701 lines
24 KiB
C++
701 lines
24 KiB
C++
#pragma once
|
|
|
|
#ifdef _MSC_VER
|
|
# define ALLOCATOR __declspec(allocator)
|
|
#else
|
|
# define ALLOCATOR
|
|
#endif
|
|
|
|
#include "../ds/ptrwrap.h"
|
|
#include "corealloc.h"
|
|
#include "freelist.h"
|
|
#include "localcache.h"
|
|
#include "pool.h"
|
|
#include "remotecache.h"
|
|
#include "sizeclasstable.h"
|
|
|
|
#ifdef SNMALLOC_PASS_THROUGH
|
|
# include "external_alloc.h"
|
|
#endif
|
|
|
|
#ifdef SNMALLOC_TRACING
|
|
# include <iostream>
|
|
#endif
|
|
#include <string.h>
|
|
#include <utility>
|
|
namespace snmalloc
|
|
{
|
|
enum Boundary
|
|
{
|
|
/**
|
|
* The location of the first byte of this allocation.
|
|
*/
|
|
Start,
|
|
/**
|
|
* The location of the last byte of the allocation.
|
|
*/
|
|
End,
|
|
/**
|
|
* The location one past the end of the allocation. This is mostly useful
|
|
* for bounds checking, where anything less than this value is safe.
|
|
*/
|
|
OnePastEnd
|
|
};
|
|
|
|
/**
|
|
* A local allocator contains the fast-path allocation routines and
|
|
* encapsulates all of the behaviour of an allocator that is local to some
|
|
* context, typically a thread. This delegates to a `CoreAllocator` for all
|
|
* slow-path operations, including anything that requires claiming new chunks
|
|
* of address space.
|
|
*
|
|
* The template parameter defines the configuration of this allocator and is
|
|
* passed through to the associated `CoreAllocator`. The `Options` structure
|
|
* of this defines one property that directly affects the behaviour of the
|
|
* local allocator: `LocalAllocSupportsLazyInit`, which defaults to true,
|
|
* defines whether the local allocator supports lazy initialisation. If this
|
|
* is true then the local allocator will construct a core allocator the first
|
|
* time it needs to perform a slow-path operation. If this is false then the
|
|
* core allocator must be provided externally by invoking the `init` method
|
|
* on this class *before* any allocation-related methods are called.
|
|
*/
|
|
template<SNMALLOC_CONCEPT(ConceptBackendGlobals) SharedStateHandle>
|
|
class LocalAllocator
|
|
{
|
|
public:
|
|
using StateHandle = SharedStateHandle;
|
|
|
|
private:
|
|
using CoreAlloc = CoreAllocator<SharedStateHandle>;
|
|
|
|
// Free list per small size class. These are used for
|
|
// allocation on the fast path. This part of the code is inspired by
|
|
// mimalloc.
|
|
// Also contains remote deallocation cache.
|
|
LocalCache local_cache{&SharedStateHandle::unused_remote};
|
|
|
|
// Underlying allocator for most non-fast path operations.
|
|
CoreAlloc* core_alloc{nullptr};
|
|
|
|
// As allocation and deallocation can occur during thread teardown
|
|
// we need to record if we are already in that state as we will not
|
|
// receive another teardown call, so each operation needs to release
|
|
// the underlying data structures after the call.
|
|
bool post_teardown{false};
|
|
|
|
/**
|
|
* Checks if the core allocator has been initialised, and runs the
|
|
* `action` with the arguments, args.
|
|
*
|
|
* If the core allocator is not initialised, then first initialise it,
|
|
* and then perform the action using the core allocator.
|
|
*
|
|
* This is an abstraction of the common pattern of check initialisation,
|
|
* and then performing the operations. It is carefully crafted to tail
|
|
* call the continuations, and thus generate good code for the fast path.
