Give each mlir::Block a stable ID within its parent region (#207617)

Assign each mlir::Block a stable ID within its parent region, mirroring
llvm::BasicBlock/llvm::Function (called ID, not number, since a block/op
number denotes position in MLIR): Block gains getBlockID() and reads -1u
while it has no parent region; Region gains nextBlockID with
getMaxBlockID() and getBlockIDEpoch(); the block ilist traits assign the
ID on add/transfer and invalidate it on removal; and
GraphTraits<mlir::Block*>/<mlir::Region*> expose
getNumber/getMaxNumber/getNumberEpoch. This makes
GraphHasNodeNumbers<mlir::Block*> true, moving MLIR's CFGLoopInfo and
dominator tree onto the number-indexed path. MLIR never renumbers
blocks,
so the epoch is a fixed 0.

Prerequisite for requiring GraphHasNodeNumbers in llvm::LoopInfoBase and
dropping its DenseMap fallback.

Aided by Claude Opus 4.8
4 files changed
tree: 7c9acfb275db83fcf89e06e4ef35685dfbefaa09
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libsycl/
  16. libunwind/
  17. lld/
  18. lldb/
  19. llvm/
  20. llvm-libgcc/
  21. mlir/
  22. offload/
  23. openmp/
  24. orc-rt/
  25. polly/
  26. runtimes/
  27. third-party/
  28. utils/
  29. .clang-format
  30. .clang-format-ignore
  31. .clang-tidy
  32. .git-blame-ignore-revs
  33. .gitattributes
  34. .gitignore
  35. .mailmap
  36. CODE_OF_CONDUCT.md
  37. CONTRIBUTING.md
  38. LICENSE.TXT
  39. pyproject.toml
  40. README.md
  41. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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Welcome to the LLVM project!

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