#
#
# Nim's Runtime Library
# (c) Copyright 2015 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# Atomic operations for Nim.
{.push stackTrace:off.}
const someGcc = defined(gcc) or defined(llvm_gcc) or defined(clang)
when someGcc and hasThreadSupport:
type AtomMemModel* = distinct cint
var ATOMIC_RELAXED* {.importc: "__ATOMIC_RELAXED", nodecl.}: AtomMemModel
## No barriers or synchronization.
var ATOMIC_CONSUME* {.importc: "__ATOMIC_CONSUME", nodecl.}: AtomMemModel
## Data dependency only for both barrier and
## synchronization with another thread.
var ATOMIC_ACQUIRE* {.importc: "__ATOMIC_ACQUIRE", nodecl.}: AtomMemModel
## Barrier to hoisting of code and synchronizes with
## release (or stronger)
## semantic stores from another thread.
var ATOMIC_RELEASE* {.importc: "__ATOMIC_RELEASE", nodecl.}: AtomMemModel
## Barrier to sinking of code and synchronizes with
## acquire (or stronger)
## semantic loads from another thread.
var ATOMIC_ACQ_REL* {.importc: "__ATOMIC_ACQ_REL", nodecl.}: AtomMemModel
## Full barrier in both directions and synchronizes
## with acquire loads
## and release stores in another thread.
var ATOMIC_SEQ_CST* {.importc: "__ATOMIC_SEQ_CST", nodecl.}: AtomMemModel
## Full barrier in both directions and synchronizes
## with acquire loads
## and release stores in all threads.
type
TAtomType* = SomeNumber|pointer|ptr|char|bool
## Type Class representing valid types for use with atomic procs
proc atomicLoadN*[T: TAtomType](p: ptr T, mem: AtomMemModel): T {.
importc: "__atomic_load_n", nodecl.}
## This proc implements an atomic load operation. It returns the contents at p.
## ATOMIC_RELAXED, ATOMIC_SEQ_CST, ATOMIC_ACQUIRE, ATOMIC_CONSUME.
proc atomicLoad*[T: TAtomType](p, ret: ptr T, mem: AtomMemModel) {.
importc: "__atomic_load", nodecl.}
## This is the generic version of an atomic load. It returns the contents at p in ret.
proc atomicStoreN*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel) {.
importc: "__atomic_store_n", nodecl.}
## This proc implements an atomic store operation. It writes val at p.
## ATOMIC_RELAXED, ATOMIC_SEQ_CST, and ATOMIC_RELEASE.
proc atomicStore*[T: TAtomType](p, val: ptr T, mem: AtomMemModel) {.
importc: "__atomic_store", nodecl.}
## This is the generic version of an atomic store. It stores the value of val at p
proc atomicExchangeN*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_exchange_n", nodecl.}
## This proc implements an atomic exchange operation. It writes val at p,
## and returns the previous contents at p.
## ATOMIC_RELAXED, ATOMIC_SEQ_CST, ATOMIC_ACQUIRE, ATOMIC_RELEASE, ATOMIC_ACQ_REL
proc atomicExchange*[T: TAtomType](p, val, ret: ptr T, mem: AtomMemModel) {.
importc: "__atomic_exchange", nodecl.}
## This is the generic version of an atomic exchange. It stores the contents at val at p.
## The original value at p is copied into ret.
proc atomicCompareExchangeN*[T: TAtomType](p, expected: ptr T, desired: T,
weak: bool, success_memmodel: AtomMemModel, failure_memmodel: AtomMemModel): bool {.
importc: "__atomic_compare_exchange_n ", nodecl.}
## This proc implements an atomic compare and exchange operation. This compares the
## contents at p with the contents at expected and if equal, writes desired at p.
## If they are not equal, the current contents at p is written into expected.
## Weak is true for weak compare_exchange, and false for the strong variation.
## Many targets only offer the strong variation and ignore the parameter.
## When in doubt, use the strong variation.
## True is returned if desired is written at p and the execution is considered
## to conform to the memory model specified by success_memmodel. There are no
## restrictions on what memory model can be used here. False is returned otherwise,
## and the execution is considered to conform to failure_memmodel. This memory model
## cannot be __ATOMIC_RELEASE nor __ATOMIC_ACQ_REL. It also cannot be a stronger model
## than that specified by success_memmodel.
proc atomicCompareExchange*[T: TAtomType](p, expected, desired: ptr T,
weak: bool, success_memmodel: AtomMemModel, failure_memmodel: AtomMemModel): bool {.
importc: "__atomic_compare_exchange_n ", nodecl.}
## This proc implements the generic version of atomic_compare_exchange.
## The proc is virtually identical to atomic_compare_exchange_n, except the desired
## value is also a pointer.
## Perform the operation return the new value, all memory models are valid
proc atomicAddFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_add_fetch", nodecl.}
proc atomicSubFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_sub_fetch", nodecl.}
proc atomicOrFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_or_fetch ", nodecl.}
proc atomicAndFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_and_fetch", nodecl.}
proc atomicXorFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_xor_fetch", nodecl.}
proc atomicNandFetch*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_nand_fetch ", nodecl.}
## Perform the operation return the old value, all memory models are valid
proc atomicFetchAdd*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_add", nodecl.}
proc atomicFetchSub*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_sub", nodecl.}
proc atomicFetchOr*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_or", nodecl.}
proc atomicFetchAnd*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_and", nodecl.}
proc atomicFetchXor*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_xor", nodecl.}
proc atomicFetchNand*[T: TAtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_nand", nodecl.}
proc atomicTestAndSet*(p: pointer, mem: AtomMemModel): bool {.