|
|
*/
|
|
template<typename Action, typename... Args>
|
|
SNMALLOC_FAST_PATH decltype(auto) check_init(Action action, Args... args)
|
|
{
|
|
if (likely(core_alloc != nullptr))
|
|
{
|
|
return core_alloc->handle_message_queue(action, core_alloc, args...);
|
|
}
|
|
return lazy_init(action, args...);
|
|
}
|
|
|
|
/**
|
|
* This initialises the fast allocator by acquiring a core allocator, and
|
|
* setting up its local copy of data structures.
|
|
*
|
|
* If the allocator does not support lazy initialisation then this assumes
|
|
* that initialisation has already taken place and invokes the action
|
|
* immediately.
|
|
*/
|
|
template<typename Action, typename... Args>
|
|
SNMALLOC_SLOW_PATH decltype(auto) lazy_init(Action action, Args... args)
|
|
{
|
|
SNMALLOC_ASSERT(core_alloc == nullptr);
|
|
if constexpr (!SharedStateHandle::Options.LocalAllocSupportsLazyInit)
|
|
{
|
|
SNMALLOC_CHECK(
|
|
false &&
|
|
"lazy_init called on an allocator that doesn't support lazy "
|
|
"initialisation");
|
|
// Unreachable, but needed to keep the type checker happy in deducing
|
|
// the return type of this function.
|
|
return static_cast<decltype(action(core_alloc, args...))>(nullptr);
|
|
}
|
|
else
|
|
{
|
|
// Initialise the thread local allocator
|
|
if constexpr (SharedStateHandle::Options.CoreAllocOwnsLocalState)
|
|
{
|
|
init();
|
|
}
|
|
|
|
// register_clean_up must be called after init. register clean up may
|
|
// be implemented with allocation, so need to ensure we have a valid
|
|
// allocator at this point.
|
|
if (!post_teardown)
|
|
// Must be called at least once per thread.
|
|
// A pthread implementation only calls the thread destruction handle
|
|
// if the key has been set.
|
|
SharedStateHandle::register_clean_up();
|
|
|
|
// Perform underlying operation
|
|
auto r = action(core_alloc, args...);
|
|
|
|
// After performing underlying operation, in the case of teardown
|
|
// already having begun, we must flush any state we just acquired.
|
|
if (post_teardown)
|
|
{
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "post_teardown flush()" << std::endl;
|
|
#endif
|
|
// We didn't have an allocator because the thread is being torndown.
|
|
// We need to return any local state, so we don't leak it.
|
|
flush();
|
|
}
|
|
|
|
return r;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Allocation that are larger than are handled by the fast allocator must be
|
|
* passed to the core allocator.
|
|
*/
|
|
template<ZeroMem zero_mem>
|
|
SNMALLOC_SLOW_PATH capptr::Alloc<void> alloc_not_small(size_t size)
|
|
{
|
|
if (size == 0)
|
|
{
|
|
// Deal with alloc zero of with a small object here.
|
|
// Alternative semantics giving nullptr is also allowed by the
|
|
// standard.
|
|
return small_alloc<NoZero>(1);
|
|
}
|
|
|
|
return check_init([&](CoreAlloc* core_alloc) {
|
|
// Grab slab of correct size
|
|
// Set remote as large allocator remote.
|
|
auto [chunk, meta] = ChunkAllocator::alloc_chunk<SharedStateHandle>(
|
|
core_alloc->get_backend_local_state(),
|
|
core_alloc->chunk_local_state,
|
|
bits::next_pow2_bits(size), // TODO
|
|
large_size_to_chunk_sizeclass(size),
|
|
large_size_to_chunk_size(size),
|
|
SharedStateHandle::fake_large_remote);
|
|
// set up meta data so sizeclass is correct, and hence alloc size, and
|
|
// external pointer.
