windows-arm64 support

[pbo-linaro]

This series allows to build and run Ruby natively on windows-arm64.

It contains fixes for build system (some of them taken from MSYS2 Ruby package).
Most of the work is detection of __pioinfo pointer, which was the blocking step. Details are available in commit message. This was tested on windows-arm64 11 retail build (not insiders).

You can find a build log here, that uses this script from an MSYS2 clangarm64 shell.

I'm not sure if Ruby community accepts a serie of patches, or if several PR are needed. Let me know.
Note: This is an effort part of my work at Linaro.

[pbo-linaro]

For now, 2 tests are failing. I can investigate and fix this, once this PR will be merged.

#209 test_fiber.rb:37: 
     Fiber.new(&Object.method(:class_eval)).resume("foo")
  #=> killed by SIGSEGV (signal 11)  [ruby-dev:34128]
#1524 test_thread.rb:336: 
     g = enum_for(:binding)
     loop { g.next }
  #=> killed by SIGSEGV (signal 11)  [ruby-dev:34128]
FAIL 2/0 tests failed

[pbo-linaro]

@dennisameling @lazka You could be interested by some of those patches for MSYS2 Ruby package. It would enable clangarm64 version of it (I didn't try yet to build additional gems).

[pbo-linaro]

@nurse You're welcome to review it, as this __pioinfo stuff should be familiar to you ;).

[Biswa96]

Most of the work is detection of __pioinfo pointer, which was the blocking step.

Out of curiosity, would it be possible to remove/replace that __pioinfo mess entirely? The assembly instructions in ucrtbase may change anytime in any Windows version.

[lazka]

@larskanis did something in that area last year: https://bugs.ruby-lang.org/issues/18605#note-6 I don't know what the status there is.

[pbo-linaro]

I completely agree that the best solution would be to get rid of pioinfo pointer. Python, Perl, and MinGW (at least) got rid of it from what I investigated. As @lazka mentioned, @larskanis started an implementation here. However, it seems it has been untouched for a while.

For now, it's a tentative to have a pragmatic solution, and hopefully, @ArminG-MSFT can make sure ucrtbase _isatty function will keep the same pattern for windows-arm64 too.

[nurse]

The patch looks good. Thank you for your contribution!

[nurse]

As lazka quoted and larskanis said, to remove __pioninfo it needs to reimplement C standard library I/O functions to use our HANDLE/SOCKET mapping table. Why the table is needed is to emulate Unix-like behavior which unifies file handle and socket. In other words to provide IO.select. The strategy larskanis wrote in https://bugs.ruby-lang.org/issues/18605#note-6 is aligned our (I and usa) understanding. The most tough part is implement CRLF handling (text mode).

I completely agree that the best solution would be to get rid of pioinfo pointer. Python, Perl, and MinGW (at least) got rid of it from what I investigated.

As far as I understand Python is under slightly different situation because they don't provide HANDLE/SOCKET unification. (their select doesn't handle files on Windows) https://docs.python.org/3/library/select.html

Perl seems similar situation, but they introduced another hack this year (!). Perl/perl5@8552f09
It looks interesting and it's worth investigating how stable the strategy is.

[lazka]

fyi, the USE_LLVM_WINDRES workaround in this PR should no longer be needed starting with llvm v18, and the relevant llvm changes are backported in MSYS2 as of today -> msys2/MINGW-packages#19524