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 6DDC43858410; Mon, 25 Mar 2024 10:09:57 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6DDC43858410
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1711361397;
	bh=ZD+eMQ17Pz8dwSQEtwfXr8UuwetlRk8HkDZ2TlJ8bUg=;
	h=From:To:Subject:Date:From;
	b=peHfgm1Mv3NuL23IxGtQD98r8W5MXEysN8nR+OL2EnzVIJXZ97XEj22navAJmEldV
	 d47J4bkaXNv5S+DJhvR8/HM+3g6WwrSw/YmcLSEWdzknmWoN0bLSAyJsCh7DkvgAl0
	 ZcEBre6EPiLWABMeoUeVp+5vgqy4mO1yMtQ0/R0s=
From: "chfast at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/114452] New: Functions invoked through
 compile-time table of function pointers not inlined
Date: Mon, 25 Mar 2024 10:09:56 +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: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: chfast at gmail dot com
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-114452-4@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=3D114452

            Bug ID: 114452
           Summary: Functions invoked through compile-time table of
                    function pointers not inlined
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chfast at gmail dot com
  Target Milestone: ---

In the following example there is a compile-time table of pointers to simple
functions. When the table is used in a simple unrolled loop with constant t=
rip
count the functions invoked by pointers are not inlined.

using F =3D int (*)(int) noexcept;

void test(int z[2]) noexcept {
    static constexpr F fs[]{
        [](int x) noexcept { return x; },
        [](int x) noexcept { return x; },
    };

    for (int i =3D 0; i < 2; ++i) {
        z[i] =3D fs[i](z[i]);
    }
}

Generated assembly:

test(int*)::{lambda(int)#1}::_FUN(int):
        mov     eax, edi
        ret
test(int*)::{lambda(int)#2}::_FUN(int):
        mov     eax, edi
        ret
test(int*):
        mov     rdx, rdi
        mov     edi, DWORD PTR [rdi]
        call    test(int*)::{lambda(int)#1}::_FUN(int)
        mov     edi, DWORD PTR [rdx+4]
        mov     DWORD PTR [rdx], eax
        call    test(int*)::{lambda(int)#2}::_FUN(int)
        mov     DWORD PTR [rdx+4], eax
        ret


https://godbolt.org/z/fGqPKh81j=