[Bug target/60520] New: stack adjustment are not merged anymore

[Bug target/60520] New: stack adjustment are not merged anymore

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

            Bug ID: 60520
           Summary: stack adjustment are not merged anymore
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ubizjak at gmail dot com

Following testcase:

--cut here--
extern void foo (int *);
extern int *bar;

void test (void)
{
  if (*bar)
    foo (bar);
}
--cut here--

compiles with gcc-4.9 to (-O2 -m32):

test:
        movl    bar, %eax
        movl    (%eax), %edx
        testl   %edx, %edx
        jne     .L7
        ret
        .p2align 4,,10
        .p2align 3
.L7:
        subl    $24, %esp
        pushl   %eax
        call    foo
        addl    $16, %esp      <<<
        addl    $12, %esp      <<<
        ret

A single "addl $28, %esp" should be emitted here, as is the case with gcc-4.8:

test:
        movl    bar, %eax
        movl    (%eax), %edx
        testl   %edx, %edx
        jne     .L7
        ret
        .p2align 4,,7
        .p2align 3
.L7:
        subl    $28, %esp
        movl    %eax, (%esp)
        call    foo
        addl    $28, %esp     <<<
        ret

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-03-13
                 CC|                            |hjl.tools at gmail dot com
     Ever confirmed|0                           |1

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
It is due to

commit 283bfef29552fdda30d92acff64cf38f210a1e58
Author: hubicka <hubicka@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Thu Jan 23 00:12:56 2014 +0000

      * config/i386/x86-tune.def (X86_TUNE_ACCUMULATE_OUTGOING_ARGS):
      Enable for generic and recent AMD targets.


    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@206947
138bc75d-0d04-0410-961f-82ee72b054a4

Adding -maccumulate-outgoing-args restores the old behavior.

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
pro_and_epilogue adds an epilogue after BB 4:

(insn 12 11 15 3 (parallel [
            (set (reg/f:SI 7 sp)
                (plus:SI (reg/f:SI 7 sp)
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) pr60520.c:7 265 {*addsi_1}
     (expr_list:REG_ARGS_SIZE (const_int 0 [0])
        (nil)))
;;  succ:       4 [100.0%]  (FALLTHRU)
;; lr  out      7 [sp]

;; basic block 4, loop depth 0, count 0, freq 3898, maybe hot
;;  prev block 3, next block 6, flags: (REACHABLE, RTL, MODIFIED)
;;  pred:       3 [100.0%]  (FALLTHRU)
;; bb 4 artificial_defs: { }
;; bb 4 artificial_uses: { u-1(7){ }}
;; lr  in       7 [sp]
;; lr  use      7 [sp]
;; lr  def     
(code_label 15 12 16 4 1 "" [0 uses])
(note 16 15 27 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
(note 27 16 28 4 NOTE_INSN_EPILOGUE_BEG)
(insn/f 28 27 32 4 (parallel [
            (set (reg/f:SI 7 sp)
                (plus:SI (reg/f:SI 7 sp)
                    (const_int 12 [0xc])))
            (clobber (reg:CC 17 flags))
            (clobber (mem:BLK (scratch) [0  A8]))
        ]) pr60520.c:8 -1
     (expr_list:REG_CFA_ADJUST_CFA (set (reg/f:SI 7 sp)
            (plus:SI (reg/f:SI 7 sp)
                (const_int 12 [0xc])))
        (nil)))
;;  succ:       6 [100.0%]  (FALLTHRU)
;; lr  out      7 [sp]

It is quite hard to optimize 2 stack adjustment cross basic blocks.

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
With -O -m32 -fno-shrink-wrap, I got

test:
.LFB0:
    .cfi_startproc
    subl    $12, %esp
    .cfi_def_cfa_offset 16
    movl    bar, %eax
    cmpl    $0, (%eax)
    je    .L1
    subl    $12, %esp
    .cfi_def_cfa_offset 28
    pushl    %eax
    .cfi_def_cfa_offset 32
    call    foo
    addl    $16, %esp
    .cfi_def_cfa_offset 16
.L1:
    addl    $12, %esp
    .cfi_def_cfa_offset 4
    ret

shrink-wrap doesn't add epilogue in such a way that stack
adjustment can be easily optimized.

