That stack space would matter if recursion was involved, but there
isn't any, and a max of 1440 bytes temporarily allocated on the stack
is not really a problem.
--HG--
extra : rebase_source : 2968fafe9d604d9e6c03ac93c21d8a3a087043a4
All uses of rb_wrap have "static" as first argument to rb_wrap, move that
in the macro itself.
--HG--
extra : rebase_source : cbfe87d0539452c044b415c725cb7ce6ebb5628c
Things left for followups:
- Full cleanup of disposed arenas: bug 1364359.
- Random arena Ids: bug 1402282.
- Enforcing the arena to match on moz_arena_{realloc,free}: bug 1402283.
- Make it impossible to use arenas not created with moz_create_arena
with moz_arena_* functions: bug 1402284.
Until it's proven to require a different data structure, arena lookup by
Id is done through the use of the same RB tree used everywhere else in
the allocator.
At this stage, the implementation of the API doesn't ride the trains,
but the API can be used safely and will fall back to normal allocations
transparently for the caller.
--HG--
extra : rebase_source : aaa9bdab5b4e0c534da0c9c7a299028fc8d66dc8
Things left for followups:
- Full cleanup of disposed arenas: bug 1364359.
- Random arena Ids: bug 1402282.
- Enforcing the arena to match on moz_arena_{realloc,free}: bug 1402283.
- Make it impossible to use arenas not created with moz_create_arena
with moz_arena_* functions: bug 1402284.
Until it's proven to require a different data structure, arena lookup by
Id is done through the use of the same RB tree used everywhere else in
the allocator.
At this stage, the implementation of the API doesn't ride the trains,
but the API can be used safely and will fall back to normal allocations
transparently for the caller.
--HG--
extra : rebase_source : 089e4cbb62c239713f40763ab819c79e5cbe28ce
The implementation is not doing anything just yet. This will be done in
a followup bug.
--HG--
extra : rebase_source : e301eac77c6bd8247c09d369074ecb8d7b5a1a2f
malloc, free, calloc, realloc and memalign constitute some sort of
minimal interface to the allocator. posix_memalign, aligned_alloc and
valloc are already defined in terms of memalign. The remaining functions
are not related to active allocation.
--HG--
extra : rebase_source : ee27ca70e271f3abef76c7782724d607b52f58b1
This effectively means malloc_hook_table_t is now C++ only, which is not
a big problem.
This also makes some functions use a return construct with functions
that don't return a value (such as free). While that is not allowed in
ISO C, it's allowed in C++, so the simplification is welcome (although,
retrospectively, it turns out C compilers don't complain about it
without -pedantic).
--HG--
extra : rebase_source : defd88ca3f6d478e61a4b970393dba60fb6ca81d
This was done in bug 736564 for the xulrunner SDK, which later became
the firefox SDK, which is now gone. So we don't actually need to keep it
separate anymore (except for logalloc/replay, which still needs to link
it directly, so we keep the library definition intact so it can be
referenced ; we just don't DIST_INSTALL it anymore, and always make it
linked into mozglue)
--HG--
extra : rebase_source : e4d0627ec907fe0139df5c0b2b9f7d04b43c7c78
In bug 1361258, we unified the initialization sequence on mac, and
chose to make the zone registration happen after jemalloc
initialization.
The order between jemalloc init and zone registration shouldn't actually
matter, because jemalloc initializes the first time the allocator is
actually used.
On the other hand, in some build setups (e.g. with light optimization),
the initialization of the thread_arena thread local variable can happen
after the forced jemalloc initialization because of the order the
corresponding static initializers run. In some levels of optimization,
the thread_arena initializer resets the value the jemalloc
initialization has set, which subsequently makes choose_arena() return
a bogus value (or hit an assertion in ThreadLocal.h on debug builds).
So instead of initializing jemalloc from a static initializer, which
then registers the zone, we instead register the zone and let jemalloc
initialize itself when used, which increases the chances of the
thread_arena initializer running first.
--HG--
extra : rebase_source : 4d9a5340d097ac8528dc4aaaf0c05bbef40b59bb
isalloc_validate is the function behind malloc_usable_size. If for some
reason malloc_usable_size is called before mozjemalloc is initialized,
this can lead to an unexpected crash.
The chance of this actually happening is rather slim on Linux
and Windows (although still possible), and impossible on Mac, due to the
fact the earlier something can end up calling it is after the
mozjemalloc zone is registered, which happens after initialization.
