Rework DFA traversal (#18016)
* enable using dbg: without a context * Optimally joining first write/last read analysis * Add test for #18002 * potLastReads -> potentialLastReads
This commit is contained in:
Clyybber
GitHub
parent
99788ee504
commit
3614523664
2 changed files with 133 additions and 109 deletions
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@ -46,6 +46,13 @@ type
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sinkArg
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sinkArg
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const toDebug {.strdefine.} = ""
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const toDebug {.strdefine.} = ""
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when toDebug.len > 0:
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var shouldDebug = false
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template dbg(body) =
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when toDebug.len > 0:
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if shouldDebug:
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body
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proc hasDestructor(c: Con; t: PType): bool {.inline.} =
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proc hasDestructor(c: Con; t: PType): bool {.inline.} =
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result = ast.hasDestructor(t)
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result = ast.hasDestructor(t)
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@ -54,11 +61,6 @@ proc hasDestructor(c: Con; t: PType): bool {.inline.} =
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if not result and c.graph.config.selectedGC in {gcArc, gcOrc}:
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if not result and c.graph.config.selectedGC in {gcArc, gcOrc}:
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assert(not containsGarbageCollectedRef(t))
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assert(not containsGarbageCollectedRef(t))
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template dbg(body) =
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when toDebug.len > 0:
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if c.owner.name.s == toDebug or toDebug == "always":
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body
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proc getTemp(c: var Con; s: var Scope; typ: PType; info: TLineInfo): PNode =
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proc getTemp(c: var Con; s: var Scope; typ: PType; info: TLineInfo): PNode =
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let sym = newSym(skTemp, getIdent(c.graph.cache, ":tmpD"), nextSymId c.idgen, c.owner, info)
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let sym = newSym(skTemp, getIdent(c.graph.cache, ":tmpD"), nextSymId c.idgen, c.owner, info)
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sym.typ = typ
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sym.typ = typ
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@ -75,106 +77,111 @@ import sets, hashes, tables
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proc hash(n: PNode): Hash = hash(cast[pointer](n))
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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 Table[(PNode, PNode), AliasKind], obj, field: 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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let key = (obj, field)
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if not cache.hasKey(key):
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if not cache.hasKey(key):
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cache[key] = aliases(obj, field)
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cache[key] = aliases(obj, field)
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cache[key]
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cache[key]
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proc collectLastReads(cfg: ControlFlowGraph; cache: var AliasCache, lastReads, potLastReads: var IntSet; pc: var int, until: int) =
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type
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template aliasesCached(obj, field: PNode): untyped =
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State = ref object
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lastReads: IntSet
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potentialLastReads: IntSet
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notLastReads: IntSet
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alreadySeen: HashSet[PNode]
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proc preprocessCfg(cfg: var ControlFlowGraph) =
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for i in 0..<cfg.len:
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if cfg[i].kind in {goto, fork} and i + cfg[i].dest > cfg.len:
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cfg[i].dest = cfg.len - i
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proc mergeStates(a: var State, b: sink State) =
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# Inplace for performance:
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# lastReads = a.lastReads + b.lastReads
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# potentialLastReads = (a.potentialLastReads + b.potentialLastReads) - (a.notLastReads + b.notLastReads)
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# notLastReads = a.notLastReads + b.notLastReads
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# alreadySeen = a.alreadySeen + b.alreadySeen
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# b is never nil
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if a == nil:
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a = b
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else:
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a.lastReads.incl b.lastReads
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a.potentialLastReads.incl b.potentialLastReads
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a.potentialLastReads.excl a.notLastReads
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a.potentialLastReads.excl b.notLastReads
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a.notLastReads.incl b.notLastReads
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a.alreadySeen.incl b.alreadySeen
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proc computeLastReadsAndFirstWrites(cfg: ControlFlowGraph) =
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var cache = initTable[(PNode, PNode), AliasKind]()
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template aliasesCached(obj, field: PNode): AliasKind =
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aliasesCached(cache, obj, field)
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aliasesCached(cache, obj, field)
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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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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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inc pc
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var cfg = cfg
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of use:
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preprocessCfg(cfg)
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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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var states = newSeq[State](cfg.len + 1)
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states[0] = State()
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inc pc
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for pc in 0..<cfg.len:
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of goto:
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template state: State = states[pc]
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pc += cfg[pc].dest
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if state != nil:
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of fork:
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case cfg[pc].kind
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var variantA = pc + 1
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of def:
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var variantB = pc + cfg[pc].dest
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var potentialLastReadsCopy = state.potentialLastReads
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var potLastReadsA, potLastReadsB = potLastReads
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for r in potentialLastReadsCopy:
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var lastReadsA, lastReadsB: IntSet
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if cfg[pc].n.aliasesCached(cfg[r].n) == yes:
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while variantA != variantB and max(variantA, variantB) < cfg.len and min(variantA, variantB) < until:
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# the path leads to a redefinition of 's' --> sink 's'.
