Re: [PATCH] c++ modules: lazy loading from within template [PR99377]
On 10/11/22 10:58, Patrick Palka wrote:
On Mon, 10 Oct 2022, Nathan Sidwell wrote:
On 10/4/22 13:36, Patrick Palka wrote:
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should probably be
clearing processing_template_decl somewhere e.g in lazy_load_binding.
This is sufficient to fix the testcase.
yeah, I remember hitting issues with this, but thought I'd got rid of the need
to override processing_template_decl. Do you also need to override it in
lazy_load_pendings though? that's a lazy loader and my suspicion is it might
be susceptible to the same issues.
Hmm yeah, looks like we need to override it in lazy_load_pendings too:
I ran the testsuite with gcc_assert (!processing_template_decl) added to
module_state::read_cluster and if we don't also override it in
lazy_load_binding then the assert triggers for pr99425-2_b.X.
But it also seems the processing_template_decl test in
note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
perhaps too strong: if the intent is to avoid deferring output for
uninstantiated templates, we should make sure that DECL in question is
an uninstantiated template by checking e.g. value_dependent_expression_p.
This too is sufficient to fix the testcase (since f isn't a template)
and survives bootstrap and regtest.
I think this is an orthogonal issue -- can we remove it from this patch?
Done.
-- >8 --
Subject: [PATCH] c++ modules: lazy loading from within template [PR99377]
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should be clearing
processing_template_decl in the entrypoints lazy_load_binding and
lazy_load_pendings.
PR c++/99377
gcc/cp/ChangeLog:
* module.cc (lazy_load_binding): Clear processing_template_decl.
(lazy_load_pendings): Likewise.
ok, thanks
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr99377-2_a.C: New test.
* g++.dg/modules/pr99377-2_b.C: New test.
---
gcc/cp/module.cc | 8
gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +
gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++
3 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 94fbee85225..7c48602136c 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19081,6 +19081,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
timevar_start (TV_MODULE_IMPORT);
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
/* Stop GC happening, even in outermost loads (because our caller
could well be building up a lookup set). */
function_depth++;
@@ -19129,6 +19133,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
void
lazy_load_pendings (tree decl)
{
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
tree key_decl;
pending_key key;
key.ns = find_pending_key (decl, &key_decl);
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
new file mode 100644
index 000..26e2bccbbbe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
@@ -0,0 +1,5 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr99377 }
+export module pr99377;
+export inline void f() { }
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
new file mode 100644
index 000..69571952c8a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
@@ -0,0 +1,6 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+import pr99377;
+template void g() { f(); }
+int main() { g(); }
--
Nathan Sidwell
Re: [PATCH] c++ modules: lazy loading from within template [PR99377]
On Mon, 10 Oct 2022, Nathan Sidwell wrote:
> On 10/4/22 13:36, Patrick Palka wrote:
> > Here when lazily loading the binding for f at parse time from the
> > template g, processing_template_decl is set and thus the call to
> > note_vague_linkage_fn from module_state::read_cluster has no effect,
> > and we never push f onto deferred_fns and end up never emitting its
> > definition.
> >
> > ISTM the behavior of the lazy loading machinery shouldn't be sensitive
> > to whether we're inside a template, and therefore we should probably be
> > clearing processing_template_decl somewhere e.g in lazy_load_binding.
> > This is sufficient to fix the testcase.
>
> yeah, I remember hitting issues with this, but thought I'd got rid of the need
> to override processing_template_decl. Do you also need to override it in
> lazy_load_pendings though? that's a lazy loader and my suspicion is it might
> be susceptible to the same issues.
Hmm yeah, looks like we need to override it in lazy_load_pendings too:
I ran the testsuite with gcc_assert (!processing_template_decl) added to
module_state::read_cluster and if we don't also override it in
lazy_load_binding then the assert triggers for pr99425-2_b.X.
>
> >
> > But it also seems the processing_template_decl test in
> > note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
> > perhaps too strong: if the intent is to avoid deferring output for
> > uninstantiated templates, we should make sure that DECL in question is
> > an uninstantiated template by checking e.g. value_dependent_expression_p.
> > This too is sufficient to fix the testcase (since f isn't a template)
> > and survives bootstrap and regtest.
>
> I think this is an orthogonal issue -- can we remove it from this patch?
Done.
-- >8 --
Subject: [PATCH] c++ modules: lazy loading from within template [PR99377]
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should be clearing
processing_template_decl in the entrypoints lazy_load_binding and
lazy_load_pendings.
