[Bug c/22429] New: -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[Bug c/22429] New: -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[akr at m17n dot org]

I found that following program exits with 1 instead of 0.

% cat z.c
int f(int n)
{
  if (-1073741824 <= n && n <= 1073741823)
    return 1;
  return 0;
}

int main()
{
  return f(1073741824);
}
% /home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/gcc -v -O  z.c    
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../../gcc/configure
--prefix=/home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449
--enable-languages=c
Thread model: posix
gcc version 4.1.0 20050712 (experimental)
 /home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../libexec/gcc/i686-pc-linux-gnu/4.1.0/cc1
-quiet -v -iprefix
/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/
z.c -quiet -dumpbase z.c -mtune=pentiumpro -auxbase z -O -version -o /tmp/cc3anyqv.s
ignoring nonexistent directory
"/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/../../../../i686-pc-linux-gnu/include"
ignoring duplicate directory
"/home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449/lib/gcc/i686-pc-linux-gnu/4.1.0/include"
ignoring nonexistent directory
"/home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449/lib/gcc/i686-pc-linux-gnu/4.1.0/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/include
 /usr/local/include
 /home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449/include
 /usr/include
End of search list.
GNU C version 4.1.0 20050712 (experimental) (i686-pc-linux-gnu)
        compiled by GNU C version 4.1.0 20050712 (experimental).
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: cab36206423b633931a3bd43d355747c
 as -V -Qy -o /tmp/ccUCeuxU.o /tmp/cc3anyqv.s
GNU assembler version 2.15 (i386-linux) using BFD version 2.15
 /home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../libexec/gcc/i686-pc-linux-gnu/4.1.0/collect2
--eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 /usr/lib/crt1.o
/usr/lib/crti.o
/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/crtbegin.o
-L/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0
-L/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc
-L/home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449/lib/gcc/i686-pc-linux-gnu/4.1.0
-L/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/../../..
-L/home/akr/ruby/chkbuild/tmp/build/gcc-trunk/20050712T134449/lib/gcc/i686-pc-linux-gnu/4.1.0/../../..
/tmp/ccUCeuxU.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed
-lgcc_s --no-as-needed
/home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/../lib/gcc/i686-pc-linux-gnu/4.1.0/crtend.o
/usr/lib/crtn.o
% ./a.out                                                                   
zsh: exit 1     ./a.out

It exists with 0 if optimization is disabled.

% /home/src/chkbuild-tmp/build/gcc-trunk/20050712T134449/bin/gcc z.c        
% ./a.out

-- 
           Summary: -1073741824 <= n && n <= 1073741823 is true where n is
                    1073741824
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: akr at m17n dot org
                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=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 06:54 -------
4.0 produced:
  D.1463 = n - -1073741824;
  if (D.1463 >= 0)

Which is wrong as overflow is undefined.

4.1 produces:
(n >= -1073741824)
as overflow is undefined.

This was exposed by:
2005-07-02  Andrew Pinski  <pinskia@physics.uc.edu>

        PR middle-end/14490
        * fold-const.c (fold_binary): Handle the return value of
        fold_to_nonsharp_ineq_using_bound if we get back the same operand back.
        Implement "X +- C1 CMP C2" folding to "X CMP C2 -+ C1".

Which means I have to look into it since I exposed it.  We should be subtracting using unsigned mode.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c                           |middle-end
     Ever Confirmed|                            |1
 GCC target triplet|i686-pc-linux-gnu           |
           Keywords|                            |wrong-code
      Known to fail|                            |4.1.0
      Known to work|                            |4.0.2
   Last reconfirmed|0000-00-00 00:00:00         |2005-07-12 06:54:16
               date|                            |
            Summary|-1073741824 <= n && n <=    |[4.1 Regression] -1073741824
                   |1073741823 is true where n  |<= n && n <= 1073741823 is
                   |is 1073741824               |true where n is 1073741824
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 07:04 -------
(In reply to comment #1)
> 4.0 produced:
>   D.1463 = n - -1073741824;
>   if (D.1463 >= 0)
> 
> Which is wrong as overflow is undefined.

