On 31.12.2010 03:02, Eliot Miranda wrote:
Hi All,
I've released a new version of Cog that has a substantially improved code generator along the lines of Peter Deutsch's HPS (VisualWorks) and various of Ian Piumarta's VMs. These all use a simple tecnique to identify constant references in bytecode and to support a register-based calling convention. While this does produce faster code it tends to accelerate low-level code much more than high-level code as you can see by the following benchmarks:
SimpleStackBasedCogit: [1 to: 100000000 do: [:i|]] timeToRun 691 StackToRegisterMappingCogit: [1 to: 100000000 do: [:i|]] timeToRun 192 192 - 691 / 6.91 -72%
SimpleStackBasedCogit: 0 tinyBenchmarks '753495217 bytecodes/sec; 64769127 sends/sec' StackToRegisterMappingCogit: 0 tinyBenchmarks '931756141 bytecodes/sec; 128157989 sends/sec' 931756141 - 753495217 / 7534952.17 -24% 128157989 - 64769127 / 647691.27 -98%
SimpleStackBasedCogit: [Compiler recompileAll] timeToRun 47013 (no transcript StackToRegisterMappingCogit: [Compiler recompileAll] timeToRun 43406 (no transcript) 43406 - 47013 / 470.13 -7.67234594686576
The status of this code is essentially beta. The test suite runs the same on the new code generator as on the old, but I think there are still bugs because I get the occasional transient error. I am therefore very interested in any reproducible errors you can find.
The VMs (http://www.mirandabanda.org/files/Cog/VM/VM.r2334/) contain a few other important changes:
- a bug fix to bytecode<->native pc mappng that produced incorrect results for methods containing blocks with ^-returns in them. One symptom is incorrect highlighting of the pc in the debugger, althoguh symptoms could be much serious.
- jitting interpreted methods on backward branches. Currently any interpreted method that performs more than 20 backward branches will be considered for JIT compilation and if it is suitable (default, <= 60 literals) will be compiled to native code.
- new callback support. I need to commit some changes to the Alien package to provide access to this but essentially the VM's callback support is now able to be ported to architectures with register-based calling conventions (ARM, PowerPC, SPARC etc). I'll try and get the Alien code released soon, and to back-port the changes to the standard VM before the end of the holiday.
One thing that is still /not/ fixed is the lack of a SoundPlugin on win32. Apologies. I'll try and get a fix for this before the end of the holidays too, but time might be too tight. There are other priorities such as harmonising the standard and Cog VMs for the 4.2 release.
I gave it a short test with the latest Seaside. First the good news, I seem to get an average performance improvement of about 10%. However in some very rare cases the temps seem to be mixed up the very first time a method is executed and fine afterwards. For example in the method below when the div 'bench' is created. The very first time it is executed #div is sent to a BlockClosure, the next time it is fine. This is reproducible, if I recompile the package or restart the image it happens again the first time and is fine afterwards. I don't know how I can provide more information but I could upload the image somewhere. renderInline: aBlock factor: factor key: key on: html | startTime endTime count backColor anAssociation title referenceValue spi context document renderer stream runTime | count := 0. runTime := 200. anAssociation := referenceDict at: key ifAbsent: [ 'Undefined' -> 100000 ]. title := anAssociation key. referenceValue := anAssociation value. stream := WriteStream on: String new. document := builder documentClass on: stream codec: builder codec. context := WARenderContext new. context document: document. context actionUrl: builder actionUrl; resourceUrl: builder resourceUrl. renderer := builder rendererClass context: context. builder openDocument: document context: context. html div class: 'bench'; with: [ html heading: title. startTime := Time millisecondClockValue. endTime := startTime + runTime. [ Time millisecondClockValue < endTime ] whileTrue: [ count := count + 1. renderer render: aBlock; flush ] ]. builder closeDocument: document. spi := (count / referenceValue * (10000 / runTime)) rounded. backColor := spi > 100 ifTrue: [ '#5f5' ] ifFalse: [ spi < 50 ifTrue: [ '#f55' ] ifFalse: [ '#55f' ] ]. duration := duration + spi. html div style: 'float:left;padding:4px'; with: [ html big: spi greaseString , ' SPI'. html span class: 'iteration'; with: '(' , count greaseString , ' iterations)'. html break. html div class: 'rect'; style: 'background:' , backColor , ';width:' , (spi * 2) greaseString , 'px' ]. html div style: 'clear:both' Cheers Philippe