[Bug bootstrap/112107] New: [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[Bug bootstrap/112107] New: [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

            Bug ID: 112107
           Summary: [14 Regression] bootstrap failure on i686-linux:
                    gcc/ira-build.o differs
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
  Target Milestone: ---

Noticed on this week's build on i686-unknown-linux-gnu build/host/target.

How to reproduce against r14-4967-g8697d3a1dcf327:

  $ ../gcc/configure --disable-multilib --enable-languages=c,c++
--enable-languages=c,c++ --enable-checking=release
  $ make STAGE1_CFLAGS=-O2
  ...
   Comparing stages 2 and 3
   Bootstrap comparison failure!
   gcc/ira-build.o differs

$ stage3-gcc/xgcc -Bstage3-gcc -v
Reading specs from stage3-gcc/specs
COLLECT_GCC=stage3-gcc/xgcc
COLLECT_LTO_WRAPPER=stage3-gcc/lto-wrapper
Target: i686-pc-linux-gnu
Configured with: /home/slyfox/dev/git/gcc/configure --disable-multilib
--enable-languages=c,c++ --enable-checking=release
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231027 (experimental) (GCC)

[Bug bootstrap/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #1 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
`diffoscope` says there is a difference in generated code in one of the
functions:

$ strip --strip-debug stage2-gcc-ira-build.o stage3-gcc-ira-build.o
$ diffoscope stage2-gcc-ira-build.o stage3-gcc-ira-build.o

│       add    $0x10,%esp
│       mov    $0x1,%edx
│       mov    %eax,0x4(%esi)
│       movl   $0x0,(%eax)
│       movl   $0x0,0x38(%esi)
│ -     jmp    363b <ira_allocate_object_conflicts(ira_object*, int)+0x5b>
│ -     lea    0x0(%esi,%eiz,1),%esi
│ -     lea    0x0(%esi),%esi
│ +     jmp    363c <ira_allocate_object_conflicts(ira_object*, int)+0x5c>
│ +     xchg   %ax,%ax

[Bug bootstrap/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |i686-unknown-linux-gnu
              Build|                            |i686-unknown-linux-gnu
           Keywords|                            |needs-bisection
   Target Milestone|---                         |14.0
               Host|                            |i686-unknown-linux-gnu

[Bug bootstrap/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #2 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Reduced ira-build.cc down to the following:

// $ cat pp.cc.cc
typedef struct ira_object *ira_object_t;
struct ira_object {
  void *conflicts_array;
  int min, max;
};
void *ira_allocate(int);
int ira_conflict_vector_profitable_p_nbytes;
void ira_conflict_vector_profitable_p(ira_object_t obj) {
  int max(obj->max);
  if (max < obj->min)
    ira_conflict_vector_profitable_p_nbytes = max - obj->min;
}
void ira_allocate_object_conflicts(ira_object_t obj) {
  ira_conflict_vector_profitable_p(obj);
  int size((obj->max - obj->min) * sizeof 0);
  obj->conflicts_array = ira_allocate(size);
}

Reproducer:

# cat trigger.bash
#!/usr/bin/env bash

f() {
    stage3-gcc/xg++ -Bstage3-gcc -nostdinc++  -fno-PIE -g -O2 -fchecking=1
-DIN_GCC    -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -fno-PIE -c
pp.cc.cc -o pp.o -Wall "$@"
    strip --strip-debug pp.o
    sha1sum pp.o
}

[[ "$(f)" == "$(f -gtoggle)" ]] && echo EQUAL || echo DIFF

Running:

$ ./trigger.bash
DIFF

[Bug bootstrap/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-10-27
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

> ./xg++ -B. -c -g -O2 -fno-exceptions -fno-rtti t.ii -fcompare-debug -m32
xg++: error: t.ii: '-fcompare-debug' failure (length)

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ra
          Component|bootstrap                   |rtl-optimization

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks like the first difference comes from reload (LRA) .

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

Sergei Trofimovich <slyfox at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at gcc dot gnu.org,
                   |                            |vmakarov at redhat dot com

--- Comment #5 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Bisected down to r14-4943-g8d2130a4e5ce36 "[RA]: Modfify cost calculation for
dealing with equivalences"

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #6 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
(In reply to Sergei Trofimovich from comment #5)
> Bisected down to r14-4943-g8d2130a4e5ce36 "[RA]: Modfify cost calculation
> for dealing with equivalences"

Sorry, pasted wrong hash. That should be a r14-4944-gf55cdce3f8dd85 "[RA]:
Modfify cost calculation for dealing with equivalences"

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[vmakarov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #7 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
Sorry for inconvenience because of my patch.

I reproduced the bug with the reproducer using stage1 gcc although strangely
the standard bootstrap works ok for me on i686 debian.

I think I know the reason for this bug.  I'll fix it today.

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #8 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
bootstrap with default options did not fail for me either. I had to use
--enable-checking=release to trigger the failure. I wonder if it exposes the
failure for you as well.

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[vmakarov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #9 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
(In reply to Sergei Trofimovich from comment #8)
> bootstrap with default options did not fail for me either. I had to use
> --enable-checking=release to trigger the failure. I wonder if it exposes the
> failure for you as well.

Yes, with --enable-checking=release I managed to reproduce a failure on clean
bootstrap.

BTW, thank you for the reproducer.  It was easier to start from it.

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Vladimir Makarov <vmakarov@gcc.gnu.org>:

https://gcc.gnu.org/g:4d3d2cdb574488223d023b590c3a34ddd93f4dae

commit r14-4986-g4d3d2cdb574488223d023b590c3a34ddd93f4dae
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Fri Oct 27 14:50:40 2023 -0400

    [RA]: Fixing i686 bootstrap failure because of pushing the equivalence
patch

    GCC with my recent patch improving cost calculation for pseudos with
    equivalence may generate different code with and without debug info
    and as the result i686 bootstrap fails on i686.  The patch fixes this
    bug.

    gcc/ChangeLog:

            PR rtl-optimization/112107
            * ira-costs.cc: (calculate_equiv_gains): Use NONDEBUG_INSN_P
            instead of INSN_P.

[Bug rtl-optimization/112107] [14 Regression] bootstrap failure on i686-linux: gcc/ira-build.o differs since r14-4944-gf55cdce3f8dd85

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112107

Sergei Trofimovich <slyfox at gcc dot gnu.org> changed:

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

--- Comment #11 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
The change fixed bootstrap for me. Thank you!

Let's declare it fixed.