[Bug tree-optimization/109777] New: [14 regression] Compare-debug failure after recent changes

[Bug tree-optimization/109777] New: [14 regression] Compare-debug failure after recent changes

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

            Bug ID: 109777
           Summary: [14 regression] Compare-debug failure after recent
                    changes
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: law at gcc dot gnu.org
  Target Milestone: ---

This change:

commit 21e2ef2dc25de318de29ec32d5390350c6717c6a (refs/bisect/bad)
Author: Andrew Pinski <apinski@marvell.com>
Date:   Tue May 2 00:10:46 2023 -0700

    Move substitute_and_fold over to use simple_dce_from_worklist

    While looking into a different issue, I noticed that it
    would take until the second forwprop pass to do some
    forward proping and it was because the ssa name was
    used more than once but the second statement was
    "dead" and we don't remove that until much later.

    So this uses simple_dce_from_worklist instead of manually
    removing of the known unused statements instead.
    Propagate engine does not do a cleanupcfg afterwards either but manually
    cleans up possible EH edges so simple_dce_from_worklist
    needs to communicate that back to the propagate engine.

    Some testcases needed to be updated/changed even because of better
optimization.
    gcc.dg/pr81192.c even had to be changed to be using the gimple FE so it
would
    be less fragile in the future too.
    gcc.dg/tree-ssa/pr98737-1.c was failing because __atomic_fetch_ was being
matched
    but in those cases, the result was not being used so both __atomic_fetch_
and
    __atomic_x_and_fetch_ are valid choices and would not make a code
generation difference.
    evrp7.c, evrp8.c, vrp35.c, vrp36.c: just needed a slightly change as the
removal message
    is different slightly.
    kernels-alias-8.c: ccp1 is able to remove an unused load which causes
ealias to have
    one less load to analysis so update the expected scan #.

    OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

    gcc/ChangeLog:

            PR tree-optimization/109691
            * tree-ssa-dce.cc (simple_dce_from_worklist): Add need_eh_cleanup
            argument.
            If the removed statement can throw, have need_eh_cleanup
            include the bb of that statement.
            * tree-ssa-dce.h (simple_dce_from_worklist): Update declaration.
            * tree-ssa-propagate.cc (struct prop_stats_d): Remove
            num_dce.
            (substitute_and_fold_dom_walker::substitute_and_fold_dom_walker):
            Initialize dceworklist instead of stmts_to_remove.
            (substitute_and_fold_dom_walker::~substitute_and_fold_dom_walker):
            Destore dceworklist instead of stmts_to_remove.
            (substitute_and_fold_dom_walker::before_dom_children):
            Set dceworklist instead of adding to stmts_to_remove.
            (substitute_and_fold_engine::substitute_and_fold):
            Call simple_dce_from_worklist instead of poping
            from the list.
            Don't update the stat on removal statements.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/evrp7.c: Update for output change.
            * gcc.dg/tree-ssa/evrp8.c: Likewise.
            * gcc.dg/tree-ssa/vrp35.c: Likewise.
            * gcc.dg/tree-ssa/vrp36.c: Likewise.
            * gcc.dg/tree-ssa/pr98737-1.c: Update scan-tree-dump-not
            to check for assignment too instead of just a call.
            * c-c++-common/goacc/kernels-alias-8.c: Update test
            for removal of load.
            * gcc.dg/pr81192.c: Rewrite testcase in gimple based test.


Is triggering a compare-debug failure on the bfin-elf port:
bfin-sim: gcc.dg/pr44023.c (test for excess errors)

If you dig into the log file:

xgcc: error: /home/jlaw/test/gcc/gcc/testsuite/gcc.dg/pr44023.c:
'-fcompare-debug' failure (length)

[Bug middle-end/109777] [14 regression] Compare-debug failure after recent changes

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |compare-debug-failure
   Target Milestone|---                         |14.0
          Component|tree-optimization           |middle-end

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This could be a latent bug, Let me at least look into where the compare debug
issue is coming from.

