[Mips] Support reserving GPRs with -ffixed-N (#217013)

NetBSD dedicates GPR $24 to mips_curlwp and passes -ffixed-24 when
building the MIPS kernel.

Add Clang driver options for numeric MIPS GPRs and lower them to
reserve-gprN target features. Teach the backend to reserve the
corresponding 32-bit register and its 64-bit super-register, and require
named-register accesses to refer to reserved registers.

Also replace the regex-based numeric register parsing with
StringRef::getAsInteger and add driver, allocation, and global-register
regression coverage.
GitOrigin-RevId: 5d063386f51b7d9925df7db5f05ec2f0a33f63c4
4 files changed
tree: 756f13e335d67f5fdb3e83301f41fa6bad33908d
  1. bindings/
  2. cmake/
  3. docs/
  4. examples/
  5. include/
  6. lib/
  7. runtime/
  8. test/
  9. tools/
  10. unittests/
  11. utils/
  12. www/
  13. .clang-format
  14. .clang-tidy
  15. .gitignore
  16. AreaTeamMembers.txt
  17. CMakeLists.txt
  18. INSTALL.txt
  19. LICENSE.TXT
  20. Maintainers.md
  21. NOTES.txt
  22. README.md
README.md

C language Family Front-end

Welcome to Clang.

This is a compiler front-end for the C family of languages (C, C++ and Objective-C) which is built as part of the LLVM compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read the relevant websites. Here are some pointers: