[Bug c/11446] New: Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[Bug c/11446] New: Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[aj at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446

           Summary: Incompatibilty with alignment of structures between 3.3
                    and 3.4 CVS
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: aj at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-linux-gnu
  GCC host triplet: i686-linux-gnu
GCC target triplet: i686-linux-gnu

On i686-linux-gnu the struct-align-1
testcase fails if I mix objects from GCC 3.3 and GCC 3.4 using current
CVS versions, the testsuite reports:

FAIL: gcc.dg/compat/struct-align-1 c_compat_x_tst.o-c_compat_y_alt.o execute 
FAIL: gcc.dg/compat/struct-align-1 c_compat_x_alt.o-c_compat_y_tst.o execute 

Here's an example compile session:

$ /opt/gcc/3.3-devel/bin/gcc -c -DDBG struct-align-1_x.c
$ /opt/gcc/3.4-devel/bin/gcc -c -DDBG struct-align-1_y.c
$ /opt/gcc/3.4-devel/bin/gcc -c -DDBG struct-align-1_main.c 
$ /opt/gcc/3.4-devel/bin/gcc -DDBG *.o -o struct-align-1
$ ./struct-align-1 
original
  global variable.......
  global array.......
  argument.......
  function result.......
packed attribute for all
  global variable.......
  global array.......
  argument.......
  function result.......
packed attribute for inner
  global variable.......
  global array.......
  argument.......
  function result.......
packed attribute for outer
  global variable.......
  global array.......
  argument.......
  function result.......
maximum useful struct alignment for all
  global variable.......
  global array.......
  argument.......
  function result.......
maximum alignment for outer, packed inner
  global variable.......
  global array.......
  argument.......
  function result.......
maximum alignment for inner, packed outer
  global variable...F.FF
  global array..FFFFF
  argument...F.FF
  function result...F.FF
failed
Aborted
gromit:~/tmp/align-1:[134]$ 

The structure that fails is:

#define DESC_m_inner_p_outer "maximum alignment for inner, packed outer"
struct B1_m_inner_p_outer {
  char c;
  double d;
} __attribute__ ((aligned)) __attribute__ ((packed));

A diff between struct_align-1_x.s between GCC 3.3 and 3.4 shows:
 .globl b2_a_max
-       .align 32
+       .align 16
...
 .globl b2_m_inner_p_outer
+       .align 16
        .type   b2_m_inner_p_outer, @object
-       .size   b2_m_inner_p_outer, 17
+       .size   b2_m_inner_p_outer, 32
...
 .globl ab2_m_inner_p_outer
-       .align 32
+       .align 16
        .type   ab2_m_inner_p_outer, @object
-       .size   ab2_m_inner_p_outer, 34
+       .size   ab2_m_inner_p_outer, 64

So, we have different alignment and therefore sizes. :-(

[Bug c/11446] [3.4] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[aj at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


aj at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2003-07-06 18:55:40
               date|                            |
            Summary|Incompatibilty with         |[3.4] Incompatibilty with
                   |alignment of structures     |alignment of structures
                   |between 3.3 and 3.4 CVS     |between 3.3 and 3.4 CVS

[Bug c/11446] [3.4] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446



------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-06 19:04 -------
Please do not confirm your own bug.
I can confirm this on the mainline (20030706) and 3.3.1 (20030616), the difference is there.

[Bug c/11446] [3.4] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[dhazeghi at yahoo dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


dhazeghi at yahoo dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code


------- Additional Comments From dhazeghi at yahoo dot com  2003-07-18 22:32 -------
Which layout is correct though?

[Bug c/11446] [3.4] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


pinskia at physics dot uc dot edu changed:

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

[Bug c/11446] [3.4] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[janis187 at us dot ibm dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


janis187 at us dot ibm dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at redhat dot com


------- Additional Comments From janis187 at us dot ibm dot com  2003-07-31 23:18 -------
The sizes and alignments of the structs in PR 11446 changed with this
patch:

--- gcc/gcc/ChangeLog ---

2003-04-03  Jason Merrill  <jason@redhat.com>

        * stor-layout.c (do_type_align): New fn, split out from...
        (layout_decl): ...here.  Do all alignment calculations for
        FIELD_DECLs here.
        (update_alignment_for_field): Not here.
        (start_record_layout, debug_rli): Remove unpadded_align.
        * tree.h (struct record_layout_info_s): Remove unpadded_align.
        * c-decl.c (finish_enum): Don't set DECL_SIZE, DECL_ALIGN
        or DECL_MODE on the CONST_DECLs.
        (finish_struct): Don't mess with DECL_ALIGN.

--- gcc/gcc/cp/ChangeLog ---

2003-04-03  Jason Merrill  <jason@redhat.com>

        * class.c (build_vtable): Set DECL_ALIGN here.
        (get_vtable_decl): Not here.
        (layout_vtable_decl): Or here.
        (create_vtable_ptr): Or here.
        (layout_class_type): Or here.
        (check_bitfield_decl): Don't mess with field alignment.

I used the following test on i686-pc-linux-gnu and watched for the size
of b2 to become 32:

------------------------------------------------------------------
struct A2_m_inner_p_outer {
  double d;
} __attribute__ ((aligned));

struct B2_m_inner_p_outer {
  char c;
  struct A2_m_inner_p_outer a2;
} __attribute__ ((packed));

struct B2_m_inner_p_outer b2 = { 1, { 2.0 } };

struct B2_m_inner_p_outer a2[2] = { { 1, { 2.0 } }, { 2, { 3.0 } } };
------------------------------------------------------------------

Here's the definition of b2 before and after the patch:

 .globl b2
        .data
+       .align 16
        .type   b2, @object
-       .size   b2, 17
+       .size   b2, 32
 b2:
        .byte   1
+       .zero   15
        .long   0
        .long   1073741824
        .zero   8

I don't know what the expected sizes and alignments are; Jason, is this
change expected?

[Bug c/11446] [3.4][3.4 regression?] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[jason at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


jason at gcc dot gnu dot org changed:

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

[Bug c/11446] [3.4][3.4 regression?] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[cvs-commit at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446



------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-10-20 22:02 -------
Subject: Bug 11446

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	jason@gcc.gnu.org	2003-10-20 22:01:59

Added files:
	gcc/testsuite/gcc.dg: pack-test-5.c 

Log message:
	PR c/11446
	* stor-layout.c (layout_decl): Fix alignment handling.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pack-test-5.c.diff?cvsroot=gcc&r1=NONE&r2=1.1

[Bug c/11446] [3.4][3.4 regression?] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[cvs-commit at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446



------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-10-20 21:57 -------
Subject: Bug 11446

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	jason@gcc.gnu.org	2003-10-20 21:57:42

Modified files:
	gcc            : tree.c stor-layout.c ChangeLog 

Log message:
	PR c/12553
	* tree.c (build1) <ADDR_EXPR>: Set TREE_SIDE_EFFECTS
	appropriately.
	
	PR c/11446
	* stor-layout.c (layout_decl): Fix alignment handling.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree.c.diff?cvsroot=gcc&r1=1.333&r2=1.334
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/stor-layout.c.diff?cvsroot=gcc&r1=1.170&r2=1.171
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.1492&r2=2.1493

[Bug c/11446] [3.4][3.4 regression?] Incompatibilty with alignment of structures between 3.3 and 3.4 CVS

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11446


pinskia at gcc dot gnu dot org changed:

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


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-10-20 22:28 -------
Fixed for 3.4.