1. `thread_tcache_ncached_max_read_sizeclass` allows users to get the
ncached_max of the bin with the input sizeclass, passed in through
oldp (will be upper casted if not an exact bin size is given).
2. `thread_tcache_ncached_max_write` takes in a char array
representing the settings for bins in the tcache.
There are several benefits to this:
1. It's cleaner and more reliable to use the builtin to
inform the compiler of assumptions instead of hoping that the
optimizer understands your intentions.
2. `clang` will warn you if any of your assumptions would produce
side-effects (which the compiler will discard). [This blog post](https://fastcompression.blogspot.com/2019/01/compiler-checked-contracts.html)
by Yann Collet highlights that a hazard of using the
`unreachable()`-based method of signaling assumptions is that it
can sometimes result in additional instructions being generated (see
[this Godbolt link](https://godbolt.org/z/lKNMs3) from the blog post
for an example).
Following from PR #2481, we replace all integer-to-pointer casts [which
hide pointer provenance information (and thus inhibit
optimizations)](https://clang.llvm.org/extra/clang-tidy/checks/performance/no-int-to-ptr.html)
with equivalent operations that preserve this information. I have
enabled the corresponding clang-tidy check in our static analysis CI so
that we do not get bitten by this again in the future.
Header files are now self-contained, which makes the relationships
between the files clearer, and crucially allows LSP tools like `clangd`
to function correctly in all of our header files. I have verified that
the headers are self-contained (aside from the various Windows shims) by
compiling them as if they were C files – in a follow-up commit I plan to
add this to CI to ensure we don't regress on this front.
This frontloads more of the miss latency. It also moves it to a pathway where
we have not yet acquired any locks, so that it should (hopefully) reduce hold
times.
The explicit compiler warning suppression controlled by this option is
universally desirable, so remove the ability to disable suppression.
This partially resolves#580.
This is the first header refactoring diff, #533. It splits the assert and util
components into separate, hermetic, header files. In the process, it splits out
two of the large sub-components of util (the stdio.h replacement, and bit
manipulation routines) into their own components (malloc_io.h and bit_util.h).
This is mostly to break up cyclic dependencies, but it also breaks off a good
chunk of the catch-all-ness of util, which is nice.
This is part of a broader change to make header files better represent the
dependencies between one another (see
https://github.com/jemalloc/jemalloc/issues/533). It breaks up component headers
into smaller parts that can be made to have a simpler dependency graph.
For the autogenerated headers (smoothstep.h and size_classes.h), no splitting
was necessary, so I didn't add support to emit multiple headers.
Add the MALLCTL_ARENAS_ALL cpp macro as a fixed index for use
in accessing the arena.<i>.{purge,decay,dss} and stats.arenas.<i>.*
mallctls, and deprecate access via the arenas.narenas index (to be
removed in 6.0.0).
Add a configure check for __builtin_unreachable instead of basing its
availability on the __GNUC__ version. On OS X using gcc (a real gcc, not the
bundled version that's just a gcc front-end) leads to a linker assertion:
https://github.com/jemalloc/jemalloc/issues/266
It turns out that this is caused by a gcc bug resulting from the use of
__builtin_unreachable():
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57438
To work around this bug, check that __builtin_unreachable() actually works at
configure time, and if it doesn't use abort() instead. The check is based on
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57438#c21.
With this `make check` passes with a homebrew installed gcc-5 and gcc-6.
In builds with profiling disabled (default), the opt_prof_prefix array
has a one byte length as a micro-optimization. This will cause the usage
of write in the unused profiling code to be statically detected as a
buffer overflow by Bionic's _FORTIFY_SOURCE implementation as it tries
to detect read overflows in addition to write overflows.
This works around the problem by informing the compiler that
not_reached() means code in unreachable in release builds.
Create and use FMT* macros that are equivalent to the PRI* macros that
inttypes.h defines. This allows uniform use of the Unix-specific format
specifiers, e.g. "%zu", as well as avoiding Windows-specific definitions
of e.g. PRIu64.
Add ffs()/ffsl() support for compiling with gcc.
Extract compatibility definitions of ENOENT, EINVAL, EAGAIN, EPERM,
ENOMEM, and ENORANGE into include/msvc_compat/windows_extra.h and
use the file for tests as well as for core jemalloc code.
Replace JEMALLOC_ATTR(format(printf, ...). with
JEMALLOC_FORMAT_PRINTF(), so that configuration feature tests can
omit the attribute if it would cause extraneous compilation warnings.
* assertion failure
* malloc_init failure
* malloc not already initialized (in malloc_init)
* running in valgrind
* thread cache disabled at runtime
Clang and GCC already consider a comparison with NULL or -1 to be cold,
so many branches (out-of-memory) are already correctly considered as
cold and marking them is not important.
