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 8E18D3844748; Tue, 14 May 2024 09:45:36 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8E18D3844748
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1715679936;
	bh=OCCZ94ZZW84yl5adOK1+QzkAmIpmujU7l436XkgG0Vs=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=maEqKL0Ujw4Oc8uhEwJ/8/wr193wSixjB7IpOZmLWA/hoplOOCBlWmPzGPtIsozKG
	 re0MXTpLE0LjYxyJ+kM6sH8SNaPZ0wOFWZNowL4ebFMJnACELubR70jkb/F5/COSme
	 ZR+nHlJcvF+GrF6TGAwnVOvytpFcPiHfmSrnpJd0=
From: "kamkaz at windowslive dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/115084] Missed optimization in division for AVR target,
 not using __*divmodpsi4
Date: Tue, 14 May 2024 09:45:36 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 14.1.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: kamkaz at windowslive 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: 
Message-ID: <bug-115084-4-AeNzTEt4QJ@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-115084-4@http.gcc.gnu.org/bugzilla/>
References: <bug-115084-4@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=3D115084

--- Comment #2 from Kamil Kaznowski <kamkaz at windowslive dot com> ---
(In reply to Andrew Pinski from comment #1)
> There is another bug dealing with division and truncation that was just
> filed. It is a generic (non-avr) issue.

I assume you mentioned this bug here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115036

It is not quite the same, since here we are dealing with literals. In case =
of
literals, it is an existing optimization.

#include <stdint.h>

uint16_t functino(uint16_t num) {
    return (7500ULL) / num;
}

This snippet, even compiled with `avr-gcc -O0`, will use __udivmodhi4, 16-b=
it
routine. It seems that 24-bit routines are simply not considered, unless the
operands are specifically typed __(u)int24.=