[Bug c/50565] New: [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[Bug c/50565] New: [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[doko at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

             Bug #: 50565
           Summary: [4.5/4.6/4.7 Regression] initializer element is not
                    computable at load time
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: doko@gcc.gnu.org


Created attachment 25379
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25379
preprocessed source

[forwarded from http://bugs.debian.org/642144]

this may be a duplicate of PR38354, compiles on 32bit targets, on 64bit targets
it succeeds with 4.4, but fails with 4.5, 4.6 and trunk:

$ gcc -c message.i 
message.i:154:2: error: initializer element is not computable at load time
message.i:154:2: error: (near initialization for 'byte_order[1].offset')

[Bug middle-end/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |middle-end
   Target Milestone|---                         |4.5.4

[Bug middle-end/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-09-29 17:03:28 UTC ---
Anyreason Why "((int)( ((void *)&(nmsgbuf.payload.part.ball.pos[0])) - ((void
*)&(nmsgbuf)) ))" is being used instead of offsetof ?

[Bug middle-end/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[mikpe at it dot uu.se]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

Mikael Pettersson <mikpe at it dot uu.se> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikpe at it dot uu.se

--- Comment #2 from Mikael Pettersson <mikpe at it dot uu.se> 2011-10-01 20:36:57 UTC ---
This test case started being rejected with r145254:
http://gcc.gnu.org/ml/gcc-cvs/2009-03/msg00761.html

[Bug middle-end/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[mikpe at it dot uu.se]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

--- Comment #3 from Mikael Pettersson <mikpe at it dot uu.se> 2011-10-02 10:43:54 UTC ---
Created attachment 25393
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25393
reduced test case

> cat pr50565.c
/* pr50565.c */
struct netmessage {
    unsigned char pos[2];
};
static struct netmessage nmsgbuf;
const int offset0 = (int)((void*)&nmsgbuf.pos[0] - (void*)&nmsgbuf) + 0*(1U);
const int offset1 = (int)((void*)&nmsgbuf.pos[0] - (void*)&nmsgbuf) + 1*(1U);
> objdir/gcc/xgcc -Bobjdir/gcc/ -O2 -S pr50565.c
pr50565.c:7: error: initializer element is not computable at load time

That's the offset1 initializer it's complaining about.  Note that the offset0
initializer is accepted.  If we comment out the offset1 definition we get:

> perl -pi -e 's,^const int offset1,//const int offset1,g' pr50565.c
> objdir/gcc/xgcc -Bobjdir/gcc/ -O2 -S pr50565.c
> cat pr50565.s
        .file   "pr50565.c"
.globl offset0
        .section        .rodata
        .align 4
        .type   offset0, @object
        .size   offset0, 4
offset0:
        .long   0
        .local  nmsgbuf
        .comm   nmsgbuf,2,1
        .ident  "GCC: (GNU) 4.5.0 20090329 (experimental)"
        .section        .note.GNU-stack,"",@progbits

The common offsetof emulation is clearly computable at compile-time, so one
would expect the same + 1 to also be computable at compile-time, but gcc
doesn't seem to think so.

[Bug c/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

Joseph S. Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-10-11
         AssignedTo|unassigned at gcc dot       |jsm28 at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #4 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-10-11 15:33:55 UTC ---
Patch (to convert.c) submitted:
http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00894.html

[Bug c/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

--- Comment #6 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-10-12 11:57:39 UTC ---
Author: jsm28
Date: Wed Oct 12 11:57:36 2011
New Revision: 179846

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179846
Log:
    PR c/50565
    * convert.c (convert_to_integer): Do not narrow operands of
    pointer subtraction.

testsuite:
    * gcc.c-torture/compile/pr50565-1.c,
    gcc.c-torture/compile/pr50565-2.c: New tests.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gcc.c-torture/compile/pr50565-1.c
    branches/gcc-4_6-branch/gcc/testsuite/gcc.c-torture/compile/pr50565-2.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/convert.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug c/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

--- Comment #5 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-10-12 11:56:06 UTC ---
Author: jsm28
Date: Wed Oct 12 11:56:03 2011
New Revision: 179845

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179845
Log:
    PR c/50565
    * convert.c (convert_to_integer): Do not narrow operands of
    pointer subtraction.

testsuite:
    * gcc.c-torture/compile/pr50565-1.c,
    gcc.c-torture/compile/pr50565-2.c: New tests.

Added:
    trunk/gcc/testsuite/gcc.c-torture/compile/pr50565-1.c
    trunk/gcc/testsuite/gcc.c-torture/compile/pr50565-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/convert.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

--- Comment #7 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-10-12 11:58:52 UTC ---
Author: jsm28
Date: Wed Oct 12 11:58:47 2011
New Revision: 179847

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179847
Log:
    PR c/50565
    * convert.c (convert_to_integer): Do not narrow operands of
    pointer subtraction.

testsuite:
    * gcc.c-torture/compile/pr50565-1.c,
    gcc.c-torture/compile/pr50565-2.c: New tests.

Added:
    branches/gcc-4_5-branch/gcc/testsuite/gcc.c-torture/compile/pr50565-1.c
    branches/gcc-4_5-branch/gcc/testsuite/gcc.c-torture/compile/pr50565-2.c
Modified:
    branches/gcc-4_5-branch/gcc/ChangeLog
    branches/gcc-4_5-branch/gcc/convert.c
    branches/gcc-4_5-branch/gcc/testsuite/ChangeLog

[Bug c/50565] [4.5/4.6/4.7 Regression] initializer element is not computable at load time

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50565

Joseph S. Myers <jsm28 at gcc dot gnu.org> changed:

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

--- Comment #8 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-10-12 12:00:02 UTC ---
Fixed for 4.5.4, 4.6.2, 4.7.