Author: serge-sans-paille Date: 2022-02-22T17:19:11+01:00 New Revision: 79c9072dc009693477242bc1347a2a6c3e419423
URL: https://github.com/llvm/llvm-project/commit/79c9072dc009693477242bc1347a2a6c3e419423 DIFF: https://github.com/llvm/llvm-project/commit/79c9072dc009693477242bc1347a2a6c3e419423.diff LOG: Restore documentation for __builtin_assume This got removed by 6cacd420a1d72bca7809e6b516fb1e18ac6056c8, and that was a mistake. Differential Revision: https://reviews.llvm.org/D120205 Added: Modified: clang/docs/LanguageExtensions.rst Removed: ################################################################################ diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index f45d88092eb4..865a877b0219 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -2205,6 +2205,39 @@ Query for this feature with ``__has_builtin(__builtin_alloca_with_align)``. .. _langext-__builtin_assume: +``__builtin_assume`` +-------------------- + +``__builtin_assume`` is used to provide the optimizer with a boolean +invariant that is defined to be true. + +**Syntax**: + +.. code-block:: c++ + + __builtin_assume(bool) + +**Example of Use**: + +.. code-block:: c++ + + int foo(int x) { + __builtin_assume(x != 0); + // The optimizer may short-circuit this check using the invariant. + if (x == 0) + return do_something(); + return do_something_else(); + } + +**Description**: + +The boolean argument to this function is defined to be true. The optimizer may +analyze the form of the expression provided as the argument and deduce from +that information used to optimize the program. If the condition is violated +during execution, the behavior is undefined. The argument itself is + +Query for this feature with ``__has_builtin(__builtin_assume)``. + ``__builtin_call_with_static_chain`` ------------------------------------ _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
