On Mon, Jan 31, 2022 at 10:34 PM Jason Merrill via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Ping.
OK.
Richard.
> On 1/26/22 18:16, Jason Merrill wrote:
> > The problem with this testcase was that since my patch for PR97900 we
> > weren't preserving DECL_UID identity for parameters of instantiations of
> > templated functions, so using those parameters as the keys for the
> > defarg_inst map broke. I think this was always fragile given the
> > possibility of redeclarations, so instead of reverting that change let's
> > switch to keying off the function.
> >
> > Memory use compiling stdc++.h is not noticeably different.
> >
> > Tested x86_64-pc-linux-gnu. Is the tree.{h,cc} change, just moving the
> > class
> > definition from one to the other, OK for trunk?
> >
> > PR c++/103186
> >
> > gcc/ChangeLog:
> >
> > * tree.h (struct tree_vec_map_cache_hasher): Move from...
> > * tree.cc (struct tree_vec_map_cache_hasher): ...here.
> >
> > gcc/cp/ChangeLog:
> >
> > * pt.cc (defarg_inst): Use tree_vec_map_cache_hasher.
> > (defarg_inst_for): New.
> > (tsubst_default_argument): Adjust.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/cpp0x/lambda/lambda-defarg10.C: New test.
> > ---
> > gcc/tree.h | 17 ++++++++
> > gcc/cp/pt.cc | 43 +++++++++++++++----
> > .../g++.dg/cpp0x/lambda/lambda-defarg10.C | 21 +++++++++
> > gcc/tree.cc | 17 --------
> > 4 files changed, 72 insertions(+), 26 deletions(-)
> > create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg10.C
> >
> > diff --git a/gcc/tree.h b/gcc/tree.h
> > index 30bc53c2996..c5617fbcc61 100644
> > --- a/gcc/tree.h
> > +++ b/gcc/tree.h
> > @@ -5559,6 +5559,23 @@ struct tree_decl_map_cache_hasher :
> > ggc_cache_ptr_hash<tree_decl_map>
> > #define tree_vec_map_hash tree_decl_map_hash
> > #define tree_vec_map_marked_p tree_map_base_marked_p
> >
> > +struct tree_vec_map_cache_hasher : ggc_cache_ptr_hash<tree_vec_map>
> > +{
> > + static hashval_t hash (tree_vec_map *m) { return DECL_UID
> > (m->base.from); }
> > +
> > + static bool
> > + equal (tree_vec_map *a, tree_vec_map *b)
> > + {
> > + return a->base.from == b->base.from;
> > + }
> > +
> > + static int
> > + keep_cache_entry (tree_vec_map *&m)
> > + {
> > + return ggc_marked_p (m->base.from);
> > + }
> > +};
> > +
> > /* Hasher for tree decls. Pointer equality is enough here, but the
> > DECL_UID
> > is a better hash than the pointer value and gives a predictable
> > traversal
> > order. Additionally it can be used across PCH save/restore. */
> > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> > index 6fbda676527..db99b988fc3 100644
> > --- a/gcc/cp/pt.cc
> > +++ b/gcc/cp/pt.cc
> > @@ -13666,7 +13666,36 @@ tsubst_aggr_type (tree t,
> > }
> > }
> >
> > -static GTY((cache)) decl_tree_cache_map *defarg_inst;
> > +/* Map from a FUNCTION_DECL to a vec of default argument instantiations.
