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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
#include <unixasmmacros.inc>
// WARNING: Code in EHHelpers.cpp makes assumptions about this helper, in particular:
// - Function "InWriteBarrierHelper" assumes an AV due to passed in null pointer will happen at RhpLockCmpXchg32AVLocation
// - Function "UnwindWriteBarrierToCaller" assumes the stack contains just the pushed return address
// x0 = destination address
// w1 = value
// w2 = comparand
LEAF_ENTRY RhpLockCmpXchg32, _TEXT
mov x8, x0 // Save value of x0 into x8 as x0 is used for the return value
ALTERNATE_ENTRY RhpLockCmpXchg32AVLocation
1: // loop
ldaxr w0, [x8] // w0 = *x8
cmp w0, w2
bne 2f // if (w0 != w2) goto exit
stlxr w9, w1, [x8] // if (w0 == w2) { try *x8 = w1 and goto loop if failed or goto exit }
cbnz w9, 1b
2: // exit
ret
LEAF_END RhpLockCmpXchg32, _TEXT
// WARNING: Code in EHHelpers.cpp makes assumptions about this helper, in particular:
// - Function "InWriteBarrierHelper" assumes an AV due to passed in null pointer will happen at RhpLockCmpXchg64AVLocation
// - Function "UnwindWriteBarrierToCaller" assumes the stack contains just the pushed return address
// x0 = destination address
// x1 = value
// x2 = comparand
LEAF_ENTRY RhpLockCmpXchg64, _TEXT
mov x8, x0 // Save value of x0 into x8 as x0 is used for the return value
ALTERNATE_ENTRY RhpLockCmpXchg64AVLocation
1: // loop
ldaxr x0, [x8] // x0 = *x8
cmp x0, x2
bne 2f // if (x0 != x2) goto exit
stlxr w9, x1, [x8] // if (x0 == x2) { try *x8 = x1 and goto loop if failed or goto exit }
cbnz w9, 1b
2: // exit
ret
LEAF_END RhpLockCmpXchg64, _TEXT
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