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* [Bug c++/56966] New: [4.7 Regression] wrong warning with -Werror (wrong code without Werror?)
@ 2013-04-15 13:32 doko at gcc dot gnu.org
  2013-04-15 17:34 ` [Bug c++/56966] " pinskia at gcc dot gnu.org
  2013-05-15 13:32 ` rguenth at gcc dot gnu.org
  0 siblings, 2 replies; 3+ messages in thread
From: doko at gcc dot gnu.org @ 2013-04-15 13:32 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56966

             Bug #: 56966
           Summary: [4.7 Regression] wrong warning with -Werror (wrong
                    code without Werror?)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: doko@gcc.gnu.org


Created attachment 29874
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29874
preprocessed source

seen when building OpenJDK-7 on x86_64-linux-gnu, no reduced test case yet.
works with 4.6 and 4.8, and a 4.7 branch from march. trying to get one
revision.


g++-4.7 -fno-rtti -fno-exceptions -fcheck-new -fvisibility=hidden -g -O3
-fno-strict-aliasing -Werror -c g1BlockOffsetTable.ii

In file included from /usr/include/string.h:638:0,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/utilities/globalDefinitions_gcc.hpp:35,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/utilities/globalDefinitions.hpp:33,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/utilities/debug.hpp:29,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/runtime/globals.hpp:28,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/memory/allocation.hpp:28,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/memory/memRegion.hpp:28,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp:28,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp:28,
                 from
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:26:
In function 'void* memset(void*, int, size_t)',
    inlined from 'void
G1BlockOffsetSharedArray::_ZN24G1BlockOffsetSharedArray16set_offset_arrayEmmh.isra.8(unsigned
char*, size_t, size_t, unsigned char)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp:169:52,
    inlined from 'void
G1BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t, size_t)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:195:67,
    inlined from 'void
G1BlockOffsetArray::_ZN18G1BlockOffsetArray31set_remainder_to_point_to_startEP8HeapWordS1_.part.55(HeapWord*,
HeapWord*)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:168:61,
    inlined from 'void
G1BlockOffsetArray::set_remainder_to_point_to_start(HeapWord*, HeapWord*)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:369:1,
    inlined from 'void G1BlockOffsetArray::alloc_block_work2(HeapWord**,
size_t*, HeapWord*, HeapWord*)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:510:53,
    inlined from 'HeapWord*
G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord*, HeapWord*,
const void*)' at
/scratch/packages/openjdk/7u15/openjdk-7-7u17-2.3.8/build/zerovm/openjdk/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp:394:59:
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
/usr/include/x86_64-linux-gnu/bits/string3.h:81:32: error: call to
'__warn_memset_zero_len' declared with attribute warning: memset used with
constant zero length parameter; this could be due to transposed parameters
[-Werror]
cc1plus: all warnings being treated as errors


^ permalink raw reply	[flat|nested] 3+ messages in thread

* [Bug c++/56966] [4.7 Regression] wrong warning with -Werror (wrong code without Werror?)
  2013-04-15 13:32 [Bug c++/56966] New: [4.7 Regression] wrong warning with -Werror (wrong code without Werror?) doko at gcc dot gnu.org
@ 2013-04-15 17:34 ` pinskia at gcc dot gnu.org
  2013-05-15 13:32 ` rguenth at gcc dot gnu.org
  1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2013-04-15 17:34 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56966

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-04-15 17:34:20 UTC ---
I don't think this is wrong code at all.  The warning is correct for the code
as given but wrong for memset in general.

The code looks like:
  void set_offset_array(size_t left, size_t right, u_char offset) {
    ;
    ;
    size_t num_cards = right - left + 1;
    memset(&_offset_array[left], offset, num_cards);
  }

....



num_cards is being turned into 0 which is fine in this case as optimization has
happened.  The problem is the memset code is just bogus when it tries to see if
the length is 0.


^ permalink raw reply	[flat|nested] 3+ messages in thread

* [Bug c++/56966] [4.7 Regression] wrong warning with -Werror (wrong code without Werror?)
  2013-04-15 13:32 [Bug c++/56966] New: [4.7 Regression] wrong warning with -Werror (wrong code without Werror?) doko at gcc dot gnu.org
  2013-04-15 17:34 ` [Bug c++/56966] " pinskia at gcc dot gnu.org
@ 2013-05-15 13:32 ` rguenth at gcc dot gnu.org
  1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-05-15 13:32 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56966

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Also this is a glibc issue then.


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2013-05-15 13:32 UTC | newest]

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2013-04-15 13:32 [Bug c++/56966] New: [4.7 Regression] wrong warning with -Werror (wrong code without Werror?) doko at gcc dot gnu.org
2013-04-15 17:34 ` [Bug c++/56966] " pinskia at gcc dot gnu.org
2013-05-15 13:32 ` rguenth at gcc dot gnu.org

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