[Bug c++/13239] New: [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[Bug c++/13239] New: [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

The following code fails the assertion, but I don't understand why. I does work
with 2.95.3. I think it fails in the builtin_expect function.

cat > test.cpp <<EOF
#include <assert.h>

struct Y {
  Y () : _y(0) {}
  int _y;
  int y () const  { return _y; }

};

struct X {
  X () {}

  Y _y;

  inline int x() const { return 0; }
  inline Y y() const { return _y; }

};


int main()
{
  X x;
  assert (x.y().y()==0);

  assert ( ((x.x()==0) && (x.y().y()==0)) );
  return 0;
}
EOF

g++ -DDEBUG -o test test.cpp && ./test

If I replace Y::y() with "return 0;" then it works.

Maybe I'm doing something wrong?? I just installed the new SuSe 9.0 and it also
fails with their compiler.

Here's also the preprocessed source in case my system is not setup right.

# 1 "test.cpp"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "test.cpp"
# 1 "/usr/include/assert.h" 1 3 4
# 36 "/usr/include/assert.h" 3 4
# 1 "/usr/include/features.h" 1 3 4
# 295 "/usr/include/features.h" 3 4
# 1 "/usr/include/sys/cdefs.h" 1 3 4
# 296 "/usr/include/features.h" 2 3 4
# 318 "/usr/include/features.h" 3 4
# 1 "/usr/include/gnu/stubs.h" 1 3 4
# 319 "/usr/include/features.h" 2 3 4
# 37 "/usr/include/assert.h" 2 3 4
# 65 "/usr/include/assert.h" 3 4
extern "C" {


extern void __assert_fail (__const char *__assertion, __const char *__file,
                           unsigned int __line, __const char *__function)
     throw () __attribute__ ((__noreturn__));


extern void __assert_perror_fail (int __errnum, __const char *__file,
                                  unsigned int __line,
                                  __const char *__function)
     throw () __attribute__ ((__noreturn__));




extern void __assert (const char *__assertion, const char *__file, int __line)
     throw () __attribute__ ((__noreturn__));


}
# 2 "test.cpp" 2

struct Y {
  Y () : _y(0) {}
  int _y;
  int y () const { return _y; }

};

struct X {
  X () {}

  Y _y;

  inline int x() const { return 0; }
  inline Y y() const { return _y; }

};


int main()
{
  X x;
  (static_cast<void> (__builtin_expect (!!(x.y().y()==0), 1) ? 0 :
(__assert_fail ("x.y().y()==0", "test.cpp", 24, __PRETTY_FUNCTION__), 0)));

  (static_cast<void> (__builtin_expect (!!(((x.x()==0) && (x.y().y()==0))), 1) ?
0 : (__assert_fail ("((x.x()==0) && (x.y().y()==0))", "test.cpp", 26,
__PRETTY_FUNCTION__), 0)));
  return 0;
}

-- 
           Summary: [3.3 REGRESSION] Assertion does not seem to work
                    correctly anymore
           Product: gcc
           Version: 3.3.3
            Status: UNCONFIRMED
          Severity: critical
          Priority: P1
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rmerkert at alphatech dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: gcc (GCC) 3.3.3 20031124 (prerelease)
  GCC host triplet: inux janus 2.4.21-144-smp4G #1 SMP


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   GCC host triplet|inux janus 2.4.21-144-smp4G |i686-pc-linux-gnu
                   |#1 SMP                      |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-01 15:54 -------
This works with my installation of 3.3.2 (release). Maybe someone else
can double-check?

W.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

------- Additional Comments From rmerkert at alphatech dot com  2003-12-02 03:13 -------
Created an attachment (id=5262)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5262&action=view)
Assembly code

This assembly code was generated from this example:

#include <assert.h>

struct Y {
  Y () : _y(0) {}
  int _y;
  int y () const  { return _y; }

};

struct X {
  X () {}

  Y _y;

  int x() const { return 1; }
  Y z() const { return _y; }

};


int main()
{
  X x;
  assert (x.z().y()==0);
  assert (((x.x()==1) && (x.z().y()==0)) );
  return 0;
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

------- Additional Comments From rmerkert at alphatech dot com  2003-12-02 03:16 -------
I've modified the code slightly and I'm attaching the generated assembly code
from :  /local/gcc-3.3.3/bin/g++ -o test.S test.cpp -S -march=i386


You can see where the problem is :
there are three functions : 
_ZNK1X1xEv
_ZNK1X1zEv
_ZNK1Y1yEv

You can see that at labels .LCFI3 and .LCFI4 there are calls to  and _ZNK1X1zEv
and _ZNK1Y1yEv, respectively (i.e. X::x, and X::z, and Y::y). This corresponds
to the first assertion.