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if variantA < variantB:
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state.lastReads.incl r
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collectLastReads(cfg, cache, lastReadsA, potLastReadsA, variantA, min(variantB, until))
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state.potentialLastReads.excl r
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else:
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elif cfg[r].n.aliasesCached(cfg[pc].n) != no:
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collectLastReads(cfg, cache, lastReadsB, potLastReadsB, variantB, min(variantA, until))
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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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state.potentialLastReads.excl r
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state.notLastReads.incl r
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# Add those last reads that were turned into last reads on both branches
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var alreadySeenThisNode = false
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lastReads.incl lastReadsA * lastReadsB
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for s in state.alreadySeen:
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# Add those last reads that were turned into last reads on only one branch,
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if cfg[pc].n.aliasesCached(s) != no or s.aliasesCached(cfg[pc].n) != no:
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# but where the read operation itself also belongs to only that branch
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alreadySeenThisNode = true; break
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lastReads.incl (lastReadsA + lastReadsB) - potLastReads
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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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let oldPotLastReads = potLastReads
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state.alreadySeen.incl cfg[pc].n
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potLastReads = initIntSet()
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potLastReads.incl potLastReadsA + potLastReadsB
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mergeStates(states[pc + 1], move(states[pc]))
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of use:
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var potentialLastReadsCopy = state.potentialLastReads
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for r in potentialLastReadsCopy:
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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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state.potentialLastReads.excl r
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state.notLastReads.incl r
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# Remove potential last reads that were invalidated in a branch,
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state.potentialLastReads.incl pc
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# but don't remove those which were turned into last reads on that branch
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potLastReads.excl ((oldPotLastReads - potLastReadsA) - lastReadsA)
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potLastReads.excl ((oldPotLastReads - potLastReadsB) - lastReadsB)
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pc = min(variantA, variantB)
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state.alreadySeen.incl cfg[pc].n
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proc collectFirstWrites(cfg: ControlFlowGraph; alreadySeen: var HashSet[PNode]; pc: var int, until: int) =
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mergeStates(states[pc + 1], move(states[pc]))
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while pc < until:
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of goto:
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case cfg[pc].kind
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mergeStates(states[pc + cfg[pc].dest], move(states[pc]))
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of def:
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of fork:
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var alreadySeenThisNode = false
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var copy = State()
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for s in alreadySeen:
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copy[] = states[pc][]
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if cfg[pc].n.aliases(s) != no or s.aliases(cfg[pc].n) != no:
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mergeStates(states[pc + cfg[pc].dest], copy)
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alreadySeenThisNode = true; break
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mergeStates(states[pc + 1], move(states[pc]))
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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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let lastReads = (states[^1].lastReads + states[^1].potentialLastReads) - states[^1].notLastReads
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var lastReadTable: Table[PNode, seq[int]]
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inc pc
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for position, node in cfg:
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of use:
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if node.kind == use:
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alreadySeen.incl cfg[pc].n
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lastReadTable.mgetOrPut(node.n, @[]).add position
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for node, positions in lastReadTable:
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inc pc
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block checkIfAllPosLastRead:
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of goto:
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for p in positions:
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pc += cfg[pc].dest
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if p notin lastReads: break checkIfAllPosLastRead
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of fork:
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node.flags.incl nfLastRead
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var variantA = pc + 1
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var variantB = pc + cfg[pc].dest
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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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if variantA < variantB:
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collectFirstWrites(cfg, alreadySeenA, variantA, min(variantB, until))
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else:
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collectFirstWrites(cfg, alreadySeenB, variantB, min(variantA, until))
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alreadySeen.incl alreadySeenA + alreadySeenB
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pc = min(variantA, variantB)
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proc isLastRead(n: PNode; c: var Con): bool =
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proc isLastRead(n: PNode; c: var Con): bool =
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let m = dfa.skipConvDfa(n)
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let m = dfa.skipConvDfa(n)
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@ -1096,6 +1103,8 @@ proc injectDefaultCalls(n: PNode, c: var Con) =
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injectDefaultCalls(n[i], c)
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injectDefaultCalls(n[i], c)
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proc injectDestructorCalls*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; n: PNode): PNode =
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proc injectDestructorCalls*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; n: PNode): PNode =
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when toDebug.len > 0:
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shouldDebug = toDebug == owner.name.s or toDebug == "always"
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if sfGeneratedOp in owner.flags or (owner.kind == skIterator and isInlineIterator(owner.typ)):
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if sfGeneratedOp in owner.flags or (owner.kind == skIterator and isInlineIterator(owner.typ)):
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return n
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return n
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var c = Con(owner: owner, graph: g, g: constructCfg(owner, n), idgen: idgen)
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var c = Con(owner: owner, graph: g, g: constructCfg(owner, n), idgen: idgen)
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@ -1107,26 +1116,7 @@ proc injectDestructorCalls*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; n:
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if optCursorInference in g.config.options:
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if optCursorInference in g.config.options:
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computeCursors(owner, n, g)
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computeCursors(owner, n, g)
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block:
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computeLastReadsAndFirstWrites(c.g)
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var cache = initTable[(PNode, PNode), AliasKind]()
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var lastReads, potLastReads: IntSet
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var pc = 0
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collectLastReads(c.g, cache, 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 alreadySeen: HashSet[PNode]
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pc = 0
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collectFirstWrites(c.g, alreadySeen, pc, c.g.len)
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var scope: Scope
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var scope: Scope
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let body = p(n, c, scope, normal)
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let body = p(n, c, scope, normal)
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@ -784,3 +784,37 @@ proc main3 =
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main3()
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main3()
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# misc
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proc smoltest(x: bool): bool =
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while true:
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if true: return x
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discard smoltest(true)
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# bug #18002
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type
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TTypeAttachedOp = enum
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attachedAsgn
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attachedSink
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attachedTrace
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PNode = ref object
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discard
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proc genAddrOf(n: PNode) =
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assert n != nil, "moved?!"
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proc atomicClosureOp =
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let x = PNode()
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genAddrOf:
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block:
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x
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case attachedTrace
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of attachedSink: discard
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of attachedAsgn: discard
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of attachedTrace: genAddrOf(x)
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atomicClosureOp()
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