[lld][MachO] Follow-up to use madvise() for threaded file page-in. (#157917)
Further to
https://github.com/llvm/llvm-project/pull/147134#discussion_r2337246489,
switch to use the madvise() api to page in mmap'd files and
1) All new code compiled in #if LLVM_ENABLE_THREADS is set so it can be
seen where the changes were from this PR.
2) The new PR moves to use madvise() instead of the ad-hoc page
referencing code I wrote which should avoid SIGSEGVs if the buffer is
deallocated.
3) A new property SerialBackgroundQueue().stopAllWork to be used to stop
background workers when there is no further call for them. Usually the
background "page-in" threads have completed first but it seems with this
troublesome test this is not always the case and buffers stored in the
static input file cache are being deallocated while being referenced.
---------
Co-authored-by: James Henderson <James.Henderson@sony.com>
llvm-project
36bed4d0 - [lld][MachO] Follow-up to use madvise() for threaded file page-in. (#157917)
