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sink parameter inference for types that have destructors (#13544)

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* ensure capitalize doesn't take an inferred sink parameter

* sink parameter inference: first version, for now disabled. Changed that sink parameters can be consumed multiple times in order to adhere to our spec.

* sink inference can now be disabled with .nosinks; sometimes for proc type interop this is required

* fixes yet another critical DFA bug

* better implementation that also understands if expressions etc

* document sink parameter inference and allow for global disabling
This commit is contained in:
Andreas Rumpf 2020-03-04 14:28:53 +01:00 • committed by GitHub
commit a0eca75182
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19 changed files with 158 additions and 28 deletions
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12
compiler/injectdestructors.nim
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@ -321,8 +321,8 @@ proc destructiveMoveVar(n: PNode; c: var Con): PNode =
proc sinkParamIsLastReadCheck(c: var Con, s: PNode) =
assert s.kind == nkSym and s.sym.kind == skParam
if not isLastRead(s, c):
localError(c.graph.config, c.otherRead.info, "sink parameter `" & $s.sym.name.s &
"` is already consumed at " & toFileLineCol(c. graph.config, s.info))
localError(c.graph.config, c.otherRead.info, "sink parameter `" & $s.sym.name.s &
"` is already consumed at " & toFileLineCol(c. graph.config, s.info))
type
ProcessMode = enum
@ -498,10 +498,10 @@ proc p(n: PNode; c: var Con; mode: ProcessMode): PNode =
elif n.kind in {nkBracket, nkObjConstr, nkTupleConstr, nkClosure, nkNilLit} +
nkCallKinds + nkLiterals:
result = p(n, c, consumed)
elif n.kind == nkSym and isSinkParam(n.sym):
elif n.kind == nkSym and isSinkParam(n.sym) and isLastRead(n, c):
# Sinked params can be consumed only once. We need to reset the memory
# to disable the destructor which we have not elided
sinkParamIsLastReadCheck(c, n)
#sinkParamIsLastReadCheck(c, n)
result = destructiveMoveVar(n, c)
elif isAnalysableFieldAccess(n, c.owner) and isLastRead(n, c):
# it is the last read, can be sinkArg. We need to reset the memory
@ -687,9 +687,9 @@ proc moveOrCopy(dest, ri: PNode; c: var Con): PNode =
of nkObjConstr, nkTupleConstr, nkClosure, nkCharLit..nkNilLit:
result = genSink(c, dest, p(ri, c, consumed))
of nkSym:
if isSinkParam(ri.sym):
if isSinkParam(ri.sym) and isLastRead(ri, c):
# Rule 3: `=sink`(x, z); wasMoved(z)
sinkParamIsLastReadCheck(c, ri)
#sinkParamIsLastReadCheck(c, ri)
let snk = genSink(c, dest, ri)
result = newTree(nkStmtList, snk, genWasMoved(ri, c))
elif ri.sym.kind != skParam and ri.sym.owner == c.owner and