Update Boost Context

[mdsitton]

I've been looking over the version in this repo vs the upstream and there is a few issues i'm finding compared to the latest version, plus we'd probably get apple silicon support which would be nice: boostorg/context@1c763c9

Here are some of the commits that should certainly be applied regardless looking over everything:
boostorg/context@50ebf5b

boostorg/context@002ed38

[RichieSams]

I'd prefer to keep it as a fork. (one of the reasons I forked it was that the boost context API kept changing). That said, we can definitely port their fixes. Apple silicon shouldn't be too hard to add, since we already have ARM for elf. MachO uses aapcs calling convention as well. So the only difference between elf and macho asm files is some calling macros

[mdsitton]

i mean to be fair the fcontext api hasn't changed at all since you forked it 6 years ago as far as i can tell: https://github.com/boostorg/context/commits/develop/include/boost/context/detail/fcontext.hpp
And development over time on the project has been trending downwards since then:

Another option is using maybe this fork which while isn't fully up-to-date with the current boost context, it's a lot newer and has all of the backends functional atleast.
https://github.com/septag/deboost.context

[RichieSams]

That's an interesting option. It's got some decent stars and is used by some facebook research project. I don't like the API change, but I'm also curmudgeonly. I'll live

[hedecai]

We want to use this project on iOS (arm64), which asm file should we using? Thanks.

[RichieSams]

You need

jump_arm64_aapcs_macho_gas.S
make_arm64_aapcs_macho_gas.S

Those currently live in the not_modified_yet folder. And thus would need a few changes before they can be used. That said, the difference between macho and elf is fairly minimal. So you could use *_arm64_aapcs_elf_gas.S as examples. And compare the differences between *_x86_64_sysv_macho_gas.S and *_x86_64_sysv_elf_gas.S.

The main asm is the same. It's just the helper macros / alignment that's slightly different.

PRs are welcome. Or I could try to take a wack at it sometime in the next few weeks.

[RichieSams]

Implemented in this PR: #160

[hedecai]

Implemented in this PR: #160

Thanks，we tried it, works well. Thanks for your excellent work.