[libc] Support  'assert.h' on the GPU

This patch adds the necessary support to provide `assert` functionality
through the GPU `libc` implementation. This implementation creates a
special-case GPU implementation rather than relying on the common
version. This is because the GPU has special considerings for printing.
The assertion is printed out in chunks with `write_to_stderr`, however
when combined with the GPU execution model this causes 32+ threads to
all execute in-lock step. Meaning that we'll get a horribly fragmented
message. Furthermore, potentially thousands of threads could hit the
assertion at once and try to print even if we had it all in one
`printf`.

This is solved by having a one-time lock that each thread group / wave /
warp will attempt to claim. We only let one thread group pass through
while the others simply stop executing. Finally only the first thread in
that group will do the printing until we finally abort execution.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D159296
12 files changed
tree: fa21a0fb6573a9b43e11c5a91f0522cdc957721d
  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. openmp/
  21. polly/
  22. pstl/
  23. runtimes/
  24. third-party/
  25. utils/
  26. .arcconfig
  27. .arclint
  28. .clang-format
  29. .clang-tidy
  30. .git-blame-ignore-revs
  31. .gitignore
  32. .mailmap
  33. CONTRIBUTING.md
  34. LICENSE.TXT
  35. README.md
  36. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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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