[Bug tree-optimization/113421] New: wrong code with -O -fno-tree-fre and _BitInt() multiplication

[Bug tree-optimization/113421] New: wrong code with -O -fno-tree-fre and _BitInt() multiplication

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113421

            Bug ID: 113421
           Summary: wrong code with -O -fno-tree-fre and _BitInt()
                    multiplication
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          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 57101
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57101&action=edit
reduced testcase

Output:
$ x86_64-pc-linux-gnu-gcc testcase.c -O -fno-tree-fre
$ ./a.out 
Aborted

On the asm level:
...
        mov     r9d, 1024       #,
        lea     r8, [rsp+16]    #,
        mov     ecx, 1024       #,
        mov     edx, OFFSET FLAT:g      #,
        mov     esi, 1024       #,
        mov     rdi, rdx        #,
        call    __mulbitint3    #
...

rdi == rdx, overlapping the "ret" and "u" arguments of __mulbitint3

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r14-7274-20240116114934-g1251d3957de-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/14.0.1/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
--disable-bootstrap --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-r14-7274-20240116114934-g1251d3957de-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.1 20240116 (experimental) (GCC)

[Bug tree-optimization/113421] wrong code with -O -fno-tree-fre and _BitInt() multiplication

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113421

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-01-16
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 57104
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57104&action=edit
gcc14-pr113421.patch

Untested fix.

[Bug tree-optimization/113421] wrong code with -O -fno-tree-fre and _BitInt() multiplication

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113421

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:9f8ba332e988fb582f6ca32465f6d65283f53b3a

commit r14-8186-g9f8ba332e988fb582f6ca32465f6d65283f53b3a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Jan 17 14:43:40 2024 +0100

    lower-bitint: Avoid overlap between destinations and sources in libgcc
calls [PR113421]

    The following testcase is miscompiled because the bitint lowering emits a
      .MULBITINT (&a, 1024, &a, 1024, &x, 1024);
    call.  The bug is in the overlap between the destination and source, that
is
    something the libgcc routines don't handle, they use the source arrays
    during the entire algorithms which computes the destination array(s).
    For the mapping of SSA_NAMEs to VAR_DECLs the code already supports that
    correctly, but the checking whether a load from memory can be used directly
    without a temporary even when earlier we decided to merge the
    multiplication/division/modulo etc. with a store didn't.

    The following patch implements that.

    2024-01-17  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/113421
            * gimple-lower-bitint.cc (stmt_needs_operand_addr): Adjust function
            comment.
            (bitint_dom_walker::before_dom_children): Add g temporary to
simplify
            formatting.  Start at vop rather than cvop even if stmt is a store
            and needs_operand_addr.

            * gcc.dg/torture/bitint-50.c: New test.

[Bug tree-optimization/113421] wrong code with -O -fno-tree-fre and _BitInt() multiplication

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113421

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.

[Bug tree-optimization/113421] wrong code with -O -fno-tree-fre and _BitInt() multiplication

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113421

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.0