Revert "fix #16185 (#16195)" (#16197)

This reverts commit bb4b27a2ca.

compiler/injectdestructors.nim

@@ -19,7 +19,7 @@ import
   lineinfos, parampatterns, sighashes, liftdestructors, optimizer,
   varpartitions
 
-from trees import exprStructuralEquivalent, getRoot, sameLocation
+from trees import exprStructuralEquivalent, getRoot
 
 type
   Scope = object  # well we do scope-based memory management. \
@@ -969,10 +969,6 @@ proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode): PNode =
       internalError(c.graph.config, n.info, "cannot inject destructors to node kind: " & $n.kind)
 
 proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope, isDecl = false): PNode =
-  if sameLocation(dest, ri):
-    # rule (self-assignment-removal):
-    result = newNodeI(nkEmpty, dest.info)
-  else:
   case ri.kind
   of nkCallKinds:
     result = c.genSink(dest, p(ri, c, s, consumed), isDecl)
@@ -1000,7 +996,10 @@ proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope, isDecl = false): PNod
   of nkObjConstr, nkTupleConstr, nkClosure, nkCharLit..nkNilLit:
     result = c.genSink(dest, p(ri, c, s, consumed), isDecl)
   of nkSym:
-      if isSinkParam(ri.sym) and isLastRead(ri, c):
+    if dest.kind == nkSym and dest.sym == ri.sym:
+      # rule (self-assignment-removal):
+      result = newNodeI(nkEmpty, dest.info)
+    elif isSinkParam(ri.sym) and isLastRead(ri, c):
       # Rule 3: `=sink`(x, z); wasMoved(z)
       let snk = c.genSink(dest, ri, isDecl)
       result = newTree(nkStmtList, snk, c.genWasMoved(ri))

compiler/trees.nim

@@ -54,21 +54,6 @@ proc exprStructuralEquivalent*(a, b: PNode; strictSymEquality=false): bool =
                                           strictSymEquality): return
         result = true
 
-proc sameLocation*(a, b: PNode): bool = 
-  if a == b: true
-  elif a == nil or b == nil: false
-  elif a.kind == b.kind:
-    case a.kind:
-      of nkCheckedFieldExpr, nkDerefExpr, nkHiddenDeref,
-        nkAddr, nkHiddenAddr, nkObjDownConv, nkObjUpConv:
-        sameLocation(a[0], b[0])  
-      of nkDotExpr, nkBracketExpr:
-        sameLocation(a[0], b[0]) and sameLocation(a[1], b[1])    
-      of nkHiddenStdConv, nkHiddenSubConv: sameLocation(a[1], b[1])
-      of nkNone..nkNilLit: exprStructuralEquivalent(a, b, strictSymEquality = true)
-      else: false
-  else: false
-
 proc sameTree*(a, b: PNode): bool =
   if a == b:
     result = true

tests/arc/t14383.nim

@@ -126,52 +126,3 @@ proc main =
   echo avals.len, " ", rankdef.len
 
 main()
-
-
-
-
-#------------------------------------------------------------------------------
-# Issue #16185, complex self-assingment elimination
-#------------------------------------------------------------------------------
-
-type
-  CpuStorage*[T] = ref CpuStorageObj[T]
-  CpuStorageObj[T] = object
-    size*: int
-    raw_buffer*: ptr UncheckedArray[T]
-  Tensor[T] = object
-    buf*: CpuStorage[T]
-  TestObject = object
-    x: Tensor[float]
-
-proc `=destroy`[T](s: var CpuStorageObj[T]) =
-  if s.raw_buffer != nil:
-    s.raw_buffer.deallocShared()
-    s.size = 0
-    s.raw_buffer = nil
-
-proc `=`[T](a: var CpuStorageObj[T]; b: CpuStorageObj[T]) {.error.}
-
-proc allocCpuStorage[T](s: var CpuStorage[T], size: int) =
-  new(s)
-  s.raw_buffer = cast[ptr UncheckedArray[T]](allocShared0(sizeof(T) * size))
-  s.size = size
-
-proc newTensor[T](size: int): Tensor[T] =
-  allocCpuStorage(result.buf, size)
-
-proc `[]`[T](t: Tensor[T], idx: int): T = t.buf.raw_buffer[idx]
-proc `[]=`[T](t: Tensor[T], idx: int, val: T) = t.buf.raw_buffer[idx] = val
-
-proc toTensor[T](s: seq[T]): Tensor[T] =
-  result = newTensor[T](s.len)
-  for i, x in s:
-    result[i] = x
-
-proc main2() =
-  var t: TestObject
-  t.x = toTensor(@[1.0, 2, 3, 4])
-  t.x = t.x  
-  doAssert(t.x.buf != nil) # self-assignment above should be eliminated
-
-main2()