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 0801E3858C54; Sun, 31 Dec 2023 02:08:15 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0801E3858C54
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1703988496;
	bh=EBVQEcjOREVu4cR4pSwydoo00KARkNK4msoPhsuKPAA=;
	h=From:To:Subject:Date:From;
	b=SKriTNQ3ketbdFLxom49Rlpmtp4RHFNnKGZUTKBtYMZ+yvy7kpW5DhZ5Oi8aV5hFY
	 UJbrNv/ILc1sCPsKhealCajn2kwUE2Xy/PA9GfGLQusJH1UrkbJuL6NwQGU4YmvIqu
	 Ni0X21IeLjSy6EYbzR72SR+76TtODEeEJ8ECo4O4=
From: "syq at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/113185] New: bad performance on
 big-endian&64bit port for struct 16 16
Date: Sun, 31 Dec 2023 02:08:10 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: syq 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-113185-4@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=3D113185

            Bug ID: 113185
           Summary: bad performance on big-endian&64bit port for struct 16
                    16
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: syq at gcc dot gnu.org
  Target Milestone: ---

```
struct xx {
        int a:16;
        int b:16;
};

struct xx xx (struct xx a, long long b) {
        a.b =3D b;
        return a;
}
```

On little-endian&64, only 1 or 2 instructions are used, such as
on AARCH64el:

```
        bfi     w0, w1, 16, 16
        ret
```
On MIPS64el
```
        move    $2,$4
        sll     $5,$5,0
        jr      $31
        ins     $2,$5,16,16
```


While for 64EB
```
        .cfi_startproc
        sub     sp, sp, #16
        .cfi_def_cfa_offset 16
        str     x0, [sp, 8]
        strh    w1, [sp, 10]
        ldr     w0, [sp, 8]
        add     sp, sp, 16
        .cfi_def_cfa_offset 0
        lsl     x0, x0, 32
        ret
        .cfi_endproc
```
```
        daddiu  $sp,$sp,-16
        sd      $4,0($sp)
        sh      $5,2($sp)
        lw      $2,0($sp)
        daddiu  $sp,$sp,16
        jr      $31
        dsll    $2,$2,32
```=