[Bug rtl-optimization/114575] New: [14 Regression] SVE addressing modes broken since g:839bc42772ba7af66af3bd16efed4a69511312ae

[Bug rtl-optimization/114575] New: [14 Regression] SVE addressing modes broken since g:839bc42772ba7af66af3bd16efed4a69511312ae

[tnfchris at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114575

            Bug ID: 114575
           Summary: [14 Regression] SVE addressing modes broken since
                    g:839bc42772ba7af66af3bd16efed4a69511312ae
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tnfchris at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64*

Created attachment 57864
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57864&action=edit
addr.cc

Since the offending commit, compiling the example attached with -O3
-march=armv8.5-a+sve2 results in:

.L14:
        lsl     x0, x1, 1
        add     x1, x1, 8
        add     x2, x3, x0
        add     x6, x0, x4
        ld1h    z2.h, p7/z, [x2]
        ld1h    z22.h, p7/z, [x6]
        add     x0, x0, x5
        fmad    z22.h, p7/m, z21.h, z2.h
        ld1h    z20.h, p7/z, [x0]
        fmad    z20.h, p7/m, z26.h, z22.h
        st1h    z20.h, p7, [x2]
        cmp     x1, 808
        bne     .L14

instead of what it was before the commit:

.L14:
        ld1h    z2.h, p7/z, [x1, x0, lsl 1]
        ld1h    z22.h, p7/z, [x2, x0, lsl 1]
        ld1h    z20.h, p7/z, [x3, x0, lsl 1]
        fmad    z22.h, p7/m, z21.h, z2.h
        fmad    z20.h, p7/m, z26.h, z22.h
        st1h    z20.h, p7, [x1, x0, lsl 1]
        add     x0, x0, 8
        cmp     x0, 808
        bne     .L14

It's now no longer pushing in the register shifts. This causes significant
performance loss as it needs to now perform the integer ALU ops before doing
the load and they're on the critical path.

[Bug rtl-optimization/114575] [14 Regression] SVE addressing modes broken since g:839bc42772ba7af66af3bd16efed4a69511312ae

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114575

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=114510
   Target Milestone|---                         |14.0
                 CC|                            |pinskia at gcc dot gnu.org

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Definitely related to PR 114510 (but that is not caused by the combine patch as
it was happening beforehand).

There does seems like some address cost model issue here too.

[Bug rtl-optimization/114575] [14 Regression] SVE addressing modes broken since g:839bc42772ba7af66af3bd16efed4a69511312ae

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114575

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I proposed reverting the offending revision but am waiting for Seghers OK.

[Bug rtl-optimization/114575] [15 Regression] SVE addressing modes broken since g:839bc42772ba7af66af3bd16efed4a69511312ae

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114575

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|14.0                        |15.0
            Summary|[14 Regression] SVE         |[15 Regression] SVE
                   |addressing modes broken     |addressing modes broken
                   |since                       |since
                   |g:839bc42772ba7af66af3bd16e |g:839bc42772ba7af66af3bd16e
                   |fed4a69511312ae             |fed4a69511312ae

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Reverted for GCC 14 but will re-appear for GCC 15.