fixes #25333; WIP

compiler/aliasanalysis.nim

@@ -21,6 +21,24 @@ proc skipConvDfa*(n: PNode): PNode =
     else: break
 
 proc isAnalysableFieldAccess*(orig: PNode; owner: PSym): bool =
+  let stripped = skipConvDfa(orig)
+  if stripped.typ != nil and isSinkType(stripped.typ):
+    var base = stripped
+    while true:
+      case base.kind
+      of nkDotExpr, nkCheckedFieldExpr:
+        base = skipConvDfa(base[0])
+      of nkHiddenDeref, nkDerefExpr:
+        base = skipConvDfa(base[0])
+      of nkHiddenStdConv, nkHiddenSubConv, nkConv:
+        base = skipConvDfa(base[1])
+      of nkObjUpConv, nkObjDownConv:
+        base = skipConvDfa(base[0])
+      else:
+        break
+    if base.kind == nkSym and base.sym.owner == owner and
+        {sfGlobal, sfThread, sfCursor} * base.sym.flags == {}:
+      return true
   var n = orig
   while true:
     case n.kind

compiler/closureiters.nim

@@ -1260,9 +1260,24 @@ proc wrapIntoStateLoop(ctx: var Ctx, n: PNode): PNode =
   #   block :stateLoop:
   #     local vars decl (if needed)
   #     body # Might get wrapped in try-except
+  var needsLoop = false
+  proc detectNonYieldGoto(n: PNode) =
+    if needsLoop: return
+    for i, c in n:
+      if c.kind == nkGotoState and c[0].kind == nkIntLit and (i > 0 and n[i - 1].kind != nkYieldStmt):
+        needsLoop = true
+        return
+      else:
+        detectNonYieldGoto(c)
+  for s in ctx.states:
+    detectNonYieldGoto(s.body)
+    if needsLoop: break
+
+  result = newNodeI(nkStmtList, n.info)
   let loopBody = newNodeI(nkStmtList, n.info)
-  result = newTree(nkWhileStmt, ctx.g.boolLit(n.info, true), loopBody)
-  result.info = n.info
+  if needsLoop:
+    result = newTree(nkWhileStmt, ctx.g.boolLit(n.info, true), loopBody)
+    result.info = n.info
 
   let localVars = newNodeI(nkStmtList, n.info)
 
@@ -1274,7 +1289,10 @@ proc wrapIntoStateLoop(ctx: var Ctx, n: PNode): PNode =
     blockBody = ctx.wrapIntoTryExcept(blockBody)
 
   blockStmt.add(blockBody)
-  loopBody.add(blockStmt)
+  if needsLoop:
+    loopBody.add(blockStmt)
+  else:
+    result = blockStmt
 
   if ctx.hasExceptions:
     # Since we have yields in tries, we must switch current exception

compiler/dfa.nim

@@ -347,23 +347,43 @@ proc skipTrivials(c: var Con, n: PNode): PNode =
       result = result[1]
     else: break
 
+proc matchesFieldAccess(orig: PNode; field: PSym): bool =
+  result = false
+  var n = skipConvDfa(orig)
+  while true:
+    case n.kind
+    of nkDotExpr, nkCheckedFieldExpr:
+      if n[1].kind == nkSym and n[1].sym == field:
+        result = true
+        break
+      n = skipConvDfa(n[0])
+    else:
+      break
+
 proc genUse(c: var Con; orig: PNode) =
   let n = c.skipTrivials(orig)
 
-  if n.kind == nkSym:
+  if c.root.kind == skField and matchesFieldAccess(orig, c.root):
+    c.code.add Instr(kind: use, n: orig)
+    inc c.interestingInstructions
+  elif n.kind == nkSym:
     if n.sym.kind in InterestingSyms and n.sym == c.root:
       c.code.add Instr(kind: use, n: orig)
       inc c.interestingInstructions
+    else:
+      discard
   else:
     gen(c, n)
 
 proc genDef(c: var Con; orig: PNode) =
   let n = c.skipTrivials(orig)
 
-  if n.kind == nkSym and n.sym.kind in InterestingSyms:
-    if n.sym == c.root:
-      c.code.add Instr(kind: def, n: orig)
-      inc c.interestingInstructions
+  if c.root.kind == skField and matchesFieldAccess(orig, c.root):
+    c.code.add Instr(kind: def, n: orig)
+    inc c.interestingInstructions
+  elif n.kind == nkSym and n.sym.kind in InterestingSyms and n.sym == c.root:
+    c.code.add Instr(kind: def, n: orig)
+    inc c.interestingInstructions
 
 proc genCall(c: var Con; n: PNode) =
   gen(c, n[0])

compiler/injectdestructors.nim

@@ -97,8 +97,22 @@ when false:
     for i in low(InstrKind)..high(InstrKind):
       echo "INSTR ", i, " ", perfCounters[i]
 
-proc isLastReadImpl(n: PNode; c: var Con; scope: var Scope): bool =
-  let root = parampatterns.exprRoot(n, allowCalls=false)
+proc fieldRootFromAccess(n: PNode): PSym =
+  result = nil
+  var it = n
+  while true:
+    case it.kind
+    of nkHiddenStdConv, nkHiddenSubConv, nkConv:
+      it = it[1]
+    of nkObjUpConv, nkObjDownConv, nkHiddenDeref, nkDerefExpr, nkHiddenAddr, nkBracketExpr:
+      it = it[0]
+    of nkDotExpr, nkCheckedFieldExpr:
+      if it[1].kind == nkSym: return it[1].sym
+      return nil
+    else:
+      return nil
+
+proc isLastReadImpl(n: PNode; c: var Con; scope: var Scope; root: PSym): bool =
   if root == nil: return false
   elif sfSingleUsedTemp in root.flags: return true
 
