On Tue, 26 Feb 2019, Jakub Jelinek wrote:
> On Tue, Feb 26, 2019 at 04:08:21PM +0100, Richard Biener wrote:
> > I think we can have multiple .ABNORMAL_DISPATCHERs - at least in theory
> > via inlining, though I see code in the inliner avoiding multiple ones
> > at least for nonlocal goto, not sure if that covers all cases.
>
> Ok.
>
> > > Shall I modify the patch for that?
> >
> > Might it even simplify the patch? If not the only comment on the
> > original patch is that it would be nice to test it on a SJLJ EH
> > target ...
>
> 1 file changed, 29 insertions(+), 16 deletions(-)
> so not really simplify it, but not terrible either.
>
> Here is the incremental (untested) diff of what handles that.
>
> I don't have access to any standard SJLJ EH targets, but will try
> --enable-sjlj-exceptions on x86_64-linux to see how far I get with that.
Indeed not terrible. Maybe Eric can help with testing on a SJLJ
target (though IIRC Ada uses its own EH scheme on such targets?)
Richard.
> --- gcc/tree-cfgcleanup.c.jj 2019-02-26 16:52:33.828719803 +0100
> +++ gcc/tree-cfgcleanup.c 2019-02-26 17:11:07.735576027 +0100
> @@ -731,12 +731,7 @@ cleanup_tree_cfg_bb (basic_block bb)
> normally are effectively unreachable as well. Additionally ignore
> __builtin_setjmp_receiver starting blocks, which have one FORCED_LABEL
> and which are always only reachable through EDGE_ABNORMAL edge. They are
> - handled in cleanup_control_flow_pre.
> - Similarly, return true for EDGE_ABNORMAL edge from any basic block to
> - .ABNORMAL_DISPATCHER basic block if the latter block has no successors.
> - .ABNORMAL_DISPATCHER basic blocks that don't dispatch to anything are
> dead,
> - don't really need any EDGE_ABNORMAL edges to them and can be safely
> - removed. */
> + handled in cleanup_control_flow_pre. */
>
> static bool
> maybe_dead_abnormal_edge_p (edge e)
> @@ -747,16 +742,7 @@ maybe_dead_abnormal_edge_p (edge e)
> gimple_stmt_iterator gsi = gsi_start_nondebug_after_labels_bb (e->src);
> gimple *g = gsi_stmt (gsi);
> if (!g || !gimple_call_internal_p (g, IFN_ABNORMAL_DISPATCHER))
> - {
> - if (EDGE_COUNT (e->dest->succs) == 0)
> - {
> - gsi = gsi_start_nondebug_after_labels_bb (e->dest);
> - g = gsi_stmt (gsi);
> - if (g && gimple_call_internal_p (g, IFN_ABNORMAL_DISPATCHER))
> - return true;
> - }
> - return false;
> - }
> + return false;
>
> tree target = NULL_TREE;
> for (gsi = gsi_start_bb (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
> @@ -846,6 +832,7 @@ cleanup_control_flow_pre ()
> bitmap_clear (visited);
>
> vec<edge, va_gc> *setjmp_vec = NULL;
> + auto_vec<basic_block, 4> abnormal_dispatchers;
>
> stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs));
>
> @@ -877,6 +864,16 @@ cleanup_control_flow_pre ()
> stack.quick_push (ei_start (setjmp_vec));
> }
>
> + if ((ei_edge (ei)->flags
> + & (EDGE_ABNORMAL | EDGE_EH)) == EDGE_ABNORMAL)
> + {
> + gimple_stmt_iterator gsi
> + = gsi_start_nondebug_after_labels_bb (dest);
> + gimple *g = gsi_stmt (gsi);
> + if (g && gimple_call_internal_p (g, IFN_ABNORMAL_DISPATCHER))
> + abnormal_dispatchers.safe_push (dest);
> + }
> +
> if (EDGE_COUNT (dest->succs) > 0)
> stack.quick_push (ei_start (dest->succs));
> }
> @@ -895,6 +892,22 @@ cleanup_control_flow_pre ()
>
> vec_free (setjmp_vec);
>
> + /* If we've marked .ABNORMAL_DISPATCHER basic block(s) as visited
> + above, but haven't marked any of their successors as visited,
> + unmark them now, so that they can be removed as useless. */
> + basic_block dispatcher_bb;
> + unsigned int k;
> + FOR_EACH_VEC_ELT (abnormal_dispatchers, k, dispatcher_bb)
> + {
> + edge e;
> + edge_iterator ei;
> + FOR_EACH_EDGE (e, ei, dispatcher_bb->succs)
> + if (bitmap_bit_p (visited, e->dest->index))
> + break;
> + if (e == NULL)
> + bitmap_clear_bit (visited, dispatcher_bb->index);
> + }
> +
> set_dom_info_availability (CDI_DOMINATORS, saved_state);
>
> /* We are deleting BBs in non-reverse dominator order, make sure
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
