https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116219
--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
DECL_NAMELESS VAR_DECL names don't leak into debug info. The -fcompare-debug
failures
I believe are solely because these fancy names appear in the
-fdump-final-insns=
dumps (e.g. inside of MEM_EXPRs or REG_EXPRs).
And, they wouldn't appear there if it was just the VAR_DECLs created by SRA
with DECL_NAMELESS set, we have that
/* For -fcompare-debug don't dump DECL_NAMELESS names at all,
-g might have created more fancy names and their indexes
could get out of sync. Usually those should be DECL_IGNORED_P
too, SRA can create even non-DECL_IGNORED_P DECL_NAMELESS fancy
names, let's hope those never get out of sync after doing the
dump_fancy_name sanitization. */
else if ((flags & TDF_COMPARE_DEBUG)
&& DECL_NAMELESS (node)
&& DECL_IGNORED_P (node))
name = NULL_TREE;
/* For DECL_NAMELESS names look for embedded uids in the
names and sanitize them for TDF_NOUID. */
else if ((flags & TDF_NOUID) && DECL_NAMELESS (node))
dump_fancy_name (pp, name);
else
pp_tree_identifier (pp, name);
where dump_fancy_name will try to look for the Dnnnnn$ inside of it, so
offset$D94316$_M_impl$D93629$_M_start_588
would be either not dumped as just _588 or
offset$Dxxxx$_M_impl$Dxxxx$_M_start_588
But the problem is that all the get_name users I've listed above grab the name
and most of them create new VAR_DECLs out of that and those aren't
DECL_NAMELESS anymore and even if we fixed that, additionally those $s in the
names are replaced with _s.
So, the question was how best to propagate next to const char *name a bool
nameless
flag so that we can avoid removing those $s and ensure DECL_NAMELESS is set.
Maybe also whether we should have similar flag to DECL_NAMELESS on SSA_NAMEs in
case they have just an IDENTIFIER_NODE rather than underlying VAR_DECL.
One C++-ish way would be to create a small class containing
const char *_M_name;
bool _M_nameless;
with a constructor from const char * which sets the flag to false, make it
default copyable/destructible so that it is passed as a struct and change
create_tmp_var* to accept that.
