https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66014
Bug ID: 66014
Summary: 5.1 mingw64 fails to perform slim bootstrap-lto:
ccEt8YNj.ltrans4.ltrans.o:<artificial>:(.text+0x628):
undefined reference to `stpcpy'
Product: gcc
Version: 5.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: breedlove.matt at gmail dot com
Target Milestone: ---
Created attachment 35461
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35461&action=edit
save-temps and object files for pex-win32 and stpcpy
Following the fix in PR 65559 (though LTO didn't work at all previously), GCC
on mingw64 is unable to perform a slim bootstrap, dying when building
liblto_plugin-0.dll. Normal -ffat-lto-object builds unaffected.
/bin/sh ./libtool --tag=CC --tag=disable-static --mode=link
/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/xgcc
-B/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/
-B/mingw64/x86_64-w64-mingw32/bin/ -L/mingw64/x86_64-w64-mingw32/lib
-L/mingw64/lib -isystem /mingw64/x86_64-w64-mingw32/include -isystem
/mingw64/include -B/mingw64/x86_64-w64-mingw32/bin/
-B/mingw64/x86_64-w64-mingw32/lib/ -isystem /mingw64/x86_64-w64-mingw32/include
-isystem /mingw64/x86_64-w64-mingw32/sys-include -Wall -O2 -march=x86-64
-mtune=native -flto=jobserver -frandom-seed=1 -Wc,-static-libgcc -no-undefined
-bindir "/mingw64/bin/gcc-5.1.0" -module -bindir
/mingw64/lib/gcc/x86_64-w64-mingw32/5.1.0 -Wc,../libiberty/libiberty.a
-Xcompiler '-static-libstdc++' -Xcompiler '-static-libgcc'
'-Wl,--stack,12582912' -o liblto_plugin.la -rpath
/mingw64/lib/gcc/x86_64-w64-mingw32/5.1.0 lto-plugin.lo
libtool: link:
/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/xgcc
-B/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/
-B/mingw64/x86_64-w64-mingw32/bin/ -L/mingw64/x86_64-w64-mingw32/lib
-L/mingw64/lib -isystem /mingw64/x86_64-w64-mingw32/include -isystem
/mingw64/include -B/mingw64/x86_64-w64-mingw32/bin/
-B/mingw64/x86_64-w64-mingw32/lib/ -isystem /mingw64/x86_64-w64-mingw32/include
-isystem /mingw64/x86_64-w64-mingw32/sys-include -shared .libs/lto-plugin.o
-L/mingw64/x86_64-w64-mingw32/lib -L/mingw64/lib -march=x86-64 -mtune=native
-static-libgcc ../libiberty/libiberty.a -static-libstdc++ -static-libgcc
-Wl,--stack -Wl,12582912 -o .libs/liblto_plugin-0.dll
-Wl,--enable-auto-image-base -Xlinker --out-implib -Xlinker
.libs/liblto_plugin.dll.a
M:\mingw64\tmp\cc5tPjOg.ltrans4.ltrans.o:<artificial>:(.text+0x628): undefined
reference to `stpcpy'
collect2.exe: error: ld returned 1 exit status
Makefile:351: recipe for target 'liblto_plugin.la' failed
make[1]: *** [liblto_plugin.la] Error 1
make[1]: Leaving directory
'/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/lto-plugin'
Makefile:264: recipe for target 'all' failed
make: *** [all] Error 2
This is following the fix to GCC by including specific object files in archives
rather than the entire library. The following shows that no symbols appear
within the slim objects for the (should be defined) stpcpy in stpcpy.o as well
as the undefined symbol in pex-win32.o
$ nm --plugin prev-lto-plugin/.libs/liblto_plugin-0.dll libiberty/pex-win32.o
U _close
U _dup
U _errno
U _get_osfhandle
U _open
U _pipe
U _read
U CloseHandle
