Date: Fri, 16 Jul 2021 00:53:48 -0700 From: Mark Millard via toolchain <toolchain@freebsd.org> To: David Chisnall <theraven@FreeBSD.org> Cc: toolchain@freebsd.org Subject: Re: Why is main's system clang (12.0.1-rc2) using /usr/local/bin/aarch64-unknown-freebsd14.0-ld ? (such breaks things) Message-ID: <9AD00B4C-8DED-4D35-9813-03FA8429DAFC@yahoo.com> In-Reply-To: <f655cb14-ffda-9bde-6d7a-56dd85230b59@FreeBSD.org> References: <7073D16F-4505-4948-8232-A9618DF2FE5F.ref@yahoo.com> <7073D16F-4505-4948-8232-A9618DF2FE5F@yahoo.com> <f655cb14-ffda-9bde-6d7a-56dd85230b59@FreeBSD.org>
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On 2021-Jul-16, at 00:42, David Chisnall <theraven at FreeBSD.org> =
wrote:
> On 16/07/2021 01:21, Mark Millard via freebsd-toolchain wrote:
>> Context:
>> # uname -apKU
>> FreeBSD CA72_16Gp_ZFS 14.0-CURRENT FreeBSD 14.0-CURRENT #10 =
main-n247756-348c41d1815d-dirty: Mon Jul 5 10:23:55 PDT 2021 =
root@CA72_16Gp_ZFS:/usr/obj/BUILDs/main-CA72-nodbg-clang/usr/main-src/arm6=
4.aarch64/sys/GENERIC-NODBG-CA72 arm64 aarch64 1400025 1400025
>> Showing a trivial example . . .
>> # cat trivial.cpp
>> // # c++ -v -o trival trivial.cpp
>> int main() {
>> }
>> # c++ -v
>> FreeBSD clang version 12.0.1 (git@github.com:llvm/llvm-project.git =
llvmorg-12.0.1-rc2-0-ge7dac564cd0e)
>> Target: aarch64-unknown-freebsd14.0
>> Thread model: posix
>> InstalledDir: /usr/bin
>> # c++ -v -o trivial trivial.cpp
>> FreeBSD clang version 12.0.1 (git@github.com:llvm/llvm-project.git =
llvmorg-12.0.1-rc2-0-ge7dac564cd0e)
>> Target: aarch64-unknown-freebsd14.0
>> Thread model: posix
>> InstalledDir: /usr/bin
>> "/usr/bin/c++" -cc1 -triple aarch64-unknown-freebsd14.0 -emit-obj =
-mrelax-all --mrelax-relocations -disable-free -disable-llvm-verifier =
-discard-value-names -main-file-name trivial.cpp -mrelocation-model =
static -mframe-pointer=3Dnon-leaf -fno-rounding-math =
-mconstructor-aliases -munwind-tables -target-cpu generic =
-target-feature +neon -target-abi aapcs =
-fallow-half-arguments-and-returns -fno-split-dwarf-inlining =
-debugger-tuning=3Dgdb -v -resource-dir /usr/lib/clang/12.0.1 =
-internal-isystem /usr/include/c++/v1 -fdeprecated-macro =
-fdebug-compilation-dir /usr/home/root/c_tests -ferror-limit 19 =
-fno-signed-char -fgnuc-version=3D4.2.1 -fcxx-exceptions -fexceptions =
-faddrsig -o /tmp/trivial-5d90b5.o -x c++ trivial.cpp
>> clang -cc1 version 12.0.1 based upon LLVM 12.0.1 default target =
aarch64-unknown-freebsd14.0
>> #include "..." search starts here:
>> #include <...> search starts here:
>> /usr/include/c++/v1
>> /usr/lib/clang/12.0.1/include
>> /usr/include
>> End of search list.
>> "/usr/local/bin/aarch64-unknown-freebsd14.0-ld" --eh-frame-hdr =
-dynamic-linker /libexec/ld-elf.so.1 --enable-new-dtags -o trivial =
/usr/lib/crt1.o /usr/lib/crti.o /usr/lib/crtbegin.o -L/usr/lib =
/tmp/trivial-5d90b5.o -lc++ -lm -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
>> CA72_16Gp_ZFS# c++ -v
>> FreeBSD clang version 12.0.1 (git@github.com:llvm/llvm-project.git =
llvmorg-12.0.1-rc2-0-ge7dac564cd0e)
>> Target: aarch64-unknown-freebsd14.0
>> Thread model: posix
>> InstalledDir: /usr/bin
>> Note the "/usr/local/bin/aarch64-unknown-freebsd14.0-ld" path
>> for ld.
>> I've an example where this usage leads to:
>> /usr/local/bin/aarch64-unknown-freebsd14.0-ld: =
/usr/bin/../lib/LLVMgold.so: error loading plugin: Cannot open =
"/usr/bin/../lib/LLVMgold.so"
>> clang++: error: linker command failed with exit code 1 (use -v to see =
invocation)
>=20
> This is the documented behaviour for clang when cross-compiling.
The host is aarch64 and the target is aarch64 and the command was:
# c++ -v -o trivial trivial.cpp
So: no cross compile is involved.
> You can specify a target in one of two ways with clang:
>=20
> - Via the -target flag.
Not used in the command line reported for the trivial example:
# c++ -v -o trivial trivial.cpp
> - By invoking clang with a symlink named {target}-clang[++]
Also not involved.
> Clang will look for all of the tools in your path (or in the tree =
specified with -B if you provide an alternative location for tools).
# echo $PATH
=
/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/home/roo=
t/bin
No -B in:
# c++ -v -o trivial trivial.cpp
> If clang finds {target}-{tool name} then it will invoke this in =
preference to {tool name}. This avoids situations where, for example, =
your system ld is BFD ld (or any other linker that doesn't support =
cross-linking) and you are cross compiling.
I'm not cross compiling.
> In general, if you are cross building anything and not specifying =
--sysroot (to tell it where to find headers and libraries for the =
target) and -B (to tell it where to find tools) then you are probably =
doing something wrong.
>=20
I'm not cross compiling.
I've no clue why the linker name it is looking for is:
aarch64-unknown-freebsd14.0-ld : seems wrong to me when
not corss compiling.
But:
# find / -name aarch64-unknown-freebsd14.0-ld -print | more
/usr/local/bin/aarch64-unknown-freebsd14.0-ld
So: it did find the only instance of what it looked for. It
just looked for the wrong thing.
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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