On Thu, Jan 04, 2024 at 03:39:15PM -0500, Patrick Palka wrote:
> On Sun, 3 Dec 2023, Nathaniel Shead wrote:
>
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
> >
> > -- >8 --
> >
> > The TYPE_DECL_SUPPRESS_DEBUG and DECL_EXTERNAL flags use the same
> > underlying bit. This is causing confusion when attempting to determine
> > the interface for a streamed-in class type, since the modules code
> > currently assumes that all DECL_EXTERNAL types are extern templates.
> > However, when -g is specified then TYPE_DECL_SUPPRESS_DEBUG (and hence
> > DECL_EXTERNAL) is marked on various other kinds of declarations, such as
> > vtables, which causes them to never be emitted.
>
> Good catch.. Maybe we should use different bits for these flags? I wouldn't
> be
> surprised if this bit sharing causes issues elsewhere in the compiler. The
> documentation in tree.h / tree-core.h says DECL_EXTERNAL is only valid for
> VAR_DECL and FUNCTION_DECL, so at one point it was safe to share the same bit
> but that's not true anymore it seems.
>
> Looking at tree-core.h:tree_decl_common luckily we have plenty of spare bits.
> We could also e.g. make TYPE_DECL_SUPPRESS_DEBUG use the decl_not_flexarray
> bit
> which is otherwise only used for FIELD_DECL.
>
That seems like a good idea, thanks. How does this look?
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
-- >8 --
Currently, DECL_EXTERNAL and TYPE_DECL_SUPPRESS_DEBUG share a bit. This
causes issues with module code, which then incorrectly assumes that
anything with suppressed debug info (such as vtables when '-g' is
specified) is an extern template and thus prevents their emission.
This patch splits the two flags up; extern templates continue to use the
DECL_EXTERNAL flag (and the documentation is updated to indicate this),
but TYPE_DECL_SUPPRESS_DEBUG now uses the 'decl_not_flexarray' flag,
which currently is only used by FIELD_DECLs.
PR c++/112820
PR c++/102607
gcc/cp/ChangeLog:
* pt.cc (mark_class_instantiated): Set DECL_EXTERNAL explicitly.
gcc/ChangeLog:
* tree-core.h (struct tree_decl_common): Update comments.
* tree.h (DECL_EXTERNAL): Update comments.
(TYPE_DECL_SUPPRESS_DEBUG): Use 'decl_not_flexarray' instead.
gcc/testsuite/ChangeLog:
* g++.dg/modules/debug-2_a.C: New test.
* g++.dg/modules/debug-2_b.C: New test.
* g++.dg/modules/debug-2_c.C: New test.
* g++.dg/modules/debug-3_a.C: New test.
* g++.dg/modules/debug-3_b.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
gcc/cp/pt.cc | 1 +
gcc/testsuite/g++.dg/modules/debug-2_a.C | 9 +++++++++
gcc/testsuite/g++.dg/modules/debug-2_b.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/debug-2_c.C | 9 +++++++++
gcc/testsuite/g++.dg/modules/debug-3_a.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/debug-3_b.C | 9 +++++++++
gcc/tree-core.h | 6 +++---
gcc/tree.h | 8 ++++----
8 files changed, 51 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_b.C
create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_c.C
create mode 100644 gcc/testsuite/g++.dg/modules/debug-3_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/debug-3_b.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index e38e7a773f0..7839745035b 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -26256,6 +26256,7 @@ mark_class_instantiated (tree t, int extern_p)
SET_CLASSTYPE_EXPLICIT_INSTANTIATION (t);
SET_CLASSTYPE_INTERFACE_KNOWN (t);
CLASSTYPE_INTERFACE_ONLY (t) = extern_p;
+ DECL_EXTERNAL (TYPE_NAME (t)) = extern_p;
TYPE_DECL_SUPPRESS_DEBUG (TYPE_NAME (t)) = extern_p;
if (! extern_p)
{
diff --git a/gcc/testsuite/g++.dg/modules/debug-2_a.C
b/gcc/testsuite/g++.dg/modules/debug-2_a.C
new file mode 100644
index 00000000000..eed0905542b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/debug-2_a.C
@@ -0,0 +1,9 @@
+// PR c++/112820
+// { dg-additional-options "-fmodules-ts -g" }
+// { dg-module-cmi io }
+
+export module io;
+
