debug/108772 - ICE with late debug generated with -flto
Commit Message
When combining -g1 with -flto we run into the DIE location annotation
machinery for globals calling dwarf2out_late_global_decl but not
having any early generated DIE for function scope statics. In
this process we'd generate a limbo DIE since also the function scope
doesn't have any early generated DIE. The limbo handling then tries
to force a DIE for the context chain which ultimatively fails and
ICEs at the std namespace decl because at -g1 we don't represent that.
The following avoids this situation by making sure to never generate
any limbo DIEs from dwarf2out_late_global_decl in the in_lto_p path
but instead for function scope globals rely on DIE generation for
the function to output a DIE for the local static (which doesn't
happen for -g1).
I explored a lot of other options to fix this but in the end this
seems to be the most spot-on fix with the least risk of unwanted
effects.
LTO bootstrapped on x86_64-unknown-linux-gnu (running into PR108984),
bootstrapped and tested on x86_64-unknown-linux-gnu.
OK?
Thanks,
Richard.
PR debug/108772
* dwarf2out.cc (dwarf2out_late_global_decl): Do not
generate a DIE for a function scope static when we do
not have a DIE for the function already.
* g++.dg/lto/pr108772_0.C: New testcase.
---
gcc/dwarf2out.cc | 12 ++++++-
gcc/testsuite/g++.dg/lto/pr108772_0.C | 46 +++++++++++++++++++++++++++
2 files changed, 57 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/lto/pr108772_0.C
@@ -27283,7 +27283,17 @@ dwarf2out_late_global_decl (tree decl)
was not enabled at compile-time or the target doesn't support
the LTO early debug scheme. */
if (! die && in_lto_p)
- dwarf2out_decl (decl);
+ {
+ /* Avoid relying on the ability to force context DIEs for
+ local entities. Instead if the function context was not
+ instantiated yet defer to it producing its local DIEs.
+ See PR108772. */
+ dw_die_ref context_die = comp_unit_die ();
+ if (local_function_static (decl))
+ context_die = lookup_decl_die (DECL_CONTEXT (decl));
+ if (context_die)
+ dwarf2out_decl (decl);
+ }
else if (die)
{
/* We get called via the symtab code invoking late_global_decl
new file mode 100644
@@ -0,0 +1,46 @@
+// { dg-lto-do link }
+// { dg-require-effective-target shared }
+// { dg-require-effective-target fpic }
+// { dg-lto-options { "-flto -fPIC -shared -O1 -fimplicit-constexpr -g1" } }
+// { dg-extra-ld-options "-shared" }
+
+namespace std {
+struct _Sp_counted_base {
+ virtual void *_M_get_deleter(const int &);
+};
+bool _S_eq(int);
+struct _Sp_make_shared_tag {
+ static const int &_S_ti() {
+ static constexpr char __tag{};
+ return reinterpret_cast<const int &>(__tag);
+ }
+};
+struct _Impl {
+ _Impl(int);
+};
+int _Sp_counted_ptr_inplace___a;
+struct _Sp_counted_ptr_inplace : _Sp_counted_base {
+ _Sp_counted_ptr_inplace() : _M_impl(_Sp_counted_ptr_inplace___a) {}
+ void *_M_get_deleter(const int &__ti) {
+ auto __ptr(_M_ptr());
+ &__ti == &_Sp_make_shared_tag::_S_ti() || _S_eq(__ti);
+ return __ptr;
+ }
+ int *_M_ptr();
+ _Impl _M_impl;
+};
+struct __shared_count {
+ __shared_count(int, int) { _Sp_counted_ptr_inplace(); }
+};
+int _M_ptr;
+struct __shared_ptr {
+ template <typename _Alloc>
+ __shared_ptr(_Alloc __tag) : _M_refcount(_M_ptr, __tag) {}
+ __shared_count _M_refcount;
+};
+int shared_ptr___tag;
+struct shared_ptr : __shared_ptr {
+ shared_ptr() : __shared_ptr(shared_ptr___tag) {}
+};
+void ArgEq() { shared_ptr(); }
+} // namespace std