[Bug target/121622] New: [16 Regression] 4-8% slowdown (2% regression against GCC 15) of xalancbmk (both 2006 and 2017) an Aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121622

            Bug ID: 121622
           Summary: [16 Regression] 4-8% slowdown (2% regression against
                    GCC 15) of xalancbmk (both 2006 and 2017) an Aarch64
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, needs-bisection
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pheeck at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: aarch64-gnu-linux
            Target: aarch64-gnu-linux

As seen here

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=588.290.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=586.290.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=587.367.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=589.367.0

there was a 4-8% exec time slowdown of the 483.xalancbmk and 523.xalancbmk_r
SPEC CPU benchmarks between commits

r16-3119-ge5bb3896036add
r16-3179-g2c0ce83c9faa1c

when compiled with -Ofast -march=native -flto on an Ampere Altra (Neoverse N1)
machine.

The slowdown is a regression against GCC 15.  However, it is a smaller one. 
Comparing GCC 15 and trunk gives us only 2% difference.


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)