Re: [PR47785] COLLECT_AS_OPTIONS

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

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On Thu, 30 Jan 2020 at 19:10, Richard Biener <richard.guenther@gmail.com> wrote:
>
> On Thu, Jan 30, 2020 at 5:31 AM Prathamesh Kulkarni
> <prathamesh.kulkarni@linaro.org> wrote:
> >
> > On Tue, 28 Jan 2020 at 17:17, Richard Biener <richard.guenther@gmail.com> wrote:
> > >
> > > On Fri, Jan 24, 2020 at 7:04 AM Prathamesh Kulkarni
> > > <prathamesh.kulkarni@linaro.org> wrote:
> > > >
> > > > On Mon, 20 Jan 2020 at 15:44, Richard Biener <richard.guenther@gmail.com> wrote:
> > > > >
> > > > > On Wed, Jan 8, 2020 at 11:20 AM Prathamesh Kulkarni
> > > > > <prathamesh.kulkarni@linaro.org> wrote:
> > > > > >
> > > > > > On Tue, 5 Nov 2019 at 17:38, Richard Biener <richard.guenther@gmail.com> wrote:
> > > > > > >
> > > > > > > On Tue, Nov 5, 2019 at 12:17 AM Kugan Vivekanandarajah
> > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > > Thanks for the review.
> > > > > > > >
> > > > > > > > On Tue, 5 Nov 2019 at 03:57, H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > > > > > >
> > > > > > > > > On Sun, Nov 3, 2019 at 6:45 PM Kugan Vivekanandarajah
> > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > >
> > > > > > > > > > Thanks for the reviews.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > On Sat, 2 Nov 2019 at 02:49, H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > On Thu, Oct 31, 2019 at 6:33 PM Kugan Vivekanandarajah
> > > > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > On Wed, 30 Oct 2019 at 03:11, H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Sun, Oct 27, 2019 at 6:33 PM Kugan Vivekanandarajah
> > > > > > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Hi Richard,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Thanks for the review.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Wed, 23 Oct 2019 at 23:07, Richard Biener <richard.guenther@gmail.com> wrote:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Mon, Oct 21, 2019 at 10:04 AM Kugan Vivekanandarajah
> > > > > > > > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Hi Richard,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Thanks for the pointers.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > On Fri, 11 Oct 2019 at 22:33, Richard Biener <richard.guenther@gmail.com> wrote:
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > On Fri, Oct 11, 2019 at 6:15 AM Kugan Vivekanandarajah
> > > > > > > > > > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Hi Richard,
> > > > > > > > > > > > > > > > > > Thanks for the review.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > On Wed, 2 Oct 2019 at 20:41, Richard Biener <richard.guenther@gmail.com> wrote:
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > On Wed, Oct 2, 2019 at 10:39 AM Kugan Vivekanandarajah
> > > > > > > > > > > > > > > > > > > <kugan.vivekanandarajah@linaro.org> wrote:
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Hi,
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > As mentioned in the PR, attached patch adds COLLECT_AS_OPTIONS for
> > > > > > > > > > > > > > > > > > > > passing assembler options specified with -Wa, to the link-time driver.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > The proposed solution only works for uniform -Wa options across all
> > > > > > > > > > > > > > > > > > > > TUs. As mentioned by Richard Biener, supporting non-uniform -Wa flags
> > > > > > > > > > > > > > > > > > > > would require either adjusting partitioning according to flags or
> > > > > > > > > > > > > > > > > > > > emitting multiple object files  from a single LTRANS CU. We could
> > > > > > > > > > > > > > > > > > > > consider this as a follow up.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Bootstrapped and regression tests on  arm-linux-gcc. Is this OK for trunk?
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > While it works for your simple cases it is unlikely to work in practice since
> > > > > > > > > > > > > > > > > > > your implementation needs the assembler options be present at the link
> > > > > > > > > > > > > > > > > > > command line.  I agree that this might be the way for people to go when
> > > > > > > > > > > > > > > > > > > they face the issue but then it needs to be documented somewhere
> > > > > > > > > > > > > > > > > > > in the manual.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > That is, with COLLECT_AS_OPTION (why singular?  I'd expected
> > > > > > > > > > > > > > > > > > > COLLECT_AS_OPTIONS) available to cc1 we could stream this string
> > > > > > > > > > > > > > > > > > > to lto_options and re-materialize it at link time (and diagnose mismatches
> > > > > > > > > > > > > > > > > > > even if we like).