+export struct error {
+ virtual const char* what() const noexcept;
+};
diff --git a/gcc/testsuite/g++.dg/modules/debug-2_b.C
b/gcc/testsuite/g++.dg/modules/debug-2_b.C
new file mode 100644
index 00000000000..fc9afbc02e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/debug-2_b.C
@@ -0,0 +1,8 @@
+// PR c++/112820
+// { dg-additional-options "-fmodules-ts -g" }
+
+module io;
+
+const char* error::what() const noexcept {
+ return "bla";
+}
diff --git a/gcc/testsuite/g++.dg/modules/debug-2_c.C
b/gcc/testsuite/g++.dg/modules/debug-2_c.C
new file mode 100644
index 00000000000..37117f69dcd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/debug-2_c.C
@@ -0,0 +1,9 @@
+// PR c++/112820
+// { dg-module-do link }
+// { dg-additional-options "-fmodules-ts -g" }
+
+import io;
+
+int main() {
+ error{};
+}
diff --git a/gcc/testsuite/g++.dg/modules/debug-3_a.C
b/gcc/testsuite/g++.dg/modules/debug-3_a.C
new file mode 100644
index 00000000000..9e33d8260fd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/debug-3_a.C
@@ -0,0 +1,8 @@
+// PR c++/102607
+// { dg-additional-options "-fmodules-ts -g" }
+// { dg-module-cmi mod }
+
+export module mod;
+export struct B {
+ virtual ~B() = default;
+};
diff --git a/gcc/testsuite/g++.dg/modules/debug-3_b.C
b/gcc/testsuite/g++.dg/modules/debug-3_b.C
new file mode 100644
index 00000000000..03c78b71b5d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/debug-3_b.C
@@ -0,0 +1,9 @@
+// PR c++/102607
+// { dg-module-do link }
+// { dg-additional-options "-fmodules-ts -g" }
+
+import mod;
+int main() {
+ struct D : B {};
+ (void)D{};
+}
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index 8a89462bd7e..1ca4d4c07bd 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -1814,8 +1814,7 @@ struct GTY(()) tree_decl_common {
In FIELD_DECL, this is DECL_FIELD_ABI_IGNORED. */
unsigned decl_flag_0 : 1;
/* In FIELD_DECL, this is DECL_BIT_FIELD
- In VAR_DECL and FUNCTION_DECL, this is DECL_EXTERNAL.
- In TYPE_DECL, this is TYPE_DECL_SUPPRESS_DEBUG. */
+ In VAR_DECL, FUNCTION_DECL, and TYPE_DECL, this is DECL_EXTERNAL. */
unsigned decl_flag_1 : 1;
/* In FIELD_DECL, this is DECL_NONADDRESSABLE_P
In VAR_DECL, PARM_DECL and RESULT_DECL, this is
@@ -1845,7 +1844,8 @@ struct GTY(()) tree_decl_common {
TYPE_WARN_IF_NOT_ALIGN. */
unsigned int warn_if_not_align : 6;
- /* In FIELD_DECL, this is DECL_NOT_FLEXARRAY. */
+ /* In FIELD_DECL, this is DECL_NOT_FLEXARRAY.
+ In TYPE_DECL, this is TYPE_DECL_SUPPRESS_DEBUG. */
unsigned int decl_not_flexarray : 1;
/* 5 bits unused. */
diff --git a/gcc/tree.h b/gcc/tree.h
index 972a067a1f7..8bdc471ad4e 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2848,9 +2848,9 @@ extern tree vector_element_bits_tree (const_tree);
#define DECL_LANG_SPECIFIC(NODE) \
(DECL_COMMON_CHECK (NODE)->decl_common.lang_specific)
-/* In a VAR_DECL or FUNCTION_DECL, nonzero means external reference:
- do not allocate storage, and refer to a definition elsewhere. Note that
- this does not necessarily imply the entity represented by NODE
+/* In a VAR_DECL, FUNCTION_DECL, or TYPE_DECL, nonzero means external
+ reference: do not allocate storage, and refer to a definition elsewhere.
+ Note that this does not necessarily imply the entity represented by NODE
has no program source-level definition in this translation unit. For
example, for a FUNCTION_DECL, DECL_SAVED_TREE may be non-NULL and
DECL_EXTERNAL may be true simultaneously; that can be the case for
@@ -3553,7 +3553,7 @@ extern vec<tree, va_gc> **decl_debug_args_insert (tree);
into stabs. Instead it will generate cross reference ('x') of names.
This uses the same flag as DECL_EXTERNAL. */
#define TYPE_DECL_SUPPRESS_DEBUG(NODE) \
- (TYPE_DECL_CHECK (NODE)->decl_common.decl_flag_1)
+ (TYPE_DECL_CHECK (NODE)->decl_common.decl_not_flexarray)
/* Getter of the imported declaration associated to the
IMPORTED_DECL node. */
--
2.43.0
