From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-483606-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 96404 invoked by alias); 15 Apr 2015 07:09:43 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 96377 invoked by uid 48); 15 Apr 2015 07:09:39 -0000
From: "kugan at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/65768] New: sub-optimimal code for constant Uses in loop
Date: Wed, 15 Apr 2015 07:09:00 -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: 6.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: kugan at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
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
Message-ID: <bug-65768-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2015-04/txt/msg01158.txt.bz2

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65768

            Bug ID: 65768
           Summary: sub-optimimal code for constant Uses in loop
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kugan at gcc dot gnu.org

#include <stdint.h>
void maskdata(int32_t * data, unsigned int len)
{
  const int32_t mask = 0x00ff00ff;
  for (int i=len; i-- > 0 ;) {
      data[i] &= mask;
  }
}

Is producing the following with arm-none-linux-gnueabi-gcc for -O2:

maskdata:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    @ link register save eliminated.
    cmp    r1, #0
    bxle    lr
    add    r1, r0, r1, lsl #2
.L3:
    ldr    r3, [r1, #-4]!
    cmp    r1, r0
    bic    r3, r3, #-16777216
    bic    r3, r3, #65280
    str    r3, [r1]
    bne    .L3
    bx    lr
    .size    maskdata, .-maskdata
    .ident    "GCC: (GNU) 5.0.0 20150409 (experimental)"
    .section    .note.GNU-stack,"",%progbits