These registers are only available on a limited set of ARM targets (those
based on XScale). Other targets should not have to pay the cost of these.
This patch shaves off about ~300 bytes of stack usage and ~1KB of code-size.
Differential revision: http://reviews.llvm.org/D21991
Reviewers: bcraig, compnerd
Change-Id: I2d7a1911a193bd70b123e78747e1a7d1482463c7
llvm-svn: 274744
Currently libunwind is built to support cross-unwinding [1] by default, which
requires the buffers unw_context_t and unw_cursor_t to be large enough to hold
the vritual register set (VRS) of any supported architecture. This is not
desirable for some platforms where the stack usage of the unwinder needs
to be kept to a minimum (e.g. bare-metal targets). The current patch introduces
a native-only (-DLIBUNWIND_ENABLE_CROSS_UNWINDING=OFF) unwinder variant that
adopts strict sizes for the buffers unw_context_t and unw_cursor_t depending
on the target architecture.
[1] http://www.nongnu.org/libunwind/man/libunwind(3).html#section_4
Change-Id: I380fff9a56c16a0fc520e3b1d8454a34b4a48373
llvm-svn: 270692
Ranjeet Singh