[Bug tree-optimization/107413] New: Perf loss ~14% on 519.lbm_r SPEC cpu2017 benchmark

["rvmallad at amazon dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107413

            Bug ID: 107413
           Summary: Perf loss ~14% on 519.lbm_r SPEC cpu2017 benchmark
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rvmallad at amazon dot com
  Target Milestone: ---

Created attachment 53775
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53775&action=edit
Input and source files.

Below is some perf data executing the 519.lbm_r benchmark on aarch64
architecture (Graviton 3 processor). I have comparison of the baseline perf
(mainline commit ID: f56d48b2471c388401174029324e1f4c4b84fcdb) vs. a fix for
the same (revert the code change in commit ID:
b5b33e113434be909e8a6d7b93824196fb6925c0).

Steps to compile:
$ gcc -std=c99 -mabi=lp64 -g -Ofast -mcpu=native lbm.i main.i -lm -flto -o
519_lbm_r_base

$ time ./519_lbm_r_base 3000 reference.dat 0 0 100_100_130_ldc.of
real    2m50.946s

Reverting the code changes in commit ID:
b5b33e113434be909e8a6d7b93824196fb6925c0
$ time ./519_lbm_r_fix 3000 reference.dat 0 0 100_100_130_ldc.of
real    2m27.157s

The code change reverted was:
    [AArch64] PR84114: Avoid reassociating FMA

Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Mon Mar 5 14:40:55 2018 +0000

Please find attached the files to reproduce this issue and the fix.