Enable crossjumping with bb-reorering

Hello,
Caroline disabled crossjumping with bb-reordering in initial patch implementing
this pass.  According to discussion with Rth it was only becuase she was unsure
how to prevent crossjumping to mix up crossing and non-crossing jumps. THis is
easy to do - we only need to avoid merging code across section as done by this
patch.

Bootstrapped/regtested x86_64-linux, will commit it tomorrow.

	* cfgcleanup.c (flow_find_cross_jump): Do not crossjump across
	hot/cold regions.
	(try_crossjump_to_edge): Do not punt on partitioned functions.

Hi Honza,

Just a couple of typo nits.

Cheers,
Kyrill

On 21/07/17 00:38, Jan Hubicka wrote:
> Hello,
> Caroline disabled crossjumping with bb-reordering in initial patch implementing
> this pass.  According to discussion with Rth it was only becuase she was unsure
> how to prevent crossjumping to mix up crossing and non-crossing jumps. THis is
> easy to do - we only need to avoid merging code across section as done by this
> patch.
>
> Bootstrapped/regtested x86_64-linux, will commit it tomorrow.
>
> 	* cfgcleanup.c (flow_find_cross_jump): Do not crossjump across
> 	hot/cold regions.
> 	(try_crossjump_to_edge): Do not punt on partitioned functions.
> Index: cfgcleanup.c
> ===================================================================
> --- cfgcleanup.c	(revision 250378)
> +++ cfgcleanup.c	(working copy)
> @@ -1435,6 +1435,13 @@ flow_find_cross_jump (basic_block bb1, b
>         if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
>   	break;
>   
> +      /* Do not turn corssing edge to non-crossing or vice versa after

"crossing"

> +	 reload. */
> +      if (BB_PARTITION (BLOCK_FOR_INSN (i1))
> +	  != BB_PARTITION (BLOCK_FOR_INSN (i2))
> +	  && reload_completed)
> +	break;
> +
>         dir = merge_dir (dir, old_insns_match_p (0, i1, i2));
>         if (dir == dir_none || (!dir_p && dir != dir_both))
>   	break;
> @@ -1958,18 +1965,6 @@ try_crossjump_to_edge (int mode, edge e1
>   
>     newpos1 = newpos2 = NULL;
>   
> -  /* If we have partitioned hot/cold basic blocks, it is a bad idea
> -     to try this optimization.
> -
> -     Basic block partitioning may result in some jumps that appear to
> -     be optimizable (or blocks that appear to be mergeable), but which really
> -     must be left untouched (they are required to make it safely across
> -     partition boundaries).  See the comments at the top of
> -     bb-reorder.c:partition_hot_cold_basic_blocks for complete details.  */
> -
> -  if (crtl->has_bb_partition && reload_completed)
> -    return false;
> -
>     /* Search backward through forwarder blocks.  We don't need to worry
>        about multiple entry or chained forwarders, as they will be optimized
>        away.  We do this to look past the unconditional jump following a
> @@ -2003,6 +1998,11 @@ try_crossjump_to_edge (int mode, edge e1
>     if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0)
>       return false;
>   
> +  /* Do not turn corssing edge to non-crossing or vice versa after reload.  */

Likewise.

> +  if (BB_PARTITION (src1) != BB_PARTITION (src2)
> +      && reload_completed)
> +    return false;
> +
>     /* Look for the common insn sequence, part the first ...  */
>     if (!outgoing_edges_match (mode, src1, src2))
>       return false;
> @@ -2024,12 +2024,10 @@ try_crossjump_to_edge (int mode, edge e1
>   
>     if (dir == dir_backward)
>       {
> -#define SWAP(T, X, Y) do { T tmp = (X); (X) = (Y); (Y) = tmp; } while (0)
> -      SWAP (basic_block, osrc1, osrc2);
> -      SWAP (basic_block, src1, src2);
> -      SWAP (edge, e1, e2);
> -      SWAP (rtx_insn *, newpos1, newpos2);
> -#undef SWAP
> +      std::swap (osrc1, osrc2);
> +      std::swap (src1, src2);
> +      std::swap (e1, e2);
> +      std::swap (newpos1, newpos2);
>       }
>   
>     /* Don't proceed with the crossjump unless we found a sufficient number