Patchwork Fix PR 48374

I'd like to ping Andrey's patch (quoted below).

Additionally, the following patch is needed to fix a different instance where
sel-sched does not expect quirky regions in the vicinity of
__builtin_unreachable.

Both patches were bootstrapped and regtested on x86_64-linux, OK for trunk?

2011-10-25  Alexander Monakov  <amonakov@ispras.ru>

	* sel-sched-ir.c (bb_has_removable_jump_to_p): Do not allow to make
	edges leading to the exit block fallthrough.



On Mon, 19 Sep 2011, Andrey Belevantsev wrote:

> Hello,
> 
> The problem here is the case where the selective scheduler doesn't expect
> having a block with zero successors.  The patch is near obvious which is why
> it was forgotten for nearly half a year, but still it applies cleanly and
> fixes the testcase, full testing is in progress.  OK for trunk and active
> branches if it succeeds?
> 
> Yours,
> Andrey
> 
> 2011-09-19  Andrey Belevantsev  <abel@ispras.ru>
> 
> 	gcc/
> 	PR rtl-optimization/48374
> 
> 	* sel-sched-ir.h (get_all_loop_exits): Stop iterating when the current
> block has zero successors.
> 
> 	gcc/testsuite
> 
> 	PR rtl-optimization/48374
> 	* gcc.dg/pr48374.c: New test.
> 
> diff --git a/gcc/sel-sched-ir.h b/gcc/sel-sched-ir.h
> index 5516da9..13af1b5 100644
> --- a/gcc/sel-sched-ir.h
> +++ b/gcc/sel-sched-ir.h
> @@ -1119,7 +1119,8 @@ get_all_loop_exits (basic_block bb)
>    /* If bb is empty, and we're skipping to loop exits, then
>       consider bb as a possible gate to the inner loop now.  */
>    while (sel_bb_empty_or_nop_p (bb)
> -        && in_current_region_p (bb))
> +        && in_current_region_p (bb)
> +        && EDGE_COUNT (bb->succs) > 0)
>      {
>        bb = single_succ (bb);
> 
> diff --git a/gcc/testsuite/gcc.dg/pr48374.c b/gcc/testsuite/gcc.dg/pr48374.c
> new file mode 100644
> index 0000000..5486cec
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr48374.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile { target powerpc*-*-* ia64-*-* x86_64-*-* } } */
> +/* { dg-options "-O -fschedule-insns2 -fsel-sched-pipelining
> -fsel-sched-pipelining-outer-loops -fselective-scheduling2 --param
> max-sched-extend-regions-iters=2"  } */
> +
> +void foo (int y)
> +{
> +  switch (y)
> +    {
> +    case 3:
> +    case 5:
> +    case 7:
> +    case 11:
> +      break;
> +    default:
> +      __builtin_unreachable ();
> +    }
> +}
> 
>