From 2873c8af66e1248734bb638a49e6bc53f5e45382 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 14 Nov 2020 09:14:19 +0100 Subject: [PATCH] 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 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. --- gcc/dwarf2out.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index 0e8436e51c4..54eb445665c 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -22779,6 +22779,7 @@ 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: @@ -22870,6 +22871,9 @@ 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 @@ -23389,6 +23393,10 @@ 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) -- 2.30.2