importc: "__atomic_test_and_set", nodecl.}
## This built-in function performs an atomic test-and-set operation on the byte at p.
## The byte is set to some implementation defined nonzero “set” value and the return
## value is true if and only if the previous contents were “set”.
## All memory models are valid.
proc atomicClear*(p: pointer, mem: AtomMemModel) {.
importc: "__atomic_clear", nodecl.}
## This built-in function performs an atomic clear operation at p.
## After the operation, at p contains 0.
## ATOMIC_RELAXED, ATOMIC_SEQ_CST, ATOMIC_RELEASE
proc atomicThreadFence*(mem: AtomMemModel) {.
importc: "__atomic_thread_fence", nodecl.}
## This built-in function acts as a synchronization fence between threads based
## on the specified memory model. All memory orders are valid.
proc atomicSignalFence*(mem: AtomMemModel) {.
importc: "__atomic_signal_fence", nodecl.}
## This built-in function acts as a synchronization fence between a thread and
## signal handlers based in the same thread. All memory orders are valid.
proc atomicAlwaysLockFree*(size: int, p: pointer): bool {.
importc: "__atomic_always_lock_free", nodecl.}
## This built-in function returns true if objects of size bytes always generate
## lock free atomic instructions for the target architecture. size must resolve
## to a compile-time constant and the result also resolves to a compile-time constant.
## ptr is an optional pointer to the object that may be used to determine alignment.
## A value of 0 indicates typical alignment should be used. The compiler may also
## ignore this parameter.
proc atomicIsLockFree*(size: int, p: pointer): bool {.
importc: "__atomic_is_lock_free", nodecl.}
## This built-in function returns true if objects of size bytes always generate
## lock free atomic instructions for the target architecture. If it is not known
## to be lock free a call is made to a runtime routine named __atomic_is_lock_free.
## ptr is an optional pointer to the object that may be used to determine alignment.
## A value of 0 indicates typical alignment should be used. The compiler may also
## ignore this parameter.
template fence*() = atomicThreadFence(ATOMIC_SEQ_CST)
elif defined(vcc) and hasThreadSupport:
proc addAndFetch*(p: ptr int, val: int): int {.
importc: "NimXadd", nodecl.}
proc fence*() {.importc: "_ReadWriteBarrier", header: "<intrin.h>".}
else:
proc addAndFetch*(p: ptr int, val: int): int {.inline.} =
inc(p[], val)
result = p[]
proc atomicInc*(memLoc: var int, x: int = 1): int =
when someGcc and hasThreadSupport:
result = atomic_add_fetch(memLoc.addr, x, ATOMIC_RELAXED)
else:
inc(memLoc, x)
result = memLoc
proc atomicDec*(memLoc: var int, x: int = 1): int =
when someGcc and hasThreadSupport:
when declared(atomic_sub_fetch):
result = atomic_sub_fetch(memLoc.addr, x, ATOMIC_RELAXED)
else:
result = atomic_add_fetch(memLoc.addr, -x, ATOMIC_RELAXED)
else:
dec(memLoc, x)
result = memLoc
when defined(windows) and not someGcc:
proc interlockedCompareExchange(p: pointer; exchange, comparand: int32): int32
{.importc: "InterlockedCompareExchange", header: "<windows.h>", cdecl.}
proc cas*[T: bool|int|ptr](p: ptr T; oldValue, newValue: T): bool =
interlockedCompareExchange(p, newValue.int32, oldValue.int32) != 0
# XXX fix for 64 bit build
else:
# this is valid for GCC and Intel C++
proc cas*[T: bool|int|ptr](p: ptr T; oldValue, newValue: T): bool
{.importc: "__sync_bool_compare_and_swap", nodecl.}
# XXX is this valid for 'int'?
when (defined(x86) or defined(amd64)) and someGcc:
proc cpuRelax* {.inline.} =
{.emit: """asm volatile("pause" ::: "memory");""".}
elif someGcc:
proc cpuRelax* {.inline.} =
{.emit: """asm volatile("" ::: "memory");""".}
elif (defined(x86) or defined(amd64)) and defined(vcc):
proc cpuRelax* {.importc: "YieldProcessor", header: "<windows.h>".}
elif defined(icl):
proc cpuRelax* {.importc: "_mm_pause", header: "xmmintrin.h".}
elif false:
from os import sleep
proc cpuRelax* {.inline.} = os.sleep(1)
when not declared(fence) and hasThreadSupport:
# XXX fixme
proc fence*() {.inline.} =
var dummy: bool
discard cas(addr dummy, false, true)
{.pop.}