> > > > > > > > > > > > > > > > > > OK. I will try to implement this. So the idea is if we provide
> > > > > > > > > > > > > > > > > > -Wa,options as part of the lto compile, this should be available
> > > > > > > > > > > > > > > > > > during link time. Like in:
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > arm-linux-gnueabihf-gcc -march=armv7-a -mthumb -O2 -flto
> > > > > > > > > > > > > > > > > > -Wa,-mimplicit-it=always,-mthumb -c test.c
> > > > > > > > > > > > > > > > > > arm-linux-gnueabihf-gcc  -flto  test.o
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > I am not sure where should we stream this. Currently, cl_optimization
> > > > > > > > > > > > > > > > > > has all the optimization flag provided for compiler and it is
> > > > > > > > > > > > > > > > > > autogenerated and all the flags are integer values. Do you have any
> > > > > > > > > > > > > > > > > > preference or example where this should be done.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > In lto_write_options, I'd simply append the contents of COLLECT_AS_OPTIONS
> > > > > > > > > > > > > > > > > (with -Wa, prepended to each of them), then recover them in lto-wrapper
> > > > > > > > > > > > > > > > > for each TU and pass them down to the LTRANS compiles (if they agree
> > > > > > > > > > > > > > > > > for all TUs, otherwise I'd warn and drop them).
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Attached patch streams it and also make sure that the options are the
> > > > > > > > > > > > > > > > same for all the TUs. Maybe it is a bit restrictive.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > What is the best place to document COLLECT_AS_OPTIONS. We don't seem
> > > > > > > > > > > > > > > > to document COLLECT_GCC_OPTIONS anywhere ?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Nowhere, it's an implementation detail then.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Attached patch passes regression and also fixes the original ARM
> > > > > > > > > > > > > > > > kernel build issue with tumb2.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Did you try this with multiple assembler options?  I see you stream
> > > > > > > > > > > > > > > them as -Wa,-mfpu=xyz,-mthumb but then compare the whole
> > > > > > > > > > > > > > > option strings so a mismatch with -Wa,-mthumb,-mfpu=xyz would be
> > > > > > > > > > > > > > > diagnosed.  If there's a spec induced -Wa option do we get to see
> > > > > > > > > > > > > > > that as well?  I can imagine -march=xyz enabling a -Wa option
> > > > > > > > > > > > > > > for example.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > +             *collect_as = XNEWVEC (char, strlen (args_text) + 1);
> > > > > > > > > > > > > > > +             strcpy (*collect_as, args_text);
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > there's strdup.  Btw, I'm not sure why you don't simply leave
> > > > > > > > > > > > > > > the -Wa option in the merged options [individually] and match
> > > > > > > > > > > > > > > them up but go the route of comparing strings and carrying that
> > > > > > > > > > > > > > > along separately.  I think that would be much better.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Is attached patch which does this is OK?
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > Don't you need to also handle -Xassembler? Since -Wa, doesn't work with comma in
> > > > > > > > > > > > > assembler options, like -mfoo=foo1,foo2, one needs to use
> > > > > > > > > > > > >
> > > > > > > > > > > > > -Xassembler  -mfoo=foo1,foo2
> > > > > > > > > > > > >
> > > > > > > > > > > > > to pass  -mfoo=foo1,foo2 to assembler.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > gcc -flto -O2 -Wa,-mcpu=zzz1 -mcpu=xxx1 -c foo.c
> > > > > > > > > > > > gcc -flto -O2 -Wa,-mcpu=zzz2 -mcpu=xxx2 -c bar.c
> > > > > > > > > > > >
> > > > > > > > > > > > What should be the option we should provide for the final
> > > > > > > > > > > > gcc -flto foo.o bar.o -o out
> > > > > > > > > > > >
> > > > > > > > > > > > I think our ultimate aim is to handle this in LTO partitioning. That
> > > > > > > > > > > > is, we should create partitioning such that each partition has the
> > > > > > > > > > > > same -Wa options. This could also handle -Xassembler  -mfoo=foo1,foo2
> > > > > > > > > > > > which H.J. Lu wanted. We need to modify the heuristics and do some
> > > > > > > > > > > > performance testing.
