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 6E9093858C36; Tue, 27 Feb 2024 14:27:55 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6E9093858C36
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1709044075;
	bh=1acNWq63Dp8TnKz7WTMNTPYqRyD0IHvtlu1vkZ1zUZ4=;
	h=From:To:Subject:Date:From;
	b=tQyg6zo8k3OOF9rKlQH33za6I1osYdR2MZAmha3lJ8kzHF19HGTNOpV00KBbgon/m
	 ECMnWw34s3QVQJ5h4Nm13UVbbEbzVb8m3L3OQ1B/zYmKR9xRc3hmO/QW42LjLwvkSk
	 9ay0yFjmD6SsTDojb3Nqr+Y7yTeiT7Yrs4M5jNzc=
From: "gjl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114132] New: [avr] Code sets up a frame pointer without
 need
Date: Tue, 27 Feb 2024 14:27:55 +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: 13.2.1
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: gjl 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-114132-4@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=3D114132

            Bug ID: 114132
           Summary: [avr] Code sets up a frame pointer without need
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gjl at gcc dot gnu.org
  Target Milestone: ---

$ avr-gcc -S -Os -mmcu=3Dattiny40=20

of=20

void funcab_c (long x, char c) {
}

sets up a frame-pointer without need.

Arguments x and c occupy all of the argument registers R25..R20, so that no=
 arg
registers are left.  Then there is this implementation of
TARGET_FRAME_POINTER_REQUIRED in avr.cc:

static bool
avr_frame_pointer_required_p (void)
{
  return (cfun->calls_alloca
          || cfun->calls_setjmp
          || cfun->has_nonlocal_label
          || crtl->args.info.nregs =3D=3D 0
          || get_frame_size () > 0);
}

Problem is that crtl->args.info.nregs =3D=3D 0 does not discriminate betwee=
n need
for arg pointer and no need for arg pointer (but all arg regs are used up, =
like
in the example).=