... except with bug 1399921, which reorders that initialization, and
puts the zone registration first. There's then a slim chance for the
zone allocator to call into zone_size, which calls malloc_usable_size,
to determine whether a pointer allocated by some other zone belongs to
mozjemalloc's.
And it turns out that does happen, during the startup of the
plugin-container process on OSX 10.10 (but not more recent versions).
--HG--
extra : rebase_source : 331d093b03add7b2c2ce440593f5aeccaaf4dd1f
Now that this is a C++ file, and that the function names are not
mangled, we can just use the actual C++ names.
We do however need to replace MOZ_MEMORY_API, which implies extern "C",
with MFBT_API.
Also use the correct type for the size given to operator new. It
happened to work before because the generated code would just jump to
malloc without touching any register, but on aarch64, unsigned int was
the wrong type.
--HG--
extra : rebase_source : 8045f30e9c609dd7d922c77d85ac017638df6961
And since the build system doesn't handle transitions from foo.c to
foo.cpp properly without a clobber, we work around the issue by
switching to unified sources.
--HG--
rename : memory/build/mozmemory_wrap.c => memory/build/mozmemory_wrap.cpp
extra : rebase_source : 3f074b4ccab255bb0eb16841f79582060fafbc86
It happens to work because of mozglue.def, but we might as well have the
right annotations (which will also make things correct when building this
file to C++)
--HG--
extra : rebase_source : 61056dc21c9c29bab62ad5d648e94dd56dc53b14
This used to be necessary because those functions might be prefixed with
__wrap_, and linked against with -Wl,--wrap, but that's not been the case
since bug 1077366. Furthermore, mozmem_malloc_impl nowadays only does
something on Windows, and those operators are only exposed on Android.
--HG--
extra : rebase_source : ca34442bfbc5fc8be20ffcfacb9afa0f2f818b82
In bug 1361258, we unified the initialization sequence on mac, and
chose to make the zone registration happen after jemalloc
initialization.
The order between jemalloc init and zone registration shouldn't actually
matter, because jemalloc initializes the first time the allocator is
actually used.
On the other hand, in some build setups (e.g. with light optimization),
the initialization of the thread_arena thread local variable can happen
after the forced jemalloc initialization because of the order the
corresponding static initializers run. In some levels of optimization,
the thread_arena initializer resets the value the jemalloc
initialization has set, which subsequently makes choose_arena() return
a bogus value (or hit an assertion in ThreadLocal.h on debug builds).
So instead of initializing jemalloc from a static initializer, which
then registers the zone, we instead register the zone and let jemalloc
initialize itself when used, which increases the chances of the
thread_arena initializer running first.
--HG--
extra : rebase_source : 4d9a5340d097ac8528dc4aaaf0c05bbef40b59bb
There is a lot of churn involved in adding new API surface to
mozjemalloc, and mozmemory.h is one. Instead of declaring
everything manually in there, "generate" the declarations through
malloc_decls.h.
--HG--
extra : rebase_source : 1416fa972319c419112c4a8b16759d90692db5b2
The bin-unused count in memory reports indicates how much memory is
used by runs of small and sub-page allocations that is not actually
allocated. This is generally thought as an indicator of fragmentation.
While this is generally true, with the use of thread local arenas by
stylo, combined with how stylo allocates memory, it ends up also being
an indicator of wasted memory.
For instance, over the lifetime of an AWSY iteration, there are only a
few allocations that ends up in the bucket for 2048 allocated bytes. In
the "worst" case, there's only one. But the run size for such
allocations is 132KiB. Which means just because we're allocating one
buffer of size between 1024 and 2048 bytes, we end up wasting 130+KiB.
Per thread.
Something similar happens with size classes of 512 and 1024, where the
run size is respectively 32KiB and 64KiB, and where there's at most a
handful of allocations of each class ever happening per thread.
Overall, an allocation log from a full AWSY iteration reveals that there
are only 448 of 860700 allocations happening on the stylo arenas that
involve sizes above (and excluding) 512 bytes, so 0.05%.
While there are improvements that can be done to mozjemalloc so that it
doesn't waste more than one page per sub-page size class, they are
changes that are too low-level to land at this time of the release
cycle. However, considering the numbers above and the fact that the
stylo arenas are only really meant to avoid lock contention during the
heavy parallel work involved, a short term, low risk, strategy is to
just delegate all sub-page (> 512, < 4096) and large (>= 4096) to the
main arena. Technically speaking, only sub-page allocations are causing
this waste, but it's more consistent to just delegate everything above
512 bytes.
