[AArch64] Prioritize STNP patterns for !nontemporal (#174138)

This patch prioritizes lowering using STNP patterns over temporal store
patterns for store instructions marked `!nontemporal`. We should
generally prioritize STNP lowering for non-temporal stores, here it
costs extra instructions for address calculation, but its explicitly
hinted by the developer so the gain from the memory subsystem should be
more significant. It adds test cases for register offset stores where
the mixed lowering has been observed.

The `AArch64stnp` pattern is sinked under `isLE` but it doesnt change
functionality because it is only matched when the custom lowering code
in `AArch64ISelLowering.cpp` prepares for it and its guarded by
`isLittleEndian()` check.

Haven't observe a significant compile time impact that could have stem
from matching more failed patterns for each store.
4 files changed
tree: 7c59defe14dc0e803bec88aead5129c4bb9e7545
  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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