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "size " << size << " pow2 size "
|
|
<< bits::next_pow2_bits(size) << std::endl;
|
|
#endif
|
|
|
|
// Note that meta data is not currently used for large allocs.
|
|
// meta->initialise(size_to_sizeclass(size));
|
|
UNUSED(meta);
|
|
|
|
if (zero_mem == YesZero)
|
|
{
|
|
SharedStateHandle::Pal::template zero<false>(
|
|
chunk.unsafe_ptr(), size);
|
|
}
|
|
|
|
return capptr_chunk_is_alloc(capptr_to_user_address_control(chunk));
|
|
});
|
|
}
|
|
|
|
template<ZeroMem zero_mem>
|
|
SNMALLOC_FAST_PATH capptr::Alloc<void> small_alloc(size_t size)
|
|
{
|
|
// SNMALLOC_ASSUME(size <= sizeclass_to_size(NUM_SIZECLASSES));
|
|
auto domesticate = [this](freelist::QueuePtr p)
|
|
SNMALLOC_FAST_PATH_LAMBDA {
|
|
return capptr_domesticate<SharedStateHandle>(
|
|
core_alloc->backend_state_ptr(), p);
|
|
};
|
|
auto slowpath = [&](
|
|
sizeclass_t sizeclass,
|
|
freelist::Iter<>* fl) SNMALLOC_FAST_PATH_LAMBDA {
|
|
if (likely(core_alloc != nullptr))
|
|
{
|
|
return core_alloc->handle_message_queue(
|
|
[](
|
|
CoreAlloc* core_alloc,
|
|
sizeclass_t sizeclass,
|
|
freelist::Iter<>* fl) {
|
|
return core_alloc->template small_alloc<zero_mem>(sizeclass, *fl);
|
|
},
|
|
core_alloc,
|
|
sizeclass,
|
|
fl);
|
|
}
|
|
return lazy_init(
|
|
[&](CoreAlloc*, sizeclass_t sizeclass) {
|
|
return small_alloc<zero_mem>(sizeclass_to_size(sizeclass));
|
|
},
|
|
sizeclass);
|
|
};
|
|
|
|
return local_cache.template alloc<zero_mem, SharedStateHandle>(
|
|
domesticate, size, slowpath);
|
|
}
|
|
|
|
/**
|
|
* Send all remote deallocation to other threads.
|
|
*/
|
|
void post_remote_cache()
|
|
{
|
|
core_alloc->post();
|
|
}
|
|
|
|
/**
|
|
* Slow path for deallocation we do not have space for this remote
|
|
* deallocation. This could be because,
|
|
* - we actually don't have space for this remote deallocation,
|
|
* and need to send them on; or
|
|
* - the allocator was not already initialised.
|
|
* In the second case we need to recheck if this is a remote deallocation,
|
|
* as we might acquire the originating allocator.
|
|
*/
|
|
SNMALLOC_SLOW_PATH void dealloc_remote_slow(capptr::Alloc<void> p)
|
|
{
|
|
if (core_alloc != nullptr)
|
|
{
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "Remote dealloc post" << p.unsafe_ptr() << " size "
|
|
<< alloc_size(p.unsafe_ptr()) << std::endl;
|
|
#endif
|
|
MetaEntry entry = SharedStateHandle::Pagemap::get_metaentry(
|
|
core_alloc->backend_state_ptr(), address_cast(p));
|
|
local_cache.remote_dealloc_cache.template dealloc<sizeof(CoreAlloc)>(
|
|
entry.get_remote()->trunc_id(), p, key_global);
|
|
post_remote_cache();
|
|
return;
|
|
}
|
|
|
|
// Recheck what kind of dealloc we should do in case the allocator we get
|
|
// from lazy_init is the originating allocator. (TODO: but note that this
|
|
// can't suddenly become a large deallocation; the only distinction is
|
|
// between being ours to handle and something to post to a Remote.)
|
|
lazy_init(
|
|
[&](CoreAlloc*, CapPtr<void, capptr::bounds::Alloc> p) {
|
|
dealloc(p.unsafe_ptr()); // TODO don't double count statistics
|
|
return nullptr;
|
|
},
|
|
p);
|
|
}
|
|
|
|
/**
|
|
* Abstracts access to the message queue to handle different
|
|
* layout configurations of the allocator.
|
|
*/
|
|
auto& message_queue()
|
|
{
|
|
return local_cache.remote_allocator;
|
|
}
|
|
|
|
/**
|
|
* Call `SharedStateHandle::is_initialised()` if it is implemented,
|
|
* unconditionally returns true otherwise.
