[Bug c/37261] New: Spurious (?) "integer overflow in expression" warnings

[Bug c/37261] New: Spurious (?) "integer overflow in expression" warnings

[roland at digitalvampire dot org]

With:

$ gcc --version
gcc (Debian 4.3.1-2) 4.3.1

running on x86-64, the code below produces seemingly spurious warnings about
integer overflow:

$ LANG=C gcc -c b.c
b.c: In function 'foo':
b.c:3: warning: integer overflow in expression
b.c:5: warning: integer overflow in expression

$ cat b.c
unsigned foo(int x)
{
        return ((x & 1) | 2) & 0x80000000;
        return ((x & 2) | 2) & 0x80000000;
        return ((x & 4) | 2) & 0x80000000;
}


-- 
           Summary: Spurious (?) "integer overflow in expression" warnings
           Product: gcc
           Version: 4.3.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: roland at digitalvampire dot org
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-08-28 09:16 -------
Confirmed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |diagnostic
      Known to fail|                            |4.3.1
      Known to work|                            |4.2.4
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-28 09:16:34
               date|                            |
            Summary|Spurious (?) "integer       |[4.3/4.4 Regression]
                   |overflow in expression"     |Spurious (?) "integer
                   |warnings                    |overflow in expression"
                   |                            |warnings
   Target Milestone|---                         |4.3.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2008-08-29 11:55 -------
Testing a fix.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2008-08-28 09:16:34         |2008-08-29 11:55:56
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2008-08-29 12:23 -------
Caused by PR33691 fix btw.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2008-08-29 19:00 -------
Subject: Bug 37261

Author: jakub
Date: Fri Aug 29 18:59:13 2008
New Revision: 139784

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=139784
Log:
        PR c/37261
        * fold-const.c (fold_binary): In (X | C1) & C2 canonicalization
        compute new & and | in type rather than TREE_TYPE (arg0).

        * gcc.dg/pr37261.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr37261.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2008-08-29 19:09 -------
Subject: Bug 37261

Author: jakub
Date: Fri Aug 29 19:08:18 2008
New Revision: 139786

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=139786
Log:
        PR c/37261
        * fold-const.c (fold_binary): In (X | C1) & C2 canonicalization
        compute new & and | in type rather than TREE_TYPE (arg0).

        * gcc.dg/pr37261.c: New test.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gcc.dg/pr37261.c
Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/fold-const.c
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261

[Bug c/37261] [4.3/4.4 Regression] Spurious (?) "integer overflow in expression" warnings

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2008-08-29 19:11 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37261