This shows that fold is doing something wrong:
void abort(void);

int f(int n)
{
  if (n< 0)
   return 1;
  n+=1073741824;
  return n >= 0;
}
int main()
{
 if (f(1073741824))
   abort ();
}

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 16:18 -------
I have a fix, the problem is that build_range_check depends on wrapping on signed types being defined 
which is not correct.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pinskia at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 22:56 -------
Patch posted here: <http://gcc.gnu.org/ml/gcc-patches/2005-07/msg00879.html>.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |http://gcc.gnu.org/ml/gcc-
                   |                            |patches/2005-
                   |                            |07/msg00879.html
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[rth at gcc dot gnu dot org]

------- Comment #14 from rth at gcc dot gnu dot org  2005-11-02 21:47 -------
Fixed.


-- 

rth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[rth at gcc dot gnu dot org]

------- Comment #13 from rth at gcc dot gnu dot org  2005-11-02 21:44 -------
Subject: Bug 22429

Author: rth
Date: Wed Nov  2 21:44:17 2005
New Revision: 106400

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=106400
Log:
        PR 22429
        * fold-const.c (build_range_check): Use unsigned when signed
        overflow is undefined also.  If etype is subtype, make sure that
        the subtraction is in the supertype.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr22429.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[rth at gcc dot gnu dot org]

-- 

rth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rth at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-10-16 21:48:15         |2005-11-02 02:42:01
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[mmitchel at gcc dot gnu dot org]

------- Comment #12 from mmitchel at gcc dot gnu dot org  2005-10-31 04:03 -------
This is a showstopper; wrong code on a primary platform using plausible inputs.


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P2                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at gcc dot gnu dot org]

------- Comment #11 from pinskia at gcc dot gnu dot org  2005-10-22 21:55 -------
I am no longer working on this and my machine went bust today, sorry.  If
someone wants to take my patch and fix up for future comments, please do.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|pinskia at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[pinskia at physics dot uc dot edu]

------- Comment #10 from pinskia at gcc dot gnu dot org  2005-10-13 16:12 -------
Subject: Re:  [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true
where n is 1073741824

> 
> 
> 
> ------- Comment #9 from bonzini at gcc dot gnu dot org  2005-10-13 16:09 -------
> As in:
> 
>   if (value != 0
>       && (!flag_wrapv || TREE_OVERFLOW (value))
>       && (flag_wrapv || !TYPE_UNSIGNED (etype)))
> 
> which in turn means
> 
>   if (value != 0
>       && (flag_wrapv ? TREE_OVERFLOW (value) : !TYPE_UNSIGNED (etype)))

That is what my patch does.

The extra stuff was needed to make sure that Ada would be able to bootstrap.

-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

Re: [Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[Andrew Pinski]

> 
> 
> 
> ------- Comment #9 from bonzini at gcc dot gnu dot org  2005-10-13 16:09 -------
> As in:
> 
>   if (value != 0
>       && (!flag_wrapv || TREE_OVERFLOW (value))
>       && (flag_wrapv || !TYPE_UNSIGNED (etype)))
> 
> which in turn means
> 
>   if (value != 0
>       && (flag_wrapv ? TREE_OVERFLOW (value) : !TYPE_UNSIGNED (etype)))

That is what my patch does.

The extra stuff was needed to make sure that Ada would be able to bootstrap.

-- Pinski

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[bonzini at gcc dot gnu dot org]

------- Comment #9 from bonzini at gcc dot gnu dot org  2005-10-13 16:09 -------
As in:

  if (value != 0
      && (!flag_wrapv || TREE_OVERFLOW (value))
      && (flag_wrapv || !TYPE_UNSIGNED (etype)))

which in turn means

  if (value != 0
      && (flag_wrapv ? TREE_OVERFLOW (value) : !TYPE_UNSIGNED (etype)))


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[bonzini at gcc dot gnu dot org]

------- Comment #8 from bonzini at gcc dot gnu dot org  2005-10-13 16:05 -------
Sorry, let me rephrase.  Could build_range_check not cast to the unsigned type
if flag_wrapv?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429

[Bug middle-end/22429] [4.1 Regression] -1073741824 <= n && n <= 1073741823 is true where n is 1073741824

[bonzini at gcc dot gnu dot org]

------- Comment #7 from bonzini at gcc dot gnu dot org  2005-10-13 15:59 -------
Why can't build_range_check first cast to an unsigned type?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22429