Date: Sat, 1 Jul 2023 20:59:55 +0100 From: Jessica Clarke <jrtc27@freebsd.org> To: John Baldwin <jhb@FreeBSD.org> Cc: "src-committers@freebsd.org" <src-committers@FreeBSD.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@FreeBSD.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org> Subject: Re: git: cc4f247fb946 - main - sys: Add [u]divmoddi4 intrinsics on i386. Message-ID: <A4EDF531-DBBC-4E4F-A725-0B093EE90619@freebsd.org> In-Reply-To: <202307011923.361JNLn6070333@gitrepo.freebsd.org> References: <202307011923.361JNLn6070333@gitrepo.freebsd.org>
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On 1 Jul 2023, at 20:23, John Baldwin <jhb@FreeBSD.org> wrote: >=20 > The branch main has been updated by jhb: >=20 > URL: = https://cgit.FreeBSD.org/src/commit/?id=3Dcc4f247fb9468bbece5286557ab2d681= 0704aaf3 >=20 > commit cc4f247fb9468bbece5286557ab2d6810704aaf3 > Author: John Baldwin <jhb@FreeBSD.org> > AuthorDate: 2023-07-01 19:22:44 +0000 > Commit: John Baldwin <jhb@FreeBSD.org> > CommitDate: 2023-07-01 19:22:44 +0000 >=20 > sys: Add [u]divmoddi4 intrinsics on i386. >=20 > GCC 12 uses these in several places when building the i386 kernel. > They are very similar to [u]divdiv3 except that they return both > the quotient and the remainder. >=20 > Reviewed by: imp > Differential Revision: https://reviews.freebsd.org/D40817 > --- > sys/conf/files.i386 | 2 ++ > sys/libkern/divmoddi4.c | 60 = ++++++++++++++++++++++++++++++++++++++++++++++++ > sys/libkern/quad.h | 2 ++ > sys/libkern/udivmoddi4.c | 46 +++++++++++++++++++++++++++++++++++++ > 4 files changed, 110 insertions(+) >=20 > diff --git a/sys/conf/files.i386 b/sys/conf/files.i386 > index f0aa4007d8d3..cd1aeb4850b7 100644 > --- a/sys/conf/files.i386 > +++ b/sys/conf/files.i386 > @@ -140,6 +140,7 @@ isa/vga_isa.c optional vga > kern/imgact_aout.c optional compat_aout > kern/subr_sfbuf.c standard > libkern/divdi3.c standard > +libkern/divmoddi4.c standard > libkern/ffsll.c standard > libkern/flsll.c standard > libkern/memcmp.c standard > @@ -149,6 +150,7 @@ libkern/qdivrem.c standard > libkern/strlen.c standard > libkern/ucmpdi2.c standard > libkern/udivdi3.c standard > +libkern/udivmoddi4.c standard > libkern/umoddi3.c standard > # > # x86 real mode BIOS support, required by dpms/pci/vesa > diff --git a/sys/libkern/divmoddi4.c b/sys/libkern/divmoddi4.c > new file mode 100644 > index 000000000000..e5bd81a90ad7 > --- /dev/null > +++ b/sys/libkern/divmoddi4.c > @@ -0,0 +1,60 @@ > +/*- > + * SPDX-License-Identifier: BSD-3-Clause > + * > + * Copyright (c) 1992, 1993 > + * The Regents of the University of California. All rights reserved. > + * > + * This software was developed by the Computer Systems Engineering = group > + * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and > + * contributed to Berkeley. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions > + * are met: > + * 1. Redistributions of source code must retain the above copyright > + * notice, this list of conditions and the following disclaimer. > + * 2. Redistributions in binary form must reproduce the above = copyright > + * notice, this list of conditions and the following disclaimer in = the > + * documentation and/or other materials provided with the = distribution. > + * 3. Neither the name of the University nor the names of its = contributors > + * may be used to endorse or promote products derived from this = software > + * without specific prior written permission. > + * > + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS = IS'' AND > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, = THE > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR = PURPOSE > + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE = LIABLE > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR = CONSEQUENTIAL > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE = GOODS > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS = INTERRUPTION) > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN = CONTRACT, STRICT > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN = ANY WAY > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE = POSSIBILITY OF > + * SUCH DAMAGE. > + */ > + > +#include <libkern/quad.h> > + > +/* > + * Divide two signed quads. > + * ??? if -1/2 should produce -1 on this machine, this code is wrong > + */ > +quad_t > +__divmoddi4(quad_t a, quad_t b, quad_t *rem) > +{ > + u_quad_t ua, ub, uq, urem; > + int neg; > + > + if (a < 0) > + ua =3D -(u_quad_t)a, neg =3D 1; > + else > + ua =3D a, neg =3D 0; > + if (b < 0) > + ub =3D -(u_quad_t)b, neg ^=3D 1; I believe you need separate negq and negr so that only negq is flipped here. Consider the four cases: +3 / +2: q =3D +1, r =3D 1 +3 / -2: q =3D -1, r =3D 1 -3 / +2: q =3D -1, r =3D -1 -3 / -2: q =3D +1, r =3D -1 At least, that=E2=80=99s what I wrote when I added __[u]divmoddi4 back = in 2019 for Debian GNU/kFreeBSD, my reading of the C spec agrees with that and so do my tests (putting the above four into godbolt.org). Jess > + else > + ub =3D b; > + uq =3D __qdivrem(ua, ub, &urem); > + if (rem !=3D 0) > + *rem =3D urem; > + return (neg ? -uq : uq); > +} > diff --git a/sys/libkern/quad.h b/sys/libkern/quad.h > index 452f331661b3..e6be1c7bde15 100644 > --- a/sys/libkern/quad.h > +++ b/sys/libkern/quad.h > @@ -105,10 +105,12 @@ quad_t __ashldi3(quad_t, qshift_t); > quad_t __ashrdi3(quad_t, qshift_t); > int __cmpdi2(quad_t a, quad_t b); > quad_t __divdi3(quad_t a, quad_t b); > +quad_t __divmoddi4(quad_t a, quad_t b, quad_t *rem); > quad_t __lshrdi3(quad_t, qshift_t); > quad_t __moddi3(quad_t a, quad_t b); > u_quad_t __qdivrem(u_quad_t u, u_quad_t v, u_quad_t *rem); > u_quad_t __udivdi3(u_quad_t a, u_quad_t b); > +u_quad_t __udivmoddi4(u_quad_t a, u_quad_t b, u_quad_t *rem); > u_quad_t __umoddi3(u_quad_t a, u_quad_t b); > int __ucmpdi2(u_quad_t a, u_quad_t b); >=20 > diff --git a/sys/libkern/udivmoddi4.c b/sys/libkern/udivmoddi4.c > new file mode 100644 > index 000000000000..bb9b06917e2e > --- /dev/null > +++ b/sys/libkern/udivmoddi4.c > @@ -0,0 +1,46 @@ > +/*- > + * SPDX-License-Identifier: BSD-3-Clause > + * > + * Copyright (c) 1992, 1993 > + * The Regents of the University of California. All rights reserved. > + * > + * This software was developed by the Computer Systems Engineering = group > + * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and > + * contributed to Berkeley. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions > + * are met: > + * 1. Redistributions of source code must retain the above copyright > + * notice, this list of conditions and the following disclaimer. > + * 2. Redistributions in binary form must reproduce the above = copyright > + * notice, this list of conditions and the following disclaimer in = the > + * documentation and/or other materials provided with the = distribution. > + * 3. Neither the name of the University nor the names of its = contributors > + * may be used to endorse or promote products derived from this = software > + * without specific prior written permission. > + * > + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS = IS'' AND > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, = THE > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR = PURPOSE > + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE = LIABLE > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR = CONSEQUENTIAL > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE = GOODS > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS = INTERRUPTION) > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN = CONTRACT, STRICT > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN = ANY WAY > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE = POSSIBILITY OF > + * SUCH DAMAGE. > + */ > + > +#include <libkern/quad.h> > + > +/* > + * Divide two unsigned quads. > + */ > +u_quad_t > +__udivmoddi4(u_quad_t a, u_quad_t b, u_quad_t *rem) > +{ > + > + return (__qdivrem(a, b, rem)); > +}
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