From: Nathaniel Shead <nathanieloshead@gmail.com>
Date: Tue, 20 Aug 2024 14:42:42 +0000 (+1000)
Subject: c++: Handle ABI for non-polymorphic dynamic classes
X-Git-Tag: basepoints/gcc-16~4934
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6713f05a2aeb852c3f4d738c8c5dbad816624323;p=thirdparty%2Fgcc.git

c++: Handle ABI for non-polymorphic dynamic classes

The Itanium ABI has specific rules for when virtual tables for dynamic
classes should be emitted.  However we didn't consider structures with
virtual inheritance but no virtual members as dynamic classes for ABI
purposes; this patch fixes this.

gcc/cp/ChangeLog:

	* decl2.cc (import_export_class): Use TYPE_CONTAINS_VPTR_P
	instead of TYPE_POLYMORPHIC_P.
	(import_export_decl): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/virt-5_a.C: New test.
	* g++.dg/modules/virt-5_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---

diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index a455eb481b1a..fa32ce35c8c4 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -2434,7 +2434,7 @@ import_export_class (tree ctype)
        translation unit, then export the class; otherwise, import
        it.  */
       import_export = -1;
-  else if (TYPE_POLYMORPHIC_P (ctype))
+  else if (TYPE_CONTAINS_VPTR_P (ctype))
     {
       tree cdecl = TYPE_NAME (ctype);
       if (DECL_LANG_SPECIFIC (cdecl) && DECL_MODULE_ATTACH_P (cdecl))
@@ -3530,7 +3530,7 @@ import_export_decl (tree decl)
 	  class_type = type;
 	  import_export_class (type);
 	  if (CLASSTYPE_INTERFACE_KNOWN (type)
-	      && TYPE_POLYMORPHIC_P (type)
+	      && TYPE_CONTAINS_VPTR_P (type)
 	      && CLASSTYPE_INTERFACE_ONLY (type)
 	      /* If -fno-rtti was specified, then we cannot be sure
 		 that RTTI information will be emitted with the
diff --git a/gcc/testsuite/g++.dg/modules/virt-5_a.C b/gcc/testsuite/g++.dg/modules/virt-5_a.C
new file mode 100644
index 000000000000..f4c6abe85ef6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/virt-5_a.C
@@ -0,0 +1,16 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi M }
+
+export module M;
+
+struct C {};
+struct B : virtual C {};
+
+// Despite no non-inline key function, this is still a dynamic class
+// and so by the Itanium ABI 5.2.3 should be uniquely emitted in this TU
+export struct A : B {
+  inline A (int) {}
+};
+
+// { dg-final { scan-assembler {_ZTTW1M1A:} } }
+// { dg-final { scan-assembler {_ZTVW1M1A:} } }
diff --git a/gcc/testsuite/g++.dg/modules/virt-5_b.C b/gcc/testsuite/g++.dg/modules/virt-5_b.C
new file mode 100644
index 000000000000..785dd92ac1ee
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/virt-5_b.C
@@ -0,0 +1,11 @@
+// { dg-module-do link }
+// { dg-additional-options "-fmodules-ts" }
+
+import M;
+
+int main() {
+  A a(0);
+}
+
+// { dg-final { scan-assembler-not {_ZTTW1M1A:} } }
+// { dg-final { scan-assembler-not {_ZTVW1M1A:} } }