[X86][MC] Add R_X86_64_CODE_4_GOTTPOFF (#116633)

For

  mov name@GOTTPOFF(%rip), %reg
  add name@GOTTPOFF(%rip), %reg

add

  `R_X86_64_CODE_4_GOTTPOFF` = 44

if the instruction starts at 4 bytes before the relocation offset. It's
similar to R_X86_64_GOTTPOFF.

Linker can treat `R_X86_64_CODE_4_GOTTPOFF` as `R_X86_64_GOTTPOFF` or
convert the instructions above to

  mov $name@tpoff, %reg
  add $name@tpoff, %reg

if the first byte of the instruction at the relocation `offset - 4` is
`0xd5` (namely, encoded w/REX2 prefix) when possible.

Binutils patch:
https://github.com/bminor/binutils-gdb/commit/a533c8df598b5ef99c54a13e2b137c98b34b043c
Binutils mailthread:
https://sourceware.org/pipermail/binutils/2023-December/131463.html
ABI discussion:
https://groups.google.com/g/x86-64-abi/c/ACwD-UQXVDs/m/vrgTenKyFwAJ
Blog: https://kanrobert.github.io/rfc/All-about-APX-relocation
3 files changed
tree: d476d968bbfa05e5eb3c2e7956e74fc891db77e4
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. libc/
  11. libclc/
  12. libcxx/
  13. libcxxabi/
  14. libunwind/
  15. lld/
  16. lldb/
  17. llvm/
  18. llvm-libgcc/
  19. mlir/
  20. offload/
  21. openmp/
  22. polly/
  23. pstl/
  24. runtimes/
  25. third-party/
  26. utils/
  27. .clang-format
  28. .clang-tidy
  29. .git-blame-ignore-revs
  30. .gitattributes
  31. .gitignore
  32. .mailmap
  33. CODE_OF_CONDUCT.md
  34. CONTRIBUTING.md
  35. LICENSE.TXT
  36. pyproject.toml
  37. README.md
  38. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

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