[clang] Limit lifetimes of temporaries to the full expression (#170517)

We have several issues describing suboptimal stack usage related to the
lifetimes of temporary objects, such as #68747, #43598, and #109204.

Previously, https://reviews.llvm.org/D74094 tried to address this. In
that review, a few issues were brought up, particularly a concern about
the lifetimes of the temporaries needing to be extended to end of the
full expression. While there are arguably more optimal lifetime bounds
we could enforce, for now we can conservatively make them extend to the
end of the full expression, and later refine the optimization to use
tighter bounds (or perhaps a better mechanism in the middle end?).

Fixes #68747

Co-authored-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Co-authored-by: Erik Pilkington <erik.pilkington@gmail.com>

---------

Co-authored-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Co-authored-by: Erik Pilkington <erik.pilkington@gmail.com>
10 files changed
tree: ea371d1fa4b731c069202852b578234284ece074
  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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