> > */
> > +
> > +static GTY((cache)) hash_table<tree_vec_map_cache_hasher> *defarg_inst;
> > +
> > +/* Return a reference to the slot for the defarg inst of PARM. */
> > +
> > +tree &
> > +defarg_inst_for (tree parm)
> > +{
> > + if (!defarg_inst)
> > + defarg_inst = hash_table<tree_vec_map_cache_hasher>::create_ggc (13);
> > + tree fn = DECL_CONTEXT (parm);
> > + tree_vec_map in = { fn, nullptr };
> > + tree_vec_map **slot
> > + = defarg_inst->find_slot_with_hash (&in, DECL_UID (fn), INSERT);
> > + if (!*slot)
> > + {
> > + *slot = ggc_alloc<tree_vec_map> ();
> > + **slot = in;
> > + }
> > +
> > + /* Index in reverse order to avoid allocating space for initial
> > parameters
> > + that don't have default arguments. */
> > + unsigned ridx = list_length (parm);
> > +
> > + vec<tree,va_gc> *&defs = (*slot)->to;
> > + if (vec_safe_length (defs) < ridx)
> > + vec_safe_grow_cleared (defs, ridx);
> > + return (*defs)[ridx - 1];
> > +}
> >
> > /* Substitute into the default argument ARG (a default argument for
> > FN), which has the indicated TYPE. */
> > @@ -13696,9 +13725,9 @@ tsubst_default_argument (tree fn, int parmnum, tree
> > type, tree arg,
> >
> > gcc_assert (same_type_ignoring_top_level_qualifiers_p (type, parmtype));
> >
> > - tree *slot;
> > - if (defarg_inst && (slot = defarg_inst->get (parm)))
> > - return *slot;
> > + tree &inst = defarg_inst_for (parm);
> > + if (inst)
> > + return inst;
> >
> > /* This default argument came from a template. Instantiate the
> > default argument here, not in tsubst. In the case of
> > @@ -13743,11 +13772,7 @@ tsubst_default_argument (tree fn, int parmnum,
> > tree type, tree arg,
> > pop_from_top_level ();
> >
> > if (arg != error_mark_node && !cp_unevaluated_operand)
> > - {
> > - if (!defarg_inst)
> > - defarg_inst = decl_tree_cache_map::create_ggc (37);
> > - defarg_inst->put (parm, arg);
> > - }
> > + inst = arg;
> >
> > return arg;
> > }
> > diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg10.C
> > b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg10.C
> > new file mode 100644
> > index 00000000000..e08eb4f5e56
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg10.C
> > @@ -0,0 +1,21 @@
> > +// PR c++/103186
> > +// { dg-do compile { target c++11 } }
> > +
> > +struct f
> > +{
> > + template<class T1>
> > + f(const T1&){}
> > +};
> > +
> > +
> > +template<typename T> class A {
> > +public:
> > + void foo(A<T> a, const f& fn = [](){}) { }
> > + void bar(A<T> a) { foo(a); }
> > +};
> > +int main() {
> > + A<int> a;
> > + a.foo(a);
> > + a.bar(a);
> > + return 0;
> > +}
> > diff --git a/gcc/tree.cc b/gcc/tree.cc
> > index c4b36619e6a..6bd3b14c93c 100644
> > --- a/gcc/tree.cc
> > +++ b/gcc/tree.cc
> > @@ -242,23 +242,6 @@ static GTY ((cache))
> > static GTY ((cache))
> > hash_table<tree_decl_map_cache_hasher> *value_expr_for_decl;
> >
> > -struct tree_vec_map_cache_hasher : ggc_cache_ptr_hash<tree_vec_map>
> > -{
> > - static hashval_t hash (tree_vec_map *m) { return DECL_UID
> > (m->base.from); }
> > -
> > - static bool
> > - equal (tree_vec_map *a, tree_vec_map *b)
> > - {
> > - return a->base.from == b->base.from;
> > - }
> > -
> > - static int
> > - keep_cache_entry (tree_vec_map *&m)
> > - {
> > - return ggc_marked_p (m->base.from);
> > - }
> > -};
> > -
> > static GTY ((cache))
> > hash_table<tree_vec_map_cache_hasher> *debug_args_for_decl;
> >
> >
> > base-commit: 9bf217920457f2e2d46b601f24721780a20a031b
> > prerequisite-patch-id: c7ab4056fcbd782232c8dc091597602ecd4a7a48
>
