[DAGCombiner] Fix exact power-of-two signed division for large integers (#177340)

Previously, the DAG combiner did not optimize exact signed division by a
power-of-two constant divisor for integer types exceeding the size of
division supported by the target architecture (e.g., i128 on x86-64).
However, such an optimization was expected by the division expansion
logic, leading to unsupported division operations making it to
instruction selection.
This commit addresses this issue by making an exception to the existing
exclusion of signed division with the exact flag for the aforementioned
operations. That is, the DAG combiner will now optimize exact signed
division if the divisor is a power-of-two constant and the integer type
exceeds the size of division supported by the target architecture.

---------

Signed-off-by: Steffen Holst Larsen <HolstLarsen.Steffen@amd.com>
4 files changed
tree: 6b446fc218ed40d3575c3a30eddd2bf894753521
  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
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