tree 3ae5a0c1653368fa96d3ab9f1b79e461070f4db6
parent 895a45972c6e21b2609fb041f19f914fb46f894d
author Leonard Chan <leonardchan@google.com> 1586214538 -0700
committer Copybara-Service <copybara-worker@google.com> 1606767612 -0800

[libcxxabi] Add macro for changing functions to support the relative vtables ABI

Under the relative vtables ABI, __dynamic_cast will not work since it assumes
the vtable pointer is 2 ptrdiff_ts away from the start of the vtable (8-byte
offset to top + 8-byte pointer to typeinfo) when it is actually 8 bytes away
(4-byte offset to top + 4-byte offset to typeinfo). This adjusts the logic under
__dynamic_cast and other areas vtable calculations are done to support this ABI
when it's used.

Differential Revision: https://reviews.llvm.org/D77606

GitOrigin-RevId: 61aec69a65dec949f3d2556c4d0efaa87869e1ee