================ @@ -26996,18 +26996,38 @@ class, structure, array, or other object. Arguments: """""""""" -The ``llvm.objectsize`` intrinsic takes four arguments. The first argument is a -pointer to or into the ``object``. The second argument determines whether -``llvm.objectsize`` returns 0 (if true) or -1 (if false) when the object size is -unknown. The third argument controls how ``llvm.objectsize`` acts when ``null`` -in address space 0 is used as its pointer argument. If it's ``false``, -``llvm.objectsize`` reports 0 bytes available when given ``null``. Otherwise, if -the ``null`` is in a non-zero address space or if ``true`` is given for the -third argument of ``llvm.objectsize``, we assume its size is unknown. The fourth -argument to ``llvm.objectsize`` determines if the value should be evaluated at -runtime. +The ``llvm.objectsize`` intrinsic takes six arguments: + +- The first argument is a pointer to or into the ``object``. +- The second argument controls which value to return when the size is unknown: + + - If it's ``false``, ``llvm.objectsize`` returns ``-1``. + - If it's ``true``, ``llvm.objectsize`` returns ``0``. + +- The third argument controls how ``llvm.objectsize`` acts when ``null`` in + address space 0 is used as its pointer argument: + + - If it's ``false``, ``llvm.objectsize`` reports 0 bytes available when given + ``null``. + - If it's ``true``, or the ``null`` pointer is in a non-zero address space, + the size is assumed to be unknown. + +- The fourth argument to ``llvm.objectsize`` determines if the value should be + evaluated at runtime. +- The fifth argument controls which size ``llvm.objectsize`` returns: + + - If it's ``false``, ``llvm.objectsize`` returns the size of the closest + surrounding subobject. + - If it's ``true``, ``llvm.objectsize`` returns the size of the whole object. + +- If non-zero, the sixth and seventh arguments encode the size and offset + information, respectively, of the original subobject's layout and is used + when the fifth argument is ``false``. +- The seventh argument encodes the offset information of the original + subobject's layout and is used when the fifth argument is ``false``. ---------------- zygoloid wrote:
As far as I can see, the "offset" value you're passing in is a difference between two pointers both of which are unknown to the middle-end -- it's the difference from the start of the two-levels-out enclosing class subobject to the one-level-out enclosing field subobject, I think. I could be misunderstanding something, but I don't see how you can use that information to get correct results from the builtin. Can you explain how the LLVM intrinsic uses this information? https://github.com/llvm/llvm-project/pull/83204 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
