[Bug middle-end/37248] New: regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[Bug middle-end/37248] New: regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[etienne_lorrain at yahoo dot fr]

In short, when passing a bitfield as parameter, each bit is converted to bytes
before being tested instead of a simple mask and test.
 Is there a way to disable bit to bytes conversion by a compilation switch,
I have never seen that producing better code up to now?

$ cat tmp2.c
struct mouse_button_str {
        unsigned char left      : 1;
        unsigned char right     : 1;
        unsigned char middle    : 1;
        } button;

char fct (struct mouse_button_str newbutton)
{
        return (newbutton.left && newbutton.right && newbutton.middle);
}
$ ./toolchain/bin/gcc --version
gcc (GCC) 4.3.2 20080819 (prerelease)
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ ./toolchain/bin/gcc -Os tmp2.c -S -o tmp2.s
$ cat tmp2.s
        .file   "tmp2.c"
        .text
.globl fct
        .type   fct, @function
fct:
        pushl   %ebp
        movl    %esp, %ebp
        movb    8(%ebp), %al
        movb    %al, %cl
        movb    %al, %dl
        shrb    %cl
        shrb    $2, %dl
        andl    $1, %ecx
        andl    $1, %edx
        testb   $1, %al
        je      .L2
        testb   %cl, %cl
        je      .L2
        movl    %edx, %eax
        andl    $1, %eax
        jmp     .L3
.L2:
        xorl    %eax, %eax
.L3:
        popl    %ebp
        ret
        .size   fct, .-fct
        .comm   button,1,1
        .ident  "GCC: (GNU) 4.3.2 20080819 (prerelease)"
        .section        .note.GNU-stack,"",@progbits
$ ./toolchain-4.3.1/bin/gcc --version
gcc (GCC) 4.3.1
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ ./toolchain-4.3.1/bin/gcc -Os tmp2.c -S -o tmp2.s
$ cat tmp2.s
        .file   "tmp2.c"
        .text
.globl fct
        .type   fct, @function
fct:
        pushl   %ebp
        movl    %esp, %ebp
        movb    8(%ebp), %al
        popl    %ebp
        andl    $7, %eax
        cmpb    $7, %al
        sete    %al
        ret
        .size   fct, .-fct
        .comm   button,1,1
        .ident  "GCC: (GNU) 4.3.1"
        .section        .note.GNU-stack,"",@progbits


-- 
           Summary: regression 4.3.1 -> 4.3.2-rc transformation bitfield to
                    individual bytes
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: etienne_lorrain at yahoo dot fr
 GCC build triplet: i386-linux-fedora
  GCC host triplet: i386-linux-fedora
GCC target triplet: i386-linux-fedora


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2008-08-26 22:50 -------
BIT_FIELD_REF was removed because it caused wrong code.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
  GCC build triplet|i386-linux-fedora           |
   GCC host triplet|i386-linux-fedora           |
 GCC target triplet|i386-linux-fedora           |
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-26 22:50:34
               date|                            |
            Summary|regression 4.3.1 -> 4.3.2-rc|[4.3/4.4 Regression]
                   |transformation bitfield to  |regression 4.3.1 -> 4.3.2-rc
                   |individual bytes            |transformation bitfield to
                   |                            |individual bytes
   Target Milestone|---                         |4.3.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[jsm28 at gcc dot gnu dot org]

------- Comment #2 from jsm28 at gcc dot gnu dot org  2008-08-27 22:05 -------
4.3.2 is released, changing milestones to 4.3.3.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.3.2                       |4.3.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2008-08-28 16:29 -------
Well, on the 4.3 branch it has been removed just because it has been removed on
the trunk and happened to make one PR away.  See PR36449 for an alternative fix
that doesn't disable the optimization.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2008-09-01 07:17 -------
Created an attachment (id=16177)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16177&action=view)
gcc43-pr37248.patch

Patch I've bootstrapped/regtested on 4 linux arches on 4.3 branch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2008-09-01 11:19 -------
FWIW the patch is ok for the 4.3 branch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.3/4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2008-09-01 11:33 -------
Subject: Bug 37248

Author: jakub
Date: Mon Sep  1 11:32:18 2008
New Revision: 139858

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=139858
Log:
        PR middle-end/37248
        PR middle-end/36449
        * fold-const.c (make_bit_field_ref): Change bitpos and bitsize
        arguments to HOST_WIDE_INT.
        (fold_truthop): Change first_bit and end_bit to HOST_WIDE_INT.

        * g++.dg/opt/pr36449.C: New test.

        Revert:
        2008-06-11  Richard Guenther  <rguenther@suse.de>
        PR middle-end/36449
        * fold-const.c (fold_truthop): Remove code generating
        BIT_FIELD_REFs of structure bases.
        (fold_binary): Likewise.
        (make_bit_field_ref): Remove.
        (optimize_bit_field_compare): Remove.
        (all_ones_mask_p): Remove.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/g++.dg/opt/pr36449.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=37248

[Bug middle-end/37248] [4.4 Regression] regression 4.3.1 -> 4.3.2-rc transformation bitfield to individual bytes

[etienne_lorrain at yahoo dot fr]

------- Comment #7 from etienne_lorrain at yahoo dot fr  2008-09-01 20:29 -------
Patch works for me, thanks.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.4 Regression] regression transformation bitfield to individual bytes

[jsm28 at gcc dot gnu dot org]

-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
   Target Milestone|4.3.3                       |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.4 Regression] regression transformation bitfield to individual bytes

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2008-12-05 17:01 -------
Subject: Bug 37248

Author: jakub
Date: Fri Dec  5 16:59:34 2008
New Revision: 142484

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=142484
Log:
        PR middle-end/37248
        * fold-const.c (make_bit_field_ref): Change bitpos and bitsize
        arguments to HOST_WIDE_INT.  If type has different signedness
        than unsignedp or different precision from bitsize, create
        the right type for BIT_FIELD_REF and cast to type.
        (fold_truthop): Change first_bit and end_bit to HOST_WIDE_INT.

        Revert:
        2008-03-05  Richard Guenther  <rguenther@suse.de>
        PR c++/35336
        * fold-const.c (fold_truthop): Remove code generating
        BIT_FIELD_REFs of structure bases.
        (fold_binary): Likewise.
        (make_bit_field_ref): Remove.
        (optimize_bit_field_compare): Remove.
        (all_ones_mask_p): Remove.

        * gcc.target/i386/pr37248-1.c: New test.
        * gcc.target/i386/pr37248-2.c: New test.
        * gcc.target/i386/pr37248-3.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/i386/pr37248-1.c
    trunk/gcc/testsuite/gcc.target/i386/pr37248-2.c
    trunk/gcc/testsuite/gcc.target/i386/pr37248-3.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.4 Regression] regression transformation bitfield to individual bytes

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2008-12-05 17:01 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248

[Bug middle-end/37248] [4.4 Regression] regression transformation bitfield to individual bytes

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.3.3                       |4.2.0 4.3.3
   Target Milestone|4.4.0                       |4.3.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37248