evan@chromium.org | 75d1cb3 | 2011-04-30 05:45:22 +0900 | [diff] [blame] | 1 | // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
license.bot | f003cfe | 2008-08-24 09:55:55 +0900 | [diff] [blame] | 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 4 | |
| 5 | // This file is an internal atomic implementation, use base/atomicops.h instead. |
| 6 | |
| 7 | #ifndef BASE_ATOMICOPS_INTERNALS_X86_GCC_H_ |
| 8 | #define BASE_ATOMICOPS_INTERNALS_X86_GCC_H_ |
| 9 | |
darin@chromium.org | e585bed | 2011-08-06 00:34:00 +0900 | [diff] [blame] | 10 | #include "base/base_export.h" |
evan@chromium.org | 75d1cb3 | 2011-04-30 05:45:22 +0900 | [diff] [blame] | 11 | |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 12 | // This struct is not part of the public API of this module; clients may not |
darin@chromium.org | e585bed | 2011-08-06 00:34:00 +0900 | [diff] [blame] | 13 | // use it. (However, it's exported via BASE_EXPORT because clients implicitly |
evan@chromium.org | 75d1cb3 | 2011-04-30 05:45:22 +0900 | [diff] [blame] | 14 | // do use it at link time by inlining these functions.) |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 15 | // Features of this x86. Values may not be correct before main() is run, |
| 16 | // but are set conservatively. |
| 17 | struct AtomicOps_x86CPUFeatureStruct { |
| 18 | bool has_amd_lock_mb_bug; // Processor has AMD memory-barrier bug; do lfence |
| 19 | // after acquire compare-and-swap. |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 20 | }; |
darin@chromium.org | e585bed | 2011-08-06 00:34:00 +0900 | [diff] [blame] | 21 | BASE_EXPORT extern struct AtomicOps_x86CPUFeatureStruct |
evan@chromium.org | 75d1cb3 | 2011-04-30 05:45:22 +0900 | [diff] [blame] | 22 | AtomicOps_Internalx86CPUFeatures; |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 23 | |
| 24 | #define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory") |
| 25 | |
| 26 | namespace base { |
| 27 | namespace subtle { |
| 28 | |
| 29 | // 32-bit low-level operations on any platform. |
| 30 | |
| 31 | inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr, |
| 32 | Atomic32 old_value, |
| 33 | Atomic32 new_value) { |
| 34 | Atomic32 prev; |
| 35 | __asm__ __volatile__("lock; cmpxchgl %1,%2" |
| 36 | : "=a" (prev) |
| 37 | : "q" (new_value), "m" (*ptr), "0" (old_value) |
| 38 | : "memory"); |
| 39 | return prev; |
| 40 | } |
| 41 | |
| 42 | inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, |
| 43 | Atomic32 new_value) { |
| 44 | __asm__ __volatile__("xchgl %1,%0" // The lock prefix is implicit for xchg. |
| 45 | : "=r" (new_value) |
| 46 | : "m" (*ptr), "0" (new_value) |
| 47 | : "memory"); |
| 48 | return new_value; // Now it's the previous value. |
| 49 | } |
| 50 | |
| 51 | inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, |
| 52 | Atomic32 increment) { |
| 53 | Atomic32 temp = increment; |
| 54 | __asm__ __volatile__("lock; xaddl %0,%1" |
| 55 | : "+r" (temp), "+m" (*ptr) |
| 56 | : : "memory"); |
| 57 | // temp now holds the old value of *ptr |
| 58 | return temp + increment; |
| 59 | } |
| 60 | |
| 61 | inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr, |
| 62 | Atomic32 increment) { |
| 63 | Atomic32 temp = increment; |
| 64 | __asm__ __volatile__("lock; xaddl %0,%1" |
| 65 | : "+r" (temp), "+m" (*ptr) |
| 66 | : : "memory"); |
| 67 | // temp now holds the old value of *ptr |
| 68 | if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) { |
| 69 | __asm__ __volatile__("lfence" : : : "memory"); |
| 70 | } |
| 71 | return temp + increment; |
| 72 | } |
| 73 | |
| 74 | inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, |
| 75 | Atomic32 old_value, |
| 76 | Atomic32 new_value) { |
| 77 | Atomic32 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 78 | if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) { |
| 79 | __asm__ __volatile__("lfence" : : : "memory"); |
| 80 | } |
| 81 | return x; |
| 82 | } |
| 83 | |
| 84 | inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr, |
| 85 | Atomic32 old_value, |
| 86 | Atomic32 new_value) { |
| 87 | return NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 88 | } |
| 89 | |
| 90 | inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 91 | *ptr = value; |
| 92 | } |
| 93 | |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 94 | inline void MemoryBarrier() { |
| 95 | __asm__ __volatile__("mfence" : : : "memory"); |
| 96 | } |
| 97 | |
| 98 | inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 99 | *ptr = value; |
| 100 | MemoryBarrier(); |
| 101 | } |
| 102 | |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 103 | inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 104 | ATOMICOPS_COMPILER_BARRIER(); |
| 105 | *ptr = value; // An x86 store acts as a release barrier. |
| 106 | // See comments in Atomic64 version of Release_Store(), below. |
| 107 | } |
| 108 | |
| 109 | inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) { |
| 110 | return *ptr; |
| 111 | } |
| 112 | |
| 113 | inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) { |