This should save 132KiB + 64KiB = 196KiB per stylo thread.
--HG--
extra : rebase_source : c7233d60305365e76aa124045b1c9492068d9415
Until bug 1361258, there was only ever one mozjemalloc arena, and the
number of dirty pages we allow to be kept dirty, fixed to 1MB per arena,
was, in fact, 1MB for an entire process.
With stylo using thread local arenas, we now can have multiple arenas
per process, multiplying that number of dirty pages.
While those dirty pages may be reused later on, when other allocations
end up filling them later on, the fact that a relatively large number of
them is kept around for each stylo thread (in proportion to the amount of
memory ever allocated by stylo), combined with the fact that the memory
use from stylo depends on the workload generated by the pages being
visited, those dirty pages may very well not be used for a rather long
time. This is less of a problem with the main arena, used for most
everything else.
So, for each arena except the main one, we decrease the number of dirty
pages we allow to be kept around to 1/8 of the current value. We do this
by introducing a per-arena configuration of that maximum number.
--HG--
extra : rebase_source : 75eebb175b3746d5ca1c371606cface50ec70f2f
Those macros are one more thing that needs to be added when the
mozjemalloc API surface is increased, but after bug 1399350, nothing
actually needs them, so remove them.
--HG--
extra : rebase_source : 2bf62cc6c179540482722a72b0d0c134d2ac2a19
The files relevant to the memory allocator are currently spread between
memory/mozjemalloc and memory/build, and the distinction was
historically from sharing some Mozilla-specific things between
mozjemalloc and jemalloc3. That distinction is not useful anymore, so
we fold everything together.
As we will likely rename the allocator at some point in the future, it
is preferable to move away from the mozjemalloc directory rather than in
its direction.
--HG--
rename : memory/mozjemalloc/Makefile.in => memory/build/Makefile.in
rename : memory/mozjemalloc/mozjemalloc.cpp => memory/build/mozjemalloc.cpp
rename : memory/mozjemalloc/mozjemalloc.h => memory/build/mozjemalloc.h
rename : memory/mozjemalloc/mozjemalloc_types.h => memory/build/mozjemalloc_types.h
rename : memory/mozjemalloc/rb.h => memory/build/rb.h
clang warns about this code in mozmemory_wrap.c in the reimplementation
of vasprintf, complaining that `fmt` cannot be null:
if (str == NULL || fmt == NULL) {
^~~ ~~~~
clang is apparently exploiting knowledge about the requirements of
vasprintf here, but defensive programming on the part of our
reimplementation seems like the wiser course. Let's turn off the
warning.
Some system libraries call malloc_zone_free directly instead of free,
and sometimes they do that with the wrong zone. When that happens, we
circle back, trying to find the right zone, and call malloc_zone_free
with the right one, but when we can't find one, we crash, which matches
what the system free() would do. Except in one case where the pointer
we're being passed is NULL, in which case we can't trace it back to any
zone, but shouldn't crash (system free() explicitly doesn't crash in
that case).
--HG--
extra : rebase_source : 17efdcd80f1a53be7ab6b7293bfb6060a9aa4a48
Because malloc_decls.h is meant to be included multiple times, it
shouldn't actually declare things itself.
--HG--
extra : rebase_source : 9d6f9b2c61407265377845963a19ace2614160f4
jemalloc_ptr_info() gives info about any pointer, such as whether it's within a
live or free allocation, and if so, info about that allocation. It's useful for
debugging.
moz_malloc_enclosing_size_of() uses jemalloc_ptr_info() to measure the size of
an allocation from an interior pointer. It's useful for memory reporting,
especially for Rust code.
--HG--
extra : rebase_source : caa19cccf8c2d1f79cf004fe6a408775de5a7b22
Back when it was added (for Windows CE, in bug 488608), mozjemalloc was
C and all the supported compilers didn't support C99 bools. Now
mozjemalloc is C++, and all the supported compilers support C99 bools
for the cases where the type is used from C.
