Re: Nested declare target support

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Nov 20, 2020 at 04:41:15PM +0000, Kwok Cheung Yeung wrote:
> Hello
> 
> > New OpenMP 5.0 features that won't be available in GCC 9, are planned for GCC 10
> > or later versions as time permits:
> > 
> ...
> > - nested declare target support
> 
> You said in an email two years ago that nested declare target was not
> supported yet. I do not see any patches that claim to implement this since
> then, but when I ran a quick test with a trunk build:
> 
> #pragma omp declare target
>   #pragma omp declare target
>     int foo() { return 1; }
>   #pragma omp end declare target
>   int bar() { return 2; }
> #pragma omp end declare target

> It looks like this was written to handle nesting to begin with (since at
> least 2013) by making current_omp_declare_target_attribute (which
> effectively tracks the nesting level) an integer. Is there anything that is
> currently missing for nested declare target support?

We used to reject omp declare target with clauses in between declare target
without clauses, but that restriction has been lifted, so I don't know what
is missing, perhaps just add testcases that aren't covered in the testsuite
already.  I'm a little bit worried about the interaction between declare
target with nohost vs. normal one etc.
But to answer the question, I don't remember anymore why it was on the
unfinished list.

	Jakub