Around label .L3, there are only calls to _ZNK1X1xEv and _ZNK1Y1yEv, which means
the call to X::z is omitted in the second assertion.


Any ideas what this problem might be? I did build the compiler with gcc from
SuSe's 9.0 distribution. Could this have caused this problem? 
I have to say that with the old SuSe8.2 this worked for me, so I suspect suse to
be the root cause. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

------- Additional Comments From rmerkert at alphatech dot com  2003-12-02 22:32 -------
Here's another, slightly simplified, example: 

#include <assert.h>

struct Y {
  Y () : _y(0) {}
  //Y (const Y& y) : _y(y._y) {}
  int _y;
};

bool foo() { return true; }
Y bar() { return Y(); }

int main()
{
  assert (bar()._y==0);
  assert ( foo() && (bar()._y)==0 );
  return 0;
}

If the copy constructor is uncommented, then it works. It almost looks as if it
does not generate the temporary Y object and just pretends it has got it. I've
tried this on a solaris and it worked and I also tried it on a cygwin (3.1 ?
maybe) which worked as well.

Can someone verify that their system is using builtin_expect rather than general
assert?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3 REGRESSION] Assertion does not seem to work correctly anymore

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-02 23:00 -------
I can confirm that this indeed fails with the gcc 3.3.1 SuSE ships. 
I don't have a 3.3.x installed (yet) on this system, so can't presently 
check that it is a problem tied to the OS or with gcc. 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.4 regression] Assertion does not seem to work correctly anymore

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-02 23:38 -------
Here's something self-contained: 
----------------------------- 
extern "C" void abort(void); 
 
struct Y { 
  int i; 
}; 
 
bool foo() { return true; } 
Y bar() { Y y = {0}; return y; } 
 
int main() 
{ 
  __builtin_expect (foo() && (bar().i)==0, 0) ? 0 : (abort(),1); 
} 
------------------------ 
This aborts when compiled with SuSE's 3.3.1. It also aborts with our 
present mainline, but not with 3.2.3. So the bug is for real. I'll 
try to figure out whether it is a mainline bug in FSF sources that SuSE 
happened to import into their tree, or if we also have this problem in 
3.3 CVS. 
 
W. 
 
W. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2003-12-02 23:38:51
               date|                            |
            Summary|[3.3 REGRESSION] Assertion  |[3.4 regression] Assertion
                   |does not seem to work       |does not seem to work
                   |correctly anymore           |correctly anymore
   Target Milestone|---                         |3.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.4 regression] Assertion does not seem to work correctly anymore

[rmerkert at alphatech dot com]

------- Additional Comments From rmerkert at alphatech dot com  2003-12-02 23:40 -------
I think it's the __builtin_expect that does not work. This example is reduced to
use of __builtin_expect only and it should be possible to replicate it on any
system that uses builtin_expect.

The key to this problem is the use the expression 
"__builtin_expect (... ,1) ? 0 : -1"  (replace -1 with any number other than 1)
and the example fails.  Use 1 and it works! 

Looks like an optimization problem.



#include <cstdio>

struct Y {
  Y () : _y(0) {}
  //Y (const Y& y) : _y(y._y) {}
  int _y;
};
extern Y bar();
extern bool foo();


int main()
{
  int x = __builtin_expect(foo() && (bar()._y)==0,1) ? 0 : -1;
  ::std::printf("%d\n",x);
  return x;
}

bool foo() { return true; }
Y bar() { return Y(); }




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-03 00:04 -------
I just built a 3.3 CVS here, and it fails, too.  
 
