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   6 <TITLE>The SUIF Version 1 Library - Parent Tree Nodes</TITLE>
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  17 <H3><A NAME="SEC27" HREF="suif1_toc.html#TOC27">Parent Tree Nodes</A></H3>
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  20 <A NAME="IDX150"></A>
  21 Each instruction automatically records the <CODE>tree_instr</CODE> node to
  22 which it is attached.  The <CODE>parent</CODE> method retrieves this pointer.
  23 In an expression tree, all of the instructions share the same parent
  24 <CODE>tree_instr</CODE> node, so an instruction may not be directly connected
  25 to its parent node.
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  29 <A NAME="IDX151"></A>
  30 The <CODE>owner</CODE> method is identical to the <CODE>parent</CODE> method except
  31 for instructions that are used as operands of <CODE>tree_for</CODE> nodes.
  32 Those operands are actually attached to dummy copy instructions on lists
  33 attached to the <CODE>tree_for</CODE> nodes (see section <A HREF="suif1_17.html#SEC17">For Nodes</A>), but many
  34 users will want to treat them as if they are directly attached to the
  35 <CODE>tree_for</CODE> nodes.  Thus, for an instruction in a <CODE>tree_for</CODE>
  36 operand, the <CODE>owner</CODE> method will return a pointer to the
  37 <CODE>tree_for</CODE> node instead of returning the actual parent
  38 <CODE>tree_instr</CODE>.  This only works if the <CODE>tree_for</CODE> operand list
  39 contains a single expression (not a flat list); otherwise, the actual
  40 <CODE>tree_instr</CODE> parent is returned.
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