|
|
*/
|
|
SNMALLOC_FAST_PATH
|
|
bool is_initialised()
|
|
{
|
|
return call_is_initialised<SharedStateHandle>(nullptr, 0);
|
|
}
|
|
|
|
/**
|
|
* SFINAE helper. Matched only if `T` implements `ensure_init`. Calls it
|
|
* if it exists.
|
|
*/
|
|
template<typename T>
|
|
SNMALLOC_FAST_PATH auto call_ensure_init(T*, int)
|
|
-> decltype(T::ensure_init())
|
|
{
|
|
T::ensure_init();
|
|
}
|
|
|
|
/**
|
|
* SFINAE helper. Matched only if `T` does not implement `ensure_init`.
|
|
* Does nothing if called.
|
|
*/
|
|
template<typename T>
|
|
SNMALLOC_FAST_PATH auto call_ensure_init(T*, long)
|
|
{}
|
|
|
|
/**
|
|
* Call `SharedStateHandle::ensure_init()` if it is implemented, do
|
|
* nothing otherwise.
|
|
*/
|
|
SNMALLOC_FAST_PATH
|
|
void ensure_init()
|
|
{
|
|
call_ensure_init<SharedStateHandle>(nullptr, 0);
|
|
}
|
|
|
|
public:
|
|
constexpr LocalAllocator() = default;
|
|
LocalAllocator(const LocalAllocator&) = delete;
|
|
LocalAllocator& operator=(const LocalAllocator&) = delete;
|
|
|
|
/**
|
|
* Initialise the allocator. For allocators that support local
|
|
* initialisation, this is called with a core allocator that this class
|
|
* allocates (from a pool allocator) the first time it encounters a slow
|
|
* path. If this class is configured without lazy initialisation support
|
|
* then this must be called externally
|
|
*/
|
|
void init(CoreAlloc* c)
|
|
{
|
|
// Initialise the global allocator structures
|
|
ensure_init();
|
|
|
|
// Should only be called if the allocator has not been initialised.
|
|
SNMALLOC_ASSERT(core_alloc == nullptr);
|
|
|
|
// Attach to it.
|
|
c->attach(&local_cache);
|
|
core_alloc = c;
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "init(): core_alloc=" << core_alloc << "@" << &local_cache
|
|
<< std::endl;
|
|
#endif
|
|
// local_cache.stats.sta rt();
|
|
}
|
|
|
|
// This is effectively the constructor for the LocalAllocator, but due to
|
|
// not wanting initialisation checks on the fast path, it is initialised
|
|
// lazily.
|
|
void init()
|
|
{
|
|
// Initialise the global allocator structures
|
|
ensure_init();
|
|
// Grab an allocator for this thread.
|
|
init(AllocPool<SharedStateHandle>::acquire(&(this->local_cache)));
|
|
}
|
|
|
|
// Return all state in the fast allocator and release the underlying
|
|
// core allocator. This is used during teardown to empty the thread
|
|
// local state.
|
|
void flush()
|
|
{
|
|
// Detached thread local state from allocator.
|
|
if (core_alloc != nullptr)
|
|
{
|
|
core_alloc->flush();
|
|
|
|
// core_alloc->stats().add(local_cache.stats);
|
|
// // Reset stats, required to deal with repeated flushing.
|
|
// new (&local_cache.stats) Stats();
|
|
|
|
// Detach underlying allocator
|
|
core_alloc->attached_cache = nullptr;
|
|
// Return underlying allocator to the system.
|
|
if constexpr (SharedStateHandle::Options.CoreAllocOwnsLocalState)
|
|
{
|
|
AllocPool<SharedStateHandle>::release(core_alloc);
|
|
}
|
|
|
|
// Set up thread local allocator to look like
|
|
// it is new to hit slow paths.
|
|
core_alloc = nullptr;
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "flush(): core_alloc=" << core_alloc << std::endl;
|
|
#endif
|
|
local_cache.remote_allocator = &SharedStateHandle::unused_remote;
|
|
local_cache.remote_dealloc_cache.capacity = 0;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Allocate memory of a dynamically known size.
