[Bug middle-end/51200] New: Wrong code sequence to store restrict volatile bitfield

[Bug middle-end/51200] New: Wrong code sequence to store restrict volatile bitfield

[joey.ye at arm dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

             Bug #: 51200
           Summary: Wrong code sequence to store restrict volatile
                    bitfield
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: joey.ye@arm.com


Trunk 179074 generates wrong code sequence with -fstrict-volatile-bitfields on
ARM and x86. 

ARM AAPCS default enable strict volatile bitfields so it is critical on ARM:

/* { dg-do run } */
/* { dg-options "-fstrict-volatile-bitfields" } */

extern void abort(void);
struct thing {
  volatile unsigned short a: 8;
  volatile unsigned short b: 8;
} t = {1,2};

int main()
{
  t.a = 3;
  if (t.a !=3 || t.b !=2) abort();
  return 0;
}

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[joey.ye at arm dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

--- Comment #1 from Joey Ye <joey.ye at arm dot com> 2011-11-18 02:23:17 UTC ---
A patch is available at http://gcc.gnu.org/ml/gcc-patches/2010-12/msg00217.html
but is pending for about 1 year.

Latest discussion is at http://gcc.gnu.org/ml/gcc-patches/2011-11/msg01623.html

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[joey.ye at arm dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

--- Comment #2 from Joey Ye <joey.ye at arm dot com> 2011-11-22 03:58:29 UTC ---
Here is a test case fix.

With this patch, backend part of Bernd's original patch can be skipped. Thus
DJ's concern of unnecessary change can be addressed.

Also this test case intends to warn a situation that is incompatible to abi
version 1, -fstrict-volatile-bitfields happenly hides the incompatibility. IMHO
it is consultable to claim strict volatile bitfields violates version 1. So
fixing the test case and make it work as intended is more reasonable to me.


--- a/gcc/testsuite/g++.dg/abi/bitfield12.C
+++ b/gcc/testsuite/g++.dg/abi/bitfield12.C
@@ -1,4 +1,4 @@
-// { dg-options "-Wabi -fabi-version=1" }
+// { dg-options "-Wabi -fabi-version=1 -fno-strict-volatile-bitfields" }

 struct S { // { dg-warning "ABI" }
   char c : 1024; // { dg-warning "width" }

 struct S { // { dg-warning "ABI" }
   char c : 1024; // { dg-warning

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

Bernd Schmidt <bernds at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |bernds at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #3 from Bernd Schmidt <bernds at gcc dot gnu.org> 2011-12-21 01:22:08 UTC ---
Fixed, I think?

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[joey.ye at arm dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

Joey Ye <joey.ye at arm dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |VERIFIED

--- Comment #4 from Joey Ye <joey.ye at arm dot com> 2011-12-21 04:34:57 UTC ---
Fixed in trunk 182545

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[jye2 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

--- Comment #5 from jye2 at gcc dot gnu.org 2011-12-26 08:43:51 UTC ---
Author: jye2
Date: Mon Dec 26 08:43:48 2011
New Revision: 182685

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182685
Log:
2011-12-26  Joey Ye  <joey.ye@arm.com>

    PR middle-end/51200
    * gcc.dg/volatile-bitfields-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/volatile-bitfields-2.c
Modified:
    trunk/gcc/testsuite/ChangeLog

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[jye2 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

--- Comment #6 from jye2 at gcc dot gnu.org 2011-12-27 02:27:01 UTC ---
Author: jye2
Date: Tue Dec 27 02:26:57 2011
New Revision: 182691

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182691
Log:
2011-12-26  Joey Ye  <joey.ye@arm.com>
    Revert original fix and backport r182545, 182649 from mainline

    Revert:
    2011-11-18  Joey Ye  <joey.ye@arm.com>

    Port Bernd's fix to volatile bitfields
    2010-12-02  Bernd Schmidt  <bernds_cb1@t-online.de>

    * expr.c (store_field): Avoid a direct store if the mode is larger
    than the size of the bit field.
    * stor-layout.c (layout_decl): If flag_strict_volatile_bitfields,
    treat non-volatile bit fields like volatile ones.
    * toplev.c (process_options): Disallow combination of
    -fstrict-volatile-bitfields and ABI versions less than 2.
    * config/arm/arm.c (arm_option_override): Don't enable
    flag_strict_volatile_bitfields if the ABI version is less than 2.

    Backport:
    2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>

    PR middle-end/51200
    * expr.c (store_field): Avoid a direct store if the mode is larger
    than the size of the bit field.
    * stor-layout.c (layout_decl): If flag_strict_volatile_bitfields,
    treat non-volatile bit fields like volatile ones.
    * toplev.c (process_options): Disallow combination of
    -fstrict-volatile-bitfields and ABI versions less than 2.
    * config/arm/arm.c (arm_option_override): Don't enable
    flag_strict_volatile_bitfields if the ABI version is less than 2.
    * config/h8300/h8300.c (h8300_option_override): Likewise.
    * config/rx/rx.c (rx_option_override): Likewise.
    * config/m32c/m32c.c (m32c_option_override): Likewise.
    * config/sh/sh.c (sh_option_override): Likewise.