U CreateFileA
U CreateProcessA
U fdopen
00000000 T funcs
U getenv
U GetExitCodeProcess
U GetVersionExA
00000000 T pex_init
U pex_init_common
U qsort
U SetHandleInformation
U WaitForSingleObject
U xmalloc
$ nm -a libiberty/pex-win32.o
0000000000000000 b .bss
0000000000000000 d .data
0000000000000000 r .gnu.lto_.decls.1
0000000000000000 r .gnu.lto_.inline.1
0000000000000000 r .gnu.lto_.opts
0000000000000000 r .gnu.lto_.refs.1
0000000000000000 r .gnu.lto_.symbol_nodes.1
0000000000000000 r .gnu.lto_.symtab.1
0000000000000000 r .gnu.lto_argv_to_argc.1
0000000000000000 r .gnu.lto_argv_to_cmdline.1
0000000000000000 r .gnu.lto_backslashify.1
0000000000000000 r .gnu.lto_env_compare.1
0000000000000000 r .gnu.lto_find_executable.1
0000000000000000 r .gnu.lto_funcs.1
0000000000000000 r .gnu.lto_pex_init.1
0000000000000000 r .gnu.lto_pex_win32_close.1
0000000000000000 r .gnu.lto_pex_win32_exec_child.1
0000000000000000 r .gnu.lto_pex_win32_fdopenr.1
0000000000000000 r .gnu.lto_pex_win32_fdopenw.1
0000000000000000 r .gnu.lto_pex_win32_open_read.1
0000000000000000 r .gnu.lto_pex_win32_open_write.1
0000000000000000 r .gnu.lto_pex_win32_pipe.1
0000000000000000 r .gnu.lto_pex_win32_wait.1
0000000000000000 r .gnu.lto_spawn_script.1
0000000000000000 r .gnu.lto_std_suffixes.1
0000000000000000 r .gnu.lto_win32_spawn.1
0000000000000000 r .rdata$zzz
0000000000000000 t .text
0000000000000001 C __gnu_lto_slim
0000000000000001 C __gnu_lto_v1
0000000000000000 ? pex-win32.c
$ nm --plugin prev-lto-plugin/.libs/liblto_plugin-0.dll libiberty/stpcpy.o
M:\msys64-backup\mingw64\bin\nm.exe: libiberty/stpcpy.o: no symbols
$ nm -a libiberty/stpcpy.o
0000000000000000 b .bss
0000000000000000 d .data
0000000000000000 r .gnu.lto_.decls.1
0000000000000000 r .gnu.lto_.inline.1
0000000000000000 r .gnu.lto_.opts
0000000000000000 r .gnu.lto_.refs.1
0000000000000000 r .gnu.lto_.symbol_nodes.1
0000000000000000 r .gnu.lto_stpcpy.1
0000000000000000 r .rdata$zzz
0000000000000000 t .text
0000000000000001 C __gnu_lto_slim
0000000000000001 C __gnu_lto_v1
0000000000000000 ? stpcpy.c
The result is that when attempting to perform the final link of
liblto_plugin-0.dll, stpcpy.o doesn't get pulled in. Putting the stpcpy.o
object file after libiberty.a such as the following, however, works perfectly
fine:
./libtool --tag=CC --tag=disable-static --mode=link
/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/xgcc
-B/build/staging/mingw-w64-x86_64-gcc5/src/build-x86_64-w64-mingw32/./prev-gcc/
-B/mingw64/x86_64-w64-mingw32/bin/ -L/mingw64/x86_64-w64-mingw32/lib
-L/mingw64/lib -isystem /mingw64/x86_64-w64-mingw32/include -isystem
/mingw64/include -B/mingw64/x86_64-w64-mingw32/bin/
-B/mingw64/x86_64-w64-mingw32/lib/ -isystem /mingw64/x86_64-w64-mingw32/include
-isystem /mingw64/x86_64-w64-mingw32/sys-include -Wall -O2 -march=x86-64
-mtune=native -flto=jobserver -frandom-seed=1 -Wc,-static-libgcc -no-undefined
-bindir "/mingw64/bin/gcc-5.1.0" -module -bindir
/mingw64/lib/gcc/x86_64-w64-mingw32/5.1.0 -Wc,../libiberty/libiberty.a
-Wc,../libiberty/stpcpy.o -Xcompiler '-static-libstdc++' -Xcompiler
'-static-libgcc' '-Wl,--stack,12582912' -o liblto_plugin.la -rpath
/mingw64/lib/gcc/x86_64-w64-mingw32/5.1.0 lto-plugin.lo
