C++: IR: faster definitionReachesRank

[jbj]

On Wireshark with 6GB RAM, I've observed definitionReachesRank to be the slowest predicate in the IR. It seems that the implementation was slow because the optimizer failed to eliminate the common reachesRank - 1 subexpression. This led to context being pushed into the not, which got implemented as MATERIALIZE. That wouldn't normally be a disaster, but this is one of the largest predicates in the IR SSA construction, and iteration 2 was very slow.

Before:

(1505s) Starting to evaluate predicate SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta/4[1]@93f592 (iteration 1)
(1535s) Tuple counts for SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta:
130670697 ~0%     {4} r1 = SCAN project#SSAConstruction::DefUse::hasDefinitionAtRank#fffff AS I OUTPUT I.<0>, I.<1>, I.<2>, (I.<2> + 1)
130670697 ~6%     {5} r2 = JOIN r1 WITH SSAConstruction::DefUse::exitRank#fff AS R ON FIRST 2 OUTPUT r1.<0>, r1.<1>, r1.<2>, r1.<3>, R.<2>
130670697 ~6%     {5} r3 = SELECT r2 ON r2.<3> <= r2.<4>
130670697 ~0%     {4} r4 = SCAN r3 OUTPUT r3.<0>, r3.<1>, r3.<2>, r3.<3>
                  return r4
(1535s) 			 - SSAConstruction::DefUse::definitionReachesRank#ffff_delta has 130670697 rows (order for disjuncts: delta=<standard>).

(1535s) Starting to evaluate predicate SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta/4[2]@866c14 (iteration 2)
(1626s) Tuple counts for SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta:
261341394 ~107%     {4} r1 = JOIN SSAConstruction::DefUse::definitionReachesRank#ffff#prev_delta AS L WITH SSAConstruction::DefUse::definitionReachesRank#ffff#join_rhs AS R ON FIRST 3 OUTPUT R.<0>, R.<1>, R.<2>, (1 + L.<3>)
261341394 ~107%     {4} r2 = r1 AND NOT SSAConstruction::DefUse::definitionReachesRank#ffff#prev AS R(r1.<0>, r1.<1>, r1.<2>, r1.<3>)
130670697 ~0%       {5} r3 = SCAN r2 OUTPUT r2.<0>, r2.<1>, (r2.<3> - 1), r2.<2>, r2.<3>
106034590 ~1%       {4} r4 = JOIN r3 WITH project#SSAConstruction::DefUse::hasDefinitionAtRank#fffff AS R ON FIRST 3 OUTPUT r3.<0>, r3.<1>, r3.<3>, r3.<4>
106034590           {4} r5 = MATERIALIZE r4 AS antijoin_rhs
24636107  ~3%       {4} r6 = r2 AND NOT r5(r2.<0>, r2.<1>, r2.<2>, r2.<3>)
24636107  ~0%       {5} r7 = JOIN r6 WITH SSAConstruction::DefUse::exitRank#fff AS R ON FIRST 2 OUTPUT r6.<0>, r6.<1>, r6.<2>, r6.<3>, R.<2>
2749441   ~0%       {5} r8 = SELECT r7 ON r7.<3> <= r7.<4>
2749441   ~4%       {4} r9 = SCAN r8 OUTPUT r8.<0>, r8.<1>, r8.<2>, r8.<3>
                    return r9
(1626s) 			 - SSAConstruction::DefUse::definitionReachesRank#ffff_delta has 2749441 rows (order for disjuncts: delta=<standard>).

After:

(12s) Tuple counts for SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta:
130670697 ~0%     {4} r1 = SCAN project#SSAConstruction::DefUse::hasDefinitionAtRank#fffff AS I OUTPUT I.<0>, I.<1>, I.<2>, (I.<2> + 1)
                  return r1
(12s) 			 - SSAConstruction::DefUse::definitionReachesRank#ffff_delta has 130670697 rows (order for disjuncts: delta=<standard>).
(12s) Starting to evaluate predicate SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta/4[2]@fff64c (iteration 2)
(34s) Tuple counts for SSAConstruction::DefUse::definitionReachesRank#ffff#cur_delta:
108784031 ~0%     {4} r1 = SSAConstruction::DefUse::definitionReachesRank#ffff#prev_delta AS L AND NOT SSAConstruction::DefUse::exitRank#fff AS R(L.<0>, L.<1>, L.<3>)
2749441   ~5%     {4} r2 = r1 AND NOT project#SSAConstruction::DefUse::hasDefinitionAtRank#fffff AS R(r1.<0>, r1.<1>, r1.<3>)
2749441   ~4%     {4} r3 = SCAN r2 OUTPUT r2.<0>, r2.<1>, r2.<2>, (r2.<3> + 1)
2749441   ~4%     {4} r4 = r3 AND NOT SSAConstruction::DefUse::definitionReachesRank#ffff#prev AS R(r3.<0>, r3.<1>, r3.<2>, r3.<3>)
                  return r4
(34s) 			 - SSAConstruction::DefUse::definitionReachesRank#ffff_delta has 2749441 rows (order for disjuncts: delta=<standard>).

Note that the row counts are exactly the same before and after.

[rdmarsh2]

LGTM