#
#
# 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, profiler:off.}
const someGcc = defined(gcc) or defined(llvm_gcc) or defined(clang)
const someVcc = defined(vcc) or defined(clang_cl)
type
AtomType* = SomeNumber|pointer|ptr|char|bool
## Type Class representing valid types for use with atomic procs
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.
proc atomicLoadN*[T: AtomType](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: AtomType](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: AtomType](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: AtomType](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: AtomType](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: AtomType](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: AtomType](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: AtomType](p, expected, desired: ptr T,
weak: bool, success_memmodel: AtomMemModel, failure_memmodel: AtomMemModel): bool {.
importc: "__atomic_compare_exchange", 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: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_add_fetch", nodecl.}
proc atomicSubFetch*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_sub_fetch", nodecl.}
proc atomicOrFetch*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_or_fetch ", nodecl.}
proc atomicAndFetch*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_and_fetch", nodecl.}
proc atomicXorFetch*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_xor_fetch", nodecl.}
proc atomicNandFetch*[T: AtomType](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: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_add", nodecl.}
proc atomicFetchSub*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_sub", nodecl.}
proc atomicFetchOr*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_or", nodecl.}
proc atomicFetchAnd*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_and", nodecl.}
proc atomicFetchXor*[T: AtomType](p: ptr T, val: T, mem: AtomMemModel): T {.
importc: "__atomic_fetch_xor", nodecl.}
proc atomicFetchNand*[T: AtomType](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 someVcc and hasThreadSupport:
type AtomMemModel* = distinct cint
const
ATOMIC_RELAXED = 0.AtomMemModel
ATOMIC_CONSUME = 1.AtomMemModel
ATOMIC_ACQUIRE = 2.AtomMemModel
ATOMIC_RELEASE = 3.AtomMemModel
ATOMIC_ACQ_REL = 4.AtomMemModel
ATOMIC_SEQ_CST = 5.AtomMemModel
proc `==`(x1, x2: AtomMemModel): bool {.borrow.}
proc readBarrier() {.importc: "_ReadBarrier", header: "<intrin.h>".}
proc writeBarrier() {.importc: "_WriteBarrier", header: "<intrin.h>".}
proc fence*() {.importc: "_ReadWriteBarrier", header: "<intrin.h>".}
template barrier(mem: AtomMemModel) =
when mem == ATOMIC_RELAXED: discard
elif mem == ATOMIC_CONSUME: readBarrier()
elif mem == ATOMIC_ACQUIRE: writeBarrier()
elif mem == ATOMIC_RELEASE: fence()
elif mem == ATOMIC_ACQ_REL: fence()
elif mem == ATOMIC_SEQ_CST: fence()
proc atomicLoadN*[T: AtomType](p: ptr T, mem: static[AtomMemModel]): T =
result = p[]
barrier(mem)
when defined(cpp):
when sizeof(int) == 8:
proc addAndFetch*(p: ptr int, val: int): int {.
importcpp: "_InterlockedExchangeAdd64(static_cast<NI volatile *>(#), #)",
header: "<intrin.h>".}
else:
proc addAndFetch*(p: ptr int, val: int): int {.
importcpp: "_InterlockedExchangeAdd(reinterpret_cast<long volatile *>(#), static_cast<long>(#))",
header: "<intrin.h>".}
else:
when sizeof(int) == 8:
proc addAndFetch*(p: ptr int, val: int): int {.
importc: "_InterlockedExchangeAdd64", header: "<intrin.h>".}
else:
proc addAndFetch*(p: ptr int, val: int): int {.
