fixes nim-lang#12669

compiler/dfa.nim

@@ -572,16 +572,6 @@ const
                 nkObjDownConv, nkObjUpConv}
   PathKinds1 = {nkHiddenStdConv, nkHiddenSubConv}
 
-proc getRoot(n: PNode): PNode =
-  result = n
-  while true:
-    case result.kind
-    of PathKinds0:
-      result = result[0]
-    of PathKinds1:
-      result = result[1]
-    else: break
-
 proc skipConvDfa*(n: PNode): PNode =
   result = n
   while true:
@@ -593,7 +583,17 @@ proc skipConvDfa*(n: PNode): PNode =
     else: break
 
 proc genUse(c: var Con; orig: PNode) =
-  let n = dfa.getRoot(orig)
+  var n = orig
+  while true:
+    case n.kind
+    of PathKinds0 - {nkBracketExpr}:
+      n = n[0]
+    of nkBracketExpr:
+      gen(c, n[1])
+      n = n[0]
+    of PathKinds1:
+      n = n[1]
+    else: break
   if n.kind == nkSym and n.sym.kind in InterestingSyms:
     c.code.add Instr(n: orig, kind: use, sym: if orig != n: nil else: n.sym)
 
@@ -673,6 +673,21 @@ proc isAnalysableFieldAccess*(orig: PNode; owner: PSym): bool =
   # lower level C++ optimizer to specialize this code.
 
 proc genDef(c: var Con; n: PNode) =
+  var m = n
+  # XXX do something about this duplicated logic here.
+  while true:
+    case m.kind
+    of nkDotExpr, nkCheckedFieldExpr, nkHiddenSubConv, nkHiddenStdConv,
+        nkObjDownConv, nkObjUpConv, nkHiddenAddr, nkAddr:
+      m = m[0]
+    of nkBracketExpr:
+      gen(c, m[1])
+      m = m[0]
+    of nkHiddenDeref, nkDerefExpr:
+      m = m[0]
+    else:
+      break
+
   if n.kind == nkSym and n.sym.kind in InterestingSyms:
     c.code.add Instr(n: n, kind: def, sym: n.sym)
   elif isAnalysableFieldAccess(n, c.owner):

tests/destructor/tarray_indexing.nim

@@ -0,0 +1,75 @@
+discard """
+  output: '''allocating 1048576 65536
+filling page from 1048576 len 65536'''
+  cmd: '''nim c --newruntime $file'''
+"""
+
+# bug #12669
+
+type
+    MemState* = enum
+        memPrivate
+
+    MemPermisison* = enum
+        memperm_Read
+
+    MemInfo* = ref object
+        base*, size*: uint32
+        state*: MemState
+        perm*: set[MemPermisison]
+
+    MemBlock = ref object
+        info: MemInfo
+        data: seq[byte]
+
+    UserProcessMemory* = ref object
+        pageAccess: array[0x40000, ptr UncheckedArray[byte]]
+        pages: array[0x40000, MemInfo]
+        blocks: seq[owned MemBlock]
+
+proc allocMemory*(mem: UserProcessMemory, base, size: uint32) =
+    let
+        roundedBase = base and not(0xFFF'u32)
+        roundedSize = (size + 0xFFF) and not(0xFFF'u32)
+
+    echo "allocating ", base, " ", size
+    for i in (roundedBase shr 12)..<((roundedBase + roundedSize) shr 12):
+        #echo "span ", i
+        doAssert mem.pages[i] == nil
+        # TODO: beserer fehler
+
+    let memBlock = MemBlock(
+        info: MemInfo(
+            base: roundedBase,
+            size: roundedSize,
+            state: memPrivate,
+            perm: {memperm_Read}
+        ),
+        data: newSeq[byte](roundedSize))
+    for i in 0..<(roundedSize shr 12):
+        mem.pages[i + (roundedBase shr 12)] = memBlock.info
+        #echo cast[uint64](addr mem.pageAccess[i + (roundedBase shr 12)])
+        mem.pageAccess[i + (roundedBase shr 12)] = cast[ptr UncheckedArray[byte]](addr memBlock.data[i * 0x1000])
+    mem.blocks.add memBlock
+
+    #for i in (roundedBase shr 12)..<((roundedBase + roundedSize) shr 12):
+    #    assert mem.pageAccess[i] != nil
+
+proc fillPages*(mem: UserProcessMemory, start: uint32, data: seq[byte]) =
+    echo "filling page from ", start, " len ", data.len
+    assert (start and not(0xFFF'u32)) == start
+    assert (uint32(data.len) and not(0xFFF'u32)) == uint32(data.len)
+    for i in (start shr 12)..<((start + uint32(data.len)) shr 12):
+        #echo cast[uint64](addr mem.pageAccess[i])
+        let page = mem.pageAccess[i]
+        assert page != nil
+        #copyMem(page, unsafeAddr data[i * 0x1000 - start], 0x1000)
+
+const base = 0x00100000
+
+proc a(): owned UserProcessMemory =
+    result = UserProcessMemory()
+    result.allocMemory(base, 0x1000 * 16)
+    result.fillPages(base, newSeq[byte](0x1000 * 16))
+
+discard a()