--HG--
extra : rebase_source : b9c710a0c48dc36cb473af59e3119131d13523ce
Back when mozjemalloc was considered third-party, and before bug
1365194, mozjemalloc was calling abort() and that was redirectory to
MOZ_CRASH through a moz_abort() function. Bug 1365194 changed that so
that moz_abort is called directly instead of abort, but the indirection
is actually not necessary anymore.
So we just kill moz_abort, which is unused anywhere else, and use
MOZ_CRASH directly.
Note this will (obviously) change crash signatures involving moz_abort.
--HG--
extra : rebase_source : 67698ffd8c5e52e62b9a0b7f28efb0352c8fe8ce
Bug 1186064 removed most of it when we started requiring VS 2015u2, but
the "frex" function exported through mozglue.def.in was only used
through the MSVCRT being patched by fixcrt.py, which is not done anymore.
So the "frex" export is not used anymore, and so the "dumb_free_thunk"
function is not used anymore as well.
--HG--
extra : rebase_source : 879c469c317c8b6749410a4a476d6c951c9a1d0f
Going through the system zone allocator for every call to realloc/free
on OSX is costly, because the zone allocator needs to first verify that
the allocations do belong to the allocator it invokes (which ends up
calling jemalloc's malloc_usable_size), which is unnecessary when we
expect the allocations to belong to jemalloc.
So, we export the malloc/realloc/free/etc. symbols from
libmozglue.dylib, such that libraries and programs linked against it
call directly into jemalloc instead of going through the system zone
allocator, effectively shortcutting the allocator verification.
The risk is that some things in Gecko try to realloc/free pointers it
got from system libraries, if those were allocated with a system zone
that is not jemalloc.
--HG--
extra : rebase_source : ee0b29e1275176f52e64f4648dfa7ce25d61292e
Going through the system zone allocator for every call to realloc/free
on OSX is costly, because the zone allocator needs to first verify that
the allocations do belong to the allocator it invokes (which ends up
calling jemalloc's malloc_usable_size), which is unnecessary when we
expect the allocations to belong to jemalloc.
So, we export the malloc/realloc/free/etc. symbols from
libmozglue.dylib, such that libraries and programs linked against it
calls directly into jemalloc instead of going through the system zone
allocator, effectively shortcutting the allocator verification.
The risk is that some things in Gecko try to realloc/free pointers it
got from system libraries, if those were allocated with a system zone
that is not jemalloc.
--HG--
extra : rebase_source : 45b9b98499760a7f946878d41d2fdaadb6dff4d6
Replace-malloc libraries, such as DMD, don't really need to care about
the details of implementing all the variants of aligned memory
allocation functions. Currently, by defining MOZ_REPLACE_ONLY_MEMALIGN
before including replace_malloc.h, they get predefined functions.
Instead of making that an opt-in at build time, we make the
replace-malloc initialization just fill the replace-malloc
malloc_table_t with implementations that rely on the replace_memalign
the library provides.
--HG--
extra : rebase_source : 0842a67d9bc27a9a86c33d14d98b9c25f39982fb
Until now, the malloc implementation functions would call the
replace-malloc functions if they exist, and fallback to the real
allocator in no such function exists. Instead of doing this, we now
fill the empty slots in the malloc_table_t with the real allocator
functions.
--HG--
extra : rebase_source : b54634f23188906939e4dc01fc5a3007de0f3f2c
We make replace_malloc_init_funcs called on all platforms and fill out a
malloc_table_t for the replace-malloc functions with what comes from
dlsym/GetProcAddress on Android/Windows, and from the dynamically linked
weak symbols replace_* on other platforms.
replace_malloc.h contains definitions of *_impl_t types for each of the
functions in the malloc_table_t, which is redundant with the
replace_*_impl_t types we were creating, so we remove those typedefs,
except for the two functions (init and get_bridge) that don't have such
a typedef. Those functions don't appear in malloc_table_t.
--HG--
extra : rebase_source : 3705a99ee07f63dbaa66973eef19ddab224e0911
We want, in a subsequent patch, to have replace_malloc_init_funcs be
called on all platforms (including those relying on the replace-malloc
library being loaded already) and perform more initialization.
To prepare for that, we move the non-platform-specific pieces out.
--HG--
extra : rebase_source : 239ed363ee168bf4f8a96e0a1ca52981cb941b71
All the _impl functions in replace-malloc.c are largely identical. This
replaces all of them with macro expansions.
--HG--
extra : rebase_source : 67a1809b0b0fc4645ea5041154fa3a6dcb6cce6b
This makes no significant difference in practice in the macro
expansions, but will help down the line.
