mirror of
https://github.com/nim-lang/Nim.git
synced 2025-12-28 17:04:41 +00:00
Remove some unnecessary initialization in string operations (#22579)
* `prepareAdd`
* `toNimStr`
* `setLengthStrV2`
* `NimAsgnStrV2`
* `prepareMutation`
* Some cleanups
(cherry picked from commit a4df44d9fb)
This commit is contained in:
Amjad Ben Hedhili
committed by
narimiran
narimiran
parent
79a1990774
commit
d7dfbf026b
@@ -34,53 +34,72 @@ template frees(s) =
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else:
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dealloc(s.p)
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template allocPayload(newLen: int): ptr NimStrPayload =
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when compileOption("threads"):
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cast[ptr NimStrPayload](allocShared(contentSize(newLen)))
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else:
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cast[ptr NimStrPayload](alloc(contentSize(newLen)))
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template allocPayload0(newLen: int): ptr NimStrPayload =
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when compileOption("threads"):
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cast[ptr NimStrPayload](allocShared0(contentSize(newLen)))
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else:
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cast[ptr NimStrPayload](alloc0(contentSize(newLen)))
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template reallocPayload(p: pointer, newLen: int): ptr NimStrPayload =
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when compileOption("threads"):
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cast[ptr NimStrPayload](reallocShared(p, contentSize(newLen)))
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else:
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cast[ptr NimStrPayload](realloc(p, contentSize(newLen)))
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template reallocPayload0(p: pointer; oldLen, newLen: int): ptr NimStrPayload =
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when compileOption("threads"):
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cast[ptr NimStrPayload](reallocShared0(p, contentSize(oldLen), contentSize(newLen)))
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else:
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cast[ptr NimStrPayload](realloc0(p, contentSize(oldLen), contentSize(newLen)))
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proc resize(old: int): int {.inline.} =
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if old <= 0: result = 4
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elif old < 65536: result = old * 2
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else: result = old * 3 div 2 # for large arrays * 3/2 is better
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proc prepareAdd(s: var NimStringV2; addlen: int) {.compilerRtl.} =
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let newLen = s.len + addlen
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proc prepareAdd(s: var NimStringV2; addLen: int) {.compilerRtl.} =
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let newLen = s.len + addLen
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if isLiteral(s):
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let oldP = s.p
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# can't mutate a literal, so we need a fresh copy here:
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when compileOption("threads"):
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s.p = cast[ptr NimStrPayload](allocShared0(contentSize(newLen)))
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else:
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s.p = cast[ptr NimStrPayload](alloc0(contentSize(newLen)))
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s.p = allocPayload(newLen)
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s.p.cap = newLen
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if s.len > 0:
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# we are about to append, so there is no need to copy the \0 terminator:
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copyMem(unsafeAddr s.p.data[0], unsafeAddr oldP.data[0], min(s.len, newLen))
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elif oldP == nil:
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# In the case of `newString(0) & ""`, since `src.len == 0`, `appendString`
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# will not set the `\0` terminator, so we set it here.
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s.p.data[0] = '\0'
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else:
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let oldCap = s.p.cap and not strlitFlag
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if newLen > oldCap:
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let newCap = max(newLen, resize(oldCap))
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when compileOption("threads"):
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s.p = cast[ptr NimStrPayload](reallocShared0(s.p, contentSize(oldCap), contentSize(newCap)))
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else:
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s.p = cast[ptr NimStrPayload](realloc0(s.p, contentSize(oldCap), contentSize(newCap)))
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s.p = reallocPayload(s.p, newCap)
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s.p.cap = newCap
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if newLen < newCap:
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zeroMem(cast[pointer](addr s.p.data[newLen+1]), newCap - newLen)
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proc nimAddCharV1(s: var NimStringV2; c: char) {.compilerRtl, inline.} =
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#if (s.p == nil) or (s.len+1 > s.p.cap and not strlitFlag):
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prepareAdd(s, 1)
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s.p.data[s.len] = c
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s.p.data[s.len+1] = '\0'
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inc s.len
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s.p.data[s.len] = '\0'
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proc toNimStr(str: cstring, len: int): NimStringV2 {.compilerproc.} =
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if len <= 0:
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result = NimStringV2(len: 0, p: nil)
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else:
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when compileOption("threads"):
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var p = cast[ptr NimStrPayload](allocShared0(contentSize(len)))
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else:
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var p = cast[ptr NimStrPayload](alloc0(contentSize(len)))
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var p = allocPayload(len)
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p.cap = len
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if len > 0:
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# we are about to append, so there is no need to copy the \0 terminator:
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copyMem(unsafeAddr p.data[0], str, len)
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copyMem(unsafeAddr p.data[0], str, len+1)
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result = NimStringV2(len: len, p: p)
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proc cstrToNimstr(str: cstring): NimStringV2 {.compilerRtl.} =
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@@ -99,18 +118,15 @@ proc appendString(dest: var NimStringV2; src: NimStringV2) {.compilerproc, inlin
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proc appendChar(dest: var NimStringV2; c: char) {.compilerproc, inline.} =
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dest.p.data[dest.len] = c
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dest.p.data[dest.len+1] = '\0'
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inc dest.len
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dest.p.data[dest.len] = '\0'
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proc rawNewString(space: int): NimStringV2 {.compilerproc.} =
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# this is also 'system.newStringOfCap'.