The bug is an interaction between __builtin_expect and the function 
call. I tried to either replace the __builtin_expect with just 
the conditional expression, or to do something like 
  return (__builtin_expect(...) ? 0 : 1); 
to avoid the call to abort(), but the bug went away in both cases. 
 
W. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[3.4 regression] Assertion  |[3.3/3.4 regression]
                   |does not seem to work       |Assertion does not seem to
                   |correctly anymore           |work correctly anymore
   Target Milestone|3.4                         |3.3.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-12-05 23:09 -------
This works correctly the tree-ssa branch, why? (is the C++ to gimple doing something which 
causes this to work?).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  GCC build triplet|gcc (GCC) 3.3.3 20031124    |
                   |(prerelease)                |
   GCC host triplet|i686-pc-linux-gnu           |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-06 20:59 -------
I remember that changing small bits in the testcase made the bug go away. It may be 
that the intermediate transformations done in tree-ssa just don't trigger the bug, i.e. it 
is not fixed there but only hidden. 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[janis187 at us dot ibm dot com]

------- Additional Comments From janis187 at us dot ibm dot com  2003-12-10 17:40 -------
The regression in PR 13239 was introduced or exposed with this patch:

2003-03-24  Jakub Jelinek  <jakub@redhat.com>

        * dojump.c (do_jump): Handle UNSAVE_EXPR specially.

The regression hunt took place with mainline on i686-pc-linux-gnu using
the test case from comment #6.  The reports of where the bug has and has
not been seen made it sound as if this might be an intermittent failure;
I built g++ from sources for every two weeks between 2003-01-01 and
2003-07-02, and the results are consistent with the patch named above
changing the behavior of the test.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-12-19 13:39 -------
Subject: Bug 13239

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	jakub@gcc.gnu.org	2003-12-19 13:39:05

Modified files:
	gcc            : ChangeLog builtins.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/opt: expect1.C 

Log message:
	PR c++/13239
	* builtins.c (expand_builtin_expect_jump): Update
	TREE_VALUE (arglist) if unsave_expr_now langhook
	created a new tree.
	
	* g++.dg/opt/expect1.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.2044&r2=2.2045
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/builtins.c.diff?cvsroot=gcc&r1=1.265&r2=1.266
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.3286&r2=1.3287
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/opt/expect1.C.diff?cvsroot=gcc&r1=NONE&r2=1.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-12-19 13:54 -------
Subject: Bug 13239

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_3-branch
Changes by:	jakub@gcc.gnu.org	2003-12-19 13:54:37

Modified files:
	gcc            : ChangeLog builtins.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/opt: expect1.C 

Log message:
	PR c++/13239
	* builtins.c (expand_builtin_expect_jump): Update
	TREE_VALUE (arglist) if unsave_expr_now langhook
	created a new tree.
	
	* g++.dg/opt/expect1.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.16114.2.849&r2=1.16114.2.850
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/builtins.c.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.165.2.8&r2=1.165.2.9
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.2261.2.338&r2=1.2261.2.339
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/opt/expect1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=NONE&r2=1.1.2.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-12-21 22:21 -------
Fixed for 3.3.3 and 3.4.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239

[Bug c++/13239] [3.3/3.4 regression] Assertion does not seem to work correctly anymore

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-01-27 15:29 -------
Subject: Bug 13239

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_2-rhl8-branch
Changes by:	jakub@gcc.gnu.org	2004-01-27 15:29:23

Modified files:
	gcc            : ChangeLog builtins.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/opt: expect1.C 

Log message:
	PR c++/13239
	* builtins.c (expand_builtin_expect_jump): Update
	TREE_VALUE (arglist) if unsave_expr_now langhook
	created a new tree.
	
	* g++.dg/opt/expect1.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_2-rhl8-branch&r1=1.13152.2.657.2.27.2.177&r2=1.13152.2.657.2.27.2.178
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/builtins.c.diff?cvsroot=gcc&only_with_tag=gcc-3_2-rhl8-branch&r1=1.142.2.2.8.13&r2=1.142.2.2.8.14
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_2-rhl8-branch&r1=1.1672.2.166.2.8.2.72&r2=1.1672.2.166.2.8.2.73
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/opt/expect1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_2-rhl8-branch&r1=NONE&r2=1.1.22.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13239