[ValueTracking] Refine SIToFP/UIToFP FPClass inference with KnownBits (#187185)

This patch propagates the KnownBits of the source integer to improve
floating-point class inference for sitofp and uitofp instructions.

Specifically,
1. The result is never -0.0.
2. The result is not +0.0 if the source integer is known non-zero.
3. The result is not negative if the source integer is known
non-negative (or for uitofp).
4. The result is not Infinity if the largest possible integer magnitude
fits within the target FP type's exponent limits.

alive2 results for added testcases:
testcase 1: https://alive2.llvm.org/ce/z/eM34LB
testcase 2: https://alive2.llvm.org/ce/z/ext7XF 
testcase 3: https://alive2.llvm.org/ce/z/g8yb6q
testcase 4: https://alive2.llvm.org/ce/z/cyFYRy
testcase 5: https://alive2.llvm.org/ce/z/LePFrm

alive2 for updated testcase in binop-itofp:

updated 1: https://alive2.llvm.org/ce/z/KPQ5bZ
udpated 2: https://alive2.llvm.org/ce/z/bGf43t
updated 3: https://alive2.llvm.org/ce/z/YKnCwU
updaetd 4: https://alive2.llvm.org/ce/z/mqKaq-
updated 5: https://alive2.llvm.org/ce/z/jYSAB5

Fix #186952
5 files changed
tree: bd989484e742b9eac2f0a0d962c102afa34ae402
  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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