    2011-12-22  Joey Ye  <joey.ye@arm.com>

    * toplev.c (process_options): Fix typo.

testsute
2011-12-26  Joey Ye  <joey.ye@arm.com>

    Revert original fix and backport r182545, r182649 from mainline

    Revert:
    2011-11-23  Joey Ye  <joey.ye@arm.com>

    Apply restrict volatile bitfield test case.
    2011-11-23  Joey Ye  <joey.ye@arm.com>
    * g++.dg/abi/bitfield12.C: Add option -fno-strict-volatile-bitfields.

    Backport:
    2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>

    PR middle-end/51200
    * gcc.target/arm/volatile-bitfields-4.c: New test.
    * c-c++-common/abi-bf.c: New test.

    2011-12-26  Joey Ye  <joey.ye@arm.com>

    PR middle-end/51200
    * gcc.dg/volatile-bitfields-2.c: New test.


Added:
    branches/ARM/embedded-4_6-branch/gcc/testsuite/c-c++-common/abi-bf.c
   
branches/ARM/embedded-4_6-branch/gcc/testsuite/gcc.dg/volatile-bitfields-2.c
   
branches/ARM/embedded-4_6-branch/gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c
Modified:
    branches/ARM/embedded-4_6-branch/gcc/ChangeLog.arm
    branches/ARM/embedded-4_6-branch/gcc/config/arm/arm.c
    branches/ARM/embedded-4_6-branch/gcc/config/h8300/h8300.c
    branches/ARM/embedded-4_6-branch/gcc/config/m32c/m32c.c
    branches/ARM/embedded-4_6-branch/gcc/config/rx/rx.c
    branches/ARM/embedded-4_6-branch/gcc/config/sh/sh.c
    branches/ARM/embedded-4_6-branch/gcc/testsuite/ChangeLog.arm
    branches/ARM/embedded-4_6-branch/gcc/testsuite/g++.dg/abi/bitfield12.C
    branches/ARM/embedded-4_6-branch/gcc/toplev.c

[Bug middle-end/51200] Wrong code sequence to store restrict volatile bitfield

[jye2 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51200

--- Comment #7 from jye2 at gcc dot gnu.org 2012-03-29 02:15:37 UTC ---
Author: jye2
Date: Thu Mar 29 02:15:29 2012
New Revision: 185944

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=185944
Log:
2012-03-28  Joey Ye  <joey.ye@arm.com>

    Backported from mainline
    2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>

    PR middle-end/51200
    * expr.c (store_field): Avoid a direct store if the mode is larger
    than the size of the bit field.
    * stor-layout.c (layout_decl): If flag_strict_volatile_bitfields,
    treat non-volatile bit fields like volatile ones.
    * toplev.c (process_options): Disallow combination of
    -fstrict-volatile-bitfields and ABI versions less than 2.
    * config/arm/arm.c (arm_option_override): Don't enable
    flag_strict_volatile_bitfields if the ABI version is less than 2.
    * config/h8300/h8300.c (h8300_option_override): Likewise.
    * config/rx/rx.c (rx_option_override): Likewise.
    * config/m32c/m32c.c (m32c_option_override): Likewise.
    * config/sh/sh.c (sh_option_override): Likewise.

    2011-12-22  Joey Ye  <joey.ye@arm.com>

    * toplev.c (process_options): Fix typo.

testcases:

    Backported from mainline
    2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>

    PR middle-end/51200
    * gcc.target/arm/volatile-bitfields-4.c: New test.
    * c-c++-common/abi-bf.c: New test.

    2011-12-26  Joey Ye  <joey.ye@arm.com>

    PR middle-end/51200
    * gcc.dg/volatile-bitfields-2.c: New test.


Added:
    branches/gcc-4_6-branch/gcc/testsuite/c-c++-common/abi-bf.c
    branches/gcc-4_6-branch/gcc/testsuite/gcc.dg/volatile-bitfields-2.c
    branches/gcc-4_6-branch/gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/config/arm/arm.c
    branches/gcc-4_6-branch/gcc/config/h8300/h8300.c
    branches/gcc-4_6-branch/gcc/config/m32c/m32c.c
    branches/gcc-4_6-branch/gcc/config/rx/rx.c
    branches/gcc-4_6-branch/gcc/config/sh/sh.c
    branches/gcc-4_6-branch/gcc/expr.c
    branches/gcc-4_6-branch/gcc/stor-layout.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_6-branch/gcc/toplev.c