[Bug target/114328] New: Using -march=armv9-a+nosve does not allow for vectorization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114328

            Bug ID: 114328
           Summary: Using -march=armv9-a+nosve does not allow for
                    vectorization
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
                CC: mjr19 at cam dot ac.uk
            Blocks: 53947
  Target Milestone: ---
            Target: aarch64

Created attachment 57689
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57689&action=edit
Testcase

I noticed this while looking into PR 114324, the cost model for
-march=armv9-a+nosve causes this code not to be vectorized using ld2/st2 using
the SIMD (non-SVE) registers.

I don't understand why though because -march=armv8.4-a still does though.

Note this is all at -Ofast.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations