summaryrefslogtreecommitdiff
path: root/boost/atomic/detail/ops_msvc_x86.hpp
blob: 85bed28ad11e08e7df6c7464c8d198cbd184b46e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
/*
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 *
 * Copyright (c) 2009 Helge Bahmann
 * Copyright (c) 2012 Tim Blechmann
 * Copyright (c) 2014 Andrey Semashev
 */
/*!
 * \file   atomic/detail/ops_msvc_x86.hpp
 *
 * This header contains implementation of the \c operations template.
 */

#ifndef BOOST_ATOMIC_DETAIL_OPS_MSVC_X86_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_OPS_MSVC_X86_HPP_INCLUDED_

#include <cstddef>
#include <boost/memory_order.hpp>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/interlocked.hpp>
#include <boost/atomic/detail/storage_type.hpp>
#include <boost/atomic/detail/operations_fwd.hpp>
#include <boost/atomic/detail/type_traits/make_signed.hpp>
#include <boost/atomic/capabilities.hpp>
#if defined(BOOST_ATOMIC_DETAIL_X86_HAS_CMPXCHG8B) || defined(BOOST_ATOMIC_DETAIL_X86_HAS_CMPXCHG16B)
#include <boost/cstdint.hpp>
#include <boost/atomic/detail/ops_cas_based.hpp>
#endif
#include <boost/atomic/detail/ops_msvc_common.hpp>
#if !defined(_M_IX86) && !(defined(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE8) && defined(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE16))
#include <boost/atomic/detail/ops_extending_cas_based.hpp>
#endif

#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif

#if defined(BOOST_MSVC)
#pragma warning(push)
// frame pointer register 'ebx' modified by inline assembly code. See the note below.
#pragma warning(disable: 4731)
#endif

#if defined(BOOST_ATOMIC_DETAIL_X86_HAS_MFENCE)
extern "C" void _mm_mfence(void);
#if defined(BOOST_MSVC)
#pragma intrinsic(_mm_mfence)
#endif
#endif

namespace boost {
namespace atomics {
namespace detail {

/*
 * Implementation note for asm blocks.
 *
 * http://msdn.microsoft.com/en-us/data/k1a8ss06%28v=vs.105%29
 *
 * Some SSE types require eight-byte stack alignment, forcing the compiler to emit dynamic stack-alignment code.
 * To be able to access both the local variables and the function parameters after the alignment, the compiler
 * maintains two frame pointers. If the compiler performs frame pointer omission (FPO), it will use EBP and ESP.
 * If the compiler does not perform FPO, it will use EBX and EBP. To ensure code runs correctly, do not modify EBX
 * in asm code if the function requires dynamic stack alignment as it could modify the frame pointer.
 * Either move the eight-byte aligned types out of the function, or avoid using EBX.
 *
 * Since we have no way of knowing that the compiler uses FPO, we have to always save and restore ebx
 * whenever we have to clobber it. Additionally, we disable warning C4731 above so that the compiler
 * doesn't spam about ebx use.
 */

struct msvc_x86_operations_base
{
    static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;

    static BOOST_FORCEINLINE void hardware_full_fence() BOOST_NOEXCEPT
    {
#if defined(BOOST_ATOMIC_DETAIL_X86_HAS_MFENCE)
        _mm_mfence();
#else
        long tmp;
        BOOST_ATOMIC_INTERLOCKED_EXCHANGE(&tmp, 0);
#endif
    }

    static BOOST_FORCEINLINE void fence_before(memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
    }

    static BOOST_FORCEINLINE void fence_after(memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
    }

    static BOOST_FORCEINLINE void fence_after_load(memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        // On x86 and x86_64 there is no need for a hardware barrier,
        // even if seq_cst memory order is requested, because all
        // seq_cst writes are implemented with lock-prefixed operations
        // or xchg which has implied lock prefix. Therefore normal loads
        // are already ordered with seq_cst stores on these architectures.
    }
};

template< typename T, typename Derived >
struct msvc_x86_operations :
    public msvc_x86_operations_base
{
    typedef T storage_type;

    static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        if (order != memory_order_seq_cst)
        {
            fence_before(order);
            storage = v;
            fence_after(order);
        }
        else
        {
            Derived::exchange(storage, v, order);
        }
    }

    static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
        storage_type v = storage;
        fence_after_load(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        typedef typename boost::atomics::detail::make_signed< storage_type >::type signed_storage_type;
        return Derived::fetch_add(storage, static_cast< storage_type >(-static_cast< signed_storage_type >(v)), order);
    }

