[Bug c++/21528] New: Boost shared_ptr_test.cpp fails with -O3

[Bug c++/21528] New: Boost shared_ptr_test.cpp fails with -O3

[pdimov at gmail dot com]

The following portion of shared_ptr_test.cpp:

#include <boost/shared_ptr.hpp>
#include <boost/detail/lightweight_test.hpp>

int main()
{
    boost::shared_ptr<int> pi(new int);
    boost::shared_ptr<void> pv(pi);

    boost::shared_ptr<int> pi2 = boost::static_pointer_cast<int>(pv);
    BOOST_TEST(pi.get() == pi2.get());
    BOOST_TEST(!(pi < pi2 || pi2 < pi));
    BOOST_TEST(pi.use_count() == 3);
    BOOST_TEST(pv.use_count() == 3);
    BOOST_TEST(pi2.use_count() == 3);

    return boost::report_errors();
}

(using the current Boost CVS HEAD that will become 1.33 soon) fails the three
use_count() tests with g++ 4.0.0 -O3, but not with -O0, 1, 2. It seems that a
reference count increment is being optimized away. This does not happen if
BOOST_TEST is replaced with assert.

-- 
           Summary: Boost shared_ptr_test.cpp fails with -O3
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pdimov at gmail dot com
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[pdimov at gmail dot com]

------- Additional Comments From pdimov at gmail dot com  2005-05-12 08:42 -------
Created an attachment (id=8871)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8871&action=view)
Preprocessed source


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[redi at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |redi at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[redi at gcc dot gnu dot org]

------- Additional Comments From redi at gcc dot gnu dot org  2005-05-12 09:12 -------
I can confirm this error for 4.0 on x86 and x86-64 but not with 4.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[redi at gcc dot gnu dot org]

------- Additional Comments From redi at gcc dot gnu dot org  2005-05-12 09:36 -------
-O2 -finline-functions shows the errors, -O3 -fno-inline-functions does not.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[redi at gcc dot gnu dot org]

------- Additional Comments From redi at gcc dot gnu dot org  2005-05-12 11:56 -------
Using 4.0.1 20050509 on x86-64 Linux

-O2 -finline-functions -finline-limit=79 is OK

-O2 -finline-functions -finline-limit=80 is not




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug c++/21528] Boost shared_ptr_test.cpp fails with -O3

[redi at gcc dot gnu dot org]

------- Additional Comments From redi at gcc dot gnu dot org  2005-05-12 12:22 -------
Also, I *do* still see the failure if I replace BOOST_TEST() with assert().

This still fails with -finline-functions -finline-limit=80

#include <boost/shared_ptr.hpp>
#include <cassert>

int main()
{
    boost::shared_ptr<int> pi(new int);
    boost::shared_ptr<void> pv(pi);

    boost::shared_ptr<int> pi2 = boost::static_pointer_cast<int>(pv);
    assert(pi.get() == pi2.get());
    assert(pi.use_count() == 3);     // fails here

    return 0;
}

*however* if I remove the first assertion it succeeds.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.0.0 4.0.1
      Known to work|                            |3.4.3 4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] Boost shared_ptr_test.cpp fails with -O3

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |middle-end
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] Boost shared_ptr_test.cpp fails with -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-12 13:17 -------
Hmm, -fno-sra works around the issue.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-12 13:28 -------
Hmm, I am starting to think there is an alias bug in 4.0.0 somewhere.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Boost shared_ptr_test.cpp   |[4.0 Regression] Boost
                   |fails with -O3              |shared_ptr_test.cpp fails
                   |                            |with -O3
   Target Milestone|---                         |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-12 13:35 -------
The difference between the mainline and the 4.0.0 branch is the following additional SRA in 4.0.x:
+Initial instantiation for pv
+  pv.pn.pi_ -> pv$pn$pi_
+  pv.px -> pv$px
+Initial instantiation for pi2
+  pi2.pn.pi_ -> pi2$pn$pi_
+  pi2.px -> pi2$px
+

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-12 13:38 -------
Also the other major difference is:
mainline:
-  #   pi_503 = V_MAY_DEF <pi_504>;
-  pi.pn.pi_ = this_45;

4.0.0:
+  #   TMT.242_3 = V_MAY_DEF <TMT.242_66>;
+  pi.pn.pi_ = this_99;

See how we used a TMT in 4.0.0 case and pi on the mainline.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dnovillo at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[dnovillo at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |dnovillo at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug middle-end/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[dnovillo at gcc dot gnu dot org]

------- Additional Comments From dnovillo at gcc dot gnu dot org  2005-06-07 19:48 -------

This seems to be an RTL bug in 4.0.  None of the tree optimizers seem to be
doing anything wrong with this code.  However, applying this patch to the test case:

--- sp_test.ii  2005-06-06 12:02:57.000000000 -0400
+++ pr21528.cc  2005-06-07 15:44:49.297961371 -0400
@@ -3152,7 +3152,9 @@ inline int atomic_exchange_and_add( int
 inline void atomic_increment( int * pw )
 {

-
+#if defined HACK
+  *pw = *pw + 1;
+#else
     __asm__
     (
         "lock\n\t"
@@ -3161,6 +3163,7 @@ inline void atomic_increment( int * pw )
         "m"( *pw ):
         "cc"
     );
+#endif
 }

 inline int atomic_conditional_increment( int * pw )

works around the problem.  The bug seems to be introduced by the RTL optimizers.
 The second call to atomic_increment is being removed in .CE1.  Here's some IRC
analysis:

