----- Mail original ----- > De: "Claes Redestad" <claes.redes...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr> > Cc: "core-libs-dev" <core-libs-dev@openjdk.java.net> > Envoyé: Lundi 25 Mai 2020 23:13:27 > Objet: Re: RFR: 8245756: Reduce bootstrap cost of StringConcatFactory > prependers
> Hi Rémi, > > in isolation (1) was the bigger win on most of my tests. I can split the > three improvements apart, if you prefer. no, i trust you, > > Not sure in which sense you mean inlining? Few of the methods in the > bootstrap code are likely hot enough to see inlining by a JIT - and the > resulting MHs should be identical, just not constructed over and over > again. I'm wondering if the code without the null tests was not simple enough to be inlined by c1, the MH creations tends to do a lot of checks that can be removed even by c1. > > /Claes Rémi > > On 2020-05-25 22:53, Remi Forax wrote: >> 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