| 114 | Atomic32 value = *ptr; // An x86 load acts as a acquire barrier. |
| 115 | // See comments in Atomic64 version of Release_Store(), below. |
| 116 | ATOMICOPS_COMPILER_BARRIER(); |
| 117 | return value; |
| 118 | } |
| 119 | |
| 120 | inline Atomic32 Release_Load(volatile const Atomic32* ptr) { |
| 121 | MemoryBarrier(); |
| 122 | return *ptr; |
| 123 | } |
| 124 | |
| 125 | #if defined(__x86_64__) |
| 126 | |
| 127 | // 64-bit low-level operations on 64-bit platform. |
| 128 | |
| 129 | inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr, |
| 130 | Atomic64 old_value, |
| 131 | Atomic64 new_value) { |
| 132 | Atomic64 prev; |
| 133 | __asm__ __volatile__("lock; cmpxchgq %1,%2" |
| 134 | : "=a" (prev) |
| 135 | : "q" (new_value), "m" (*ptr), "0" (old_value) |
| 136 | : "memory"); |
| 137 | return prev; |
| 138 | } |
| 139 | |
| 140 | inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, |
| 141 | Atomic64 new_value) { |
| 142 | __asm__ __volatile__("xchgq %1,%0" // The lock prefix is implicit for xchg. |
| 143 | : "=r" (new_value) |
| 144 | : "m" (*ptr), "0" (new_value) |
| 145 | : "memory"); |
| 146 | return new_value; // Now it's the previous value. |
| 147 | } |
| 148 | |
| 149 | inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, |
| 150 | Atomic64 increment) { |
| 151 | Atomic64 temp = increment; |
| 152 | __asm__ __volatile__("lock; xaddq %0,%1" |
| 153 | : "+r" (temp), "+m" (*ptr) |
| 154 | : : "memory"); |
| 155 | // temp now contains the previous value of *ptr |
| 156 | return temp + increment; |
| 157 | } |
| 158 | |
| 159 | inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, |
| 160 | Atomic64 increment) { |
| 161 | Atomic64 temp = increment; |
| 162 | __asm__ __volatile__("lock; xaddq %0,%1" |
| 163 | : "+r" (temp), "+m" (*ptr) |
| 164 | : : "memory"); |
| 165 | // temp now contains the previous value of *ptr |
| 166 | if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) { |
| 167 | __asm__ __volatile__("lfence" : : : "memory"); |
| 168 | } |
| 169 | return temp + increment; |
| 170 | } |
| 171 | |
| 172 | inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 173 | *ptr = value; |
| 174 | } |
| 175 | |
| 176 | inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 177 | *ptr = value; |
| 178 | MemoryBarrier(); |
| 179 | } |
| 180 | |
| 181 | inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 182 | ATOMICOPS_COMPILER_BARRIER(); |
| 183 | |
| 184 | *ptr = value; // An x86 store acts as a release barrier |
| 185 | // for current AMD/Intel chips as of Jan 2008. |
| 186 | // See also Acquire_Load(), below. |
| 187 | |
| 188 | // When new chips come out, check: |
| 189 | // IA-32 Intel Architecture Software Developer's Manual, Volume 3: |
| 190 | // System Programming Guide, Chatper 7: Multiple-processor management, |
| 191 | // Section 7.2, Memory Ordering. |
| 192 | // Last seen at: |
| 193 | // http://developer.intel.com/design/pentium4/manuals/index_new.htm |
| 194 | // |
| 195 | // x86 stores/loads fail to act as barriers for a few instructions (clflush |
| 196 | // maskmovdqu maskmovq movntdq movnti movntpd movntps movntq) but these are |
| 197 | // not generated by the compiler, and are rare. Users of these instructions |
| 198 | // need to know about cache behaviour in any case since all of these involve |
| 199 | // either flushing cache lines or non-temporal cache hints. |
| 200 | } |
| 201 | |
| 202 | inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) { |
| 203 | return *ptr; |
| 204 | } |
| 205 | |
| 206 | inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) { |
| 207 | Atomic64 value = *ptr; // An x86 load acts as a acquire barrier, |
| 208 | // for current AMD/Intel chips as of Jan 2008. |
| 209 | // See also Release_Store(), above. |
| 210 | ATOMICOPS_COMPILER_BARRIER(); |
| 211 | return value; |
| 212 | } |
| 213 | |
| 214 | inline Atomic64 Release_Load(volatile const Atomic64* ptr) { |
| 215 | MemoryBarrier(); |
| 216 | return *ptr; |
| 217 | } |
deanm@chromium.org | dc8b492 | 2009-07-28 06:17:23 +0900 | [diff] [blame] | 218 | |
| 219 | inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr, |
| 220 | Atomic64 old_value, |
| 221 | Atomic64 new_value) { |
| 222 | Atomic64 x = NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 223 | if (AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug) { |
| 224 | __asm__ __volatile__("lfence" : : : "memory"); |
| 225 | } |
| 226 | return x; |
| 227 | } |
| 228 | |
| 229 | inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr, |
| 230 | Atomic64 old_value, |
| 231 | Atomic64 new_value) { |
| 232 | return NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 233 | } |
| 234 | |
deanm@google.com | 1579ec7 | 2008-08-05 18:57:36 +0900 | [diff] [blame] | 235 | #endif // defined(__x86_64__) |
| 236 | |
| 237 | } // namespace base::subtle |
| 238 | } // namespace base |
| 239 | |
| 240 | #undef ATOMICOPS_COMPILER_BARRIER |
| 241 | |
| 242 | #endif // BASE_ATOMICOPS_INTERNALS_X86_GCC_H_ |