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
This change:

diff --git a/gcc/function.c b/gcc/function.c
index a61e475..3b6718f 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -6238,6 +6238,7 @@ thread_prologue_and_epilogue_insns (void)
         }
       /* Now duplicate the tails.  */
       if (!bitmap_empty_p (&bb_tail))
+        {
         FOR_EACH_BB_REVERSE_FN (bb, cfun)
           {
         basic_block copy_bb, tbb;
@@ -6304,6 +6305,17 @@ thread_prologue_and_epilogue_insns (void)
         if (bitmap_empty_p (&bb_tail))
           break;
           }
+
+        /* Basic blocks may have been changed.  Merge each basic block
+           with its successor if possible.  */
+        FOR_EACH_BB_FN (bb, cfun)
+          if (single_succ_p (bb))
+        {
+          basic_block succ_bb = single_succ (bb);
+          if (can_merge_blocks_p (bb, succ_bb))
+            merge_blocks (bb, succ_bb);
+        }
+        }
     }

     fail_shrinkwrap:

seems to work.

[Bug target/60520] stack adjustment are not merged anymore

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #4)
> This change:
> 
> diff --git a/gcc/function.c b/gcc/function.c
> index a61e475..3b6718f 100644
> --- a/gcc/function.c
> +++ b/gcc/function.c
> @@ -6238,6 +6238,7 @@ thread_prologue_and_epilogue_insns (void)
>  	    }
>  	  /* Now duplicate the tails.  */
>  	  if (!bitmap_empty_p (&bb_tail))
> +	    {
>  	    FOR_EACH_BB_REVERSE_FN (bb, cfun)
>  	      {
>  		basic_block copy_bb, tbb;
> @@ -6304,6 +6305,17 @@ thread_prologue_and_epilogue_insns (void)
>  		if (bitmap_empty_p (&bb_tail))
>  		  break;
>  	      }
> +
> +	    /* Basic blocks may have been changed.  Merge each basic block
> +	       with its successor if possible.  */
> +	    FOR_EACH_BB_FN (bb, cfun)
> +	      if (single_succ_p (bb))
> +		{
> +		  basic_block succ_bb = single_succ (bb);
> +		  if (can_merge_blocks_p (bb, succ_bb))
> +		    merge_blocks (bb, succ_bb);
> +		}
> +	    }
>  	}
>  
>      fail_shrinkwrap:
> 
> seems to work.

We have cfg_cleanup for this, no?
>From gcc-bugs-return-446260-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Mar 14 08:05:37 2014
Return-Path: <gcc-bugs-return-446260-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 11422 invoked by alias); 14 Mar 2014 08:05:37 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 11379 invoked by uid 48); 14 Mar 2014 08:05:34 -0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/60518] [4.9 Regression] ICE: in verify_loop_structure, at cfgloop.c:1647
Date: Fri, 14 Mar 2014 08:05:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: ipa
X-Bugzilla-Version: 4.9.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.9.0
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_status cf_reconfirmed_on assigned_to target_milestone everconfirmed
Message-ID: <bug-60518-4-G8BAUsy1TE@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-60518-4@http.gcc.gnu.org/bugzilla/>
References: <bug-60518-4@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: 2014-03/txt/msg01129.txt.bz2
Content-length: 631

http://gcc.gnu.org/bugzilla/show_bug.cgi?id`518

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2014-03-14
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
   Target Milestone|---                         |4.9.0
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed, mine.

[Bug target/60520] stack adjustment are not merged anymore

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|---                         |FIXED

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Furthermore, it is already fixed since r208551.