> > > > > > > > > > > >
> > > > > > > > > > > > In the meantime we could push a simpler solution which is to accept
> > > > > > > > > > > > -Wa option if they are identical. This would fix at least some of the
> > > > > > > > > > > > reported cases. Trying to work out what is compatible options, even if
> > > > > > > > > > > > we ask the back-end to do this, is not a straightforward strategy and
> > > > > > > > > > > > can be a maintenance nightmare. Unless we can query GNU AS somehow. If
> > > > > > > > > > > > I am missing something please let me know.
> > > > > > > > > > >
> > > > > > > > > > > +/* Store switches specified for as with -Wa in COLLECT_AS_OPTIONS
> > > > > > > > > > > +   and place that in the environment.  */
> > > > > > > > > > > +static void
> > > > > > > > > > > +putenv_COLLECT_AS_OPTIONS (vec<char_p> vec)
> > > > > > > > > > > +{
> > > > > > > > > > > +  unsigned ix;
> > > > > > > > > > > +  char *opt;
> > > > > > > > > > > +  int len = vec.length ();
> > > > > > > > > > > +
> > > > > > > > > > > +  if (!len)
> > > > > > > > > > > +     return;
> > > > > > > > > > > +
> > > > > > > > > > > +  obstack_init (&collect_obstack);
> > > > > > > > > > > +  obstack_grow (&collect_obstack, "COLLECT_AS_OPTIONS=",
> > > > > > > > > > > + sizeof ("COLLECT_AS_OPTIONS=") - 1);
> > > > > > > > > > > +  obstack_grow (&collect_obstack, "-Wa,", strlen ("-Wa,"));
> > > > > > > > > > > +
> > > > > > > > > > > +  FOR_EACH_VEC_ELT (vec, ix, opt)
> > > > > > > > > > > +  {
> > > > > > > > > > > +      obstack_grow (&collect_obstack, opt, strlen (opt));
> > > > > > > > > > > +      --len;
> > > > > > > > > > > +      if (len)
> > > > > > > > > > > + obstack_grow (&collect_obstack, ",", strlen (","));
> > > > > > > > > > > +  }
> > > > > > > > > > > +
> > > > > > > > > > > +  xputenv (XOBFINISH (&collect_obstack, char *));
> > > > > > > > > > >
> > > > > > > > > > > This missed the null terminator.
> > > > > > > > > >
> > > > > > > > > > Attached patch addresses the review comments I got so far.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > +      if (len)
> > > > > > > > > + obstack_grow (&collect_obstack, ",", strlen (","));
> > > > > > > > >
> > > > > > > > > Why not sizeof (",")  - 1?
> > > > > > > > I guess I copied and pasted it from elsewhere else. We seem to use
> > > > > > > > both. I have changed it now.
> > > > > > > >
> > > > > > > > >
> > > > > > > > > diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
> > > > > > > > > index 9a7bbd0c022..148c52906d1 100644
> > > > > > > > > --- a/gcc/lto-wrapper.c
> > > > > > > > > +++ b/gcc/lto-wrapper.c
> > > > > > > > > @@ -253,6 +253,11 @@ merge_and_complain (struct cl_decoded_option
> > > > > > > > > **decoded_options,
> > > > > > > > >     break;
> > > > > > > > >
> > > > > > > > >   default:
> > > > > > > > > +   if (foption->opt_index == OPT_Wa_)
> > > > > > > > > +     {
> > > > > > > > > +       append_option (decoded_options, decoded_options_count, foption);
> > > > > > > > > +       break;
> > > > > > > > > +     }
> > > > > > > > >     if (!(cl_options[foption->opt_index].flags & CL_TARGET))
> > > > > > > > >       break;
> > > > > > > > >
> > > > > > > > > Why not use "case OPT_Wa_:" here?
