[SLP] Fix cost estimation of external uses with wrong VF (#148185)

It assumed that the VF remains constant throughout the tree. That's not
always true. This meant that we could query the extraction cost for a
lane that is out of bounds.

While experimenting with re-vectorisation for AArch64, we ran into this
issue. We cannot add a proper AArch64 test as more changes would need to
be brought in.

This commit is only fixing the computation of VF and adding an assert.
Some tests were failing after adding the assert:
 - foo() in llvm/test/Transforms/SLPVectorizer/X86/horizontal.ll
- test() in
llvm/test/Transforms/SLPVectorizer/X86/reduction-with-removed-extracts.ll
- test_with_extract() in
llvm/test/Transforms/SLPVectorizer/RISCV/segmented-loads.ll
2 files changed
tree: 043afed751a02c823c5926c0bfe906e33e4bbea3
  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. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. runtimes/
  25. third-party/
  26. utils/
  27. .clang-format
  28. .clang-format-ignore
  29. .clang-tidy
  30. .git-blame-ignore-revs
  31. .gitattributes
  32. .gitignore
  33. .mailmap
  34. CODE_OF_CONDUCT.md
  35. CONTRIBUTING.md
  36. LICENSE.TXT
  37. pyproject.toml
  38. README.md
  39. SECURITY.md
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