|
|
*/
|
|
template<ZeroMem zero_mem = NoZero>
|
|
SNMALLOC_FAST_PATH ALLOCATOR void* alloc(size_t size)
|
|
{
|
|
#ifdef SNMALLOC_PASS_THROUGH
|
|
// snmalloc guarantees a lot of alignment, so we can depend on this
|
|
// make pass through call aligned_alloc with the alignment snmalloc
|
|
// would guarantee.
|
|
void* result = external_alloc::aligned_alloc(
|
|
natural_alignment(size), round_size(size));
|
|
if constexpr (zero_mem == YesZero)
|
|
memset(result, 0, size);
|
|
return result;
|
|
#else
|
|
// Perform the - 1 on size, so that zero wraps around and ends up on
|
|
// slow path.
|
|
if (likely((size - 1) <= (sizeclass_to_size(NUM_SIZECLASSES - 1) - 1)))
|
|
{
|
|
// Small allocations are more likely. Improve
|
|
// branch prediction by placing this case first.
|
|
return capptr_reveal(small_alloc<zero_mem>(size));
|
|
}
|
|
|
|
return capptr_reveal(alloc_not_small<zero_mem>(size));
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* Allocate memory of a statically known size.
|
|
*/
|
|
template<size_t size, ZeroMem zero_mem = NoZero>
|
|
SNMALLOC_FAST_PATH ALLOCATOR void* alloc()
|
|
{
|
|
// TODO optimise
|
|
return alloc<zero_mem>(size);
|
|
}
|
|
|
|
SNMALLOC_FAST_PATH void dealloc(void* p_raw)
|
|
{
|
|
#ifdef SNMALLOC_PASS_THROUGH
|
|
external_alloc::free(p_raw);
|
|
#else
|
|
// TODO:
|
|
// Care is needed so that dealloc(nullptr) works before init
|
|
// The backend allocator must ensure that a minimal page map exists
|
|
// before init, that maps null to a remote_deallocator that will never
|
|
// be in thread local state.
|
|
|
|
capptr::AllocWild<void> p_wild = capptr_from_client(p_raw);
|
|
|
|
/*
|
|
* p_tame may be nullptr, even if p_raw/p_wild are not, in the case
|
|
* where domestication fails. We exclusively use p_tame below so that
|
|
* such failures become no ops; in the nullptr path, which should be
|
|
* well off the fast path, we could be slightly more aggressive and test
|
|
* that p_raw is also nullptr and Pal::error() if not. (TODO)
|
|
*
|
|
* We do not rely on the bounds-checking ability of domestication here,
|
|
* and just check the address (and, on other architectures, perhaps
|
|
* well-formedness) of this pointer. The remainder of the logic will
|
|
* deal with the object's extent.
|
|
*/
|
|
capptr::Alloc<void> p_tame = capptr_domesticate<SharedStateHandle>(
|
|
core_alloc->backend_state_ptr(), p_wild);
|
|
|
|
const MetaEntry& entry = SharedStateHandle::Pagemap::get_metaentry(
|
|
core_alloc->backend_state_ptr(), address_cast(p_tame));
|
|
if (likely(local_cache.remote_allocator == entry.get_remote()))
|
|
{
|
|
if (likely(CoreAlloc::dealloc_local_object_fast(
|
|
entry, p_tame, local_cache.entropy)))
|
|
return;
|
|
core_alloc->dealloc_local_object_slow(entry);
|
|
return;
|
|
}
|
|
|
|
if (likely(entry.get_remote() != SharedStateHandle::fake_large_remote))
|
|
{
|
|
// Check if we have space for the remote deallocation
|
|
if (local_cache.remote_dealloc_cache.reserve_space(entry))
|
|
{
|
|
local_cache.remote_dealloc_cache.template dealloc<sizeof(CoreAlloc)>(
|
|
entry.get_remote()->trunc_id(), p_tame, key_global);
|
|
# ifdef SNMALLOC_TRACING
|
|
std::cout << "Remote dealloc fast" << p_raw << " size "
|
|
<< alloc_size(p_raw) << std::endl;
|
|
# endif
|
|
return;
|
|
}
|
|
|
|
dealloc_remote_slow(p_tame);
|
|
return;
|
|
}
|
|
|
|
// Large deallocation or null.
