On Tue, 24 Jul 2018, Richard Biener wrote:
>
> I am testing the following patch to avoid forcing DIEs for a type context
> for method clones late via limbo processing. Instead hang them off
> comp_unit_die if there is no early DIE for the function.
>
> One question is whether the comment "If we're a nested function"
> matches up with the decl_function_context (decl) check or whether
> we really wanted to check DECL_CONTEXT (decl) == FUNCTION_DECL
> which would have made this particular case not match (DECL_CONTEXT
> is a RECORD_TYPE which context is a FUNCTION_DECL).
>
> Another option is of course to make clones not inherit
> DECL_CONTEXT from the cloned function (for an artificial
> instance the "context" is somewhat arbitrary since it isn't
> going to be found by lookup). In fact I long wanted to
> represent clones as artificial containers for an
> inline instance of the cloned function...
>
> LTO bootstrap and regtest running on x86_64-unknown-linux-gnu.
>
> If that succeeds I'm going to apply it as a stop-gap measure to
> make Firefox build again with LTO but I'm open to revising it.
So there was fallout, namely
FAIL: g++.dg/debug/dwarf2/lambda1.C -std=gnu++11 scan-assembler-times
DW_TAG_variable[^.]*.ascii "this.0" 2
FAIL: g++.dg/debug/dwarf2/lambda1.C -std=gnu++14 scan-assembler-times
DW_TAG_variable[^.]*.ascii "this.0" 2
see the PR for analysis. The following revised patch mitigates this
by relying not on !context_die but on an explicit local_scope_p
for fulfilling the last part of the overall comment of this section:
to have the same parent. For local class methods, this doesn't
apply; we just use the old DIE. */
LTO bootstrapped and tested on x86_64-unknown-linux-gnu, bootstrapped
and tested on x86_64-unknown-linux-gnu.
I have applied the patch for now, as said, I'm happy to revise later.
Richard.
2018-07-24 Richard Biener <rguent...@suse.de>
PR debug/86654
* dwarf2out.c (dwarf2out_decl): Do not handle nested functions
special wrt context_die late.
(gen_subprogram_die): Re-use DIEs in local scope.
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c (revision 262940)
+++ gcc/dwarf2out.c (working copy)
@@ -22766,6 +22766,7 @@ gen_subprogram_die (tree decl, dw_die_re
*/
|| (old_die->die_parent
&& old_die->die_parent->die_tag == DW_TAG_module)
+ || local_scope_p (old_die->die_parent)
|| context_die == NULL)
&& (DECL_ARTIFICIAL (decl)
|| (get_AT_file (old_die, DW_AT_decl_file) == file_index
@@ -26702,8 +26703,11 @@ dwarf2out_decl (tree decl)
case FUNCTION_DECL:
/* If we're a nested function, initially use a parent of NULL; if we're
a plain function, this will be fixed up in decls_for_scope. If
- we're a method, it will be ignored, since we already have a DIE. */
- if (decl_function_context (decl)
+ we're a method, it will be ignored, since we already have a DIE.
+ Avoid doing this late though since clones of class methods may
+ otherwise end up in limbo and create type DIEs late. */
+ if (early_dwarf
+ && decl_function_context (decl)
/* But if we're in terse mode, we don't care about scope. */
&& debug_info_level > DINFO_LEVEL_TERSE)
context_die = NULL;
