This reverts commit 216be4060a.
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Clyybber
GitHub
parent
00f86f5591
commit
70b9e9962f
7 changed files with 130 additions and 147 deletions
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@ -26,6 +26,7 @@ type
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owner: PSym
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g: ControlFlowGraph
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graph: ModuleGraph
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otherRead: PNode
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inLoop, inSpawn, inLoopCond: int
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uninit: IntSet # set of uninit'ed vars
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uninitComputed: bool
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@ -71,56 +72,23 @@ proc nestedScope(parent: var Scope): Scope =
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proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode): PNode
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proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope; isDecl = false): PNode
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import sets, hashes, tables
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proc hash(n: PNode): Hash = hash(cast[pointer](n))
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type AliasCache = Table[(PNode, PNode), AliasKind]
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proc aliasesCached(cache: var AliasCache, obj, field: PNode): AliasKind =
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let key = (obj, field)
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if not cache.hasKey(key):
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cache[key] = aliases(obj, field)
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cache[key]
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proc collectLastReads(cfg: ControlFlowGraph; cache: var AliasCache, alreadySeen: var HashSet[PNode], lastReads, potLastReads: var IntSet; pc: var int, until: int) =
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template aliasesCached(obj, field: PNode): untyped =
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aliasesCached(cache, obj, field)
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while pc < until:
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proc isLastRead(location: PNode; cfg: ControlFlowGraph; otherRead: var PNode; pc, until: int): int =
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var pc = pc
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while pc < cfg.len and pc < until:
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case cfg[pc].kind
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of def:
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let potLastReadsCopy = potLastReads
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for r in potLastReadsCopy:
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if cfg[pc].n.aliasesCached(cfg[r].n) == yes:
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# the path leads to a redefinition of 's' --> sink 's'.
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lastReads.incl r
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potLastReads.excl r
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elif cfg[r].n.aliasesCached(cfg[pc].n) != no:
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# only partially writes to 's' --> can't sink 's', so this def reads 's'
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# or maybe writes to 's' --> can't sink 's'
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cfg[r].n.comment = '\n' & $pc
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potLastReads.excl r
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var alreadySeenThisNode = false
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for s in alreadySeen:
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if cfg[pc].n.aliases(s) != no or s.aliases(cfg[pc].n) != no:
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alreadySeenThisNode = true; break
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if alreadySeenThisNode: cfg[pc].n.flags.excl nfFirstWrite
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else: cfg[pc].n.flags.incl nfFirstWrite
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alreadySeen.incl cfg[pc].n
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if instrTargets(cfg[pc].n, location) == Full:
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# the path leads to a redefinition of 's' --> abandon it.
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return high(int)
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elif instrTargets(cfg[pc].n, location) == Partial:
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# only partially writes to 's' --> can't sink 's', so this def reads 's'
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otherRead = cfg[pc].n
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return -1
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inc pc
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of use:
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let potLastReadsCopy = potLastReads
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for r in potLastReadsCopy:
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if cfg[pc].n.aliasesCached(cfg[r].n) != no or cfg[r].n.aliasesCached(cfg[pc].n) != no:
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cfg[r].n.comment = '\n' & $pc
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potLastReads.excl r
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potLastReads.incl pc
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alreadySeen.incl cfg[pc].n
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if instrTargets(cfg[pc].n, location) != None:
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otherRead = cfg[pc].n
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return -1
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inc pc
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of goto:
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pc += cfg[pc].dest
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@ -128,37 +96,99 @@ proc collectLastReads(cfg: ControlFlowGraph; cache: var AliasCache, alreadySeen:
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# every branch must lead to the last read of the location:
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var variantA = pc + 1
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var variantB = pc + cfg[pc].dest
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var potLastReadsA, potLastReadsB = potLastReads
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var lastReadsA, lastReadsB: IntSet
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var alreadySeenA, alreadySeenB = alreadySeen
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while variantA != variantB and max(variantA, variantB) < cfg.len and min(variantA, variantB) < until:
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while variantA != variantB:
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if min(variantA, variantB) < 0: return -1
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if max(variantA, variantB) >= cfg.len or min(variantA, variantB) >= until:
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break
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if variantA < variantB:
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collectLastReads(cfg, cache, alreadySeenA, lastReadsA, potLastReadsA, variantA, min(variantB, until))
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variantA = isLastRead(location, cfg, otherRead, variantA, min(variantB, until))
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else:
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collectLastReads(cfg, cache, alreadySeenB, lastReadsB, potLastReadsB, variantB, min(variantA, until))
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alreadySeen.incl alreadySeenA + alreadySeenB
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lastReads.incl lastReadsA * lastReadsB
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lastReads.incl (lastReadsA + lastReadsB) - potLastReads
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let oldPotLastReads = potLastReads
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potLastReads = initIntSet()
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potLastReads.incl (lastReadsA + lastReadsB) - lastReads
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potLastReads.incl potLastReadsA * potLastReadsB
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potLastReads.incl (potLastReadsA + potLastReadsB) - oldPotLastReads
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variantB = isLastRead(location, cfg, otherRead, variantB, min(variantA, until))
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pc = min(variantA, variantB)
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return pc
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proc isCursor(n: PNode; c: Con): bool =
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case n.kind
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of nkSym:
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sfCursor in n.sym.flags
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of nkDotExpr:
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isCursor(n[1], c)
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of nkCheckedFieldExpr:
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isCursor(n[0], c)
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else:
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false
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proc isLastRead(n: PNode; c: var Con): bool =
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# first we need to search for the instruction that belongs to 'n':
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var instr = -1
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let m = dfa.skipConvDfa(n)
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(m.kind == nkSym and sfSingleUsedTemp in m.sym.flags) or nfLastRead in m.flags
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if m.kind == nkSym and sfSingleUsedTemp in m.sym.flags: return true
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for i in 0..<c.g.len:
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# This comparison is correct and MUST not be ``instrTargets``:
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if c.g[i].kind == use and c.g[i].n == m:
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if instr < 0:
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instr = i
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break
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dbg: echo "starting point for ", n, " is ", instr, " ", n.kind
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if instr < 0: return false
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# we go through all paths beginning from 'instr+1' and need to
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# ensure that we don't find another 'use X' instruction.
