From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 763643858401; Tue, 31 Aug 2021 08:45:36 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 763643858401 From: "ubizjak at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/102143] New: ABI incompatibility with clang when passing 32bit vectors on 32bit i686 Date: Tue, 31 Aug 2021 08:45:36 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: ubizjak at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: 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: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone Message-ID: 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: Tue, 31 Aug 2021 08:45:36 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102143 Bug ID: 102143 Summary: ABI incompatibility with clang when passing 32bit vectors on 32bit i686 Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: ubizjak at gmail dot com Target Milestone: --- Following testcase: --cut here-- typedef short __v2hi __attribute__((__vector_size__ (4))); __v2hi foo (__v2hi x, __v2hi y) { return x + y; } --cut here-- exhibits ABI incompatibility with clang when passing 32bit vectors on 32bit i686. gcc-12 compiles with "-O2 -msse2" to: foo: movd 4(%esp), %xmm0 movd 8(%esp), %xmm1 paddw %xmm1, %xmm0 movd %xmm0, %eax ret (gcc before version 12 uses the same ABI). while clang-11 compiles the testacse to: foo: paddw %xmm1, %xmm0 retl So, clang is passing 32bit vectors via vector registers, while gcc is passi= ng them like integer values in memory and returns them in integer return regis= ter.=