public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "miladfarca at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/107736] New: call to a function, generated by inline asm, is off by one byte Date: Thu, 17 Nov 2022 19:21:34 +0000 [thread overview] Message-ID: <bug-107736-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107736 Bug ID: 107736 Summary: call to a function, generated by inline asm, is off by one byte Product: gcc Version: 12.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: miladfarca at gmail dot com Target Milestone: --- Tested on Arm64, PPC64 and s390x with gcc 12. ``` const char num = 0; void call(); asm( ".globl call \n" ".type call, %function \n" ".hidden call \n" "call: \n" // Just return. "ret \n"); int main(){ call(); return 0; } ``` TL;DR: The instruction generated for `call();` is jumping to the address of `num` and causing a crash as `num` is not an instruction, seems to be an alignment issue? Details: - This doesn't happen on x64 and call is made to the correct address. It also does not happen with clang on either platforms (tested with version 6.0). - gcc is putting "call" into .rodata section of memory including on x64. Not sure if this is a separate bug or intentional. clang is putting it under ".text" as expected. - gcc is incorrectly assuming `&num` is the address of `call` and jumping to it which is off by 1 byte. - Workarounds include adding either ".text \n" or ".align 8" to the inline asm, tho call should be made to the correct address even without them?
next reply other threads:[~2022-11-17 19:21 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-17 19:21 miladfarca at gmail dot com [this message] 2022-11-17 19:34 ` [Bug c/107736] " pinskia at gcc dot gnu.org 2022-11-17 19:39 ` miladfarca at gmail dot com 2022-11-17 19:43 ` pinskia at gcc dot gnu.org 2022-11-17 19:50 ` miladfarca at gmail dot com 2022-11-17 19:58 ` pinskia at gcc dot gnu.org 2022-12-04 5:37 ` pinskia 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-107736-4@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).