importc: "_InterlockedExchangeAdd", 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 = atomicAddFetch(memLoc.addr, x, ATOMIC_RELAXED)
elif someVcc and hasThreadSupport:
result = addAndFetch(memLoc.addr, x)
inc(result, x)
else:
inc(memLoc, x)
result = memLoc
proc atomicDec*(memLoc: var int, x: int = 1): int =
when someGcc and hasThreadSupport:
when declared(atomicSubFetch):
result = atomicSubFetch(memLoc.addr, x, ATOMIC_RELAXED)
else:
result = atomicAddFetch(memLoc.addr, -x, ATOMIC_RELAXED)
elif someVcc and hasThreadSupport:
result = addAndFetch(memLoc.addr, -x)
dec(result, x)
else:
dec(memLoc, x)
result = memLoc
when someVcc:
when defined(cpp):
proc interlockedCompareExchange64(p: pointer; exchange, comparand: int64): int64
{.importcpp: "_InterlockedCompareExchange64(static_cast<NI64 volatile *>(#), #, #)", header: "<intrin.h>".}
proc interlockedCompareExchange32(p: pointer; exchange, comparand: int32): int32
{.importcpp: "_InterlockedCompareExchange(static_cast<NI volatile *>(#), #, #)", header: "<intrin.h>".}
proc interlockedCompareExchange8(p: pointer; exchange, comparand: byte): byte
{.importcpp: "_InterlockedCompareExchange8(static_cast<char volatile *>(#), #, #)", header: "<intrin.h>".}
else:
proc interlockedCompareExchange64(p: pointer; exchange, comparand: int64): int64
{.importc: "_InterlockedCompareExchange64", header: "<intrin.h>".}
proc interlockedCompareExchange32(p: pointer; exchange, comparand: int32): int32
{.importc: "_InterlockedCompareExchange", header: "<intrin.h>".}
proc interlockedCompareExchange8(p: pointer; exchange, comparand: byte): byte
{.importc: "_InterlockedCompareExchange8", header: "<intrin.h>".}
proc cas*[T: bool|int|ptr](p: ptr T; oldValue, newValue: T): bool =
when sizeof(T) == 8:
interlockedCompareExchange64(p, cast[int64](newValue), cast[int64](oldValue)) ==
cast[int64](oldValue)
elif sizeof(T) == 4:
interlockedCompareExchange32(p, cast[int32](newValue), cast[int32](oldValue)) ==
cast[int32](oldValue)
elif sizeof(T) == 1:
interlockedCompareExchange8(p, cast[byte](newValue), cast[byte](oldValue)) ==
cast[byte](oldValue)
else:
{.error: "invalid CAS instruction".}
elif defined(tcc):
when defined(amd64):
{.emit:"""
static int __tcc_cas(int *ptr, int oldVal, int newVal)
{
unsigned char ret;
__asm__ __volatile__ (
" lock\n"
" cmpxchgq %2,%1\n"
" sete %0\n"
: "=q" (ret), "=m" (*ptr)
: "r" (newVal), "m" (*ptr), "a" (oldVal)
: "memory");
return ret;
}
""".}
else:
#assert sizeof(int) == 4
{.emit:"""
static int __tcc_cas(int *ptr, int oldVal, int newVal)
{
unsigned char ret;
__asm__ __volatile__ (
" lock\n"
" cmpxchgl %2,%1\n"
" sete %0\n"
: "=q" (ret), "=m" (*ptr)
: "r" (newVal), "m" (*ptr), "a" (oldVal)
: "memory");
return ret;
}
""".}
proc tcc_cas(p: ptr int; oldValue, newValue: int): bool
{.importc: "__tcc_cas", nodecl.}
proc cas*[T: bool|int|ptr](p: ptr T; oldValue, newValue: T): bool =
tcc_cas(cast[ptr int](p), cast[int](oldValue), cast[int](newValue))
elif declared(atomicCompareExchangeN):
proc cas*[T: bool|int|ptr](p: ptr T; oldValue, newValue: T): bool =
atomicCompareExchangeN(p, oldValue.unsafeAddr, newValue, false, ATOMIC_SEQ_CST, ATOMIC_SEQ_CST)
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 someVcc:
proc cpuRelax* {.importc: "YieldProcessor", header: "<windows.h>".}
elif (defined(x86) or defined(amd64)) and (someGcc or defined(bcc)):
proc cpuRelax* {.inline.} =
{.emit: """asm volatile("pause" ::: "memory");""".}
elif someGcc or defined(tcc):
proc cpuRelax* {.inline.} =
{.emit: """asm volatile("" ::: "memory");""".}
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.}