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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.
.syntax unified
.thumb
#include <AsmOffsets.inc> // generated by the build from AsmOffsets.cpp
#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
// r0 = destination address
// r1 = value
// r2 = comparand
LEAF_ENTRY RhpLockCmpXchg32, _TEXT
dmb
ALTERNATE_ENTRY RhpLockCmpXchg32AVLocation
LOCAL_LABEL(CmpXchg32Retry):
ldrex r3, [r0]
cmp r2, r3
bne LOCAL_LABEL(CmpXchg32Exit)
strex r12, r1, [r0]
cmp r12, #0
bne LOCAL_LABEL(CmpXchg32Retry)
LOCAL_LABEL(CmpXchg32Exit):
mov r0, r3
dmb
bx lr
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
// r0 = destination address
// {r2,r3} = value
// sp[0+8] = comparand
LEAF_ENTRY RhpLockCmpXchg64, _TEXT
ALTERNATE_ENTRY RhpLockCmpXchg64AVLocation
ldr r12, [r0] // dummy read for null check
PROLOG_PUSH "{r4-r6,lr}"
dmb
ldrd r4, r5, [sp,#0x10]
LOCAL_LABEL(CmpXchg64Retry):
ldrexd r6, r1, [r0]
cmp r6, r4
bne LOCAL_LABEL(CmpXchg64Exit)
cmp r1, r5
bne LOCAL_LABEL(CmpXchg64Exit)
strexd r12, r2, r3, [r0]
cmp r12, #0
bne LOCAL_LABEL(CmpXchg64Retry)
LOCAL_LABEL(CmpXchg64Exit):
mov r0, r6
dmb
EPILOG_POP "{r4-r6,pc}"
LEAF_END RhpLockCmpXchg64, _TEXT
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