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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug debug/108996] Proposal for adding DWARF call site information in GCC with -O0 Date: Tue, 07 Mar 2023 08:53:28 +0000 [thread overview] Message-ID: <bug-108996-4-yXLVZAoOSb@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-108996-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108996 --- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Ulrich Weigand from comment #8) > (In reply to Jakub Jelinek from comment #5) > > Though, relying on DW_OP_entry_value is not reliable, if e.g. tail calls are > > (or could be) involved, then GDB needs to punt. > > The only way a tail call could happen is if the return value is > passed through directly to the (caller's) caller, so the return > buffer address should still be correct, right? If there is just a single possible tail call, I think GDB still handles it, so that would be ok. But if you have multiple possible tail calls, I think GDB for DW_OP_entry_value evaluation punts (at least should, because it doesn't know which sequence of calls has been taken). > I don't think it is possible to track the value in the callee - the value > may not be available *anywhere* because it is no longer needed. (Also, I > don't think the implicit return buffer address is guaranteed to be spilled > to the stack even at -O0.) Well, at -O0 we can certainly guarantee it is available somewhere, even if we currently don't do it already (it would surprise me if it is not spilled).
prev parent reply other threads:[~2023-03-07 8:53 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-02 20:28 [Bug c/108996] New: Proposal for adding DWARF call site information got " cel at us dot ibm.com 2023-03-03 8:37 ` [Bug debug/108996] Proposal for adding DWARF call site information in " rguenth at gcc dot gnu.org 2023-03-03 9:20 ` jakub at gcc dot gnu.org 2023-03-03 9:24 ` jakub at gcc dot gnu.org 2023-03-03 13:14 ` uweigand at gcc dot gnu.org 2023-03-03 13:51 ` jakub at gcc dot gnu.org 2023-03-03 15:39 ` mark at gcc dot gnu.org 2023-03-03 18:24 ` pinskia at gcc dot gnu.org 2023-03-07 8:46 ` uweigand at gcc dot gnu.org 2023-03-07 8:49 ` uweigand at gcc dot gnu.org 2023-03-07 8:53 ` jakub at gcc dot gnu.org [this message]
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