[Bug target/60520] stack adjustment are not merged anymore

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #6)
> Furthermore, it is already fixed since r208551.

Indeed, the fix for PR57320 also fixed this one.
>From gcc-bugs-return-446266-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Mar 14 08:53:26 2014
Return-Path: <gcc-bugs-return-446266-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 11697 invoked by alias); 14 Mar 2014 08:53:26 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 11680 invoked by uid 48); 14 Mar 2014 08:53:22 -0000
From: "david at westcontrol dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/60523] New: Warning flag for octal literals
Date: Fri, 14 Mar 2014 08:53:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords:
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: david at westcontrol dot com
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-60523-4@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: 2014-03/txt/msg01135.txt.bz2
Content-length: 1308

http://gcc.gnu.org/bugzilla/show_bug.cgi?id`523

            Bug ID: 60523
           Summary: Warning flag for octal literals
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: david at westcontrol dot com

It would be nice if there were a warning flag that triggered on octal literals.

Octal literals are rarely used in modern C and C++ code, but can easily be
introduced by mistake - "int x = 050;" appears at first reading to set x to 50,
but in C and C++ the leading 0 means it is interpreted as octal and therefore
sets x to 40 (decimal).

As octal literals are seldom useful, and often confusing or accidental, they
are banned by coding standards like MISRA.  But as they are part of the
language defined by the C and C++ standards, and are used in some existing
code, they obviously cannot be removed.  As a compromise, I would like to
propose the introduction of a warning flags "-Woctal" which would produce a
diagnostic message when a literal is interpreted as an octal number.  Of
preference, this would be included in "-Wextra" (it probably should not be in
"-Wall", since octal literals are valid C and C++).

[Bug target/60520] stack adjustment are not merged anymore

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Uroš Bizjak from comment #7)
> (In reply to Jakub Jelinek from comment #6)
> > Furthermore, it is already fixed since r208551.
> 
> Indeed, the fix for PR57320 also fixed this one.

However, using "-O2 -m32 -fno-omit-frame-pointer" an unnecessary stack
adjustment remains, even after r208551:

test:
        movl    bar, %eax
        movl    (%eax), %edx
        testl   %edx, %edx
        jne     .L7
        ret
        .p2align 4,,10
        .p2align 3
        pushl   %ebp
        movl    %esp, %ebp
        subl    $20, %esp
        pushl   %eax
        call    foo
        addl    $16, %esp     <<<<
        leave
        ret
>From gcc-bugs-return-446269-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Mar 14 09:01:05 2014
Return-Path: <gcc-bugs-return-446269-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 17302 invoked by alias); 14 Mar 2014 09:01:05 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 17250 invoked by uid 48); 14 Mar 2014 09:01:01 -0000
From: "dominiq at lps dot ens.fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/60522] WHERE construct causes an ICE in gfc_trans_where_2
Date: Fri, 14 Mar 2014 09:01:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: fortran
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dominiq at lps dot ens.fr
X-Bugzilla-Status: NEW
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_status cf_reconfirmed_on cc everconfirmed
Message-ID: <bug-60522-4-zYaUSbAUVE@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-60522-4@http.gcc.gnu.org/bugzilla/>
References: <bug-60522-4@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: 2014-03/txt/msg01138.txt.bz2
Content-length: 801

http://gcc.gnu.org/bugzilla/show_bug.cgi?id`522

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-03-14
                 CC|                            |tkoenig at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Confirmed. The ICE goes away when compiling with -fno-frontend-optimize. The
test compiles with r171100 (2011-03-17) and gives the ICE with r171653
(2011-03-29).
The changes of frontend-passes.c in this range are r171653, r171575, and
r171207.

