Re: git: 349cc55c9796 - main - Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

On Wed, May 18, 2022 at 09:17:58PM +0200, Dimitry Andric wrote:
> On 18 May 2022, at 02:33, Konstantin Belousov <kostikbel@gmail.com> wrote:
> > 
> > On Tue, May 17, 2022 at 10:56:14AM -0700, John Baldwin wrote:
> >> On 5/16/22 8:09 PM, Charlie Li wrote:
> >>> Brooks Davis wrote:
> >>>> On Mon, May 16, 2022 at 10:47:49AM -0400, Charlie Li wrote:
> >>>>> Dimitry Andric wrote:
> >>>>>> This was also reported by another user, and it turned out they were
> >>>>>> using WITHOUT_CROSS_COMPILER= in src.conf. If you also have that, try
> >>>>>> removing it and rebuilding.
> >>>>>> 
> >>>>> Yeah I eventually figured that part out. Worked around (first attempt)
> >>>>> by building with devel/llvm14 CROSS_TOOLCHAIN, but resulted in certain
> >>>>> kernel modules (zfs and a few more) with malformed relocations.
> >>>>> Subsequent rebuild with the new world's toolchain corrected that.
> >>>> 
> >>>> Does that mean we're missing patches in the port? Hopefully anything
> >>>> this critical can be merged into LLVM 14.0.3.
> >>>> 
> >>> Probably:
> >>> 
> >>> May 15 22:34:08 current-builder kernel: ---<<BOOT>>---
> >>> May 15 22:34:08 current-builder kernel: Copyright (c) 1992-2022 The
> >>> FreeBSD Project.
> >>> May 15 22:34:08 current-builder kernel: Copyright (c) 1979, 1980, 1983,
> >>> 1986, 1988, 1989, 1991, 1992, 1993, 1994
> >>> May 15 22:34:08 current-builder kernel: The Regents of the
> >>> University of California. All rights reserved.
> >>> May 15 22:34:08 current-builder kernel: FreeBSD is a registered
> >>> trademark of The FreeBSD Foundation.
> >>> May 15 22:34:08 current-builder kernel: FreeBSD 14.0-CURRENT #121
> >>> main-n255657-48a1a6be196: Sun May 15 21:59:12 EDT 2022
> >>> May 15 22:34:08 current-builder kernel:
> >>> root@current-builder:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG amd64
> >>> May 15 22:34:08 current-builder kernel: clang version 14.0.2
> >>> [...]
> >>> May 15 22:34:08 current-builder kernel: kldload: unexpected relocation
> >>> type 42, symbol index 8321
> >> 
> >> These are all type 42:
> >> 
> >> #define	R_X86_64_REX_GOTPCRELX	42
> >> 
> >> It's not a LLVM bug so much as it is probably missing support in the kernel and/or
> >> loader for this type of relocation. kldxref might also need updating.
> >> 
> >> I suspect due to a mismatch of old lld with new clang or some such that the old
> >> lld failed to resolve these relocations to some other type or something weird like
> >> that?
> > 
> > I do think this is a toolchain bug, or at least new and undesired behavior.
> > 
> > For practical purposes, R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX are
> > same as R_X86_64_GOTPCREL64, I believe, but we do not expect GOT relocations
> > in the .o object modules on amd64.
> 
> I don't see this with clang 14.0.3 from base on 14-CURRENT. None of my
> kernel modules has any of these relocations, and I also get no warnings
> from kldxref.
> 
> Btw, I know that clang from ports will use /usr/local/bin/ld if it is
> available, so this might be GNU ld specific behavior? Charlie, do you
> have the binutils port installed?

I don't believe this is true in all but the weirdest configurations.  I
just tested on a system with binutils installed (providing
/usr/local/bin/ld) and clang13 uses /usr/local/llvm13/bin/ld as I'd
expect.  Because of the foo## wrappers, clang doesn't know it's being
found via /usr/local/bin so doesn't look there by default.  Instead it's
invoked as /usr/local/llvm##/bin/clang and looks for
/usr/local/llvm##/bin/ld.  Maybe if you didn't install LLD it would
eventually look in PATH and find /usr/local/bin/ld.

-- Brooks

$ clang13 -### ~/hello.c 
clang version 13.0.1
Target: x86_64-portbld-freebsd13.0
Thread model: posix
InstalledDir: /usr/local/llvm13/bin
 "/usr/local/llvm13/bin/clang-13" "-cc1" "-triple" "x86_64-portbld-freebsd13.0" "-emit-obj" "-mrelax-all" "--mrelax-relocations" "-disable-free" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "hello.c" "-mrelocation-model" "static" "-mframe-pointer=all" "-fno-rounding-math" "-mconstructor-aliases" "-munwind-tables" "-target-cpu" "x86-64" "-tune-cpu" "generic" "-debugger-tuning=gdb" "-fcoverage-compilation-dir=/home/bed22/git/ports/devel" "-resource-dir" "/usr/local/llvm13/lib/clang/13.0.1" "-fdebug-compilation-dir=/home/bed22/git/ports/devel" "-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fcolor-diagnostics" "-faddrsig" "-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o" "/tmp/hello-7a4c72.o" "-x" "c" "/home/bed22/hello.c"
  "/usr/local/llvm13/bin/ld" "--eh-frame-hdr" "-dynamic-linker" "/libexec/ld-elf.so.1" "--hash-style=both" "--enable-new-dtags" "-o" "a.out" "/usr/lib/crt1.o" "/usr/lib/crti.o" "/usr/lib/crtbegin.o" "-L/usr/lib" "/tmp/hello-7a4c72.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "/usr/lib/crtend.o" "/usr/lib/crtn.o"