From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 569C3385DC11; Sat, 1 Jan 2022 19:19:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 569C3385DC11 From: "krystalgamer at protonmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/103882] Register corruption in ASM only functions when optization is -O2/-Os/-O3 Date: Sat, 01 Jan 2022 19:19:15 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 10.3.0 X-Bugzilla-Keywords: inline-asm X-Bugzilla-Severity: normal X-Bugzilla-Who: krystalgamer at protonmail dot com X-Bugzilla-Status: RESOLVED X-Bugzilla-Resolution: WONTFIX X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: resolution Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 01 Jan 2022 19:19:15 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103882 Jose Silva changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|INVALID |WONTFIX --- Comment #11 from Jose Silva --- > much more important is that it needs to know what the inline asm does for= code generation within the function, it needs to know in which registers o= r memory it can spill values live across the inline asm etc. > if you are unable or not willing to tell the compiler how it behaves Read the title of issue. This problem only manifests with O2/Os/O3, O0 and = O1 don't exhibit it because IPA RA doesn't kick in. So no, the compiler doesn't need to be told how it behaves if it takes precautions. The only reason to = tell a compiler something is to further optimize something, in any other circumstance it should treat the piece of code as a black-box as you said. What we're arguing here is about sensible compiler defaults. By default a compiler should be cautious about asm statements and protect the surrounding code by respecting the ABI. The programmer should be able to override this behavior, not the other way around like GCC does. There is absolutely no need to tell the compiler something he could've easi= ly accounted for. > Don't use inline asm=20 Wish I didn't need to, but there's no way of doing syscalls without it. On the other hand, since you avoided answering my question regarding modify= ing GCC I suppose you're not familiar with the codebase. Please refrain from polluting this discussion with unnecessary noise if you don't wish to help.=