#
# Nim's Runtime Library
# (c) Copyright 2016 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# "Stack GC" for embedded devices or ultra performance requirements.
when defined(nimphpext):
proc roundup(x, v: int): int {.inline.} =
result = (x + (v-1)) and not (v-1)
proc emalloc(size: int): pointer {.importc: "_emalloc".}
proc efree(mem: pointer) {.importc: "_efree".}
proc osAllocPages(size: int): pointer {.inline.} =
emalloc(size)
proc osTryAllocPages(size: int): pointer {.inline.} =
emalloc(size)
proc osDeallocPages(p: pointer, size: int) {.inline.} =
efree(p)
else:
include osalloc
# We manage memory as a thread local stack. Since the allocation pointer
# is detached from the control flow pointer, this model is vastly more
# useful than the traditional programming model while almost as safe.
# Individual objects can also be deleted but no coalescing is performed.
# Stacks can also be moved from one thread to another.
# We also support 'finalizers'.
type
Finalizer {.compilerproc.} = proc (self: pointer) {.nimcall, benign.}
# A ref type can have a finalizer that is called before the object's
# storage is freed.
AlignType = BiggestFloat
ObjHeader = object
typ: PNimType
nextFinal: ptr ObjHeader # next object with finalizer
Hole = object # stacks can have holes. Otherwise 'growObj' would be insane.
zeroTyp: pointer # overlaid with 'typ' field. Always 'nil'.
size: int # size of the free slot
Chunk = ptr BaseChunk
BaseChunk = object
next: Chunk
size: int
head, tail: ptr ObjHeader # first and last object in chunk that
# has a finalizer attached to it
type
StackPtr = object
bump: pointer
remaining: int
current: Chunk
MemRegion* = object
remaining: int
bump: pointer
head, tail: Chunk
nextChunkSize, totalSize: int
hole: ptr Hole # we support individual freeing
when hasThreadSupport:
lock: SysLock
var
tlRegion {.threadVar.}: MemRegion
template withRegion*(r: MemRegion; body: untyped) =
let oldRegion = tlRegion
tlRegion = r
try:
body
finally:
tlRegion = oldRegion
template inc(p: pointer, s: int) =
p = cast[pointer](cast[int](p) +% s)
template `+!`(p: pointer, s: int): pointer =
cast[pointer](cast[int](p) +% s)
template `-!`(p: pointer, s: int): pointer =
cast[pointer](cast[int](p) -% s)