|
|
if (likely(p_tame != nullptr))
|
|
{
|
|
size_t entry_sizeclass = entry.get_sizeclass();
|
|
|
|
// Check this is managed by this pagemap.
|
|
//
|
|
// TODO: Should this be tested even in the !CHECK_CLIENT case? Things
|
|
// go fairly pear-shaped, with the ASM's ranges[] getting cross-linked
|
|
// with a ChunkAllocator's chunk_stack[0], which seems bad.
|
|
check_client(entry_sizeclass != 0, "Not allocated by snmalloc.");
|
|
|
|
size_t size = bits::one_at_bit(entry_sizeclass);
|
|
size_t slab_sizeclass =
|
|
metaentry_chunk_sizeclass_to_slab_sizeclass(entry_sizeclass);
|
|
|
|
// Check for start of allocation.
|
|
check_client(
|
|
pointer_align_down(p_tame, size) == p_tame,
|
|
"Not start of an allocation.");
|
|
|
|
# ifdef SNMALLOC_TRACING
|
|
std::cout << "Large deallocation: " << size
|
|
<< " chunk sizeclass: " << slab_sizeclass << std::endl;
|
|
# else
|
|
UNUSED(size);
|
|
# endif
|
|
|
|
auto slab_record =
|
|
static_cast<ChunkRecord*>(entry.get_metaslab_no_remote());
|
|
|
|
SNMALLOC_ASSERT(
|
|
address_cast(slab_record->meta_common.chunk) == address_cast(p_tame));
|
|
|
|
check_init(
|
|
[](
|
|
CoreAlloc* core_alloc,
|
|
ChunkRecord* slab_record,
|
|
size_t slab_sizeclass) {
|
|
ChunkAllocator::dealloc<SharedStateHandle>(
|
|
core_alloc->get_backend_local_state(),
|
|
core_alloc->chunk_local_state,
|
|
slab_record,
|
|
slab_sizeclass);
|
|
return nullptr;
|
|
},
|
|
slab_record,
|
|
slab_sizeclass);
|
|
return;
|
|
}
|
|
|
|
# ifdef SNMALLOC_TRACING
|
|
std::cout << "nullptr deallocation" << std::endl;
|
|
# endif
|
|
return;
|
|
#endif
|
|
}
|
|
|
|
SNMALLOC_FAST_PATH void dealloc(void* p, size_t s)
|
|
{
|
|
UNUSED(s);
|
|
dealloc(p);
|
|
}
|
|
|
|
template<size_t size>
|
|
SNMALLOC_FAST_PATH void dealloc(void* p)
|
|
{
|
|
UNUSED(size);
|
|
dealloc(p);
|
|
}
|
|
|
|
void teardown()
|
|
{
|
|
#ifdef SNMALLOC_TRACING
|
|
std::cout << "Teardown: core_alloc=" << core_alloc << "@" << &local_cache
|
|
<< std::endl;
|
|
#endif
|
|
post_teardown = true;
|
|
if (core_alloc != nullptr)
|
|
{
|
|
flush();
|
|
}
|
|
}
|
|
|
|
SNMALLOC_FAST_PATH size_t alloc_size(const void* p_raw)
|
|
{
|
|
#ifdef SNMALLOC_PASS_THROUGH
|
|
return external_alloc::malloc_usable_size(const_cast<void*>(p_raw));
|
|
#else
|
|
// TODO What's the domestication policy here? At the moment we just
|
|
// probe the pagemap with the raw address, without checks. There could
|
|
// be implicit domestication through the `SharedStateHandle::Pagemap` or
|
|
// we could just leave well enough alone.
|
|
|
|
// Note that alloc_size should return 0 for nullptr.
|
|
// Other than nullptr, we know the system will be initialised as it must
|
|
// be called with something we have already allocated.
