[Bug target/45843] New: [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg overwrites into adjacent stack location

[Bug target/45843] New: [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg overwrites into adjacent stack location

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

           Summary: [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg
                    overwrites into adjacent stack location
           Product: gcc
           Version: 4.3.6
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jakub@gcc.gnu.org
                CC: gcc-bugs@gcc.gnu.org, hubicka@gcc.gnu.org,
                    hjl.tools@gmail.com, matz@gcc.gnu.org,
                    eraman@google.com
        Depends on: 44575
              Host: x86_64-unknown-linux-gnu
            Target: x86_64-unknown-linux-gnu
             Build: x86_64-unknown-linux-gnu


+++ This bug was initially created as a clone of Bug #44575 +++

This is a variation of the same problem where __builtin_va_arg overwrites into
adjacent stack location [Not sure if I should reopen this bug or file a new
one]:

$ cat vararg.cc

#include <stdarg.h>
#include <stdlib.h>
struct S933 { struct{struct{}b[6];union{}c[7];}a;char d;char e; };

struct S933 arg;
void check933va (int z, ...) {
  char c;
  va_list ap;
  __builtin_va_start(ap,z);
  c = 'a';
  arg = __builtin_va_arg(ap,struct S933);
  if (c != 'a')
    abort();

}
int main() {
  struct S933 s933;
  check933va (1, s933);
}

$ ./trunk-g++  -O0  vararg.cc && ./a.out
Aborted

./trunk-g++ is GNU C++  version 4.6.0 20100924 (experimental)
(x86_64-unknown-linux-gnu)

The relevant portion of the gimple is below:
  D.2773_4 = ap.reg_save_area;
  D.2774_5 = ap.gp_offset;
  D.2775_6 = (long unsigned int) D.2774_5;
  int_addr.1_7 = D.2773_4 + D.2775_6;
  addr.0_8 = &va_arg_tmp.3;
  D.2777_9 = addr.0_8 + 8;
  D.2778_10 = MEM[(long unsigned int *)int_addr.1_7];
  *D.2777_9 = D.2778_10;    <--- Bad move

The move to address D.2777_9 is the problem

For this struct type, construct_container returns the following:

(parallel:BLK [
        (expr_list:REG_DEP_TRUE (reg:DI 0 ax)
            (const_int 8 [0x8]))
    ])

The destination of the move is at offset 8 (INTVAL (XEXP (slot, 1))) of the
temporary created. The size of the temp (sizeof(S933)) is 15 bytes and the move
is in DI mode. I think the problem is the check  if (prev_size + cur_size >
size) doesn't really check if the destination is overwritten.

[Bug target/45843] [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg overwrites into adjacent stack location

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2010.09.30 10:45:21
               date|                            |
     Ever Confirmed|0                           |1

[Bug target/45843] [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg overwrites into adjacent stack location

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|x86_64-unknown-linux-gnu    |x86_64-linux
      Known to work|                            |3.4.6
               Host|x86_64-unknown-linux-gnu    |
   Target Milestone|---                         |4.3.6
      Known to fail|                            |4.3.5, 4.4.4, 4.5.1, 4.6.0
              Build|x86_64-unknown-linux-gnu    |

[Bug target/45843] [4.3/4.4/4.5/4.6 Regression] __builtin_va_arg overwrites into adjacent stack location

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug target/45843] [4.3/4.4 Regression] __builtin_va_arg overwrites into adjacent stack location

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-10-01 13:13:36 UTC ---
Author: jakub
Date: Fri Oct  1 13:13:31 2010
New Revision: 164884

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164884
Log:
    Backport from mainline
    2010-09-30  Jakub Jelinek  <jakub@redhat.com>

    PR target/45843
    * config/i386/i386.c (ix86_gimplify_va_arg): Use
    INTVAL (XEXP (slot, 1)) as prev_size.

    2010-06-21  Jakub Jelinek  <jakub@redhat.com>

    PR target/44575
    * config/i386/i386.c (ix86_gimplify_va_arg): When copying
    va_arg from a set of register save slots into a temporary,
    if the container is bigger than type size, do the copying
    using smaller mode or using memcpy.

    Backport from mainline
    2010-09-30  Jakub Jelinek  <jakub@redhat.com>

    * g++.dg/torture/pr45843.C: New test.

    2010-06-21  Jakub Jelinek  <jakub@redhat.com>

    PR target/44575
    * gcc.c-torture/execute/pr44575.c: New test.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr45843.C
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr44575.c
Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/config/i386/i386.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog

[Bug target/45843] [4.3 Regression] __builtin_va_arg overwrites into adjacent stack location

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.4.6
            Summary|[4.3/4.4 Regression]        |[4.3 Regression]
                   |__builtin_va_arg overwrites |__builtin_va_arg overwrites
                   |into adjacent stack         |into adjacent stack
                   |location                    |location
      Known to fail|4.4.4                       |4.4.5

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-10-01 13:25:18 UTC ---
Fixed even for 4.4.6.

[Bug target/45843] [4.3 Regression] __builtin_va_arg overwrites into adjacent stack location

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45843

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|4.3.6                       |4.4.6

--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-06-27 11:59:00 UTC ---
Fixed for 4.4.6.