[gcc r15-4621] c++/modules: Support decloned cdtors

[Nathaniel Shead via Gcc-cvs]

https://gcc.gnu.org/g:29efc621b7c66ec67d10fc87cddbb3f1ab709fb2

commit r15-4621-g29efc621b7c66ec67d10fc87cddbb3f1ab709fb2
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date:   Wed Aug 21 01:08:36 2024 +1000

    c++/modules: Support decloned cdtors
    
    When compiling with '-fdeclone-ctor-dtor' (enabled by default with -Os),
    we run into issues where we don't correctly emit the underlying
    functions.  We also need to ensure that COMDAT constructors are marked
    as such before 'maybe_clone_body' attempts to propagate COMDAT groups to
    the new thunks.
    
    gcc/cp/ChangeLog:
    
            * module.cc (post_load_processing): Mark COMDAT as needed, emit
            declarations if maybe_clone_body fails.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/modules/clone-2_a.C: New test.
            * g++.dg/modules/clone-2_b.C: New test.
            * g++.dg/modules/clone-3_a.C: New test.
            * g++.dg/modules/clone-3_b.C: New test.
    
    Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>

Diff:
---
 gcc/cp/module.cc                         | 20 ++++++++++++++++----
 gcc/testsuite/g++.dg/modules/clone-2_a.C |  7 +++++++
 gcc/testsuite/g++.dg/modules/clone-2_b.C |  5 +++++
 gcc/testsuite/g++.dg/modules/clone-3_a.C |  9 +++++++++
 gcc/testsuite/g++.dg/modules/clone-3_b.C |  8 ++++++++
 5 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index d7494cc813a0..90ad67daf72b 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -17959,10 +17959,22 @@ post_load_processing ()
       dump () && dump ("Post-load processing of %N", decl);
 
       gcc_checking_assert (DECL_MAYBE_IN_CHARGE_CDTOR_P (decl));
-      /* Cloning can cause loading -- specifically operator delete for
-        the deleting dtor.  */
-      if (!TREE_ASM_WRITTEN (decl) && maybe_clone_body (decl))
-       TREE_ASM_WRITTEN (decl) = 1;
+
+      if (DECL_COMDAT (decl))
+       comdat_linkage (decl);
+      if (!TREE_ASM_WRITTEN (decl))
+       {
+         /* Cloning can cause loading -- specifically operator delete for
+            the deleting dtor.  */
+         if (maybe_clone_body (decl))
+           TREE_ASM_WRITTEN (decl) = 1;
+         else
+           {
+             /* We didn't clone the cdtor, make sure we emit it.  */
+             note_vague_linkage_fn (decl);
+             cgraph_node::finalize_function (decl, true);
+           }
+       }
     }
 
   cfun = old_cfun;
diff --git a/gcc/testsuite/g++.dg/modules/clone-2_a.C 
b/gcc/testsuite/g++.dg/modules/clone-2_a.C
new file mode 100644
index 000000000000..47e21581fdc5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/clone-2_a.C
@@ -0,0 +1,7 @@
+// { dg-additional-options "-fmodules-ts -fdeclone-ctor-dtor" }
+// { dg-module-cmi M }
+
+export module M;
+export struct S {
+  inline S(int) {}
+};
diff --git a/gcc/testsuite/g++.dg/modules/clone-2_b.C 
b/gcc/testsuite/g++.dg/modules/clone-2_b.C
new file mode 100644
index 000000000000..80c1e149518b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/clone-2_b.C
@@ -0,0 +1,5 @@
+// { dg-additional-options "-fmodules-ts -fdeclone-ctor-dtor" }
+
+import M;
+
+S s(0);
diff --git a/gcc/testsuite/g++.dg/modules/clone-3_a.C 
b/gcc/testsuite/g++.dg/modules/clone-3_a.C
new file mode 100644
index 000000000000..87de746f5c2c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/clone-3_a.C
@@ -0,0 +1,9 @@
+// { dg-additional-options "-fmodules-ts -fdeclone-ctor-dtor" }
+// { dg-module-cmi M }
+
+export module M;
+
+struct A {};
+export struct B : virtual A {
+  inline B (int) {}
+};
diff --git a/gcc/testsuite/g++.dg/modules/clone-3_b.C 
b/gcc/testsuite/g++.dg/modules/clone-3_b.C
new file mode 100644
index 000000000000..23c9ac4a8046
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/clone-3_b.C
@@ -0,0 +1,8 @@
+// { dg-module-do link }
+// { dg-additional-options "-fmodules-ts -fdeclone-ctor-dtor" }
+
+import M;
+
+int main() {
+  B b(0);
+}