From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-483310-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 56744 invoked by alias); 10 Apr 2015 15:25:25 -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 56653 invoked by uid 48); 10 Apr 2015 15:25:22 -0000
From: "evstupac at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/65710] [4.9/5 Regression] Thumb1 ICE caused by no register to spill
Date: Fri, 10 Apr 2015 15:25:00 -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: 5.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: evstupac at gmail dot com
X-Bugzilla-Status: REOPENED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.9.3
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields:
Message-ID: <bug-65710-4-paLgv83a6O@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-65710-4@http.gcc.gnu.org/bugzilla/>
References: <bug-65710-4@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/msg00862.txt.bz2

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65710

--- Comment #13 from Stupachenko Evgeny <evstupac at gmail dot com> ---
The issue reproduced with -march=corei7 as well.

Currently the hottest loop looks as following:
L1.
mov    (%esp),%ebp /* potentially redundant.  */
and    $0x7fff,%ebp                                          
movzwl 0x400(%esi,%ebp,2),%ecx                               
mov    %ecx,(%esp) 
cmp    %ecx,0x4(%esp) /*  Why not reuse ebp?  */        
jae    380                                                   
subl   $0x1,0x8(%esp)                                        
je     380                                                   
mov    (%esp),%ebp /* ebp could contain correct value (if reused above).  */
add    %edi,%ebp                                             
cmp    0x0(%ebp,%ebx,1),%al                                  
jne    L1
movzbl 0xf(%esp),%edx                                       
cmp    -0x1(%ebp,%ebx,1),%dl                               
jne    L1

Unnecessary fills and spills of ebp added.
Before the patch the loop was 2 instruction shorter.

L1.
and    $0x7fff,%edx                                             
movzwl 0x400(%esi,%edx,2),%edx                                  
cmp    %edx,0x4(%esp)                                           
jae    3c0                                                      
sub    $0x1,%ebp                                                
je     3c0                                                      
lea    (%edi,%edx,1),%ecx                                       
movzbl (%esp),%eax                                              
cmp    (%ecx,%ebx,1),%al                                        
jne    L1
movzbl 0xb(%esp),%eax                                           
cmp    -0x1(%ecx,%ebx,1),%al                                    
jne    L1.

Please let me know if you need dumps.