[Bug target/118351] New: [15 Regression] 6% regression in 470.lbm_r in SPECCPU 2006 on AArch64

[tnfchris at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118351

            Bug ID: 118351
           Summary: [15 Regression] 6% regression in 470.lbm_r in SPECCPU
                    2006 on AArch64
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tnfchris at gcc dot gnu.org
                CC: wilco at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64*

There is a 6% regression on lbm in SPECCPU2006 on Neoverse-V1 after this
change:

commit c5db3f50bdf34ea96fd193a2a66d686401053bd2
Author: Wilco Dijkstra <wilco.dijks...@arm.com>
Date:   Fri Nov 1 14:40:26 2024 +0000

    AArch64: Switch off early scheduling

The hot loop seems to now spill simple constants instead of rematerializing
them through an fmov.

The same regression also shows up in lbm in SPECCPU 2017 but only with PGO.