[Info-vax] RMS and SSIO (again)

[John Reagan]

On Saturday, January 8, 2022 at 8:38:32 PM UTC-5, tink... at gmail.com wrote:
> On Sunday, 9 January 2022 at 12:09:36 pm UTC+11, Arne Vajhøj wrote: 
> It would be great if VSI published what they did to make clang/llvm work on Linux to build bits for VMS... 
> 
I've discussed this before but we'll provide the code.  I still want to push the LLVM code back to the LLVM git repo.

Essentially, the LLVM changes are
- add an argcount
- add some extra ELF .note sections for module name, etc. but the linker will be ok without it
- add some extra code to make sure we always go through the GOT for static data (like the medium model but not quite) since code will be in 64-bit space but static data is always 32-bit.  If you like with /SEGMENT=CODE=P0, you don't need it
- add code to specify .personality routines as specified by the frontend.  LLVM is still biased to thinking that .personality routines are all about C++ try/catch.
- add code to deal with more complex LTCEs for "symbol - symbol" relocations

You can go watch my LLVM 5-minute lightning talk from a few years back.  Head over to the LLVM channel on YouTube and search for my name.  You'll find both talks I've presented.

For clang, that's still a work-in-progress, but RTL prefixing, dual-size pointers (leveraging the existing support in clang), pragma nomember_alignment (almost like pack), headers from TLB files, etc.