--HG--
extra : rebase_source : 6d61c1f28c558321478d7e5f26390d27ae8ae3ac
MOZ_REPLACE_JEMALLOC was only defined when building jemalloc4 as a
replace-malloc library.
--HG--
extra : rebase_source : fa5c402da07fa96448c170b6db99629469691efe
This avoids many additions of `extern "C"` in C++ code and will avoid
having to do the same to mozjemalloc once built as C++.
--HG--
extra : rebase_source : af55696262f40a9dd16a19c29edcb9bb307d4957
This avoids many additions of `extern "C"` in C++ code and will avoid
having to do the same to mozjemalloc once built as C++.
--HG--
extra : rebase_source : af55696262f40a9dd16a19c29edcb9bb307d4957
NO_TLS used to be hardcoded on mac because up to 10.6, __thread was not
supported. Until recently, we still supported for 10.6, and it's not the
case anymore, so we could make mac builds use __thread.
Unfortunately, on OSX, __thread circles back calling malloc to allocate
storage on first access, so we have an infinite loop problem here.
Fortunately, pthread_keys don't have this property, so we can use that
instead. It doesn't appear to have significantly more overhead (and TLS
overhead is small anyways compared to the amount of work involved in
allocating memory with mozjemalloc).
At the same time, we uniformize the initialization sequence between
mozjemalloc and mozjemalloc+replace-malloc, such that we have less
occasions for surprises when riding the trains (replace-malloc being
nightly only), ensuring the zone registration happens at the end of
mozjemalloc's initialization.
Adapted from
4e2e3dd9cf
and
d9f7b2a430
As per the latter commit, it would seem unlocking, in fork() child
processes, mutexes that were locked in the parent process is not really
well supported on OSX 10.12. The addition of the zone_reinit_lock
function in 10.12 supports this idea.
--HG--
extra : rebase_source : b3b58558cc195d63200078085c7e9b6c9b8d83ff
Some system libraries are using malloc_default_zone() and then using
some of the malloc_zone_* API. Under normal conditions, those functions
check the malloc_zone_t/malloc_introspection_t struct for the values
that are allowed to be NULL, so that a NULL deref doesn't happen.
As of OSX 10.12, malloc_default_zone() doesn't return the actual default
zone anymore, but returns a fake, wrapper zone. The wrapper zone defines
all the possible functions in the malloc_zone_t/malloc_introspection_t
struct (almost), and calls the function from the registered default zone
(jemalloc in our case) on its own. Without checking whether the pointers
are NULL.
This means that a system library that calls e.g.
malloc_zone_batch_malloc(malloc_default_zone(), ...) ends up trying to
call jemalloc_zone.batch_malloc, which is NULL, and crash follows.
So as of OSX 10.12, the default zone is required to have all the
functions available (really, the same as the wrapper zone), even if they
do nothing.
This is arguably a bug in libsystem_malloc in OSX 10.12, but jemalloc
still needs to work in that case.
[Adapted from
c6943acb3c]
--HG--
extra : rebase_source : 7d7a5b47fa18f56183e99c3655aee003c9be161e
The SDK jemalloc is built against might be not be the latest for various
reasons, but the resulting binary ought to work on newer versions of
OSX.
In order to ensure this, we need the fullest definitions possible, so
copy what we need from the latest version of malloc/malloc.h available
on opensource.apple.com.
[Adapted from
c68bb41793]
--HG--
extra : rebase_source : ab19c478b568ea24095a3be62c39fb81efc1920a
We have been using a different zone allocator between mozjemalloc and
replace-malloc for a long time. Jemalloc 4 uses the same as
replace-malloc, albeit as part of the jemalloc upstream code base.
We've been bitten many times in the past with Apple changes breaking the
zone allocator, and each time we've had to make changes to the three
instances, although two of them are similar and the changes there are
straightforward.
It also turns out that the way the mozjemalloc zone allocator is set up,
when a new version of OSX appears with a new version of the system zone
allocator, Firefox ends up using the system allocator, because the zone
allocator version is not supported.
So, we use the same zone allocator for both replace-malloc and
mozjemalloc, making everything on par with jemalloc 4.
--HG--
extra : rebase_source : 9c0e245b5f82bb71294370d607e690c05cc89fbc
The intent here is to reuse the zone allocator for mozjemalloc, to avoid
all the shortcomings of mozjemalloc using a different one. This change
only moves the replace-malloc zone allocator out of replace-malloc.c, to
make changes for mozjemalloc integration clearer.
