[PR47785] COLLECT_AS_OPTIONS

[Kugan Vivekanandarajah]

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.

Thanks,
Kugan



>
> Richard.
>
> > Thanks,
> > Kugan
> >
> >
> > gcc/ChangeLog:
> >
> > 2019-10-02  kugan.vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >
> > PR lto/78353
> > * gcc.c (putenv_COLLECT_AS_OPTION): New to set COLLECT_AS_OPTION in env.
> > (driver::main): Call putenv_COLLECT_AS_OPTION.
> > * lto-wrapper.c (run_gcc): use COLLECT_AS_OPTION from env.
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2019-10-02  kugan.vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >
> > PR lto/78353
> > * gcc.target/arm/pr78353-1.c: New test.
> > * gcc.target/arm/pr78353-2.c: New test.