Add QuickJS as default Javascript engine

[JerrySievert]

• adds QuickJS
• makes QuickJS the default Javascript engine

uses modified version of QuickJS that lives at https://github.com/JerrySievert/QuickJS

added git clone to Makefile, you will likely want to change this to a submodule to lock down the commit id.

I've tested builds on Mac, linux, and windows, tested running on Mac and windows.

There is a horrible hack that executes Javascript to convert ArrayBuffer to Float32Array, my change to quickjs.c for this was not successful - I will make another attempt later to hopefully remove the hack. https://github.com/JerrySievert/VCV-Prototype/blob/master/src/QuickJSEngine.cpp#L191-L201

otherwise, this is a pretty faithful port.

QuickJS changes:

• removes two stack overflow checks, these are #if 0 to hopefully be able to add them back in if it is possible to change the method that is used to determine stack size
• removes assert that checked if variables were still allocated at context free, now just frees the allocated memory instead of dying
• added -fPIC to the Makefile, required for Linux
• removed -g from Makefile
• added -O3 to Makefile for some compile-time optimizations
• removed building of examples as the javascript compiler is not supported on windows and were extraneous anyways

[JerrySievert]

oh, and I added myself as a contributor, and fixed the spelling of contributor to be correct.

[AndrewBelt]

Merged. A few things you should fix in your QuickJS fork.

• In QuickJS's Makefile, it overwrites CFLAGS with the syntax CFLAGS=. If you change this to CFLAGS +=, you can remove the -O3 -fPIC stuff because Rack's dep build automatically injects that, as well as -march=nocona etc into CFLAGS.
• It also uses prefix= which is bad because I can't overwrite with the command line. You'll need to change this to prefix ?= in the QuickJS repo and then update the submodule in this repo in order for the current master to work.

[AndrewBelt]

Patch which implements the above.

patch.txt

Apply with git apply patch.txt

[JerrySievert]

why did you remove -fPIC in your patch?

nevermind, just saw:

because Rack's dep build automatically injects that, as well as -march=nocona etc into CFLAGS.

teaches me to reply while still half asleep.

[AndrewBelt]

It's already in the CFLAGS environment variable for Rack plugins. Not sure if it should be default, but it wasn't in the original QuickJS source.

[JerrySievert]

yeah, I knew it wasn't in the original QuickJS source, gcc gave me the error on Linux when embedding it within rack. I have the same issue when embedding on Linux with other code that uses -fPIC when compiling:

/usr/bin/ld: deps/quickjs/libquickjs.a(quickjs.nolto.o): relocation R_X86_64_PC32 against symbol `lre_id_start_table_ascii' can not be used when making a shared object; recompile with -fPIC

given that I usually only embed with code that's compiled as a .so, it should probably live there as being able to relocate isn't a problem when compiling against an executable.

[AndrewBelt]

@JerrySievert I've switched QuickJS from a submodule to the Makefile calling git clone .... This will probably change your workflow if maintaining QuickJS in the future, so you should know.