[Bug target/100623] New: [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args

[Bug target/100623] New: [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

            Bug ID: 100623
           Summary: [10/11/12 Regression] wrong code with -Os -fno-dce
                    -fno-defer-pop -fno-forward-propagate
                    -flive-range-shrinkage -fno-rerun-cse-after-loop
                    -mno-push-args
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Created attachment 50819
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50819&action=edit
reduced testcase (from openssl sources)

Output:
$ x86_64-pc-linux-gnu-gcc -Os -fno-dce -fno-defer-pop -fno-forward-propagate
-flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args testcase.c
$ ./a.out 
Aborted

bn_add_words() is called with r == NULL

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r12-815-20210516001637-g1ba3f0ef546-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r12-815-20210516001637-g1ba3f0ef546-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20210516 (experimental) (GCC)

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-05-17
            Summary|[10/11/12 Regression] wrong |[10/11/12 Regression] wrong
                   |code with -Os -fno-dce      |code with -Os -fno-dce
                   |-fno-defer-pop              |-fno-defer-pop
                   |-fno-forward-propagate      |-fno-forward-propagate
                   |-flive-range-shrinkage      |-flive-range-shrinkage
                   |-fno-rerun-cse-after-loop   |-fno-rerun-cse-after-loop
                   |-mno-push-args              |-mno-push-args since
                   |                            |r10-7515-g2c0fa3ecf70d199a
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, started with r10-7515-g2c0fa3ecf70d199a.

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.4
           Priority|P3                          |P2

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |11.2.0
           Keywords|                            |needs-bisection

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks to be fixed on the trunk.

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
There seems to be some IR difference on the gimple level which might be making
this latent.
In GCC 11.2.0 we have (bn_add_words) :
  _2 = n_3 & -4;
...
  if (_2 != 0)

While on the trunk we have:
  _14 = (unsigned int) n_3;
  if (_14 > 3)

This does look like a valid transformation knowing that n is subtracted by 4.

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> There seems to be some IR difference on the gimple level which might be
> making this latent.

But that is not where the problem is located really as far as I can tell, the
assembly for bn_mul_recursive is different too (and it looks like the
difference in the assembly for bn_add_words is only different in the comparison
and nothing else [no other code changes]).

[Bug target/100623] [10/11/12 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |

--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
It's fixed on master with r12-5944-ga7acb6dca941db2b. Which is a revision that
changes LRA costs.

[Bug target/100623] [10/11/12/13 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug target/100623] [11/12/13/14 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.

[Bug target/100623] [11 Regression] wrong code with -Os -fno-dce -fno-defer-pop -fno-forward-propagate -flive-range-shrinkage -fno-rerun-cse-after-loop -mno-push-args since r10-7515-g2c0fa3ecf70d199a

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100623

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[11/12/13/14 Regression]    |[11 Regression] wrong code
                   |wrong code with -Os         |with -Os -fno-dce
                   |-fno-dce -fno-defer-pop     |-fno-defer-pop
                   |-fno-forward-propagate      |-fno-forward-propagate
                   |-flive-range-shrinkage      |-flive-range-shrinkage
                   |-fno-rerun-cse-after-loop   |-fno-rerun-cse-after-loop
                   |-mno-push-args since        |-mno-push-args since
                   |r10-7515-g2c0fa3ecf70d199a  |r10-7515-g2c0fa3ecf70d199a
                 CC|                            |law at gcc dot gnu.org

--- Comment #8 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Fixed in gcc-12 and newer.  Adjusting regression markers.