<rth> dnovillo: pong
<dnovillo> rth: been looking at 21528 (4.0 regression) for a while now and
afaict none of the tree optimizers are doing anything wrong.  i think it may be
an inline asm thing:
<dnovillo> inline void atomic_increment( int * pw )
<dnovillo> {
<dnovillo> #if defined HACK
<dnovillo>   *pw = *pw + 1;
<dnovillo> #else
<dnovillo>     __asm__
<dnovillo>     (
<dnovillo>         "lock\n\t"
<dnovillo>         "incl %0":
<dnovillo>         "=m"( *pw ):
<dnovillo>         "m"( *pw ):
<dnovillo>         "cc"
<dnovillo>     );
<dnovillo> #endif
<dnovillo> }
<dnovillo> if i compile with -DHACK, it works.  Otherwise, it fails.
<dnovillo> (at -O3)
<pinskia> hmm is there a V_MAY_DEF for the inline-asm?
<rth> dnovillo: inline asm looks ok.  you've not logged anything to the pr that
looks useful.  or wrong pr number?
<dnovillo> rth: not yet.  first i wanted to know if the inline looked fine.
<dnovillo> the tree dumps are identical modulo the __asm__ bits, the .s files
only differ in:
<dnovillo> --- 00bad/pr21528.s     2005-06-07 15:24:37.651935299 -0400
<dnovillo> +++ 00good/pr21528.s    2005-06-07 15:25:11.150401900 -0400
<dnovillo> @@ -384,10 +384,7 @@ main:
<dnovillo>         movl    -16(%ebp), %esi
<dnovillo>         testl   %esi, %esi
<dnovillo>         je      .L57
<dnovillo> -#APP
<dnovillo> -       lock
<dnovillo> -       incl 4(%esi)
<dnovillo> -#NO_APP
<dnovillo> +       addl    $2, 4(%esi)
<dnovillo>         testl   %esi, %esi
<dnovillo>         je      .L57
<dnovillo>         cmpl    $3, 4(%esi)
<dnovillo> which is odd.
<rth> that is odd.
<dnovillo> it's as if one __asm__ call is being lost
<rth> well, is it?
<dnovillo> not in the tree optimizers, for sure.  gimme a minute.
<DannyB> It's like thousands of inline lock routines shouted out all at once
<DannyB> and then vanished
<rth> actually, no it isn't.
<rth> i don't believe in anthromorphic lock routines.
<DannyB> so where did the lock go
<DannyB> oh
<DannyB> :)
<DannyB> just wait till we have biological computers
<rth> there's an extra couple of letters in that word.  i'll let you fix them up
on your end.
<pinskia> in .expand, there is only one lock incl
<pinskia> :q
<dnovillo> well, the trees look fine at .final_cleanup
<dnovillo>     pw = &pv$pn$pi_->use_count_;        |    pw = &pv$pn$pi_->use_count_;
<dnovillo>     #   TMT.247_999 = V_MAY_DEF <TMT.247|    #   TMT.247_1003 =
V_MAY_DEF <TMT.2
<dnovillo>     __asm__("lock\n\tincl %0":"=m" *pw:"|    *pw = *pw + 1;
<dnovillo>     [ ... ]                             |
<dnovillo>     pw = &pv$pn$pi_->use_count_;        |    pw = &pv$pn$pi_->use_count_;
<dnovillo>     #   TMT.247_998 = V_MAY_DEF <TMT.247|    #   TMT.247_1002 =
V_MAY_DEF <TMT.2
<dnovillo>     __asm__("lock\n\tincl %0":"=m" *pw:"|    *pw = *pw + 1;
<pinskia> never mind looking at the wrong dump
<dnovillo> what's the rtl dump switch?
<pinskia> -da or -fdump-rtl-all
<rth> -fdump-tree-expand.
<dnovillo> It disappears in pr21528.cc.11.ce1
<dnovillo> (the second __asm__ ("lock"), that is)
<rth> hmm.  cse bug invalidating memories?
<rth> dump state into the pr and i'll look at it
<dnovillo> will do.  thanks.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|dnovillo at gcc dot gnu dot |rth at gcc dot gnu dot org
                   |org                         |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug rtl-optimization/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-06-07 23:45 -------
Subject: Bug 21528

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	rth@gcc.gnu.org	2005-06-07 23:45:09

Modified files:
	gcc            : ChangeLog rtlanal.c 

Log message:
	PR rtl-opt/21528
	* rtlanal.c (reg_overlap_mentioned_p) <MEM>: Handle 'E' formats.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.9078&r2=2.9079
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/rtlanal.c.diff?cvsroot=gcc&r1=1.215&r2=1.216



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug rtl-optimization/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-06-07 23:48 -------
Subject: Bug 21528

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-4_0-branch
Changes by:	rth@gcc.gnu.org	2005-06-07 23:48:31

Modified files:
	gcc            : ChangeLog rtlanal.c 

Log message:
	PR rtl-opt/21528
	* rtlanal.c (reg_overlap_mentioned_p) <MEM>: Handle 'E' formats.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=2.7592.2.282&r2=2.7592.2.283
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/rtlanal.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.211&r2=1.211.8.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528

[Bug rtl-optimization/21528] [4.0 Regression] Boost shared_ptr_test.cpp fails with -O3

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-06-07 23:49 -------
Fixed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21528