proc allocSlowPath(r: var MemRegion; size: int) =
# we need to ensure that the underlying linked list
# stays small. Say we want to grab 16GB of RAM with some
# exponential growth function. So we allocate 16KB, then
# 32 KB, 64 KB, 128KB, 256KB, 512KB, 1MB, 2MB, 4MB,
# 8MB, 16MB, 32MB, 64MB, 128MB, 512MB, 1GB, 2GB, 4GB, 8GB,
# 16GB --> list contains only 20 elements! That's reasonable.
if (r.totalSize and 1) == 0:
r.nextChunkSize =
if r.totalSize < 64 * 1024: PageSize*4
else: r.nextChunkSize*2
var s = roundup(size+sizeof(BaseChunk), PageSize)
var fresh: Chunk
if s > r.nextChunkSize:
fresh = cast[Chunk](osAllocPages(s))
else:
fresh = cast[Chunk](osTryAllocPages(r.nextChunkSize))
if fresh == nil:
fresh = cast[Chunk](osAllocPages(s))
# lowest bit in totalSize is the "don't increase nextChunkSize"
inc r.totalSize
else:
s = r.nextChunkSize
fresh.size = s
fresh.head = nil
fresh.tail = nil
fresh.next = nil
inc r.totalSize, s
let old = r.tail
if old == nil:
r.head = fresh
else:
r.tail.next = fresh
r.bump = fresh +! sizeof(BaseChunk)
r.tail = fresh
r.remaining = s - sizeof(BaseChunk)
proc alloc(r: var MemRegion; size: int): pointer {.inline.} =
if size > r.remaining:
allocSlowPath(r, size)
sysAssert(size <= r.remaining, "size <= r.remaining")
dec(r.remaining, size)
result = r.bump
inc r.bump, size
proc runFinalizers(c: Chunk) =
var it = c.head
while it != nil:
# indivually freed objects with finalizer stay in the list, but
# their typ is nil then:
if it.typ != nil and it.typ.finalizer != nil:
(cast[Finalizer](it.typ.finalizer))(it+!sizeof(ObjHeader))
it = it.nextFinal
when false:
proc dealloc(r: var MemRegion; p: pointer) =
let it = cast[ptr ObjHeader](p-!sizeof(ObjHeader))
if it.typ != nil and it.typ.finalizer != nil:
(cast[Finalizer](it.typ.finalizer))(p)
it.typ = nil
proc deallocAll(r: var MemRegion; head: Chunk) =
var it = head
while it != nil:
let nxt = it.next
runFinalizers(it)
dec r.totalSize, it.size
osDeallocPages(it, it.size)
it = nxt
proc deallocAll*(r: var MemRegion) =
deallocAll(r, r.head)
zeroMem(addr r, sizeof r)
proc obstackPtr*(r: MemRegion): StackPtr =
result.bump = r.bump
result.remaining = r.remaining
result.current = r.tail
template computeRemaining(r): untyped =
r.tail.size -% (cast[int](r.bump) -% cast[int](r.tail))
proc setObstackPtr*(r: var MemRegion; sp: StackPtr) =
# free everything after 'sp':
if sp.current != nil:
deallocAll(r, sp.current.next)
sp.current.next = nil
else:
deallocAll(r, r.head)
r.head = nil
r.bump = sp.bump
r.tail = sp.current
r.remaining = sp.remaining
proc obstackPtr*(): StackPtr = tlRegion.obstackPtr()
proc setObstackPtr*(sp: StackPtr) = tlRegion.setObstackPtr(sp)
proc deallocAll*() = tlRegion.deallocAll()
proc deallocOsPages(r: var MemRegion) = r.deallocAll()
proc joinRegion*(dest: var MemRegion; src: MemRegion) =
# merging is not hard.
if dest.head.isNil:
dest.head = src.head
else:
dest.tail.next = src.head
dest.tail = src.tail
dest.bump = src.bump
dest.remaining = src.remaining
dest.nextChunkSize = max(dest.nextChunkSize, src.nextChunkSize)
inc dest.totalSize, src.totalSize
proc isOnHeap*(r: MemRegion; p: pointer): bool =
# the tail chunk is the largest, so check it first. It's also special
# in that contains the current bump pointer:
if r.tail >= p and p < r.bump:
return true
var it = r.head
while it != r.tail:
if it >= p and p <= it+!it.size: return true
it = it.next
when false:
# essential feature for later: copy data over from one region to another
proc isInteriorPointer(r: MemRegion; p: pointer): pointer =
discard " we cannot patch stack pointers anyway!"
type
PointerStackChunk = object
next, prev: ptr PointerStackChunk
len: int
data: array[128, pointer]
template head(s: PointerStackChunk): untyped = s.prev
template tail(s: PointerStackChunk): untyped = s.next
include chains
proc push(r: var MemRegion; s: var PointerStackChunk; x: pointer) =
if s.len < high(s.data):
s.data[s.len] = x
inc s.len
else:
let fresh = cast[ptr PointerStackChunk](alloc(r, sizeof(PointerStackChunk)))
fresh.len = 1
fresh.data[0] = x
fresh.next = nil
fresh.prev = nil
append(s, fresh)
proc genericDeepCopyAux(dr: var MemRegion; stack: var PointerStackChunk;
dest, src: pointer, mt: PNimType) {.benign.}
proc genericDeepCopyAux(dr: var MemRegion; stack: var PointerStackChunk;
dest, src: pointer, n: ptr TNimNode) {.benign.} =
var
d = cast[ByteAddress](dest)
s = cast[ByteAddress](src)
case n.kind
of nkSlot:
genericDeepCopyAux(cast[pointer](d +% n.offset),
cast[pointer](s +% n.offset), n.typ)
of nkList:
for i in 0..n.len-1:
genericDeepCopyAux(dest, src, n.sons[i])
of nkCase:
var dd = selectBranch(dest, n)
var m = selectBranch(src, n)