PR c++/99377
gcc/cp/ChangeLog:
* module.cc (lazy_load_binding): Clear processing_template_decl.
(lazy_load_pendings): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr99377-2_a.C: New test.
* g++.dg/modules/pr99377-2_b.C: New test.
---
gcc/cp/module.cc | 8
gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +
gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++
3 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 94fbee85225..7c48602136c 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19081,6 +19081,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
timevar_start (TV_MODULE_IMPORT);
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
/* Stop GC happening, even in outermost loads (because our caller
could well be building up a lookup set). */
function_depth++;
@@ -19129,6 +19133,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
void
lazy_load_pendings (tree decl)
{
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
tree key_decl;
pending_key key;
key.ns = find_pending_key (decl, &key_decl);
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
new file mode 100644
index 000..26e2bccbbbe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
@@ -0,0 +1,5 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr99377 }
+export module pr99377;
+export inline void f() { }
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
new file mode 100644
index 000..69571952c8a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
@@ -0,0 +1,6 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+import pr99377;
+template void g() { f(); }
+int main() { g(); }
--
2.38.0.15.gbbe21b64a0
Re: [PATCH] c++ modules: lazy loading from within template [PR99377]
On 10/4/22 13:36, Patrick Palka wrote:
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should probably be
clearing processing_template_decl somewhere e.g in lazy_load_binding.
This is sufficient to fix the testcase.
yeah, I remember hitting issues with this, but thought I'd got rid of the need
to override processing_template_decl. Do you also need to override it in
lazy_load_pendings though? that's a lazy loader and my suspicion is it might be
susceptible to the same issues.
But it also seems the processing_template_decl test in
note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
perhaps too strong: if the intent is to avoid deferring output for
uninstantiated templates, we should make sure that DECL in question is
an uninstantiated template by checking e.g. value_dependent_expression_p.
This too is sufficient to fix the testcase (since f isn't a template)
and survives bootstrap and regtest.
I think this is an orthogonal issue -- can we remove it from this patch?
Does one or the other approach look like the correct fix for this PR?
PR c++/99377
gcc/cp/ChangeLog:
* decl2.cc (note_vague_linkage_fn): Relax processing_template_decl
test to value_dependent_expression_p.
* module.cc (lazy_load_binding): Clear processing_template_decl.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr99377-2_a.C: New test.
* g++.dg/modules/pr99377-2_b.C: New test.
---
gcc/cp/decl2.cc| 2 +-
gcc/cp/module.cc | 2 ++
gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +
gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++
4 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 9f18466192f..5af4d17ee3b 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -876,7 +876,7 @@ check_classfn (tree ctype, tree function, tree
template_parms)
void
note_vague_linkage_fn (tree decl)
{
- if (processing_template_decl)
+ if (value_dependent_expression_p (decl))
return;
DECL_DEFER_OUTPUT (decl) = 1;
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 500ac06563a..79cbb346ffa 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19074,6 +19074,8 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
timevar_start (TV_MODULE_IMPORT);
+ processing_template_decl_sentinel ptds;
+
/* Stop GC happening, even in outermost loads (because our caller
could well be building up a lookup set). */
function_depth++;
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
new file mode 100644
index 000..26e2bccbbbe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
@@ -0,0 +1,5 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr99377 }
+export module pr99377;
+export inline void f() { }
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
new file mode 100644
index 000..69571952c8a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
@@ -0,0 +1,6 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+import pr99377;
+template void g() { f(); }
+int main() { g(); }
--
Nathan Sidwell
Re: [PATCH] c++ modules: lazy loading from within template [PR99377]
On Tue, 4 Oct 2022, Patrick Palka wrote:
> Here when lazily loading the binding for f at parse time from the
> template g, processing_template_decl is set and thus the call to
> note_vague_linkage_fn from module_state::read_cluster has no effect,
> and we never push f onto deferred_fns and end up never emitting its
> definition.
>
> ISTM the behavior of the lazy loading machinery shouldn't be sensitive
> to whether we're inside a template, and therefore we should probably be
> clearing processing_template_decl somewhere e.g in lazy_load_binding.
> This is sufficient to fix the testcase.
>
> But it also seems the processing_template_decl test in
> note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
> perhaps too strong: if the intent is to avoid deferring output for
> uninstantiated templates, we should make sure that DECL in question is
> an uninstantiated template by checking e.g. value_dependent_expression_p.
