus the existing
check in build_new_method_call_1 is exactly what we need. The below does
that and passes testing, in it I didn't keep the checks of DECL_VINDEX
(fn) && ! (flags & LOOKUP_NONVIRTUAL) which don't seem necessary, might
avoid function calls, though. Let me know...
Thanks, Paolo.
////////////////////
Index: cp/call.c
===================================================================
--- cp/call.c (revision 273076)
+++ cp/call.c (working copy)
@@ -8241,10 +8241,17 @@ build_over_call (struct z_candidate *cand, int fla
return error_mark_node;
}
- /* See if the function member or the whole class type is declared
- final and the call can be devirtualized. */
+ /* Optimize away vtable lookup if we know that this
+ function can't be overridden. We need to check if
+ the context and the type where we found fn are the same,
+ actually FN might be defined in a different class
+ type because of a using-declaration. In this case, we
+ do not want to perform a non-virtual call. Note that
+ resolves_to_fixed_type_p checks CLASSTYPE_FINAL too. */
if (DECL_FINAL_P (fn)
- || CLASSTYPE_FINAL (TYPE_METHOD_BASETYPE (TREE_TYPE (fn))))
+ || (resolves_to_fixed_type_p (arg, 0)
+ && same_type_ignoring_top_level_qualifiers_p
+ (DECL_CONTEXT (fn), BINFO_TYPE (cand->conversion_path))))
flags |= LOOKUP_NONVIRTUAL;
/* [class.mfct.nonstatic]: If a nonstatic member function of a class
@@ -9845,17 +9852,6 @@ build_new_method_call_1 (tree instance, tree fns,
if (call != error_mark_node)
{
- /* Optimize away vtable lookup if we know that this
- function can't be overridden. We need to check if
- the context and the type where we found fn are the same,
- actually FN might be defined in a different class
- type because of a using-declaration. In this case, we
- do not want to perform a non-virtual call. */
- if (DECL_VINDEX (fn) && ! (flags & LOOKUP_NONVIRTUAL)
- && same_type_ignoring_top_level_qualifiers_p
- (DECL_CONTEXT (fn), BINFO_TYPE (binfo))
- && resolves_to_fixed_type_p (instance, 0))
- flags |= LOOKUP_NONVIRTUAL;
if (explicit_targs)
flags |= LOOKUP_EXPLICIT_TMPL_ARGS;
/* Now we know what function is being called. */
Index: testsuite/g++.dg/other/final4.C
===================================================================
--- testsuite/g++.dg/other/final4.C (nonexistent)
+++ testsuite/g++.dg/other/final4.C (working copy)
@@ -0,0 +1,16 @@
+// PR c++/67184
+// { dg-do compile { target c++11 } }
+// { dg-options "-fdump-tree-original" }
+
+struct B
+{
+ virtual void operator()();
+ virtual operator int();
+ virtual int operator++();
+};
+
+struct D final : B { };
+
+void foo(D& d) { d(); int t = d; ++d; }
+
+// { dg-final { scan-tree-dump-times "OBJ_TYPE_REF" 0 "original" } }