> > > > > > > > Done.
> > > > > > > > >
> > > > > > > > > For
> > > > > > > > >
> > > > > > > > > +  static const char *collect_as;
> > > > > > > > > +  for (unsigned int j = 1; j < count; ++j)
> > > > > > > > > +    {
> > > > > > > > > +      struct cl_decoded_option *option = &opts[j];
> > > > > > > > > +      if (j == 1)
> > > > > > > > > + collect_as = NULL;
> > > > > > > > >
> > > > > > > > > why not simply
> > > > > > > > >
> > > > > > > > >  const char *collect_as = NULL?
> > > > > > > >
> > > > > > > > I wanted to make sure that if we call this from multiple places, it
> > > > > > > > still works. I guess it is still going to be the same. I have changed
> > > > > > > > it now as you have suggested.
> > > > > > > >
> > > > > > > > Is this revised patch OK? I will do a fresh bootstrap and regression
> > > > > > > > testing before committing.
> > > > > > >
> > > > > > > In putenv_COLLECT_AS_OPTIONS you'll happily make
> > > > > > > -Wa,-march=foo,bar out of -Xassembler -march=foo,bar which
> > > > > > > will later cause us to fail to assemble with unknown assembler options.
> > > > > > > May I suggest to instead always use -Xassembler syntax in
> > > > > > > COLLECT_AS_OPTIONS?  Please also make sure to quote
> > > > > > > options the same way set_collect_gcc_options does
> > > > > > > (with '', separated by spaces).  Then the lto-opts.c part
> > > > > > > becomes "easier" as you can simply copy the string to the
> > > > > > > obstack without wrapping it again with append_to_collect_gcc_options.
> > > > > > >
> > > > > > > In lto-wrapper you then only have to handle OPT_Xassembler.
> > > > > > >
> > > > > > > You simply end up appending _all_ assembler options in order
> > > > > > > of TUs processed by lto-wrapper to the final command (N times
> > > > > > > even if exactly the same).  I'm also not sure how you can check
> > > > > > > for positional equivalence (or if we even should).  With -Wa
> > > > > > > we could compare the full option string but with separate -Xassembler
> > > > > > > we're having a more difficult task here.  OTOH your patch doesn't
> > > > > > > do any comparing here.
> > > > > > >
> > > > > > > Your append_compiler_wa_options should be merged into
> > > > > > > append_compiler_options, passing -Xassembler through.
> > > > > > Hi Richard,
> > > > > > Since Kugan has left Linaro (and GCC), I'd like to take up this task.
> > > > > > I have modified his patch to always pass assembler options via -Xassembler.
> > > > > > Does it look OK ?
> > > > > >
> > > > > > I am not sure how we should proceed with error-checking for Xassembler ?
> > > > > > In lto-wrapper, I suppose, we can append all Xassembler options for a
> > > > > > TU into a single string, and then
> > > > > > do strcmp similar to previous patch(es) doing strcmp for -Wa options
> > > > > > string, although not sure if that's a good idea.
> > > > >
> > > > > I think there are multiple issues with the main one being how to
> > > > > actually interpret -Xassembler in the LTO context.
> > > > >
> > > > > First let me point out some bits in the COLLECT_AS_OPTIONS parts.
> > > > >
> > > > > +  FOR_EACH_VEC_ELT (vec, ix, opt)
> > > > > +    {
> > > > > +      obstack_grow (&collect_obstack, "\'-Xassembler\' ",
> > > > > +                   strlen ("\'-Xassembler\' "));
> > > > >
> > > > > quoting of -Xassembler is not necessary.
> > > > >
> > > > > +      obstack_1grow (&collect_obstack, '\'');
> > > > > +      obstack_grow (&collect_obstack, opt, strlen (opt));
> > > > > +      obstack_grow (&collect_obstack, "\' ", 2);
> > > > >
> > > > > This adds a stray space after the last option.
> > > > >
> > > > > Note that COLLECT_AS_OPTIONS gives the impression of listing
> > > > > assembler options but the above adds GCC driver options - assembler
> > > > > options prepended by -Xassembler.  IMHO we should drop the
> > > > > -Xassembler emission from the above loop and simply emit the plain
> > > > > assembler options.  That requires adjustments to lto_write_options,
> > > > > adding those -Xassembler options.