[Bug target/109777] [14 regression] Compare-debug failure after recent changes

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
          Component|middle-end                  |target
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-05-08

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The place where the first difference in IR (not withstanding the debug insns)
is mach.

Without -g, there is an forced_nop instruction being added:
(insn:SI # # # 6 (set (reg:SI 3 R3 [177])
        (ashift:SI (reg:SI 4 R4 [orig:87 x$0 ] [87])
            (const_int 1 [0x1]))) "t.c":44:47# {*ashlsi3_insn}
     (nil))

(insn:SI # # # 6 (set (reg:SI 2 R2)
        (mem/c:SI (plus:SI (reg/f:SI 14 SP)
                (const_int 8 [0x8])) [4 %sfp+-4 S4 A32])) "t.c":44:47#
{*movsi_insn}
     (nil))

(insn:QI # # # 6 (unspec [
            (const_int 0 [0])
        ] 12) "t.c":44:47# {forced_nop}
     (nil))

(insn:TI # # # 6 (set (reg:SI 6 R6)
        (reg:SI 19 I3 [165])) "t.c":44:53# {*movsi_insn}
     (nil))

While with -g, it is not there:
(insn:TI # # # 6 (set (reg:SI 3 R3 [177])
        (ashift:SI (reg:SI 4 R4 [orig:87 x$0 ] [87])
            (const_int 1 [0x1]))) "t.c":44:47# {*ashlsi3_insn}
     (nil))

(debug_insn # # # 6 (var_location:SI D#14 (ior:SI (reg:SI 3 R3 [177])
        (const_int 31 [0x1f])))#
     (nil))

(insn # # # 6 (set (reg:SI 2 R2)
        (mem/c:SI (plus:SI (reg/f:SI 14 SP)
                (const_int 8 [0x8])) [4 %sfp+-4 S4 A32])) "t.c":45:14#
{*movsi_insn}
     (nil))

(insn:TI # # # 6 (set (reg:SI 6 R6)
        (reg:SI 19 I3 [165])) "t.c":44:53# {*movsi_insn}
     (nil))

[Bug target/109777] [14 regression] Compare-debug failure after recent changes

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Something is going different inside bfin_gen_bundles with and without debug
instructions but that is all I can tell from my quick debugging.

[Bug target/109777] [14 regression] Compare-debug failure after recent changes

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4

--- Comment #4 from Jeffrey A. Law <law at gcc dot gnu.org> ---
If it's inside the bfin bundling code, let's just mark it as a p4 and we can
chase it down whenever it's convenient.   My primary motivation is to catch
generic issues.  A target specific issue on a barely used target just isn't
that interesting IMHO.

[Bug target/109777] [14 regression] Compare-debug failure after recent changes

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #4)
> If it's inside the bfin bundling code, let's just mark it as a p4 and we can
> chase it down whenever it's convenient.   My primary motivation is to catch
> generic issues.  A target specific issue on a barely used target just isn't
> that interesting IMHO.

Thanks, it actaully might be the scheduler which is introducing the difference
such that bfin bundling is different.

I just noticed the modes of the two instructions:

(insn:SI # # # 6 (set (reg:SI 3 R3 [177])
        (ashift:SI (reg:SI 4 R4 [orig:87 x$0 ] [87])
            (const_int 1 [0x1]))) "t.c":44:47# {*ashlsi3_insn}
     (nil))

vs with -g:
(insn:TI # # # 6 (set (reg:SI 3 R3 [177])
        (ashift:SI (reg:SI 4 R4 [orig:87 x$0 ] [87])
            (const_int 1 [0x1]))) "t.c":44:47# {*ashlsi3_insn}
     (nil))

---
I think this is caused by having the debug insn afterwards:
(debug_insn # # # 6 (var_location:SI D#14 (ior:SI (reg:SI 3 R3 [177])
        (const_int 31 [0x1f])))#
     (nil))

which might be saying it is scheduled with the above one while without -g, it
is not schedule with another instruction; hence the SImode.

[Bug target/109777] [14/15 regression] Compare-debug failure after recent changes

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109777

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|14.0                        |14.2

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14.1 is being released, retargeting bugs to GCC 14.2.