    static BOOST_FORCEINLINE bool compare_exchange_weak(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
    {
        return Derived::compare_exchange_strong(storage, expected, desired, success_order, failure_order);
    }

    static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
        return !!Derived::exchange(storage, (storage_type)1, order);
    }

    static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
        store(storage, (storage_type)0, order);
    }
};

template< bool Signed >
struct operations< 4u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 4u, Signed >::type, operations< 4u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 4u, Signed >::type, operations< 4u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 4u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 4u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE_ADD(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE(&storage, v));
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        storage_type previous = expected;
        storage_type old_val = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE(&storage, desired, previous));
        expected = old_val;
        return (previous == old_val);
    }

#if defined(BOOST_ATOMIC_INTERLOCKED_AND)
    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_AND(&storage, v));
    }
#else
    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        storage_type res = storage;
        while (!compare_exchange_strong(storage, res, res & v, order, memory_order_relaxed)) {}
        return res;
    }
#endif

#if defined(BOOST_ATOMIC_INTERLOCKED_OR)
    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_OR(&storage, v));
    }
#else
    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        storage_type res = storage;
        while (!compare_exchange_strong(storage, res, res | v, order, memory_order_relaxed)) {}
        return res;
    }
#endif

#if defined(BOOST_ATOMIC_INTERLOCKED_XOR)
    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_XOR(&storage, v));
    }
#else
    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        storage_type res = storage;
        while (!compare_exchange_strong(storage, res, res ^ v, order, memory_order_relaxed)) {}
        return res;
    }
#endif
};

#if defined(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE8)

template< bool Signed >
struct operations< 1u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 1u, Signed >::type, operations< 1u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 1u, Signed >::type, operations< 1u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 1u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 1u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE_ADD8(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE8(&storage, v));
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        storage_type previous = expected;
        storage_type old_val = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE8(&storage, desired, previous));
        expected = old_val;
        return (previous == old_val);
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_AND8(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_OR8(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_XOR8(&storage, v));
    }
};

#elif defined(_M_IX86)

template< bool Signed >
struct operations< 1u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 1u, Signed >::type, operations< 1u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 1u, Signed >::type, operations< 1u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 1u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 1u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        __asm
        {
            mov edx, storage
            movzx eax, v
            lock xadd byte ptr [edx], al
            mov v, al
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        __asm
        {
            mov edx, storage
            movzx eax, v
            xchg byte ptr [edx], al
            mov v, al
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order) BOOST_NOEXCEPT
    {
        base_type::fence_before(success_order);
        bool success;
        __asm
        {
            mov esi, expected
            mov edi, storage
            movzx eax, byte ptr [esi]
            movzx edx, desired
            lock cmpxchg byte ptr [edi], dl
            mov byte ptr [esi], al
            sete success
        };
        // The success and failure fences are equivalent anyway
        base_type::fence_after(success_order);
        return success;
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, byte ptr [edi]
            align 16
        again:
            mov dl, al
            and dl, bl
            lock cmpxchg byte ptr [edi], dl
            jne again
            mov v, al
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, byte ptr [edi]
            align 16
        again:
            mov dl, al
            or dl, bl
            lock cmpxchg byte ptr [edi], dl
            jne again
            mov v, al
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, byte ptr [edi]
            align 16
        again:
            mov dl, al
            xor dl, bl
            lock cmpxchg byte ptr [edi], dl
            jne again
            mov v, al
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }
};

#else

template< bool Signed >
struct operations< 1u, Signed > :
    public extending_cas_based_operations< operations< 4u, Signed >, 1u, Signed >
{
};

#endif

#if defined(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE16)

template< bool Signed >
struct operations< 2u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 2u, Signed >::type, operations< 2u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 2u, Signed >::type, operations< 2u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 2u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 2u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE_ADD16(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE16(&storage, v));
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        storage_type previous = expected;
        storage_type old_val = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE16(&storage, desired, previous));
        expected = old_val;
        return (previous == old_val);
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_AND16(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_OR16(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_XOR16(&storage, v));
    }
};