> > > > >
> > > > > +  char *asm_opts = XOBFINISH (&collect_obstack, char *);
> > > > > +  xputenv (XOBFINISH (&collect_obstack, char *));
> > > > > +  xputenv (asm_opts);
> > > > >
> > > > > That outputs the ENV twice.
> > > > >
> > > > > Note that we record things like --version or --help into
> > > > > assembler_options but I'm not sure the merging of assembler
> > > > > options should be affected on whether one TU was compiled with -v
> > > > > or not.  This might mean simply pruning those in lto-options.c
> > > > > (not listing them in COLLECT_AS_OPTIONS wouldn't tell the truth).
> > > > >
> > > > > @@ -252,6 +252,10 @@ merge_and_complain (struct cl_decoded_option
> > > > > **decoded_options,
> > > > >         case OPT_SPECIAL_input_file:
> > > > >           break;
> > > > >
> > > > > +       case OPT_Xassembler:
> > > > > +         append_option (decoded_options, decoded_options_count, foption);
> > > > > +         break;
> > > > > +
> > > > >
> > > > > this adds the same option over-and-over again, possibly becoming unwieldly.
> > > > > Most of the function also assumes that option position isn't important
> > > > > which might or might not be true.  So I think a better course of action
> > > > > would be to not handle Xassembler in the above loop but do a separate
> > > > > one checking 1:1 equality of passed assembler options like
> > > > >
> > > > >   /* Verify -Xassembler options are the same on all TUs.  */
> > > > >   j = 0;
> > > > >   i = 0;
> > > > >   unsigned Xascount = 0;
> > > > >   while (j < *decoded_options_count && i < fdeconded_options_count)
> > > > >     {
> > > > >        while (fdecoded_options[i].opt_index != OPT_Xassembler) ++i;
> > > > >        same for *decoded_options
> > > > >        if (stray Xassembler on one side)
> > > > >          fatal_error (...);
> > > > >        if (strcmp (...) != 0)
> > > > >          fatal_error (...);
> > > > >     }
> > > > >
> > > > > which means we use the -Xassembler options from the first TU and
> > > > > above only verify those match those from all other TUs.
> > > > Hi Richard,
> > > > Thanks for the suggestions, I tried to address them in the attached patch.
> > > > It now gives errors on following cases during link command:
> > > >
> > > > 1]
> > > > gcc -O -flto -c -Xassembler -mfoo f1.c
> > > > gcc -O -flto -c f2.c
> > > > gcc -O -flto f1.o f2.o
> > > >
> > > > 2]
> > > > gcc -O -flto -c -Xassembler -mfoo f1.c
> > > > gcc -O -flto -c -Xassembler -mbar f2.c
> > > > gcc -O -flto f1.o f2.o
> > > >
> > > > 3]
> > > > gcc -O -flto -c -Xassembler -mfoo -Xassembler -mbar f1.c
> > > > gcc -O -flto -c -Xassembler -mbar -Xassembler -mfoo f2.c
> > > > gcc -O -flto f1.o f2.o
> > > >
> > > > 4]
> > > > gcc -O -flto -c f1.c
> > > > gcc -O -flto -Xassembler -mfoo f1.c
> > > > gcc -O -flto f1.o f2.o
> > > >
> > > > 5]
> > > > gcc -O -flto -Xassembler -mfoo f1.c
> > > > gcc -O -flto -Xassembler -mfoo f2.c
> > > > gcc -O -flto -Xassembler -mbar f1.o f2.o
> > > >
> > > > The following correct case works:
> > > > gcc -O -flto -Xassembler -mfoo f1.c
> > > > gcc -O -flto -Xassembler -mfoo f2.c
> > > > gcc -O -flto f1.o f2.o
> > >
> > > I think 5] should work as well and behave as -mfoo -mbar at assembler time.
> > > Add
> > >
> > > 6]
> > > gcc -O -flto f1.c
> > > gcc -O -flto f2.c
> > > gcc -O -flto -Xassembler -mfoo f1.o f2.o
> > >
> > > which should work as well (I think even this use doesn't work right now?)
