[MacPorts] #58493: cctools: using clang < 5.0 as default assembler generates assembly errors in some cases
MacPorts
noreply at macports.org
Sat May 18 21:13:38 UTC 2019
#58493: cctools: using clang < 5.0 as default assembler generates assembly errors
in some cases
--------------------+----------------------
Reporter: kencu | Owner: jeremyhu
Type: defect | Status: assigned
Priority: Normal | Milestone:
Component: ports | Version:
Keywords: | Port: cctools
--------------------+----------------------
To fix errors in newer ports that require gcc (fortran) to assemble newer
assembly, the `as` in `cctools` was modified to send the assembly to a
specific version of `clang` for processing, if present. For SnowLeopard,
that default `clang` version is `clang-3.4`.
It turns out there is (at least one) bug in the `clang` i386 assembler
that was not fixed until after `clang-3.7`. It is fixed in `clang-5.0`.
This error shows up during the build or bootstrapping of `gcc / libgcc`,
and perhaps will turn up elsewhere:
{{{
pt/local/i386-apple-darwin10/bin/ -nostdinc++
-B/opt/local/var/macports/build/_opt_macports-
ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/src/.libs -B/opt/local/var/macports/build
/_opt_macports-ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/libsupc++/.libs -isystem
/opt/local/var/macports/build/_opt_macports-
ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/include/i386-apple-darwin10 -isystem
/opt/local/var/macports/build/_opt_macports-
ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/include -isystem /opt/local/var/macports/build
/_opt_macports-
ports_lang_gcc9/libgcc9/work/gcc-9.1.0/libstdc++-v3/libsupc++
-L/opt/local/var/macports/build/_opt_macports-
ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/src/.libs -L/opt/local/var/macports/build
/_opt_macports-ports_lang_gcc9/libgcc9/work/build/prev-i386-apple-
darwin10/libstdc++-v3/libsupc++/.libs -g -O2 -fno-checking -mdynamic-
no-pic -gtoggle -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-
unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual
-Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -DHAVE_CONFIG_H -static-
libstdc++ -static-libgcc -o cc1 c/c-lang.o c-family/stub-objc.o attribs.o
c/c-errors.o c/c-decl.o c/c-typeck.o c/c-convert.o c/c-aux-info.o c/c
-objc-common.o c/c-parser.o c/c-fold.o c/gimple-parser.o
c-family/c-common.o c-family/c-cppbuiltin.o c-family/c-dump.o
c-family/c-format.o c-family/c-gimplify.o c-family/c-indentation.o
c-family/c-lex.o c-family/c-omp.o c-family/c-opts.o c-family/c-pch.o
c-family/c-ppoutput.o c-family/c-pragma.o c-family/c-pretty-print.o
c-family/c-semantics.o c-family/c-ada-spec.o c-family/c-ubsan.o c-family
/known-headers.o c-family/c-attribs.o c-family/c-warn.o
c-family/c-spellcheck.o i386-c.o darwin-c.o \
cc1-checksum.o libbackend.a main.o libcommon-target.a
libcommon.a ../libcpp/libcpp.a ../libdecnumber/libdecnumber.a libcommon.a
../libcpp/libcpp.a -liconv ../libbacktrace/.libs/libbacktrace.a
../libiberty/libiberty.a ../libdecnumber/libdecnumber.a -L/opt/local/lib
-lisl -L/opt/local/lib -L/opt/local/lib -L/opt/local/lib -lmpc -lmpfr
-lgmp -lz
ld: in libbackend.a(i386.o), in section __TEXT,__text reloc 5479:
unsupported r_length=0 for scattered vanilla reloc for architecture i386
}}}
This is a known clang assembler error
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63773>.
There is a reduced test case for it:
{{{
.text
.align 4,0x90
.globl _choose_tmpdir
_choose_tmpdir:
sbbl $3+_vartmp, %esi
ret
.space 254
.const
.align 2
_vartmp:
.byte 47
}}}
and I confirm that `clang-3.4` and `clang-3.7` error out on this assembly,
but `clang-5.0` can compile it successfully:
{{{
$ clang-mp-3.4 -arch i386 testi386asm.S
ld: in /var/folders/If/IfyiELboGT08qyd+9nD3DU+++TI/-Tmp-/testi386asm-
fc6237.o, in section __TEXT,__text reloc 0: unsupported r_length=0 for
scattered vanilla reloc for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
$ clang-mp-3.7 -arch i386 testi386asm.S
ld: in /var/folders/If/IfyiELboGT08qyd+9nD3DU+++TI/-Tmp-/testi386asm-
c2fa0b.o, in section __TEXT,__text reloc 0: unsupported r_length=0 for
scattered vanilla reloc for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
$ clang-mp-5.0 -arch i386 testi386asm.S
Undefined symbols for architecture i386:
"_main", referenced from:
start in crt1.10.6.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
}}}
Likewise, the same assembly generates errors when compiling in `x86_64`
mode.
{{{
$ clang-mp-3.4 -arch x86_64 testi386asm.S
ld: in /var/folders/If/IfyiELboGT08qyd+9nD3DU+++TI/-Tmp-/testi386asm-
07fc5b.o, in section __TEXT,__text reloc 0: length < 2 and
X86_64_RELOC_UNSIGNED not supported for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
$ clang-mp-3.7 -arch x86_64 testi386asm.S
ld: in /var/folders/If/IfyiELboGT08qyd+9nD3DU+++TI/-Tmp-/testi386asm-
52d45e.o, in section __TEXT,__text reloc 0: length < 2 and
X86_64_RELOC_UNSIGNED not supported for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
$ clang-mp-5.0 -arch x86_64 testi386asm.S
Undefined symbols for architecture x86_64:
"_main", referenced from:
start in crt1.10.6.o
ld: symbol(s) not found for architecture x86_64
}}}
So - it appears that `clang` should not be used as the default assembler
unless it is `clang-5.0` or greater, and for the system `clang` should not
be used (according to the gcc bug report) unless the Xcode version is at
least `7.3.1`.
This probably requires only a rather minor adjustment to the `cctools`
port.
--
Ticket URL: <https://trac.macports.org/ticket/58493>
MacPorts <https://www.macports.org/>
Ports system for macOS
More information about the macports-tickets
mailing list