Ping for https://gcc.gnu.org/pipermail/gcc-patches/2024-August/660957.html
On Wed, Aug 21, 2024 at 09:40:25AM +1000, Nathaniel Shead wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
>
> -- >8 --
>
> The ICE in the linked PR is caused because maybe_clone_decl is not
> prepared to be called on a declaration that has already had clones
> created; what happens otherwise is that start_preparsed_function early
> exits and never sets up cfun, causing a segfault later on.
>
> To fix this we ensure that post_load_processing only calls
> maybe_clone_decl if TREE_ASM_WRITTEN has not been marked on the
> declaration yet, and (if maybe_clone_decls succeeds) marks this flag on
> the decl so that it doesn't get called again later when finalising
> deferred vague linkage declarations in c_parse_final_cleanups.
>
> As a bonus this now allows us to only keep the DECL_SAVED_TREE around in
> expand_or_defer_fn_1 for modules which have CMIs, which will have
> benefits for LTO performance in non-interface TUs.
>
> For clarity we also update the streaming code to do post_load_decls for
> maybe in-charge cdtors rather than any DECL_ABSTRACT_P declaration, as
> this is more accurate to the decls affected by maybe_clone_body.
>
> PR c++/115007
>
> gcc/cp/ChangeLog:
>
> * module.cc (module_state::read_cluster): Replace
> DECL_ABSTRACT_P with DECL_MAYBE_IN_CHARGE_CDTOR_P.
> (post_load_processing): Check and mark TREE_ASM_WRITTEN.
> * semantics.cc (expand_or_defer_fn_1): Use the more specific
> module_maybe_has_cmi_p instead of modules_p.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/modules/virt-6_a.C: New test.
> * g++.dg/modules/virt-6_b.C: New test.
>
> Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
> ---
> gcc/cp/module.cc | 7 ++++---
> gcc/cp/semantics.cc | 2 +-
> gcc/testsuite/g++.dg/modules/virt-6_a.C | 13 +++++++++++++
> gcc/testsuite/g++.dg/modules/virt-6_b.C | 6 ++++++
> 4 files changed, 24 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/modules/virt-6_a.C
> create mode 100644 gcc/testsuite/g++.dg/modules/virt-6_b.C
>
> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
> index 7c42aea05ee..5cd4f313933 100644
> --- a/gcc/cp/module.cc
> +++ b/gcc/cp/module.cc
> @@ -15525,7 +15525,7 @@ module_state::read_cluster (unsigned snum)
>
> if (abstract)
> ;
> - else if (DECL_ABSTRACT_P (decl))
> + else if (DECL_MAYBE_IN_CHARGE_CDTOR_P (decl))
> vec_safe_push (post_load_decls, decl);
> else
> {
> @@ -17947,10 +17947,11 @@ post_load_processing ()
>
> dump () && dump ("Post-load processing of %N", decl);
>
> - gcc_checking_assert (DECL_ABSTRACT_P (decl));
> + gcc_checking_assert (DECL_MAYBE_IN_CHARGE_CDTOR_P (decl));
> /* Cloning can cause loading -- specifically operator delete for
> the deleting dtor. */
> - maybe_clone_body (decl);
> + if (!TREE_ASM_WRITTEN (decl) && maybe_clone_body (decl))
> + TREE_ASM_WRITTEN (decl) = 1;
> }
>
> cfun = old_cfun;
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 5ab2076b673..f7ae8e68dcf 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -5122,7 +5122,7 @@ expand_or_defer_fn_1 (tree fn)
> demand, so we also need to keep the body. Otherwise we don't
> need it anymore. */
> if (!DECL_DECLARED_CONSTEXPR_P (fn)
> - && !(modules_p () && vague_linkage_p (fn)))
> + && !(module_maybe_has_cmi_p () && vague_linkage_p (fn)))
> DECL_SAVED_TREE (fn) = NULL_TREE;
> return false;
> }
> diff --git a/gcc/testsuite/g++.dg/modules/virt-6_a.C
> b/gcc/testsuite/g++.dg/modules/virt-6_a.C
> new file mode 100644
> index 00000000000..68e466ace3f
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/virt-6_a.C
> @@ -0,0 +1,13 @@
> +// PR c++/115007
> +// { dg-additional-options "-fmodules-ts -Wno-global-module" }
> +// { dg-module-cmi M:a }
> +
> +module;
> +struct S {
> + virtual ~S() = default;
> + virtual void f() = 0;
> +};
> +module M:a;
> +extern S* p;
> +template <typename T> void format(T) { p->~S(); }
> +template void format(int);
> diff --git a/gcc/testsuite/g++.dg/modules/virt-6_b.C
> b/gcc/testsuite/g++.dg/modules/virt-6_b.C
> new file mode 100644
> index 00000000000..c53f5fac742
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/virt-6_b.C
> @@ -0,0 +1,6 @@
> +// PR c++/115007
> +// { dg-additional-options "-fmodules-ts" }
> +// { dg-module-cmi M }
> +
> +export module M;
> +import :a;
> --
> 2.43.2
>
