public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "uweigand 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 08:46:10 +0000 [thread overview] Message-ID: <bug-108996-4-klJTTmwa6Q@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 #8 from Ulrich Weigand <uweigand at gcc dot gnu.org> --- (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? > So, I wonder if we just shouldn't ask for a DWARF 6 extension here, have > some way for the compiler to specify DW_AT_location for the return value. > Then for -O1+ -g with var-tracking that address could be for PowerPC r3 > register in such functions or wherever its initial value is tracked > (including DW_OP_entry_value). > While for -O0, we'd see we've spilled that parameter to stack and would set > DW_AT_location to that place spilled on the stack. 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.)
next prev parent reply other threads:[~2023-03-07 8:46 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 [this message] 2023-03-07 8:49 ` uweigand at gcc dot gnu.org 2023-03-07 8:53 ` jakub at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-108996-4-klJTTmwa6Q@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).