[Bug lto/110844] New: LTO sometimes fail with -save-temp -dumpdir options

[Bug lto/110844] New: LTO sometimes fail with -save-temp -dumpdir options

[frankhb1989 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110844

            Bug ID: 110844
           Summary: LTO sometimes fail with -save-temp -dumpdir options
           Product: gcc
           Version: 13.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: frankhb1989 at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

Cases:

$ cd /tmp
$ g++ --version
g++ (GCC) 13.1.1 20230714
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ echo 'int main(){}' > a.cc
$ g++ -flto -c a.cc -o a.o
$ g++ -flto -save-temps -dumpdir . a.o
$ g++ -flto -c a.cc -o a.o -save-temps -dumpdir .
$ g++ -flto -save-temps -dumpdir . a.o
$ g++ -flto -save-temps -dumpdir /tmp/ a.o
/usr/sbin/ld: error: could not open arguments file
collect2: error: ld returned 1 exit status

The error message is from lto-plugin.c. Setting the environment variables 
(indicated by 'g++ -v' and then 'collect2 -v' from the result) properly, by "b
fopen if *(char*)$rsi == 'w'" for ld running in gdb a few times, it shows
something goes wrong in 'link_output_name' which forms 'arguments_file_name':
the variable incorrectly contains all the remain characters in the command
line. (This is also reproduced in MSYS2 ld which has no debug symbols
distributed together, after changing $rsi to $rdx.) The parsing implementation
of '-dumpdir' arguments introduced in 1dedc12d186a110854537e1279b4e6c29f2df35a
then looks quite suspicious.

[Bug lto/110844] LTO sometimes fail with -save-temp -dumpdir options

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110844

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 55655
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55655&action=edit
strace output

Attached is the `strace -f` output of invoking `g++ -flto -save-temps -dumpdir
/tmp/ a.o` for the trunk.

[Bug lto/110844] LTO sometimes fail with -save-temp -dumpdir options

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110844

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-07-28
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |link-failure

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The file that is being tried to open is:
[pid 1299400] openat(AT_FDCWD, "/tmp/ -v -shared-libgcc -mtune=generic
-march=x86-64 -dumpdir /tmp/lto_wrapper_args", O_WRONLY|O_CREAT|O_TRUNC, 0666)
= -1 ENOENT (No such file or directory)


COLLECT_GCC_OPTIONS='-flto' '-save-temps' '-dumpdir' '/tmp/' '-v'
'-shared-libgcc' '-mtune=generic' '-march=x86-64' '-dumpdir' '/tmp/'


The code in lto-plugin/lto-plugin.c:1614 does not handle the case where there
are 2 -dumpdir option.

[Bug lto/110844] LTO sometimes fail with -save-temp -dumpdir options

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110844

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
we shouldn't pass it two times either