[gcc r10-9076] dwarf2: Emit DW_TAG_unspecified_parameters even in late DWARF [PR97599]
Jakub Jelinek
jakub@gcc.gnu.org
Wed Nov 25 11:56:45 GMT 2020
https://gcc.gnu.org/g:812258b07c1a80e8dc79a0beb3ec0e17be62f5e5
commit r10-9076-g812258b07c1a80e8dc79a0beb3ec0e17be62f5e5
Author: Jakub Jelinek <jakub@redhat.com>
Date: Sat Nov 14 09:14:19 2020 +0100
dwarf2: Emit DW_TAG_unspecified_parameters even in late DWARF [PR97599]
Aldy's PR71855 fix avoided emitting multiple redundant
DW_TAG_unspecified_parameters sub-DIEs of a single DIE by restricting
it to early dwarf only. That unfortunately means if we need to emit
another DIE for the function (whether it is for LTO, or e.g. because of
IPA cloning), we don't emit DW_TAG_unspecified_parameters, it remains
solely in the DW_AT_abstract_origin's referenced DIE.
But DWARF consumers don't really use DW_TAG_unspecified_parameters
from there, like we duplicate DW_TAG_formal_parameter sub-DIEs even in the
clones because either they have some more specific location, or e.g.
a function clone could have fewer or different argument types etc.,
they need to assume that originally stdarg function isn't later stdarg etc.
Unfortunately, while for DW_TAG_formal_parameter sub-DIEs, we can use the
hash tabs to look the PARM_DECLs if we already have the DIEs, for
DW_TAG_unspecified_parameters we don't have an easy way to look it up.
The following patch handles it by trying to figure out if we are creating a
fresh new DIE (in that case we add DW_TAG_unspecified_parameters if it is
stdarg), or if gen_subprogram_die is called again on an pre-existing DIE
to fill in some further details (then it will not touch it).
Except for lto, subr_die != old_die would be good enough, but unfortunately
for LTO the new DIE that will refer to early dwarf created DIE is created
on the fly during lookup_decl_die. So the patch tracks if the DIE has
no children before any children are added to it.
2020-11-14 Jakub Jelinek <jakub@redhat.com>
PR debug/97599
* dwarf2out.c (gen_subprogram_die): Call
gen_unspecified_parameters_die even if not early dwarf, but only
if subr_die is a newly created DIE.
(cherry picked from commit 2873c8af66e1248734bb638a49e6bc53f5e45382)
Diff:
---
gcc/dwarf2out.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index cd12a76b67a..343d4a313f8 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -22688,6 +22688,7 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
tree origin = decl_ultimate_origin (decl);
dw_die_ref subr_die;
dw_die_ref old_die = lookup_decl_die (decl);
+ bool old_die_had_no_children = false;
/* This function gets called multiple times for different stages of
the debug process. For example, for func() in this code:
@@ -22779,6 +22780,9 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
if (old_die && declaration)
return;
+ if (in_lto_p && old_die && old_die->die_child == NULL)
+ old_die_had_no_children = true;
+
/* Now that the C++ front end lazily declares artificial member fns, we
might need to retrofit the declaration into its class. */
if (!declaration && !origin && !old_die
@@ -23298,6 +23302,10 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
else if (DECL_INITIAL (decl) == NULL_TREE)
gen_unspecified_parameters_die (decl, subr_die);
}
+ else if ((subr_die != old_die || old_die_had_no_children)
+ && prototype_p (TREE_TYPE (decl))
+ && stdarg_p (TREE_TYPE (decl)))
+ gen_unspecified_parameters_die (decl, subr_die);
}
if (subr_die != old_die)
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