|
|
//
|
|
// To handle this case we require the uninitialised pagemap contain an
|
|
// entry for the first chunk of memory, that states it represents a
|
|
// large object, so we can pull the check for null off the fast path.
|
|
MetaEntry entry = SharedStateHandle::Pagemap::get_metaentry(
|
|
core_alloc->backend_state_ptr(), address_cast(p_raw));
|
|
|
|
if (likely(entry.get_remote() != SharedStateHandle::fake_large_remote))
|
|
return sizeclass_to_size(entry.get_sizeclass());
|
|
|
|
// Sizeclass zero is for large is actually zero
|
|
if (likely(entry.get_sizeclass() != 0))
|
|
return bits::one_at_bit(entry.get_sizeclass());
|
|
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* Returns the Start/End of an object allocated by this allocator
|
|
*
|
|
* It is valid to pass any pointer, if the object was not allocated
|
|
* by this allocator, then it give the start and end as the whole of
|
|
* the potential pointer space.
|
|
*/
|
|
template<Boundary location = Start>
|
|
void* external_pointer(void* p_raw)
|
|
{
|
|
#ifndef SNMALLOC_PASS_THROUGH
|
|
// TODO What's the domestication policy here? At the moment we just
|
|
// probe the pagemap with the raw address, without checks. There could
|
|
// be implicit domestication through the `SharedStateHandle::Pagemap` or
|
|
// we could just leave well enough alone.
|
|
|
|
capptr::AllocWild<void> p = capptr_from_client(p_raw);
|
|
|
|
MetaEntry entry =
|
|
SharedStateHandle::Pagemap::template get_metaentry<true>(
|
|
core_alloc->backend_state_ptr(), address_cast(p));
|
|
auto sizeclass = entry.get_sizeclass();
|
|
if (likely(entry.get_remote() != SharedStateHandle::fake_large_remote))
|
|
{
|
|
auto rsize = sizeclass_to_size(sizeclass);
|
|
auto offset = address_cast(p) & (sizeclass_to_slab_size(sizeclass) - 1);
|
|
auto start_offset = round_by_sizeclass(sizeclass, offset);
|
|
if constexpr (location == Start)
|
|
{
|
|
UNUSED(rsize);
|
|
return capptr_reveal_wild(pointer_offset(p, start_offset - offset));
|
|
}
|
|
else if constexpr (location == End)
|
|
return capptr_reveal_wild(
|
|
pointer_offset(p, rsize + start_offset - offset - 1));
|
|
else
|
|
return capptr_reveal_wild(
|
|
pointer_offset(p, rsize + start_offset - offset));
|
|
}
|
|
|
|
// Sizeclass zero of a large allocation is used for not managed by us.
|
|
if (likely(sizeclass != 0))
|
|
{
|
|
// This is a large allocation, find start by masking.
|
|
auto rsize = bits::one_at_bit(sizeclass);
|
|
auto start = pointer_align_down(p, rsize);
|
|
if constexpr (location == Start)
|
|
return capptr_reveal_wild(start);
|
|
else if constexpr (location == End)
|
|
return capptr_reveal_wild(pointer_offset(start, rsize - 1));
|
|
else
|
|
return capptr_reveal_wild(pointer_offset(start, rsize));
|
|
}
|
|
#else
|
|
UNUSED(p_raw);
|
|
#endif
|
|
|
|
if constexpr ((location == End) || (location == OnePastEnd))
|
|
// We don't know the End, so return MAX_PTR
|
|
return reinterpret_cast<void*>(UINTPTR_MAX);
|
|
else
|
|
// We don't know the Start, so return MIN_PTR
|
|
return nullptr;
|
|
}
|
|
|
|
/**
|
|
* Accessor, returns the local cache. If embedding code is allocating the
|
|
* core allocator for use by this local allocator then it needs to access
|
|
* this field.
|
|
*/
|
|
LocalCache& get_local_cache()
|
|
{
|
|
return local_cache;
|
|
}
|
|
};
|
|
} // namespace snmalloc
|