# reset if different branches are in use; note different branches also
# imply that's not self-assignment (``x = x``)!
if m != dd and dd != nil:
genericResetAux(dest, dd)
copyMem(cast[pointer](d +% n.offset), cast[pointer](s +% n.offset),
n.typ.size)
if m != nil:
genericDeepCopyAux(dest, src, m)
of nkNone: sysAssert(false, "genericDeepCopyAux")
proc copyDeepString(dr: var MemRegion; stack: var PointerStackChunk; src: NimString): NimString {.inline.} =
result = rawNewStringNoInit(dr, src.len)
result.len = src.len
copyMem(result.data, src.data, src.len + 1)
proc genericDeepCopyAux(dr: var MemRegion; stack: var PointerStackChunk;
dest, src: pointer, mt: PNimType) =
var
d = cast[ByteAddress](dest)
s = cast[ByteAddress](src)
sysAssert(mt != nil, "genericDeepCopyAux 2")
case mt.kind
of tyString:
var x = cast[PPointer](dest)
var s2 = cast[PPointer](s)[]
if s2 == nil:
x[] = nil
else:
x[] = copyDeepString(cast[NimString](s2))
of tySequence:
var s2 = cast[PPointer](src)[]
var seq = cast[PGenericSeq](s2)
var x = cast[PPointer](dest)
if s2 == nil:
x[] = nil
return
sysAssert(dest != nil, "genericDeepCopyAux 3")
x[] = newSeq(mt, seq.len)
var dst = cast[ByteAddress](cast[PPointer](dest)[])
for i in 0..seq.len-1:
genericDeepCopyAux(dr, stack,
cast[pointer](dst +% i*% mt.base.size +% GenericSeqSize),
cast[pointer](cast[ByteAddress](s2) +% i *% mt.base.size +%
GenericSeqSize),
mt.base)
of tyObject:
# we need to copy m_type field for tyObject, as it could be empty for
# sequence reallocations:
var pint = cast[ptr PNimType](dest)
pint[] = cast[ptr PNimType](src)[]
if mt.base != nil:
genericDeepCopyAux(dr, stack, dest, src, mt.base)
genericDeepCopyAux(dr, stack, dest, src, mt.node)
of tyTuple:
genericDeepCopyAux(dr, stack, dest, src, mt.node)
of tyArray, tyArrayConstr:
for i in 0..(mt.size div mt.base.size)-1:
genericDeepCopyAux(dr, stack,
cast[pointer](d +% i*% mt.base.size),
cast[pointer](s +% i*% mt.base.size), mt.base)
of tyRef:
let s2 = cast[PPointer](src)[]
if s2 == nil:
cast[PPointer](dest)[] = nil
else:
# we modify the header of the cell temporarily; instead of the type
# field we store a forwarding pointer. XXX This is bad when the cloning
# fails due to OOM etc.
let x = usrToCell(s2)
let forw = cast[int](x.typ)
if (forw and 1) == 1:
# we stored a forwarding pointer, so let's use that:
let z = cast[pointer](forw and not 1)
unsureAsgnRef(cast[PPointer](dest), z)
else:
let realType = x.typ
let z = newObj(realType, realType.base.size)
unsureAsgnRef(cast[PPointer](dest), z)
x.typ = cast[PNimType](cast[int](z) or 1)
genericDeepCopyAux(dr, stack, z, s2, realType.base)
x.typ = realType
else:
copyMem(dest, src, mt.size)
proc joinAliveDataFromRegion*(dest: var MemRegion; src: var MemRegion;