@@ -172,7 +186,12 @@ proc isLastRead(n: PNode; c: var Con; s: var Scope): bool =
   if not hasDestructorOrAsgn(c, n.typ): return true
 
   let m = skipConvDfa(n)
-  result = isLastReadImpl(n, c, s)
+  let root = parampatterns.exprRoot(n, allowCalls=false)
+  if n.typ != nil and isSinkType(n.typ) and isAnalysableFieldAccess(n, c.owner):
+    let fieldRoot = fieldRootFromAccess(n)
+    if fieldRoot != nil:
+      return isLastReadImpl(n, c, s, fieldRoot)
+  result = isLastReadImpl(n, c, s, root)
 
 proc isFirstWrite(n: PNode; c: var Con): bool =
   let m = skipConvDfa(n)
@@ -814,34 +833,35 @@ proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSing
     elif n.kind in {nkBracket, nkObjConstr, nkTupleConstr, nkClosure, nkNilLit} +
          nkCallKinds + nkLiterals:
       result = p(n, c, s, consumed)
-    elif ((n.kind == nkSym and isSinkParam(n.sym)) or isAnalysableFieldAccess(n, c.owner)) and
-        isLastRead(n, c, s) and not (n.kind == nkSym and isCursor(n)):
-      # Sinked params can be consumed only once. We need to reset the memory
-      # to disable the destructor which we have not elided
-      result = destructiveMoveVar(n, c, s)
-    elif n.kind in {nkHiddenSubConv, nkHiddenStdConv, nkConv}:
-      result = copyTree(n)
-      if n.typ.skipTypes(abstractInst-{tyOwned}).kind != tyOwned and
-          n[1].typ.skipTypes(abstractInst-{tyOwned}).kind == tyOwned:
-        # allow conversions from owned to unowned via this little hack:
-        let nTyp = n[1].typ
-        n[1].typ = n.typ
-        result[1] = p(n[1], c, s, sinkArg)
-        result[1].typ = nTyp
-      else:
-        result[1] = p(n[1], c, s, sinkArg)
-    elif n.kind in {nkObjDownConv, nkObjUpConv}:
-      result = copyTree(n)
-      result[0] = p(n[0], c, s, sinkArg)
-    elif n.kind == nkCast and n.typ.skipTypes(abstractInst).kind in {tyString, tySequence}:
-      result = copyTree(n)
-      result[1] = p(n[1], c, s, sinkArg)
-    elif n.typ == nil:
-      # 'raise X' can be part of a 'case' expression. Deal with it here:
-      result = p(n, c, s, normal)
     else:
-      # copy objects that are not temporary but passed to a 'sink' parameter
-      result = passCopyToSink(n, c, s)
+      if ((n.kind == nkSym and isSinkParam(n.sym)) or isAnalysableFieldAccess(n, c.owner)) and
+          isLastRead(n, c, s) and not (n.kind == nkSym and isCursor(n)):
+        # Sinked params can be consumed only once. We need to reset the memory
+        # to disable the destructor which we have not elided
+        result = destructiveMoveVar(n, c, s)
+      elif n.kind in {nkHiddenSubConv, nkHiddenStdConv, nkConv}:
+        result = copyTree(n)
+        if n.typ.skipTypes(abstractInst-{tyOwned}).kind != tyOwned and
+            n[1].typ.skipTypes(abstractInst-{tyOwned}).kind == tyOwned:
+          # allow conversions from owned to unowned via this little hack:
+          let nTyp = n[1].typ
+          n[1].typ = n.typ
+          result[1] = p(n[1], c, s, sinkArg)
+          result[1].typ = nTyp
+        else:
+          result[1] = p(n[1], c, s, sinkArg)
+      elif n.kind in {nkObjDownConv, nkObjUpConv}:
+        result = copyTree(n)
+        result[0] = p(n[0], c, s, sinkArg)
+      elif n.kind == nkCast and n.typ.skipTypes(abstractInst).kind in {tyString, tySequence}:
+        result = copyTree(n)
+        result[1] = p(n[1], c, s, sinkArg)
+      elif n.typ == nil:
+        # 'raise X' can be part of a 'case' expression. Deal with it here:
+        result = p(n, c, s, normal)
+      else:
+        # copy objects that are not temporary but passed to a 'sink' parameter
+        result = passCopyToSink(n, c, s)
   else:
     case n.kind
     of nkBracket, nkTupleConstr, nkClosure, nkCurly:

compiler/parampatterns.nim

@@ -187,6 +187,20 @@ type
 
 proc exprRoot*(n: PNode; allowCalls = true): PSym =
   result = nil
+  if n.typ != nil and isSinkType(n.typ):
+    var probe = n
+    while true:
+      case probe.kind
+      of nkHiddenStdConv, nkHiddenSubConv, nkConv:
+        probe = probe[1]
+      of nkObjUpConv, nkObjDownConv, nkHiddenDeref, nkDerefExpr, nkHiddenAddr, nkBracketExpr:
+        probe = probe[0]
+      of nkDotExpr, nkCheckedFieldExpr:
+        if probe[1].kind == nkSym:
+          return probe[1].sym
+        break
+      else:
+        break
   var it = n
   while true:
     case it.kind