Some platforms (like those using Newlib) don't have ffs/ffsl. This
commit adds a check to configure.ac for __builtin_ffsl if ffsl isn't
found. __builtin_ffsl performs the same function as ffsl, and has the
added benefit of being available on any platform utilizing
Gcc-compatible compiler.
This change does not address the used of ffs in the MALLOCX_ARENA()
macro.
Add size class computation capability, currently used only as validation
of the size class lookup tables. Generalize the size class spacing used
for bins, for eventual use throughout the full range of allocation
sizes.
Add unit tests for pow2_ceil(), malloc_strtoumax(), and
malloc_snprintf().
Fix numerous bugs in malloc_strotumax() error handling/reporting. These
bugs could have caused application-visible issues for some seldom used
(0X... and 0... prefixes) or malformed MALLOC_CONF or mallctl() argument
strings, but otherwise they had no impact.
Fix numerous bugs in malloc_snprintf(). These bugs were not exercised
by existing malloc_*printf() calls, so they had no impact.
Refactor tests to use explicit testing assertions, rather than diff'ing
test output. This makes the test code a bit shorter, more explicitly
encodes testing intent, and makes test failure diagnosis more
straightforward.
Refactor the test harness to support three types of tests:
- unit: White box unit tests. These tests have full access to all
internal jemalloc library symbols. Though in actuality all symbols
are prefixed by jet_, macro-based name mangling abstracts this away
from test code.
- integration: Black box integration tests. These tests link with
the installable shared jemalloc library, and with the exception of
some utility code and configure-generated macro definitions, they have
no access to jemalloc internals.
- stress: Black box stress tests. These tests link with the installable
shared jemalloc library, as well as with an internal allocator with
symbols prefixed by jet_ (same as for unit tests) that can be used to
allocate data structures that are internal to the test code.
Move existing tests into test/{unit,integration}/ as appropriate.
Split out internal parts of jemalloc_defs.h.in and put them in
jemalloc_internal_defs.h.in. This reduces internals exposure to
applications that #include <jemalloc/jemalloc.h>.
Refactor jemalloc.h header generation so that a single header file
results, and the prototypes can be used to generate jet_ prototypes for
tests. Split jemalloc.h.in into multiple parts (jemalloc_defs.h.in,
jemalloc_macros.h.in, jemalloc_protos.h.in, jemalloc_mangle.h.in) and
use a shell script to generate a unified jemalloc.h at configure time.
Change the default private namespace prefix from "" to "je_".
Add missing private namespace mangling.
Remove hard-coded private_namespace.h. Instead generate it and
private_unnamespace.h from private_symbols.txt. Use similar logic for
public symbols, which aids in name mangling for jet_ symbols.
Add test_warn() and test_fail(). Replace existing exit(1) calls with
test_fail() calls.
Theses newly added macros will be used to implement the equivalent under
MSVC. Also, move the definitions to headers, where they make more sense,
and for some, are even more useful there (e.g. malloc).
- Use the extensions autoconf finds for object and executable files.
- Remove the sorev variable, and replace SOREV definition with sorev's.
- Default to je_ prefix on win32.
Using errno on win32 doesn't quite work, because the value set in a shared
library can't be read from e.g. an executable calling the function setting
errno.
At the same time, since buferror always uses errno/GetLastError, don't pass
it.
Implement Valgrind support, as well as the redzone and quarantine
features, which help Valgrind detect memory errors. Redzones are only
implemented for small objects because the changes necessary to support
redzones around large and huge objects are complicated by in-place
reallocation, to the point that it isn't clear that the maintenance
burden is worth the incremental improvement to Valgrind support.
Merge arena_salloc() and arena_salloc_demote().
Refactor i[v]salloc() to expose the 'demote' option.
Use FreeBSD-specific functions (_pthread_mutex_init_calloc_cb(),
_malloc_{pre,post}fork()) to avoid bootstrapping issues due to
allocation in libc and libthr.
Add malloc_strtoumax() and use it instead of strtoul(). Disable
validation code in malloc_vsnprintf() and malloc_strtoumax() until
jemalloc is initialized. This is necessary because locale
initialization causes allocation for both vsnprintf() and strtoumax().
Force the lazy-lock feature on in order to avoid pthread_self(),
because it causes allocation.
Use syscall(SYS_write, ...) rather than write(...), because libthr wraps
write() and causes allocation. Without this workaround, it would not be
possible to print error messages in malloc_conf_init() without
substantially reworking bootstrapping.
Fix choose_arena_hard() to look at how many threads are assigned to the
candidate choice, rather than checking whether the arena is
uninitialized. This bug potentially caused more arenas to be
initialized than necessary.
