[Vm-dev] OSVM on WebAssembly

Mon Jun 27 21:31:13 UTC 2022

Hi Manuel,

   cool beans!

On Mon, Jun 27, 2022 at 3:54 AM Manuel Leuenberger <maenuleu at gmail.com>
wrote:

>
> Hi,
>
> Ever since WebAssembly became a thing, I was wondering if this could
> become a target for VMs. People are already compiling FFMPEG and other
> complex tools. So I thought I would try as well.
>
> So here I am to report to whom it may concern: OSVM compiles to
> WebAssembly, starts up (nearly), then looping infinitely
> Meaning: The VM mmaps the image file, loads plugins (SecurityPlugin made
> EXTERNAL), starts interpreter loop, but then loops the same bytecode
> sequence forever
>
> Code lives at
> https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm if
> you want to try it out.
>
> Below is the current Readme, including a short list of issues. Maybe some
> of you could give me a hint?
>
> Cheers,
> Manuel
>
> pharo.stack.spur.wasm
>
> Compiles OSVM Stack interpreter to WebAssembly using the Emscripten
> compiler. Emscripten can be used as a drop-in replacement for gcc/clang and
> cmake. Based on MinHeadless Linux 32bit sources, as Emscripten provides
> Linux-like environment (pthreads, nanosleep, dlopen, file system). Check
> the latest few commits of maenu to see changed files.
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#current-issues>Current
> issues
>
>    -
>
>    Most adjustments are just putting EMSCRIPTEN in a macro or script.
>    Should be fine, but should be tested to not interfere with other builds.
>    -
>
>    Compiles and runs, but seems to be stuck in initial GC and Heartbeat.
>    Those could be related to incorrect get/set64() implementation.
>    -
>
>    Removed mmap address hint, as it caused errors.
>    -
>
>    Using argv eval '1 + 3' to do a simple eval does not terminate.
>    -
>
>    Interpreter repeats these bytecodes forever (what is this?):
>
>
Taking these from e.g. src/spur64.stack/interp.c they are

       CASE(112)
        CASE(332) /*76*/
            /* pushReceiverBytecode */

> 332
>
>         CASE(208)
        CASE(209)
        CASE(210)
        CASE(211)
        CASE(212)
        CASE(213)
        CASE(214)
        CASE(215)
        CASE(216)
        CASE(217)
        CASE(218)
        CASE(219)
        CASE(220)
        CASE(221)
        CASE(222)
        CASE(223)
        CASE(384) /*128*/ i.e. send literal selector 0 with 0 args
        CASE(385) /*129*/
        CASE(386) /*130*/
        CASE(387) /*131*/
        CASE(388) /*132*/
        CASE(389) /*133*/
        CASE(390) /*134*/
        CASE(391) /*135*/
        CASE(392) /*136*/
        CASE(393) /*137*/
        CASE(394) /*138*/
        CASE(395) /*139*/
        CASE(396) /*140*/
        CASE(397) /*141*/
        CASE(398) /*142*/
        CASE(399) /*143*/
            /* sendLiteralSelector0ArgsBytecode */

> 384
>
>
hence send literal selector 1 with 0 args

385
>
>
        CASE(124)
        CASE(348) /*92*/
            /* returnTopFromMethod */

> 348
>
>
        CASE(501) /*245*/
            /* longStoreTemporaryVariableBytecode */

> 501
>
>         CASE(136)
        CASE(339) /*83*/
            /* duplicateTopBytecode */

> 339
>
>         CASE(16)
        CASE(320) /*64*/
            /* pushTemporaryVariableBytecode */

> 320
>
>
        CASE(224)
        CASE(225)
        CASE(226)
        CASE(227)
        CASE(228)
        CASE(229)
        CASE(230)
        CASE(231)
        CASE(232)
        CASE(233)
        CASE(234)
        CASE(235)
        CASE(236)
        CASE(237)
        CASE(238)
        CASE(239)
        CASE(400) /*144*/
        CASE(401) /*145*/ i.e. send literal selector 1 with 1 arg
        CASE(402) /*146*/
        CASE(403) /*147*/
        CASE(404) /*148*/
        CASE(405) /*149*/
        CASE(406) /*150*/
        CASE(407) /*151*/
        CASE(408) /*152*/
        CASE(409) /*153*/
        CASE(410) /*154*/
        CASE(411) /*155*/
        CASE(412) /*156*/
        CASE(413) /*157*/
        CASE(414) /*158*/
        CASE(415) /*159*/
            /* sendLiteralSelector1ArgBytecode */

> 401
>
>         CASE(64)
        CASE(272) /*16*/
            /* pushLiteralVariableBytecode */

> 272
>
>          CASE(204)
        CASE(380) /*124*/
            /* bytecodePrimNew */ i.e. a send of #new from the special
selector bytecode

> 380
>
>
If I had to guess what's going wrong I'd guess that the return bytecode 348
isn't correctly implemented.

>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#build--run>Build
> & Run
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#1-install-emscripten>1.
> Install Emscripten
>
> I installed Emscripten SDK
> <https://emscripten.org/docs/getting_started/downloads.html> to get an
> all-in-one package.
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#2-grab-an-image>2.
> Grab an image
>
> Grab a 32bit Smalltalk image and but it in the image folder. I used Pharo
> 9.
>
> cd building/minheadless.cmake/x86/pharo.stack.spur.wasm
> mkdir image
> cd image
> curl https://get.pharo.org/32/90 | bash
>
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#3-build-vm>3.
> Build VM
>
> ./mvm_configure_variant debug Debug && make -C debug install
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#4-run-a-web-server>4.
> Run a web server
>
> emrun --port 9090 --serve_root ../../../../ --no_browser .
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#5-launch-vm>5.
> Launch VM
>
>
> http://localhost:9090/building/minheadless.cmake/x86/pharo.stack.spur.wasm/debug/dist/squeak.html
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#6-inspect-running-vm>6.
> Inspect running VM
>
> The VM is compiled with DWARF debug information, which is understood by
> the Chrome debugger. So we can step through the C sources of the
> WebAssembly, pretty nifty.
>
> <https://github.com/maenu/opensmalltalk-vm/tree/Cog/building/minheadless.cmake/x86/pharo.stack.spur.wasm#resources>
> Resources
>
>    - Inspect WebAssembly (at the bottom)
>    <https://webassembly.org/getting-started/developers-guide/>
>    - Emscripten doc (Porting)
>    <https://emscripten.org/docs/porting/index.html>
>    - Emscripten settings <https://emsettings.surma.technology/>
>
>
>

-- 
_,,,^..^,,,_
best, Eliot
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