[Bug tree-optimization/114238] New: Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[Bug tree-optimization/114238] New: Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114238

            Bug ID: 114238
           Summary: Multiple 554.roms_r run-time regressions (4%-20%)
                    since r14-9193-ga0b1798042d033
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jamborm at gcc dot gnu.org
                CC: rguenth at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: x86_64-linux, aarch64-linux
            Target: x86_64-linux, aarch64-linux

Our LNT instance has detected that runtime of benchmark 554.roms_r
from the SPEC 2017 FPUrate suite regressed on all machines on most
configurations by 4-20%.

For example:

simple -O2 -flto on AMD Zen 3 regressed by 14%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=470.537.0

on Zen2 -O2 -flto regression is the worst, 20%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=298.537.0

-Ofast -march=native -flto on AMD Zen 4 regressed by 7%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=959.537.0

-Ofast -march=native on AMD Zen 2 regressed by 17%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=295.537.0

but it also happens on Intel Skylake:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=800.537.0

or Aarch64:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=587.537.0

and there are smaller regressions on the PGO configurations too.

I have bisected the Zen3 -O2 -flto case to r14-9193-ga0b1798042d033
(Richard Biener: tree-optimization/114074 - CHREC multiplication and
undefined overflow).  I have then verified that the zen 4 -Ofast
-march=natice -flto and zen 2 -Ofast -march=native cases have also
been introduces by it:

commit a0b1798042d033fd2cc2c806afbb77875dd2909b
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Feb 26 13:33:21 2024 +0100

    tree-optimization/114074 - CHREC multiplication and undefined overflow

    When folding a multiply CHRECs are handled like {a, +, b} * c
    is {a*c, +, b*c} but that isn't generally correct when overflow
    invokes undefined behavior.  The following uses unsigned arithmetic
    unless either a is zero or a and b have the same sign.

    I've used simple early outs for INTEGER_CSTs and otherwise use
    a range-query since we lack a tree_expr_nonpositive_p and
    get_range_pos_neg isn't a good fit.

            PR tree-optimization/114074
            * tree-chrec.h (chrec_convert_rhs): Default at_stmt arg to NULL.
            * tree-chrec.cc (chrec_fold_multiply): Canonicalize inputs.
            Handle poly vs. non-poly multiplication correctly with respect
            to undefined behavior on overflow.

            * gcc.dg/torture/pr114074.c: New testcase.
            * gcc.dg/pr68317.c: Adjust expected location of diagnostic.
            * gcc.dg/vect/vect-early-break_119-pr114068.c: Do not expect
            loop to be vectorized.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)

[Bug tree-optimization/114238] [14 regression] Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114238

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Multiple 554.roms_r         |[14 regression] Multiple
                   |run-time regressions        |554.roms_r run-time
                   |(4%-20%) since              |regressions (4%-20%) since
                   |r14-9193-ga0b1798042d033    |r14-9193-ga0b1798042d033
   Target Milestone|---                         |14.0

[Bug tree-optimization/114238] [14 regression] Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114238

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
                 CC|                            |law at gcc dot gnu.org

[Bug tree-optimization/114238] [14 regression] Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114238

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

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

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
r14-9391-g018ddc86b92851 fixed this on Zen2 for me as well.

[Bug tree-optimization/114238] [14 regression] Multiple 554.roms_r run-time regressions (4%-20%) since r14-9193-ga0b1798042d033

[haochen.jiang at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114238

Haochen Jiang <haochen.jiang at intel dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |haochen.jiang at intel dot com

--- Comment #2 from Haochen Jiang <haochen.jiang at intel dot com> ---
(In reply to Richard Biener from comment #1)
> r14-9391-g018ddc86b92851 fixed this on Zen2 for me as well.

The commit also fixed the regression on SPR for me as well.