libsanitizer/sanitizer_common/sanitizer_atomic_clang_x86.h

   1 //===-- sanitizer_atomic_clang_x86.h ----------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of ThreadSanitizer/AddressSanitizer runtime.
  10 // Not intended for direct inclusion. Include sanitizer_atomic.h.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef SANITIZER_ATOMIC_CLANG_X86_H
  15 #define SANITIZER_ATOMIC_CLANG_X86_H
  16
  17 namespace __sanitizer {
  18
  19 inline void proc_yield(int cnt) {
  20   __asm__ __volatile__("" ::: "memory");
  21   for (int i = 0; i < cnt; i++)
  22     __asm__ __volatile__("pause");
  23   __asm__ __volatile__("" ::: "memory");
  24 }
  25
  26 template<typename T>
  27 inline typename T::Type atomic_load(
  28     const volatile T *a, memory_order mo) {
  29   DCHECK(mo & (memory_order_relaxed | memory_order_consume
  30       | memory_order_acquire | memory_order_seq_cst));
  31   DCHECK(!((uptr)a % sizeof(*a)));
  32   typename T::Type v;
  33
  34   if (sizeof(*a) < 8 || sizeof(void*) == 8) {
  35     // Assume that aligned loads are atomic.
  36     if (mo == memory_order_relaxed) {
  37       v = a->val_dont_use;
  38     } else if (mo == memory_order_consume) {
  39       // Assume that processor respects data dependencies
  40       // (and that compiler won't break them).
  41       __asm__ __volatile__("" ::: "memory");
  42       v = a->val_dont_use;
  43       __asm__ __volatile__("" ::: "memory");
  44     } else if (mo == memory_order_acquire) {
  45       __asm__ __volatile__("" ::: "memory");
  46       v = a->val_dont_use;
  47       // On x86 loads are implicitly acquire.
  48       __asm__ __volatile__("" ::: "memory");
  49     } else {  // seq_cst
  50       // On x86 plain MOV is enough for seq_cst store.
  51       __asm__ __volatile__("" ::: "memory");
  52       v = a->val_dont_use;
  53       __asm__ __volatile__("" ::: "memory");
  54     }
  55   } else {
  56     // 64-bit load on 32-bit platform.
  57     __asm__ __volatile__(
  58         "movq %1, %%mm0;"  // Use mmx reg for 64-bit atomic moves
  59         "movq %%mm0, %0;"  // (ptr could be read-only)
  60         "emms;"            // Empty mmx state/Reset FP regs
  61         : "=m" (v)
  62         : "m" (a->val_dont_use)
  63         : // mark the mmx registers as clobbered
  64 #ifdef __MMX__
  65           "mm0", "mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm7",
  66 #endif  // #ifdef __MMX__
  67           "memory");
  68   }
  69   return v;
  70 }
  71
  72 template<typename T>
  73 inline void atomic_store(volatile T *a, typename T::Type v, memory_order mo) {
  74   DCHECK(mo & (memory_order_relaxed | memory_order_release
  75       | memory_order_seq_cst));
  76   DCHECK(!((uptr)a % sizeof(*a)));
  77
  78   if (sizeof(*a) < 8 || sizeof(void*) == 8) {
  79     // Assume that aligned loads are atomic.
  80     if (mo == memory_order_relaxed) {
  81       a->val_dont_use = v;
  82     } else if (mo == memory_order_release) {
  83       // On x86 stores are implicitly release.
  84       __asm__ __volatile__("" ::: "memory");
  85       a->val_dont_use = v;
  86       __asm__ __volatile__("" ::: "memory");
  87     } else {  // seq_cst
  88       // On x86 stores are implicitly release.
  89       __asm__ __volatile__("" ::: "memory");
  90       a->val_dont_use = v;
  91       __sync_synchronize();
  92     }
  93   } else {
  94     // 64-bit store on 32-bit platform.
  95     __asm__ __volatile__(
  96         "movq %1, %%mm0;"  // Use mmx reg for 64-bit atomic moves
  97         "movq %%mm0, %0;"
  98         "emms;"            // Empty mmx state/Reset FP regs
  99         : "=m" (a->val_dont_use)
 100         : "m" (v)
 101         : // mark the mmx registers as clobbered
 102 #ifdef __MMX__
 103           "mm0", "mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm7",
 104 #endif  // #ifdef __MMX__
 105           "memory");
 106     if (mo == memory_order_seq_cst)
 107       __sync_synchronize();
 108   }
 109 }
 110
 111 }  // namespace __sanitizer
 112
 113 #endif  // #ifndef SANITIZER_ATOMIC_CLANG_X86_H