[Bug c/37882] New: [4.3/4.4 Regression] Bitfield miscompilation

[Bug c/37882] New: [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

struct S
{
  int a : 21;
  unsigned char b : 3;
} s;

int
main ()
{
  s.b = 4;
  if (s.b > 0 && s.b < 4)
    __builtin_abort ();
  return 0;
}

See http://gcc.gnu.org/ml/gcc-bugs/2008-10/msg01324.html
Works till 4.2, fails at -O with 4.3 and trunk.


-- 
           Summary: [4.3/4.4 Regression] Bitfield miscompilation
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-10-21 16:15 -------
It's fold:

;; enabled by -tree-original


{
  foo.z = 83778;
  foo.probe = 0;
  foo.val = 4;
  if ((signed char) foo.val > 0)


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c                           |middle-end
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-10-21 16:15:25
               date|                            |
   Target Milestone|---                         |4.3.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2008-10-22 10:17 -------
Indeed.


-- 

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|2008-10-21 16:15:25         |2008-10-22 10:17:51
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2008-10-22 18:23 -------
Subject: Bug 37882

Author: jakub
Date: Wed Oct 22 18:21:55 2008
New Revision: 141303

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=141303
Log:
        PR middle-end/37882
        * fold-const.c (build_range_type): For 1 .. signed_max
        range call build_nonstandard_inter_type if signed_type_for
        returned a type with bigger precision.

        * gcc.c-torture/execute/pr37882.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr37882.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2008-10-22 20:09 -------
Subject: Bug 37882

Author: jakub
Date: Wed Oct 22 20:08:01 2008
New Revision: 141306

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=141306
Log:
        PR middle-end/37882
        * fold-const.c (build_range_type): For 1 .. signed_max
        range call build_nonstandard_inter_type if signed_type_for
        returned a type with bigger precision.

        * gcc.c-torture/execute/pr37882.c: New test.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gcc.c-torture/execute/pr37882.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=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2008-10-22 20:09 -------
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=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[eric dot weddington at atmel dot com]

------- Comment #6 from eric dot weddington at atmel dot com  2008-10-23 23:21 -------
New test case fails for AVR target, as test case assumes that an integer is
32-bits. An integer on the AVR is 16 bits and the test case fails for -O[0123s]
with:
/gcc/testsuite/gcc.c-torture/execute/pr37882.c:5: error: width of 'a' exceeds
its type


-- 

eric dot weddington at atmel dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2008-10-23 23:33 -------
Guess you can leave the int a : 21; line completely out, the testcase used to
fail apparently even without that.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2008-10-24 09:16 -------
Subject: Bug 37882

Author: jakub
Date: Fri Oct 24 09:14:57 2008
New Revision: 141339

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=141339
Log:
        PR middle-end/37882
        * gcc.c-torture/execute/pr37882.c: Remove a field.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.c-torture/execute/pr37882.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882

[Bug middle-end/37882] [4.3/4.4 Regression] Bitfield miscompilation

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2008-10-24 09:17 -------
Test adjusted.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37882