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="UTF-8", Size: 4492 bytes --]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #9 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Uroš Bizjak from comment #8)
> However, using "-O2 -m32 -fno-omit-frame-pointer" an unnecessary stack
> adjustment remains, even after r208551:
> 
> test:
>         movl    bar, %eax
>         movl    (%eax), %edx
>         testl   %edx, %edx
>         jne     .L7
>         ret
>         .p2align 4,,10
>         .p2align 3
>         pushl   %ebp
>         movl    %esp, %ebp
>         subl    $20, %esp
>         pushl   %eax
>         call    foo
>         addl    $16, %esp     <<<<
>         leave
>         ret

ix86_expand_epilogue restores SP and BP:

(insn 12 11 29 3 (parallel [
            (set (reg/f:SI 7 sp)
                (plus:SI (reg/f:SI 7 sp)
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) /tmp/p.i:7 253 {*addsi_1}
     (expr_list:REG_ARGS_SIZE (const_int 0 [0])
        (nil)))
(note 29 12 30 3 NOTE_INSN_EPILOGUE_BEG)
(insn/f 30 29 34 3 (parallel [
            (set (reg/f:SI 7 sp)
                (plus:SI (reg/f:SI 6 bp)
                    (const_int 4 [0x4])))
            (set (reg/f:SI 6 bp)
                (mem:SI (reg/f:SI 6 bp) [0  S4 A8]))
            (clobber (mem:BLK (scratch) [0  A8]))
        ]) /tmp/p.i:8 -1
     (expr_list:REG_CFA_RESTORE (reg/f:SI 6 bp)
        (expr_list:REG_CFA_DEF_CFA (plus:SI (reg/f:SI 7 sp)
                (const_int 4 [0x4]))
            (nil))))

But none of the passes after it kill insn 12.
>From gcc-bugs-return-446302-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Mar 14 15:51:15 2014
Return-Path: <gcc-bugs-return-446302-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 24048 invoked by alias); 14 Mar 2014 15:51:14 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 24009 invoked by uid 48); 14 Mar 2014 15:51:11 -0000
From: "nicklas.ekstrand at sonymobile dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/60527] New: Incorrectly removed if statement while doing int arithmetics
Date: Fri, 14 Mar 2014 15:51:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 4.6.3
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: nicklas.ekstrand at sonymobile dot com
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 attachments.created
Message-ID: <bug-60527-4@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: 2014-03/txt/msg01171.txt.bz2
Content-length: 1081

http://gcc.gnu.org/bugzilla/show_bug.cgi?id`527

            Bug ID: 60527
           Summary: Incorrectly removed if statement while doing int
                    arithmetics
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nicklas.ekstrand at sonymobile dot com

Created attachment 32349
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id2349&actioníit
Test program modtest.c

In the following code:

static int getZ() {
    int tmp;
    Z = Z * A + B;
    tmp = Z;
    if (tmp == INT_MIN)
        tmp++;
    if (tmp < 0)
        tmp = -tmp;
    return tmp % MEMSIZE;
}

The if-statement tmp==INT_MIN is optimized away when using -O2 or higher, e.g.,

$ gcc -Wall -Wextra -g -O2 modtest.c -o pc_modtest -lrt
$ ./pc_modtest
arr=0x7fc1608be010
i=0 A”5 BA1
z1#1029 z2=-7483648
Segmentation fault

When using -O0 the problem doesn't happen and the program will not cause a
segmentation fault.

[Bug target/60520] stack adjustment are not merged anymore

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |rth at gcc dot gnu.org
         Resolution|FIXED                       |---

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Supposedly csa pass could remove sp additions followed by setting of sp to
something not based on sp?

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

--- Comment #11 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 32353
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32353&action=edit
A patch

This patch checks LEAVE and remove stack deallocation.
It removes 5 stack deallocations in cc1plus on Linux/i686.

[Bug target/60520] stack adjustment are not merged anymore

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60520

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #32353|0                           |1
        is obsolete|                            |

--- Comment #12 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 32399
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32399&action=edit
An updated patch

This patch passed regression test on Linux/x86-64
and Linux/x86.  I am not sure if this patch is x86
specific.  If it is, we can turn it into a target hook.