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

[Niclas Adlertz]

CTW and JPRT doesn't trigger this (that's why it was pushed unnoticed).
However, I have tested 'java/lang/Character/CheckScript.java' with this fix and it now works.

(java/lang/Character/CheckScript.java was a failing test in nightlies)

Kind Regards,
Niclas Adlertz

On 2013-10-22 05:27, Christian Thalinger wrote:
> 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
>>          }
>