[APFloat] Fix getExactInverse for DoubleAPFloat

Some background: getExactInverse()'s callers expect that
the result is not subnormal.

DoubleAPFloat implemented getExactInverse() by going through
semPPCDoubleDoubleLegacy.

This means that numbers like 0x1p1022 which would have a normal inverse
in semPPCDoubleDouble would not in semPPCDoubleDoubleLegacy.

This commit refactors the logic into a single method on APFloat which
uses getExactLog2Abs() and scalbn() to calculate the inverse without
having to compute a reciprocal and test if it is inexact.
This approach works for both IEEEFloat and DoubleAPFloat.
3 files changed
tree: 7c3f847059f778ba0d83f527e012cac363c95001
  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. polly/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. SECURITY.md
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