Hi Claes, do you have evaluated the improvement (1) in separation of the others ?
(2) or (3) are clearly improvement but (1) is a trade of because you are adding a second lookup into another table and make prepender() less likely to be inlined. Rémi ----- Mail original ----- > De: "Claes Redestad" <claes.redes...@oracle.com> > À: "core-libs-dev" <core-libs-dev@openjdk.java.net> > Envoyé: Lundi 25 Mai 2020 22:23:23 > Objet: RFR: 8245756: Reduce bootstrap cost of StringConcatFactory prependers > Hi, > > let's improve the StringConcatFactory a bit! > > - prependers where both prefix and suffix is null are common in typical > expressions; caching these specifically is profitable > > - current prepender argument ordering is unfortunate: String prefix, > <arg>, String suffix. This means we have to do two back-to-back > insertArguments rather than one if they were grouped together > > - add a bridge to the String mix function in StringConcatHelper to avoid > method handle invokes in the bootstrap path. > > Webrev: http://cr.openjdk.java.net/~redestad/8245756/open.00/ > Bug: https://bugs.openjdk.java.net/browse/JDK-8245756 > > All together I see a substantial improvement on a number of > concatenation bootstrap tests. On one stress test[1] I get these numbers > before: > > 4,257,229,918 instructions # 1.10 insn per cycle ( +- 0.84% ) > 847,230,764 branches # 504.826 M/sec ( +- 0.87% ) > 34,600,787 branch-misses # 4.08% of all branches ( +- 0.91% ) > 0.319545331 seconds time elapsed ( +- 1.18% ) > > And after: > > 3,692,867,129 instructions # 1.10 insn per cycle ( +- 0.73% ) > 734,054,515 branches # 498.753 M/sec ( +- 0.74% ) > 30,699,692 branch-misses # 4.18% of all branches ( +- 0.75% ) > 0.295842958 seconds time elapsed ( +- 1.10% ) > > So ~13% reduction on this test. > > Testing: tier1+2 > > Thanks! > > /Claes > > [1] > http://cr.openjdk.java.net/~redestad/scratch/erase_scf_types.00/ObjStringCombos.java
