Re: Re: [PATCH 1/8] PR ld/17878: Add bfd_maybe_object_p

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Feb 19, 2015 at 8:59 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Feb 19, 2015 at 8:55 AM, Alex Velenko <Alex.Velenko@arm.com> wrote:
>>
>>
>> On 09/02/15 04:36, H.J. Lu wrote:
>>>
>>> On Sat, Feb 7, 2015 at 4:50 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>
>>>> On Sat, Feb 7, 2015 at 1:42 AM, Alan Modra <amodra@gmail.com> wrote:
>>>>>
>>>>> On Thu, Feb 05, 2015 at 05:54:40AM -0800, H.J. Lu wrote:
>>>>>>
>>>>>> This patch adds bfd_maybe_object_p which is similar to
>>>>>>
>>>>>> bfd_check_format (abfd, bfd_object)
>>>>>>
>>>>>> The difference is bfd_maybe_object_p takes an argument to indicate if a
>>>>>> compiler plug-in library is applied.  When a compiler plug-in library
>>>>>> is
>>>>>> active, it also returns TRUE if the file is not an archive or a
>>>>>> coredump
>>>>>> file.
>>>>>
>>>>>
>>>>> Hmm, in other words, if it is unknown.  (bfd_format takes the values
>>>>> bfd_unknown, bfd_object, bfd_archive, bfd_core.)
>>>>
>>>>
>>>> Yes.
>>>>
>>>>>> +bfd_boolean
>>>>>> +bfd_maybe_object_p (bfd *abfd, bfd_boolean plugin_active_p)
>>>>>> +{
>>>>>> +  /* LTO IR object file may look like a bfd_object file or a file
>>>>>> which
>>>>>> +     is not bfd_core nor bfd_archive.  */
>>>>>> +  return (bfd_check_format (abfd, bfd_object)
>>>>>> +       || (plugin_active_p
>>>>>> +           && !bfd_check_format (abfd, bfd_core)
>>>>>> +           && !bfd_check_format (abfd, bfd_archive)));
>>>>>> +}
>>>>>
>>>>>
>>>>> I find this really strange.  If plugins are active then you're
>>>>> willing to accept anything except cores and archives.  To throw out
>>>>> cores and archives you'll be iterating over all compiled-in bfd
>>>>> targets, asking "is this a core file", then asking "is this an
>>>>> archive".  That's quite a bit of processing, and won't exclude your
>>>>> average text file!
>>>>
>>>>
>>>> LTO IR could be stored in the average text file.  The new plug tests
>>>> use this feature.   We can add a new type, bfd_maybe_object.
>>>>
>>>>> I think you need to find a way of answering the question "is this a
>>>>> file accepted by a plugin?" in a more robust way.  One possibility is
>>>>> merging the linker handling of plugins into the bfd plugin support.
>>>>>
>>>>
>>>> I have considered it before.  This approach has many implications.
>>>> If we do this, we need to add bfd_plugin_object and bfd_all_object.
>>>> bfd_all_object includes bfd_object and bfd_plugin_object.  We need
>>>> bfd_plugin_object so that we won't update dummy BFD info from the
>>>> LTO IR input.  Let me take another look.
>>>>
>>>
>>> Here is a draft to make linker plugin_object_p available to BFD:
>>>
>>>
>>> https://sourceware.org/git/?p=binutils-gdb.git;a=patch;h=23903a326cd1cb205902698bb61f9deb1d1bf9a9
>>>
>>> I will submit a proper patch tomorrow.
>>>
>>
>> Hi Lu,
>> After this patch on arm-none-eabi and arm-none-linux-gnueabihf I see
>> following regressions:
>> FAIL: load plugin 2 with source
>> FAIL: load plugin 3 with source
>> FAIL: plugin 2 with source lib
>> FAIL: plugin 3 with source lib
>> FAIL: plugin claimfile replace symbol with source
>> FAIL: plugin claimfile resolve symbol with source
>>
>> when I run test src/binutils-gdb/ld/testsuite/ld-plugin/func.c
>> , I see:
>> /work/fsf-trunk-3/build-arm-none-eabi/install/bin/arm-none-eabi-gcc
>> -B/work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/ld/
>> -I/work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin -O2
>> -specs=rdimon.specs -Wa,-mno-warn-deprecated    -mthumb  -O2 -c
>> /work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/text.c -o
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/text.o
>> /work/fsf-trunk-3/build-arm-none-eabi/install/bin/arm-none-eabi-gcc
>> -B/work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/ld/
>> -I/work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin -O2
>> -specs=rdimon.specs -Wa,-mno-warn-deprecated    -mthumb  -O2 -c
>> /work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/main.c -o
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/main.o
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/ld-new   -o
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/main.x
>> -L/work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin -plugin
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/.libs/libldtestplug2.so.0
>> -plugin-opt registerclaimfile -plugin-opt registerallsymbolsread -plugin-opt
>> registercleanup  -plugin-opt dumpresolutions
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/main.o
>> /work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/func.c
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/text.o --defsym
>> __stack_chk_fail=0 --defsym __gccmain=0 --defsym printf=main --defsym
>> puts=main
>> hook called: all symbols read.
>> Input: /work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/func.c
>> (/work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/func.c)
>> Sym: 'func' Resolution: LDPR_PREVAILING_DEF
>> Sym: '_func' Resolution: LDPR_PREVAILING_DEF_IRONLY
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/ld-new:
>> /work/fsf-trunk-3/src/binutils-gdb/ld/testsuite/ld-plugin/func.c (symbol
>> from plugin)(func): warning: interworking not enabled.
>>   first occurrence:
>> /work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/main.o: Thumb
>> call to ARM
>
> I think those failures are caused by those extra messages.
> I am not familiar with ARM linker.  I can skip those tests
> for ARM.
>

It looks like an ARM linker bug.  ARM linker shouldn't complain
anything on input BFDs with BFD_PLUGIN since it is a dummy
input file.

-- 
H.J.