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if space <= 0:
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result = NimStringV2(len: 0, p: nil)
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else:
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when compileOption("threads"):
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var p = cast[ptr NimStrPayload](allocShared(contentSize(space)))
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else:
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var p = cast[ptr NimStrPayload](alloc(contentSize(space)))
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var p = allocPayload(space)
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p.cap = space
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p.data[0] = '\0'
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result = NimStringV2(len: 0, p: p)
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@@ -119,10 +135,7 @@ proc mnewString(len: int): NimStringV2 {.compilerproc.} =
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if len <= 0:
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result = NimStringV2(len: 0, p: nil)
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else:
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when compileOption("threads"):
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var p = cast[ptr NimStrPayload](allocShared0(contentSize(len)))
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else:
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var p = cast[ptr NimStrPayload](alloc0(contentSize(len)))
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var p = allocPayload0(len)
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p.cap = len
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result = NimStringV2(len: len, p: p)
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@@ -130,8 +143,25 @@ proc setLengthStrV2(s: var NimStringV2, newLen: int) {.compilerRtl.} =
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if newLen == 0:
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discard "do not free the buffer here, pattern 's.setLen 0' is common for avoiding allocations"
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else:
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if newLen > s.len or isLiteral(s):
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prepareAdd(s, newLen - s.len)
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if isLiteral(s):
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let oldP = s.p
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s.p = allocPayload(newLen)
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s.p.cap = newLen
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if s.len > 0:
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copyMem(unsafeAddr s.p.data[0], unsafeAddr oldP.data[0], min(s.len, newLen))
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if newLen > s.len:
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zeroMem(cast[pointer](addr s.p.data[s.len]), newLen - s.len + 1)
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else:
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s.p.data[newLen] = '\0'
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else:
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zeroMem(cast[pointer](addr s.p.data[0]), newLen + 1)
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elif newLen > s.len:
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let oldCap = s.p.cap and not strlitFlag
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if newLen > oldCap:
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let newCap = max(newLen, resize(oldCap))
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s.p = reallocPayload0(s.p, oldCap, newCap)
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s.p.cap = newCap
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s.p.data[newLen] = '\0'
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s.len = newLen
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@@ -148,10 +178,7 @@ proc nimAsgnStrV2(a: var NimStringV2, b: NimStringV2) {.compilerRtl.} =
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# 'let y = newStringOfCap(); var x = y'
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# on the other hand... These get turned into moves now.
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frees(a)
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when compileOption("threads"):
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a.p = cast[ptr NimStrPayload](allocShared0(contentSize(b.len)))
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else:
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a.p = cast[ptr NimStrPayload](alloc0(contentSize(b.len)))
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a.p = allocPayload(b.len)
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a.p.cap = b.len
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a.len = b.len
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copyMem(unsafeAddr a.p.data[0], unsafeAddr b.p.data[0], b.len+1)
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@@ -159,10 +186,7 @@ proc nimAsgnStrV2(a: var NimStringV2, b: NimStringV2) {.compilerRtl.} =
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proc nimPrepareStrMutationImpl(s: var NimStringV2) =
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let oldP = s.p
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# can't mutate a literal, so we need a fresh copy here:
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when compileOption("threads"):
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s.p = cast[ptr NimStrPayload](allocShared0(contentSize(s.len)))
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else:
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s.p = cast[ptr NimStrPayload](alloc0(contentSize(s.len)))
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s.p = allocPayload(s.len)
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s.p.cap = s.len
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copyMem(unsafeAddr s.p.data[0], unsafeAddr oldP.data[0], s.len+1)
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