[lldb] Support reading DW_OP_piece from file address (#94026)

We received a bug report where someone was trying to print a global
variable without a process. This would succeed in a debug build but fail
in a on optimized build. We traced the issue back to the location being
described by a DW_OP_addr + DW_OP_piece.

The issue is that the DWARF expression evaluator only support reading
pieces from a load address. There's no reason it cannot do the same for
a file address, and indeed, that solves the problem.

I unsuccessfully tried to craft a test case to illustrate the original
example, using a global struct and trying to trick the compiler into
breaking it apart with SROA. Instead I wrote a unit test that uses a
mock target to read memory from.

rdar://127435923
3 files changed
tree: 61326c5301048f00532c202417b5a73148c80b88
  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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