#elif defined(_M_IX86)

template< bool Signed >
struct operations< 2u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 2u, Signed >::type, operations< 2u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 2u, Signed >::type, operations< 2u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 2u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 2u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        __asm
        {
            mov edx, storage
            movzx eax, v
            lock xadd word ptr [edx], ax
            mov v, ax
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        __asm
        {
            mov edx, storage
            movzx eax, v
            xchg word ptr [edx], ax
            mov v, ax
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order) BOOST_NOEXCEPT
    {
        base_type::fence_before(success_order);
        bool success;
        __asm
        {
            mov esi, expected
            mov edi, storage
            movzx eax, word ptr [esi]
            movzx edx, desired
            lock cmpxchg word ptr [edi], dx
            mov word ptr [esi], ax
            sete success
        };
        // The success and failure fences are equivalent anyway
        base_type::fence_after(success_order);
        return success;
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, word ptr [edi]
            align 16
        again:
            mov dx, ax
            and dx, bx
            lock cmpxchg word ptr [edi], dx
            jne again
            mov v, ax
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, word ptr [edi]
            align 16
        again:
            mov dx, ax
            or dx, bx
            lock cmpxchg word ptr [edi], dx
            jne again
            mov v, ax
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        base_type::fence_before(order);
        int backup;
        __asm
        {
            mov backup, ebx
            xor edx, edx
            mov edi, storage
            movzx ebx, v
            movzx eax, word ptr [edi]
            align 16
        again:
            mov dx, ax
            xor dx, bx
            lock cmpxchg word ptr [edi], dx
            jne again
            mov v, ax
            mov ebx, backup
        };
        base_type::fence_after(order);
        return v;
    }
};

#else

template< bool Signed >
struct operations< 2u, Signed > :
    public extending_cas_based_operations< operations< 4u, Signed >, 2u, Signed >
{
};

#endif


#if defined(BOOST_ATOMIC_DETAIL_X86_HAS_CMPXCHG8B)

template< bool Signed >
struct msvc_dcas_x86
{
    typedef typename make_storage_type< 8u, Signed >::type storage_type;
    typedef typename make_storage_type< 8u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 8u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    // Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 3A, 8.1.1. Guaranteed Atomic Operations:
    //
    // The Pentium processor (and newer processors since) guarantees that the following additional memory operations will always be carried out atomically:
    // * Reading or writing a quadword aligned on a 64-bit boundary
    //
    // Luckily, the memory is almost always 8-byte aligned in our case because atomic<> uses 64 bit native types for storage and dynamic memory allocations
    // have at least 8 byte alignment. The only unfortunate case is when atomic is placed on the stack and it is not 8-byte aligned (like on 32 bit Windows).

    static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        storage_type volatile* p = &storage;
        if (((uint32_t)p & 0x00000007) == 0)
        {
#if defined(_M_IX86_FP) && _M_IX86_FP >= 2
#if defined(__AVX__)
            __asm
            {
                mov edx, p
                vmovq xmm4, v
                vmovq qword ptr [edx], xmm4
            };
#else
            __asm
            {
                mov edx, p
                movq xmm4, v
                movq qword ptr [edx], xmm4
            };
#endif
#else
            __asm
            {
                mov edx, p
                fild v
                fistp qword ptr [edx]
            };
#endif
        }
        else
        {
            int backup;
            __asm
            {
                mov backup, ebx
                mov edi, p
                mov ebx, dword ptr [v]
                mov ecx, dword ptr [v + 4]
                mov eax, dword ptr [edi]
                mov edx, dword ptr [edi + 4]
                align 16
            again:
                lock cmpxchg8b qword ptr [edi]
                jne again
                mov ebx, backup
            };
        }

        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
    }

    static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        storage_type const volatile* p = &storage;
        storage_type value;

        if (((uint32_t)p & 0x00000007) == 0)
        {
#if defined(_M_IX86_FP) && _M_IX86_FP >= 2
#if defined(__AVX__)
            __asm
            {
                mov edx, p
                vmovq xmm4, qword ptr [edx]
                vmovq value, xmm4
            };
#else
            __asm
            {
                mov edx, p
                movq xmm4, qword ptr [edx]
                movq value, xmm4
            };
#endif
#else
            __asm
            {
                mov edx, p
                fild qword ptr [edx]
                fistp value
            };
#endif
        }
        else
        {
            // We don't care for comparison result here; the previous value will be stored into value anyway.
            // Also we don't care for ebx and ecx values, they just have to be equal to eax and edx before cmpxchg8b.
            __asm
            {
                mov edi, p
                mov eax, ebx
                mov edx, ecx
                lock cmpxchg8b qword ptr [edi]
                mov dword ptr [value], eax
                mov dword ptr [value + 4], edx
            };
        }