--HG--
rename : memory/build/replace_malloc.c => memory/build/zone.c
extra : rebase_source : 8b98efaa4a88862f2967c855b511e92beb9c4031
Somehow, we never called those hooks when replace-malloc is enabled. I'd
expect this to cause random deadlocks when forking, and I'm surprised
this hasn't surfaced. Maybe it actually causes some intermittent oranges
on automation, who knows.
This also brings consistency with what is done for jemalloc 4, and with
the mozjemalloc implementation, too, that we're going to replace with
this one in a subsequent changeset.
--HG--
extra : rebase_source : 059567d17f928098db8367e9081b631ced351110
This removes the unnecessary setting of c-basic-offset from all
python-mode files.
This was automatically generated using
perl -pi -e 's/; *c-basic-offset: *[0-9]+//'
... on the affected files.
The bulk of these files are moz.build files but there a few others as
well.
MozReview-Commit-ID: 2pPf3DEiZqx
--HG--
extra : rebase_source : 0a7dcac80b924174a2c429b093791148ea6ac204
Jemalloc 4 purges dirty pages regularly during free() when the ratio of dirty
pages compared to active pages is higher than 1 << lg_dirty_mult. We set
lg_dirty_mult in jemalloc_config to limit RSS usage, but it also has an impact
on performance.
So instead of enforcing a high ratio to force more pages being purged, we keep
jemalloc's default ratio of 8, and force a regular purge of all dirty pages,
after cycle collection.
Keeping jemalloc's default ratio avoids cycle-collection-triggered purge to
have to go through really all dirty pages when there are a lot, in which case
the normal jemalloc purge during free() will already have kicked in. It also
takes care of everything that doesn't run the cycle collector still having
a level of purge, like plugins in the plugin-container.
At the same time, since jemalloc_purge_freed_pages does nothing with jemalloc 4,
repurpose the MEMORY_FREE_PURGED_PAGES_MS telemetry probe to track the time
spent in this cycle-collector-triggered purge.
The patch removes 455 occurrences of FAIL_ON_WARNINGS from moz.build files, and
adds 78 instances of ALLOW_COMPILER_WARNINGS. About half of those 78 are in
code we control and which should be removable with a little effort.
--HG--
extra : rebase_source : 82e3387abfbd5f1471e953961d301d3d97ed2973
The bulk of this commit was generated by running:
run-clang-tidy.py \
-checks='-*,llvm-namespace-comment' \
-header-filter=^/.../mozilla-central/.* \
-fix
Bug 818922 made MOZ_REPLACE_MALLOC a global define, and that changed the
defines set when building mozjemalloc_compat.c for the jemalloc3
replace-malloc library. In turn, this made the symbol munging wrong for
that library, making the jemalloc_* functions exported as je_jemalloc_*
instead of replace_jemalloc_*.
This also effectively changes how DMD is enabled from requiring both
replace-malloc initialization and the DMD environment variable to
requiring only the former. The DMD environment variable can still be
used to specify options, but not to disable entirely.
This however doesn't touch all the parts that do enable DMD by setting
the DMD environment variable to 1, so the code to handle this value
is kept.
There are, sadly, many combinations of linkage in use throughout the tree.
The main differentiator, though, is between program/libraries related to
Gecko or not. Kind of. Some need mozglue, some don't. Some need dependent
linkage, some standalone.
Anyways, these new templates remove the need to manually define the
right dependencies against xpcomglue, nspr, mozalloc and mozglue
in most cases.
Places that build programs and were resetting MOZ_GLUE_PROGRAM_LDFLAGS
or that build libraries and were resetting MOZ_GLUE_LDFLAGS can now
just not use those Gecko-specific templates.
It appears to be an unnecessary optimization, since the compiler is still inlining
the functions when they're not marked static. OTOH, following patches will require
the _impl functions not to be static.
Since essentially everything is linked to libmozglue and libmozglue takes
precedence in symbol resolution in our dynamic linker, there is no need
to wrap most symbols. PR_GetEnv/PR_SetEnv still needs wrapping because
there's no other way to actually wrap the calls from NSPR itself and NSS,
as well as the symbols wrapped because our dynamic linker can't find them
in system libraries on some devices because they're weak.