[Bug gcov-profile/60008] New: x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[Bug gcov-profile/60008] New: x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[peter.oberparleiter at de dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60008

            Bug ID: 60008
           Summary: x86_64: Segmentation fault if compiled with
                    -fcall-saved-rdi -O2 --coverage
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: peter.oberparleiter at de dot ibm.com

Programs compiled on x86_64 with GCC and options "-fcall-saved-rdi -O2
--coverage" cause a segmentation fault.

Minimal test case:
echo "int main() { return 0; }" | gcc -xc - -o /tmp/test --coverage -O2
-fcall-saved-rdi && /tmp/test

Release:
- gcc version 4.9.0 20140116 (experimental) [master revision
  c334d99:760dcd4:018db0b6e750f01880f0d601e1cf167948f55ab5] (GCC)
  Configured with: configure --prefix=gcc-head-install --enable-shared
  --with-system-zlib --enable-threads=posix --enable-__cxa_atexit
  --enable-checking --enable-gnu-indirect-function --program-suffix=-4.9.0
  --with-as=binutils/install/bin/as --with-ld=binutils/install/bin/ld
  --enable-languages=c

Also found on:
- gcc version 4.8.2 20131212 (Red Hat 4.8.2-7) (GCC)
- gcc version 4.7.2 (Debian 4.7.2-5)
- gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC)

Environment:
GNU/Linux

Additional information:
The cause for the segmentation fault can be found when comparing the
generated constructor functions:

gcc --coverage -O2 -fcall-saved-rdi
0000000000400c10 <_GLOBAL__I_65535_0_main>:
  400c10:       57                      push   %rdi
  400c11:       5f                      pop    %rdi
  400c12:       e9 09 00 00 00          jmpq   400c20 <__gcov_init>

-> Nothing is loaded into %rdi, __gcov_init() accesses random memory

gcc --coverage -O2
0000000000400c10 <_GLOBAL__I_65535_0_main>:
  400c10:       48 83 ec 08             sub    $0x8,%rsp
  400c14:       bf 60 2a 60 00          mov    $0x602a60,%edi
  400c19:       48 83 c4 08             add    $0x8,%rsp
  400c1d:       e9 0e 00 00 00          jmpq   400c30 <__gcov_init>

-> %rdi contains pointer to gcov_info structure when __gcov_init() is called

gcc --coverage -fcall-saved-rdi
0000000000400c11 <_GLOBAL__I_65535_0_main>:
  400c11:       55                      push   %rbp
  400c12:       48 89 e5                mov    %rsp,%rbp
  400c15:       57                      push   %rdi
  400c16:       48 83 ec 08             sub    $0x8,%rsp
  400c1a:       bf 80 2a 60 00          mov    $0x602a80,%edi
  400c1f:       e8 0c 00 00 00          callq  400c30 <__gcov_init>
  400c24:       48 83 c4 08             add    $0x8,%rsp
  400c28:       5f                      pop    %rdi
  400c29:       c9                      leaveq
  400c2a:       c3                      retq

-> %rdi contains pointer to gcov_info structure when __gcov_init() is called

[Bug gcov-profile/60008] x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60008

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Don't do it then?  %rdi is the first parameter register on x86_64, so making it
call saved is a very bad idea for many reasons.

[Bug gcov-profile/60008] x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60008

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
E.g. -fcall-saved-rdi option is ABI changing option, so you'd need to have
everything (from libc, libgcov, libgcc, libstdc++, ...) built that way. 
Furthermore, I don't think we consider this case e.g. to disallow tail call
optimization (which is generally not possible under such weird ABI).

[Bug gcov-profile/60008] x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60008

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Yep.  Cite from invoke.texi

"It is an error to use this flag with the frame pointer or stack pointer.
Use of this flag for other registers that have fixed pervasive roles in
the machine's execution model produces disastrous results."

[Bug gcov-profile/60008] x86_64: Segmentation fault if compiled with -fcall-saved-rdi -O2 --coverage

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60008

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |idan.horowitz at gmail dot com

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 108595 has been marked as a duplicate of this bug. ***