> > >
> > > > Could you please suggest how to add the above cases in dejaGNU format ?
> > > > I am not sure how to write multiple files test with dejaGNU.
> > >
> > > look at multi-file testcases in gcc.dg/lto/, use testcase_0.c testcase_1.c,
> > > you can use dg-additional-options to pass -Xassembler (but eventually
> > > that doesn't work on the first TU), also there's some additional option
> > > for the link step directive (just look into the existing tests).
> > >
> > > > Also, do you think it's better if we append xassembler options to
> > > > COLLECT_GCC itself rather
> > > > than maintaining COLLECT_AS_OPTIONS with "Xassembler" prepended ?
> > > > Because in both lto_write_options,
> > > > and run_gcc, I am reconstructing "-Xassembler" <opt> for each opt in
> > > > COLLECT_AS_OPTIONS.
> > > >
> > > > I am not quite sure how Xassembler options were added to
> > > > fdecoded_options because I am not appending them
> > > > explicitly. IIUC, find_and_merge_options will add -Xassembler to
> > > > fdecoded_options when it's NULL ?
> > > >     if (!fdecoded_options)
> > > >        {
> > > >          fdecoded_options = f2decoded_options;
> > > >          fdecoded_options_count = f2decoded_options_count;
> > > >        }
> > > > since merge_and_complain does not handle OPT_Xassembler.
> > >
> > > Yes.
> > >
> > > Comments on the patch.  First avoid <algorithm>, just use MIN/MAX
> > > if really needed.  I'd elide xassembler_opts[_count].  For 6] you want
> > > to unconditionally append the options.
> > >
> > > In find_and_merge_options I'd have avoided xassembler_opts[_count]
> > > by simply adding another nested loop over both decoded options
> > > requiring matching up OPT_Xassembler 1:1.
> > Hi Richard,
> > Thanks for the suggestions. The current patch removes
> > xasembler_opts[_count] and uses nested loop
> > for comparison.
> > In find_and_merge_options, I used curr_xopts[_count] to hold all the
> > options passed to current TU.
> > IIUC, f2decoded_options will be overwritten each time in the loop
> > while fetching strings from .opts section, and will
> > not contain all options passed to current TU. And I dropped validating
> > for cmdline opts which passes 5] and 6].
> > Does that look OK ?
>
> Huh, it looks odd.  Why didn't you simply add the loop to merge_and_complain?
> That way you verify each TUs arguments against the first TUs.
My concern was that it might perhaps not work if .opts section in LTO
object file
contained multiple strings ? So fdecoded_options in merge_and_complain
may not hold all options passed to TU. Currently that isn't an issue,
since the section
contains only one string (since we append '\0' once at end of
lto_write_options).
I was wondering will this break if that changed and .opts contains
multiple strings instead ?
In attached patch, I placed the loop in merge_and_complain.
Does that look OK ?
>
> >
> > How should we handle conflicting argument to options passed on cmdline ?
> > For eg:
> > gcc -O -flto -Xassembler -mfoo=arg1 f1.c -o f1.o
> > gcc -O -flto -Xassembler -mfoo=arg1 f2.c -o f2.o
> > gcc -O -flto -Xassembler -mfoo=arg2 f1.o f2.o
> > Should we complain that arg1, arg2 differ or let arg2 take precedence
> > over arg1 for -mfoo ?
> > (It seems currently, the patch does latter).
>
> I think appending the linker -Xassembler makes most sense, appropriately
> diagnosing is difficult here and repeating compile-time assembler options
> will be common.
OK, thanks for the clarification.

Thanks,
Prathamesh
>
> Richard.
>
> >
> > I am still looking into the tests part, will address that in next patch.
> >
> > Thanks,
> > Prathamesh
> >
> >
> >
> >
> >
> >
> >
> > >
> > > Richard.
> > >
> > > >
> > > > Thanks,
> > > > Prathamesh
> > > > >
> > > > > Richard.
> > > > >
> > > > > > Thanks,
> > > > > > Prathamesh
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Richard.
> > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Kugan
> > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > H.J.

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