root: pointer): pointer =
# we mark the alive data and copy only alive data over to 'dest'.
# This is O(liveset) but it nicely compacts memory, so it's fine.
# We use the 'typ' field as a forwarding pointer. The forwarding
# pointers have bit 0 set, so we can disambiguate them.
# We allocate a temporary stack in 'src' that we later free:
var s: PointerStackChunk
s.len = 1
s.data[0] = root
while s.len > 0:
var p: pointer
if s.tail == nil:
p = s.data[s.len-1]
dec s.len
else:
p = s.tail.data[s.tail.len-1]
dec s.tail.len
if s.tail.len == 0:
unlink(s, s.tail)
proc rawNewObj(r: var MemRegion, typ: PNimType, size: int): pointer =
var res = cast[ptr ObjHeader](alloc(r, size + sizeof(ObjHeader)))
res.typ = typ
if typ.finalizer != nil:
res.nextFinal = r.head.head
r.head.head = res
result = res +! sizeof(ObjHeader)
proc newObj(typ: PNimType, size: int): pointer {.compilerRtl.} =
result = rawNewObj(tlRegion, typ, size)
zeroMem(result, size)
when defined(memProfiler): nimProfile(size)
proc newObjNoInit(typ: PNimType, size: int): pointer {.compilerRtl.} =
result = rawNewObj(tlRegion, typ, size)
when defined(memProfiler): nimProfile(size)
proc newSeq(typ: PNimType, len: int): pointer {.compilerRtl.} =
let size = addInt(mulInt(len, typ.base.size), GenericSeqSize)
result = newObj(typ, size)
cast[PGenericSeq](result).len = len
cast[PGenericSeq](result).reserved = len
proc newObjRC1(typ: PNimType, size: int): pointer {.compilerRtl.} =
result = rawNewObj(tlRegion, typ, size)
zeroMem(result, size)
proc newSeqRC1(typ: PNimType, len: int): pointer {.compilerRtl.} =
let size = addInt(mulInt(len, typ.base.size), GenericSeqSize)
result = newObj(typ, size)
cast[PGenericSeq](result).len = len
cast[PGenericSeq](result).reserved = len
proc growObj(region: var MemRegion; old: pointer, newsize: int): pointer =
let typ = cast[ptr ObjHeader](old -! sizeof(ObjHeader)).typ
result = rawNewObj(region, typ, newsize)
let elemSize = if typ.kind == tyString: 1 else: typ.base.size
let oldsize = cast[PGenericSeq](old).len*elemSize + GenericSeqSize
copyMem(result, old, oldsize)
zeroMem(result +! oldsize, newsize-oldsize)
proc growObj(old: pointer, newsize: int): pointer {.rtl.} =
result = growObj(tlRegion, old, newsize)
proc unsureAsgnRef(dest: PPointer, src: pointer) {.compilerproc, inline.} =
dest[] = src
proc asgnRef(dest: PPointer, src: pointer) {.compilerproc, inline.} =
dest[] = src
proc asgnRefNoCycle(dest: PPointer, src: pointer) {.compilerproc, inline.} =
dest[] = src
proc alloc(size: Natural): pointer =
result = c_malloc(size)
if result == nil: raiseOutOfMem()
proc alloc0(size: Natural): pointer =
result = alloc(size)
zeroMem(result, size)
proc realloc(p: pointer, newsize: Natural): pointer =
result = c_realloc(p, newsize)
if result == nil: raiseOutOfMem()
proc dealloc(p: pointer) = c_free(p)
proc alloc0(r: var MemRegion; size: Natural): pointer =
# ignore the region. That is correct for the channels module
# but incorrect in general. XXX
result = alloc0(size)
proc dealloc(r: var MemRegion; p: pointer) = dealloc(p)
proc allocShared(size: Natural): pointer =
result = c_malloc(size)
if result == nil: raiseOutOfMem()
proc allocShared0(size: Natural): pointer =
result = alloc(size)
zeroMem(result, size)
proc reallocShared(p: pointer, newsize: Natural): pointer =
result = c_realloc(p, newsize)
if result == nil: raiseOutOfMem()
proc deallocShared(p: pointer) = c_free(p)
when hasThreadSupport:
proc getFreeSharedMem(): int = 0
proc getTotalSharedMem(): int = 0
proc getOccupiedSharedMem(): int = 0
proc GC_disable() = discard
proc GC_enable() = discard
proc GC_fullCollect() = discard
proc GC_setStrategy(strategy: GC_Strategy) = discard
proc GC_enableMarkAndSweep() = discard
proc GC_disableMarkAndSweep() = discard
proc GC_getStatistics(): string = return ""
proc getOccupiedMem(): int =
result = tlRegion.totalSize - tlRegion.remaining
proc getFreeMem(): int = tlRegion.remaining
proc getTotalMem(): int =
result = tlRegion.totalSize
proc setStackBottom(theStackBottom: pointer) = discard