        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        return value;
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        // MSVC-11 in 32-bit mode sometimes generates messed up code without compiler barriers,
        // even though the _InterlockedCompareExchange64 intrinsic already provides one.
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        storage_type volatile* p = &storage;
#if defined(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE64)
        const storage_type old_val = (storage_type)BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE64(p, desired, expected);
        const bool result = (old_val == expected);
        expected = old_val;
#else
        bool result;
        int backup;
        __asm
        {
            mov backup, ebx
            mov edi, p
            mov esi, expected
            mov ebx, dword ptr [desired]
            mov ecx, dword ptr [desired + 4]
            mov eax, dword ptr [esi]
            mov edx, dword ptr [esi + 4]
            lock cmpxchg8b qword ptr [edi]
            mov dword ptr [esi], eax
            mov dword ptr [esi + 4], edx
            mov ebx, backup
            sete result
        };
#endif
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        return result;
    }

    static BOOST_FORCEINLINE bool compare_exchange_weak(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
    {
        return compare_exchange_strong(storage, expected, desired, success_order, failure_order);
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        storage_type volatile* p = &storage;
        int backup;
        __asm
        {
            mov backup, ebx
            mov edi, p
            mov ebx, dword ptr [v]
            mov ecx, dword ptr [v + 4]
            mov eax, dword ptr [edi]
            mov edx, dword ptr [edi + 4]
            align 16
        again:
            lock cmpxchg8b qword ptr [edi]
            jne again
            mov ebx, backup
            mov dword ptr [v], eax
            mov dword ptr [v + 4], edx
        };

        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();

        return v;
    }
};

template< bool Signed >
struct operations< 8u, Signed > :
    public cas_based_operations< msvc_dcas_x86< Signed > >
{
};

#elif defined(_M_AMD64)

template< bool Signed >
struct operations< 8u, Signed > :
    public msvc_x86_operations< typename make_storage_type< 8u, Signed >::type, operations< 8u, Signed > >
{
    typedef msvc_x86_operations< typename make_storage_type< 8u, Signed >::type, operations< 8u, Signed > > base_type;
    typedef typename base_type::storage_type storage_type;
    typedef typename make_storage_type< 8u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 8u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE_ADD64(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE64(&storage, v));
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        storage_type previous = expected;
        storage_type old_val = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE64(&storage, desired, previous));
        expected = old_val;
        return (previous == old_val);
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_AND64(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_OR64(&storage, v));
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        return static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_XOR64(&storage, v));
    }
};

#endif

#if defined(BOOST_ATOMIC_DETAIL_X86_HAS_CMPXCHG16B)

template< bool Signed >
struct msvc_dcas_x86_64
{
    typedef typename make_storage_type< 16u, Signed >::type storage_type;
    typedef typename make_storage_type< 16u, Signed >::aligned aligned_storage_type;

    static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;

    static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = 16u;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;

    static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
    {
        storage_type value = const_cast< storage_type& >(storage);
        while (!BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE128(&storage, v, &value)) {}
    }

    static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order) BOOST_NOEXCEPT
    {
        storage_type value = storage_type();
        BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE128(&storage, value, &value);
        return value;
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
    {
        return !!BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE128(&storage, desired, &expected);
    }

    static BOOST_FORCEINLINE bool compare_exchange_weak(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
    {
        return compare_exchange_strong(storage, expected, desired, success_order, failure_order);
    }
};

template< bool Signed >
struct operations< 16u, Signed > :
    public cas_based_operations< cas_based_exchange< msvc_dcas_x86_64< Signed > > >
{
};

#endif // defined(BOOST_ATOMIC_DETAIL_X86_HAS_CMPXCHG16B)

BOOST_FORCEINLINE void thread_fence(memory_order order) BOOST_NOEXCEPT
{
    BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
    if (order == memory_order_seq_cst)
        msvc_x86_operations_base::hardware_full_fence();
    BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
}

BOOST_FORCEINLINE void signal_fence(memory_order order) BOOST_NOEXCEPT
{
    if (order != memory_order_relaxed)
        BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
}

} // namespace detail
} // namespace atomics
} // namespace boost

#if defined(BOOST_MSVC)
#pragma warning(pop)
#endif

#endif // BOOST_ATOMIC_DETAIL_OPS_MSVC_X86_HPP_INCLUDED_