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if instr+1 >= c.g.len: return true
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c.otherRead = nil
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result = isLastRead(n, c.g, c.otherRead, instr+1, int.high) >= 0
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dbg: echo "ugh ", c.otherRead.isNil, " ", result
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proc isFirstWrite(location: PNode; cfg: ControlFlowGraph; pc, until: int): int =
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var pc = pc
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while pc < until:
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case cfg[pc].kind
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of def:
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if instrTargets(cfg[pc].n, location) != None:
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# a definition of 's' before ours makes ours not the first write
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return -1
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inc pc
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of use:
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if instrTargets(cfg[pc].n, location) != None:
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return -1
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inc pc
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of goto:
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pc += cfg[pc].dest
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of fork:
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# every branch must not contain a def/use of our location:
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var variantA = pc + 1
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var variantB = pc + cfg[pc].dest
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while variantA != variantB:
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if min(variantA, variantB) < 0: return -1
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if max(variantA, variantB) > until:
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break
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if variantA < variantB:
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variantA = isFirstWrite(location, cfg, variantA, min(variantB, until))
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else:
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variantB = isFirstWrite(location, cfg, variantB, min(variantA, until))
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pc = min(variantA, variantB)
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return pc
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proc isFirstWrite(n: PNode; c: var Con): bool =
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# first we need to search for the instruction that belongs to 'n':
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var instr = -1
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let m = dfa.skipConvDfa(n)
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nfFirstWrite in m.flags
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for i in countdown(c.g.len-1, 0): # We search backwards here to treat loops correctly
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if c.g[i].kind == def and c.g[i].n == m:
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if instr < 0:
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instr = i
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break
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if instr < 0: return false
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# we go through all paths going to 'instr' and need to
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# ensure that we don't find another 'def/use X' instruction.
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if instr == 0: return true
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result = isFirstWrite(n, c.g, 0, instr) >= 0
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proc initialized(code: ControlFlowGraph; pc: int,
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init, uninit: var IntSet; until: int): int =
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@ -198,33 +228,20 @@ proc initialized(code: ControlFlowGraph; pc: int,
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inc pc
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return pc
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proc isCursor(n: PNode; c: Con): bool =
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case n.kind
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of nkSym:
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sfCursor in n.sym.flags
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of nkDotExpr:
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isCursor(n[1], c)
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of nkCheckedFieldExpr:
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isCursor(n[0], c)
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else:
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false
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template isUnpackedTuple(n: PNode): bool =
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## we move out all elements of unpacked tuples,
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## hence unpacked tuples themselves don't need to be destroyed
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(n.kind == nkSym and n.sym.kind == skTemp and n.sym.typ.kind == tyTuple)
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from strutils import parseInt
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proc checkForErrorPragma(c: Con; t: PType; ri: PNode; opname: string) =
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var m = "'" & opname & "' is not available for type <" & typeToString(t) & ">"
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if (opname == "=" or opname == "=copy") and ri != nil:
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m.add "; requires a copy because it's not the last read of '"
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m.add renderTree(ri)
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m.add '\''
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if ri.comment.startsWith('\n'):
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if c.otherRead != nil:
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m.add "; another read is done here: "
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m.add c.graph.config $ c.g[parseInt(ri.comment[1..^1])].n.info
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m.add c.graph.config $ c.otherRead.info
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elif ri.kind == nkSym and ri.sym.kind == skParam and not isSinkType(ri.sym.typ):
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m.add "; try to make "
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m.add renderTree(ri)
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@ -338,6 +355,7 @@ proc genCopy(c: var Con; dest, ri: PNode): PNode =
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let t = dest.typ
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if tfHasOwned in t.flags and ri.kind != nkNilLit:
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# try to improve the error message here:
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if c.otherRead == nil: discard isLastRead(ri, c)
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c.checkForErrorPragma(t, ri, "=copy")
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result = c.genCopyNoCheck(dest, ri)
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@ -1079,24 +1097,6 @@ proc injectDestructorCalls*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; n:
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if optCursorInference in g.config.options:
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computeCursors(owner, n, g)
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block:
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var cache = initTable[(PNode, PNode), AliasKind]()
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var alreadySeen: HashSet[PNode]
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var lastReads, potLastReads: IntSet
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var pc = 0
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collectLastReads(c.g, cache, alreadySeen, lastReads, potLastReads, pc, c.g.len)
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lastReads.incl potLastReads
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var lastReadTable: Table[PNode, seq[int]]
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for position, node in c.g:
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if node.kind == use:
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lastReadTable.mgetOrPut(node.n, @[]).add position
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for node, positions in lastReadTable:
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var allPositionsLastRead = true
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for p in positions:
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if p notin lastReads: allPositionsLastRead = false; break
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if allPositionsLastRead:
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node.flags.incl nfLastRead
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var scope: Scope
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let body = p(n, c, scope, normal)
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