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

[Alex Velenko <Alex dot Velenko at arm dot com>]

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
/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
/work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/ld-new: warning: 
cannot find entry symbol _start; defaulting to 0000000000008000
/work/fsf-trunk-3/build-arm-none-eabi/obj/binutils/ld/tmpdir/main.o: In 
function `main':
main.c:(.text.startup+0xa): undefined reference to `func'
hook called: cleanup.

Kind regards,
Alex