2946cd7010
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
72 lines
2.3 KiB
C++
72 lines
2.3 KiB
C++
//===-- sanitizer_persistent_allocator.h ------------------------*- C++ -*-===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// A fast memory allocator that does not support free() nor realloc().
|
|
// All allocations are forever.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef SANITIZER_PERSISTENT_ALLOCATOR_H
|
|
#define SANITIZER_PERSISTENT_ALLOCATOR_H
|
|
|
|
#include "sanitizer_internal_defs.h"
|
|
#include "sanitizer_mutex.h"
|
|
#include "sanitizer_atomic.h"
|
|
#include "sanitizer_common.h"
|
|
|
|
namespace __sanitizer {
|
|
|
|
class PersistentAllocator {
|
|
public:
|
|
void *alloc(uptr size);
|
|
|
|
private:
|
|
void *tryAlloc(uptr size);
|
|
StaticSpinMutex mtx; // Protects alloc of new blocks for region allocator.
|
|
atomic_uintptr_t region_pos; // Region allocator for Node's.
|
|
atomic_uintptr_t region_end;
|
|
};
|
|
|
|
inline void *PersistentAllocator::tryAlloc(uptr size) {
|
|
// Optimisic lock-free allocation, essentially try to bump the region ptr.
|
|
for (;;) {
|
|
uptr cmp = atomic_load(®ion_pos, memory_order_acquire);
|
|
uptr end = atomic_load(®ion_end, memory_order_acquire);
|
|
if (cmp == 0 || cmp + size > end) return nullptr;
|
|
if (atomic_compare_exchange_weak(®ion_pos, &cmp, cmp + size,
|
|
memory_order_acquire))
|
|
return (void *)cmp;
|
|
}
|
|
}
|
|
|
|
inline void *PersistentAllocator::alloc(uptr size) {
|
|
// First, try to allocate optimisitically.
|
|
void *s = tryAlloc(size);
|
|
if (s) return s;
|
|
// If failed, lock, retry and alloc new superblock.
|
|
SpinMutexLock l(&mtx);
|
|
for (;;) {
|
|
s = tryAlloc(size);
|
|
if (s) return s;
|
|
atomic_store(®ion_pos, 0, memory_order_relaxed);
|
|
uptr allocsz = 64 * 1024;
|
|
if (allocsz < size) allocsz = size;
|
|
uptr mem = (uptr)MmapOrDie(allocsz, "stack depot");
|
|
atomic_store(®ion_end, mem + allocsz, memory_order_release);
|
|
atomic_store(®ion_pos, mem, memory_order_release);
|
|
}
|
|
}
|
|
|
|
extern PersistentAllocator thePersistentAllocator;
|
|
inline void *PersistentAlloc(uptr sz) {
|
|
return thePersistentAllocator.alloc(sz);
|
|
}
|
|
|
|
} // namespace __sanitizer
|
|
|
|
#endif // SANITIZER_PERSISTENT_ALLOCATOR_H
|