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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
LLVM libc ========= This directory and its subdirectories contain source code for llvm-libc, a retargetable implementation of the C standard library. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.