1 //===-- sanitizer_lfstack.h -=-----------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 // Uses 32/17 bits as ABA-counter on 32/64-bit platforms.
12 // The memory passed to Push() must not be ever munmap'ed.
13 // The type T must contain T *next field.
15 //===----------------------------------------------------------------------===//
17 #ifndef SANITIZER_LFSTACK_H
18 #define SANITIZER_LFSTACK_H
20 #include "sanitizer_internal_defs.h"
21 #include "sanitizer_common.h"
22 #include "sanitizer_atomic.h"
24 namespace __sanitizer {
29 atomic_store(&head_, 0, memory_order_relaxed);
33 return (atomic_load(&head_, memory_order_relaxed) & kPtrMask) == 0;
37 u64 cmp = atomic_load(&head_, memory_order_relaxed);
39 u64 cnt = (cmp & kCounterMask) + kCounterInc;
40 u64 xch = (u64)(uptr)p | cnt;
41 p->next = (T*)(uptr)(cmp & kPtrMask);
42 if (atomic_compare_exchange_weak(&head_, &cmp, xch,
43 memory_order_release))
49 u64 cmp = atomic_load(&head_, memory_order_acquire);
51 T *cur = (T*)(uptr)(cmp & kPtrMask);
55 u64 cnt = (cmp & kCounterMask);
56 u64 xch = (u64)(uptr)nxt | cnt;
57 if (atomic_compare_exchange_weak(&head_, &cmp, xch,
58 memory_order_acquire))
64 static const int kCounterBits = FIRST_32_SECOND_64(32, 17);
65 static const u64 kPtrMask = ((u64)-1) >> kCounterBits;
66 static const u64 kCounterMask = ~kPtrMask;
67 static const u64 kCounterInc = kPtrMask + 1;
69 atomic_uint64_t head_;
71 } // namespace __sanitizer
73 #endif // SANITIZER_LFSTACK_H