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optimize setLen (#6816)

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inline the call to setLengthSeq and avoid decref for types if ntfNoRefs

closes #6721 and speeds setLen when newLen < len for non reference
types.
This commit is contained in:
Brent Pedersen 2017-12-07 12:25:39 -07:00 • committed by Varriount
commit e016c9253e
1 changed files with 6 additions and 5 deletions
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11
lib/system/sysstr.nim
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@ -259,7 +259,7 @@ proc incrSeqV2(seq: PGenericSeq, elemSize: int): PGenericSeq {.compilerProc.} =
result.reserved = r
proc setLengthSeq(seq: PGenericSeq, elemSize, newLen: int): PGenericSeq {.
compilerRtl.} =
compilerRtl, inl.} =
result = seq
if result.space < newLen:
let r = max(resize(result.space), newLen)
@ -282,10 +282,11 @@ proc setLengthSeq(seq: PGenericSeq, elemSize, newLen: int): PGenericSeq {.
doDecRef(gch.tempStack.d[i], LocalHeap, MaybeCyclic)
gch.tempStack.len = len0
else:
for i in newLen..result.len-1:
forAllChildrenAux(cast[pointer](cast[ByteAddress](result) +%
GenericSeqSize +% (i*%elemSize)),
extGetCellType(result).base, waZctDecRef)
if ntfNoRefs notin extGetCellType(result).base.flags:
for i in newLen..result.len-1:
forAllChildrenAux(cast[pointer](cast[ByteAddress](result) +%
GenericSeqSize +% (i*%elemSize)),
extGetCellType(result).base, waZctDecRef)
# XXX: zeroing out the memory can still result in crashes if a wiped-out
# cell is aliased by another pointer (ie proc parameter or a let variable).