Rename member 'Size' to 'AllocatedSize' in order to provide a hint that the
allocated size may be different than the requested size. Comments are added to
clarify this point. Updated the InMemoryBuffer in FileOutputBuffer.cpp to track
the requested buffer size.
Patch by Machiel van Hooren. Thanks Machiel!
https://reviews.llvm.org/D61599
llvm-svn: 361195
This patch changes the return type of sys::Process::getPageSize to
Expected<unsigned> to account for the fact that the underlying syscalls used to
obtain the page size may fail (see below).
For clients who use the page size as an optimization only this patch adds a new
method, getPageSizeEstimate, which calls through to getPageSize but discards
any error returned and substitues a "reasonable" page size estimate estimate
instead. All existing LLVM clients are updated to call getPageSizeEstimate
rather than getPageSize.
On Unix, sys::Process::getPageSize is implemented in terms of getpagesize or
sysconf, depending on which macros are set. The sysconf call is documented to
return -1 on failure. On Darwin getpagesize is implemented in terms of sysconf
and may also fail (though the manpage documentation does not mention this).
These failures have been observed in practice when highly restrictive sandbox
permissions have been applied. Without this patch, the result is that
getPageSize returns -1, which wreaks havoc on any subsequent code that was
assuming a sane page size value.
<rdar://problem/41654857>
Reviewers: dblaikie, echristo
Subscribers: kristina, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59107
llvm-svn: 360221
This patch introduces Memory::MF_HUGE_HINT which indicates that allocateMappedMemory() shall return a pointer to a large memory page.
However the flag is a hint because we're not guaranteed in any way that we will get back a large memory page. There are several restrictions:
- Large/huge memory pages aren't enabled by default on modern OSes (Windows 10 and Linux at least), and should be manually enabled/reserved.
- Once enabled, it should be kept in mind that large pages are physical only, they can't be swapped.
- Memory fragmentation can affect the availability of large pages, especially after running the OS for a long time and/or running along many other applications.
Memory::allocateMappedMemory() will fallback to 4KB pages if it can't allocate 2MB large pages (if Memory::MF_HUGE_HINT is provided)
Currently, Memory::MF_HUGE_HINT only works on Windows. The hint will be ignored on Linux, 4KB pages will always be returned.
Differential Revision: https://reviews.llvm.org/D58718
llvm-svn: 355065
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Skip all MappedMemoryTest variants that rely on memory pages being
mapped for MF_WRITE|MF_EXEC when MPROTECT is enabled on NetBSD. W^X
protection causes all those mmap() calls to fail, causing the tests
to fail.
Differential Revision: https://reviews.llvm.org/D54080
llvm-svn: 347337
Benjamin Kramer