RFR(XS) 8026939: assert(Reachblock != NULL) failed: Reachblock must be non-NULL

[Christian Thalinger]

What testing did you do?

On Oct 21, 2013, at 7:08 AM, Niclas Adlertz <niclas.adlertz at oracle.com> wrote:

> Hi all,
> 
> Now that more nodes can be rematerialized due to fix JDK-8022783, a rematerialized node can have a spilled live range as input even when rematerializing input for phi nodes (in the Phi Node Splitting pass).
> Prior to the JDK-8013830 and JDK-8005956 fixes, the Reachblock pointer could be wrong (hence the warning in JDK-8013830). Now, we pass in the correct block-reaches, i.e. the reaches for the 'pred' block.
> 
> Kind Regards,
> Niclas Adlertz
> 
> JBS:    https://bugs.openjdk.java.net/browse/JDK-8026939
> WEBREV: cr.openjdk.net is down so I'm pasting the diff here:
> 
> diff -r 52575a17a36c src/share/vm/opto/reg_split.cpp
> --- a/src/share/vm/opto/reg_split.cpp	Mon Oct 21 09:21:41 2013 +0400
> +++ b/src/share/vm/opto/reg_split.cpp	Mon Oct 21 15:34:42 2013 +0200
> @@ -365,7 +365,6 @@
>       }
>        if (lidx < _lrg_map.max_lrg_id() && lrgs(lidx).reg() >= LRG::SPILL_REG) {
> -        assert(Reachblock != NULL, "Reachblock must be non-NULL");
>         Node *rdef = Reachblock[lrg2reach[lidx]];
>         if (rdef) {
>           spill->set_req(i, rdef);
> @@ -476,7 +475,6 @@
>    uint                 bidx, pidx, slidx, insidx, inpidx, twoidx;
>   uint                 non_phi = 1, spill_cnt = 0;
> -  Node               **Reachblock;
>   Node                *n1, *n2, *n3;
>   Node_List           *defs,*phis;
>   bool                *UPblock;
> @@ -559,7 +557,7 @@
>      b  = _cfg.get_block(bidx);
>     // Reaches & UP arrays for this block
> -    Reachblock = Reaches[b->_pre_order];
> +    Node** Reachblock = Reaches[b->_pre_order];
>     UPblock    = UP[b->_pre_order];
>     // Reset counter of start of non-Phi nodes in block
>     non_phi = 1;
> @@ -1315,6 +1313,7 @@
>       pidx = pred->_pre_order;
>       // Grab reaching def
>       Node *def = Reaches[pidx][slidx];
> +      Node** Reachblock = Reaches[pidx];
>       assert( def, "must have reaching def" );
>       // If input up/down sense and reg-pressure DISagree
>       if (def->rematerialize()) {
> @@ -1327,8 +1326,7 @@
>                _lrg_map.find(pred->get_node(insert - 1)) >= lrgs_before_phi_split) {
>           insert--;
>         }
> -        // since the def cannot contain any live range input, we can pass in NULL as Reachlock parameter
> -        def = split_Rematerialize(def, pred, insert, maxlrg, splits, slidx, lrg2reach, NULL, false);
> +        def = split_Rematerialize(def, pred, insert, maxlrg, splits, slidx, lrg2reach, Reachblock, false);
>         if (!def) {
>           return 0;    // Bail out
>         }