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fuchsia / third_party / llvm-project / b6e102e08cd35543175459494211a3a15f793302
commitb6e102e08cd35543175459494211a3a15f793302[log] [tgz]
authorNikita Popov <npopov@redhat.com>Mon May 20 07:40:54 2024 +0200
committerGitHub <noreply@github.com>Mon May 20 07:40:54 2024 +0200
tree2d623ef8fcdb3a9c77ec05d106031ff1ffff6ffc
parentd316a0bd48ceb4a0ee851d729291a2cdcc8818eb [diff]
[SCEV] Don't use non-deterministic constant folding for trip counts (#90942)

When calculating the exit count exhaustively, if any of the involved
operations is non-deterministic, the exit count we compute at
compile-time and the exit count at run-time may differ. Using these
non-deterministic constant folding results is only correct if we
actually replace all uses of the instruction with the value. SCEV (or
its consumers) generally don't do this.

Handle this by adding a new AllowNonDeterministic flag to the constant
folding API, and disabling it in SCEV. If non-deterministic results are
not allowed, do not fold FP lib calls in general, and FP operations
returning NaNs in particular. This could be made more precise (some FP
libcalls like fabs are fully deterministic), but I don't think this that
precise handling here is worthwhile.

Fixes the interesting part of
https://github.com/llvm/llvm-project/issues/89885.
4 files changed
tree: 2d623ef8fcdb3a9c77ec05d106031ff1ffff6ffc
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. libc/
  11. libclc/
  12. libcxx/
  13. libcxxabi/
  14. libunwind/
  15. lld/
  16. lldb/
  17. llvm/
  18. llvm-libgcc/
  19. mlir/
  20. offload/
  21. openmp/
  22. polly/
  23. pstl/
  24. runtimes/
  25. third-party/
  26. utils/
  27. .clang-format
  28. .clang-tidy
  29. .git-blame-ignore-revs
  30. .gitattributes
  31. .gitignore
  32. .mailmap
  33. CODE_OF_CONDUCT.md
  34. CONTRIBUTING.md
  35. LICENSE.TXT
  36. pyproject.toml
  37. README.md
  38. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

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