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fuchsia / third_party / github.com / llvm / llvm-project / refs/heads/users/bjope/demandedbits_bitcast_1
commit9f0273a6d84bb05cd93e78ef5d1af0384c5fd6ad[log] [tgz]
authorBjorn Pettersson <bjorn.a.pettersson@ericsson.com>Wed Nov 12 23:03:13 2025 +0100
committerBjorn Pettersson <bjorn.a.pettersson@ericsson.com>Wed Nov 12 23:03:13 2025 +0100
treed1680223885aec350a8e2185a99d116ec80a3db0
parentcf9cb542f22e18cc9c567bc952e91b52e310070f [diff]
[SelectionDAG] Fix bug related to demanded bits/elts for BITCAST

When we have a BITCAST and the source type is a vector with smaller
elements compared to the destination type, then we need to demand
all the source elements that make up the demanded elts for the
result when doing recursive calls to SimplifyDemandedBits,
SimplifyDemandedVectorElts and SimplifyMultipleUseDemandedBits.
Problem is that those simplifications are allowed to turn non-demanded
elements of a vector into POISON, so unless we demand all source
elements that make up the result there is a risk that the result
would be more poisonous (even for demanded elts) after the
simplification.

The patch fixes some bugs in SimplifyMultipleUseDemandedBits and
SimplifyDemandedBits for situations when we did not consider the
problem described above. Now we make sure that we also demand vector
elements that "must not be turned into poison" even if those elements
correspond to bits that does not need to be defined according to
the DemandedBits mask.

Fixes #138513
125 files changed
tree: d1680223885aec350a8e2185a99d116ec80a3db0
  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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