From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 8EF733860763; Thu, 14 Dec 2023 22:44:40 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8EF733860763
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1702593880;
	bh=uXAnC4VQcFy2Os/8H3hEKRNeL31JxNn7FJ5kOkrQVfY=;
	h=From:To:Subject:Date:From;
	b=aVExS3lhD73h4ebqs05bYnmpU031RpLfVcQr2hPEnJHVTLrLG2qHCD1sA9Q2ls1ox
	 F+9xWSRk6r9lddvv25AAKJQXAj2m7Wdc9h2i6McamzLhrhrcKX52Q9loa2UGx84vCQ
	 SgK6HkrUlLlp0OlypiHV6U48+hHG2nKQPjgHzdMk=
From: "rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113027] New: aarch64 is missing vec_set and vec_extract
 for structure modes
Date: Thu, 14 Dec 2023 22:44:40 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rsandifo at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-113027-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113027

            Bug ID: 113027
           Summary: aarch64 is missing vec_set and vec_extract for
                    structure modes
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rsandifo at gcc dot gnu.org
  Target Milestone: ---

The lack of vec_set and vec_extract optabs for structure modes means that t=
he
following testcase spills to the stack when compiled at -O2:

#include <arm_neon.h>

float64x2x2_t f1 (float64x2x2_t x) { x.val[0][1] +=3D 1.0; return x; }
float64x2x3_t f2 (float64x2x3_t x) { x.val[0][0] =3D x.val[1][1] + x.val[2]=
[0];
return x; }
float64x2x4_t f3 (float64x2x4_t x) { x.val[0][0] =3D x.val[1][1] + x.val[2]=
[0] -
x.val[3][1]; return x; }

For example:

f1:
        sub     sp, sp, #32
        fmov    d31, 1.0e+0
        st1     {v0.2d - v1.2d}, [sp]
        ldr     d30, [sp, 8]
        fadd    d31, d31, d30
        str     d31, [sp, 8]
        ld1     {v0.2d - v1.2d}, [sp]
        add     sp, sp, 32
        ret

With the extra patterns, we instead get:

f1:
        dup     d31, v0.d[1]
        fmov    d30, 1.0e+0
        fadd    d30, d31, d30
        ins     v0.d[1], v30.d[0]
        ret
f2:
        dup     d31, v1.d[1]
        fadd    d31, d31, d2
        ins     v0.d[0], v31.d[0]
        ret
f3:
        dup     d31, v1.d[1]
        dup     d30, v3.d[1]
        fadd    d31, d31, d2
        fsub    d30, d31, d30
        ins     v0.d[0], v30.d[0]
        ret

Fixing this might also make it possible to use structure modes for arrays (=
c.f.
PR109543).=