From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 2D6E13857C71; Thu, 7 Apr 2022 14:57:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2D6E13857C71 From: "palmer at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/104338] RISC-V: Subword atomics result in library calls Date: Thu, 07 Apr 2022 14:57:35 +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: 12.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: palmer at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: patrick at rivosinc dot com X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: 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: Thu, 07 Apr 2022 14:57:35 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104338 --- Comment #5 from palmer at gcc dot gnu.org --- (In reply to rvalue from comment #4) > In short term, maybe we can change the spec to link against libatomic by > default (implemented in > https://github.com/riscv-collab/riscv-gcc/commit/ > 2c4857d0981501b7c50bbf228de9e287611f8ae5). It will solve a lot of build > errors if we revert the value of `LIB_SPEC` instead of only link against > libatomic when `-pthread` is present. >=20 > Detailed talk about this: > https://github.com/riscv-collab/riscv-gcc/issues/337 We talked through some options like that and decided it was too risky for GCC-12. We already found one ABI break related to this (see 84568), and wa= nt to make sure we give distros adequate advance notice before something that = we know to break ABIs. That said, it's really not a GCC ABI break, it's a per-package configure is= sue. We can fix the libstdcxx fallout, which is the only bit we know about right now (though it's not like we've scrubbed builds for this). If the folks building distros think it's better to risk the ABI breaks rather than chase around the build failures, then I'm fine rushing something in to GCC-12. I see Andreas is already here, I'm having some trouble adding anyone else though (I can never quite figure out Bugzilla...).=