> This too is sufficient to fix the testcase (since f isn't a template)
> and survives bootstrap and regtest.
>
> Does one or the other approach look like the correct fix for this PR?
>
> PR c++/99377
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (note_vague_linkage_fn): Relax processing_template_decl
> test to value_dependent_expression_p.
> * module.cc (lazy_load_binding): Clear processing_template_decl.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/modules/pr99377-2_a.C: New test.
> * g++.dg/modules/pr99377-2_b.C: New test.
> ---
> gcc/cp/decl2.cc| 2 +-
> gcc/cp/module.cc | 2 ++
> gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +
> gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++
> 4 files changed, 14 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
> create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
>
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index 9f18466192f..5af4d17ee3b 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -876,7 +876,7 @@ check_classfn (tree ctype, tree function, tree
> template_parms)
> void
> note_vague_linkage_fn (tree decl)
> {
> - if (processing_template_decl)
> + if (value_dependent_expression_p (decl))
> return;
>
>DECL_DEFER_OUTPUT (decl) = 1;
> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
> index 500ac06563a..79cbb346ffa 100644
> --- a/gcc/cp/module.cc
> +++ b/gcc/cp/module.cc
> @@ -19074,6 +19074,8 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
> binding_slot *mslot)
>
>timevar_start (TV_MODULE_IMPORT);
>
> + processing_template_decl_sentinel ptds;
> +
>/* Stop GC happening, even in outermost loads (because our caller
> could well be building up a lookup set). */
>function_depth++;
> diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
> b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
> new file mode 100644
> index 000..26e2bccbbbe
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
> @@ -0,0 +1,5 @@
> +// PR c++/99377
> +// { dg-additional-options -fmodules-ts }
> +// { dg-module-cmi pr99377 }
> +export module pr99377;
> +export inline void f() { }
> diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
> b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
> new file mode 100644
> index 000..69571952c8a
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
> @@ -0,0 +1,6 @@
> +// PR c++/99377
> +// { dg-additional-options -fmodules-ts }
> +// { dg-do link }
> +import pr99377;
> +template void g() { f(); }
> +int main() { g(); }
This test can be simplified to:
import pr99377;
template void g() { f(); }
int main() { f(); }
which probably illustrates the bug better: we lazily load f at the
point of its first use, which in this case is in the (uninstantiated)
template g with processing_template_decl != 0. Thus during lazy loading
the call to note_vague_linkage_fn has no effect and we never emit the
definition of f.
[PATCH] c++ modules: lazy loading from within template [PR99377]
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should probably be
clearing processing_template_decl somewhere e.g in lazy_load_binding.
This is sufficient to fix the testcase.
But it also seems the processing_template_decl test in
note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
perhaps too strong: if the intent is to avoid deferring output for
uninstantiated templates, we should make sure that DECL in question is
an uninstantiated template by checking e.g. value_dependent_expression_p.
This too is sufficient to fix the testcase (since f isn't a template)
and survives bootstrap and regtest.
Does one or the other approach look like the correct fix for this PR?
PR c++/99377
gcc/cp/ChangeLog:
* decl2.cc (note_vague_linkage_fn): Relax processing_template_decl
test to value_dependent_expression_p.
* module.cc (lazy_load_binding): Clear processing_template_decl.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr99377-2_a.C: New test.
* g++.dg/modules/pr99377-2_b.C: New test.
---
gcc/cp/decl2.cc| 2 +-
gcc/cp/module.cc | 2 ++
gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +
gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++
4 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 9f18466192f..5af4d17ee3b 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -876,7 +876,7 @@ check_classfn (tree ctype, tree function, tree
template_parms)
void
note_vague_linkage_fn (tree decl)
{
- if (processing_template_decl)
+ if (value_dependent_expression_p (decl))
return;
DECL_DEFER_OUTPUT (decl) = 1;
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 500ac06563a..79cbb346ffa 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19074,6 +19074,8 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
timevar_start (TV_MODULE_IMPORT);
+ processing_template_decl_sentinel ptds;
+
/* Stop GC happening, even in outermost loads (because our caller
could well be building up a lookup set). */
function_depth++;
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
new file mode 100644
index 000..26e2bccbbbe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
@@ -0,0 +1,5 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr99377 }
+export module pr99377;
+export inline void f() { }
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
new file mode 100644
index 000..69571952c8a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
@@ -0,0 +1,6 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+import pr99377;
+template void g() { f(); }
+int main() { g(); }
--
2.38.0.rc2
