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  16
  17 <H2><A NAME="SEC100" HREF="suif1_toc.html#TOC100">Immediate Values</A></H2>
  18 <P>
  19 <A NAME="IDX695"></A>
  20
  21 </P>
  22 <P>
  23 <A NAME="IDX696"></A>
  24 An immediate value may be an integer constant, string constant,
  25 floating-point constant, SUIF type, symbolic address, expression
  26 operand, or instruction, or it can be undefined.  It can be used as
  27 the source of an <CODE>ldc</CODE> (load constant) instruction (see section <A HREF="suif1_34.html#SEC34">Load Constant Instructions</A>) or as an element of an annotation
  28 (see section <A HREF="suif1_69.html#SEC69">Annotations</A>).  Only integers, floating-point values, and
  29 symbolic addresses may be used in <CODE>ldc</CODE> instructions, while any
  30 kind of immediate value may appear in an annotation.  Immediate values
  31 are implemented by the <CODE>immed</CODE> class defined in the files
  32 <TT>`immed.h'</TT> and <TT>`immed.cc'</TT>.
  33
  34 </P>
  35 <P>
  36 <A NAME="IDX697"></A>
  37 The kind of value in an <CODE>immed</CODE> is identified by the <CODE>kind</CODE>
  38 method.  This returns a member of the <CODE>immed_kinds</CODE> enumerated
  39 type.  The members of this enumeration are:
  40
  41 </P>
  42 <DL COMPACT>
  43
  44 <DT><CODE>im_int</CODE>
  45 <DD>
  46 <A NAME="IDX698"></A>
  47 <A NAME="IDX699"></A>
  48 Integer.  The <CODE>is_integer</CODE> method tests for this kind of immediate
  49 and the <CODE>integer</CODE> method returns the integer value.
  50
  51 <DT><CODE>im_string</CODE>
  52 <DD>
  53 <A NAME="IDX700"></A>
  54 <A NAME="IDX701"></A>
  55 Character string.  The string is automatically entered in the lexicon
  56 (see section <A HREF="suif1_102.html#SEC102">Lexicon</A>) when the <CODE>immed</CODE> is created.  The
  57 <CODE>is_string</CODE> method checks if an <CODE>immed</CODE> is a string, and the
  58 <CODE>string</CODE> method returns a pointer to the string.
  59
  60 <DT><CODE>im_float</CODE>
  61 <DD>
  62 <A NAME="IDX702"></A>
  63 <A NAME="IDX703"></A>
  64 Floating-point value.  The SUIF library stores all floating-point values
  65 using the <CODE>double</CODE> type, so the precision is limited by the
  66 precision for the <CODE>double</CODE> type.  The <CODE>is_flt</CODE> method checks
  67 for this kind of immediate, and the <CODE>flt</CODE> method returns the value.
  68
  69 <DT><CODE>im_symbol</CODE>
  70 <DD>
  71 <A NAME="IDX704"></A>
  72 <A NAME="IDX705"></A>
  73 <A NAME="IDX706"></A>
  74 <A NAME="IDX707"></A>
  75 Symbolic address.  See section <A HREF="suif1_101.html#SEC101">Symbolic Addresses</A>.  The <CODE>is_symbol</CODE>
  76 method checks if an <CODE>immed</CODE> is a symbolic address.  The <CODE>addr</CODE>
  77 method returns the entire <CODE>sym_addr</CODE> object, but the <CODE>symbol</CODE>
  78 and <CODE>offset</CODE> methods are also available to retrieve the symbol
  79 pointer and integer offset separately.
  80
  81 <DT><CODE>im_type</CODE>
  82 <DD>
  83 <A NAME="IDX708"></A>
  84 <A NAME="IDX709"></A>
  85 SUIF type.  The <CODE>is_type</CODE> method checks for this kind of immediate,
  86 and the <CODE>type</CODE> method returns a pointer to the SUIF type node.
  87
  88 <DT><CODE>im_op</CODE>
  89 <DD>
  90 <A NAME="IDX710"></A>
  91 <A NAME="IDX711"></A>
  92 Expression operand.  The immed is considered to "own" the entire
  93 expression tree when it's in an annotation, so the same expression
  94 shouldn't be used in another annotation or as the source for an
  95 instruction; instead a copy should be made with the <CODE>clone</CODE>
  96 method.  The <CODE>is_op</CODE> method checks for this kind of immediate,
  97 and the <CODE>op</CODE> method returns the expression.
  98
  99 <DT><CODE>im_instr</CODE>
 100 <DD>
 101 <A NAME="IDX712"></A>
 102 <A NAME="IDX713"></A>
 103 SUIF instruction.  The immed is considered to "own" the instruction
 104 and its expression trees when it's in an annotation, so the same
 105 instruction shouldn't be used in another annotation or in a
 106 <CODE>tree_node</CODE> or expression; instead a copy should be made with the
 107 <CODE>clone</CODE> method.  The <CODE>is_instr</CODE> method checks for this kind
 108 of immediate, and the <CODE>instr</CODE> method returns the instruction.
 109
 110 <DT><CODE>im_undef</CODE>
 111 <DD>
 112 <A NAME="IDX714"></A>
 113 Undefined value.  This is included to signal errors by marking an
 114 immediate as undefined.  The <CODE>is_error</CODE> method also checks for this
 115 condition.
 116 </DL>
 117
 118 <P>
 119 Since an immediate value is small, there are no methods to change the
 120 value of an <CODE>immed</CODE>.  Instead a variety of constructors are
 121 provided to make it easy to create new immediate values.  That is, you
 122 can initialize different kinds of immediates by providing arguments of
 123 various types to constructors.
 124
 125 </P>
 126 <P>
 127 <A NAME="IDX715"></A>
 128 <A NAME="IDX716"></A>
 129 The <CODE>immed</CODE> class provides two print methods, <CODE>print</CODE> and
 130 <CODE>rawprint</CODE>.  The difference between them is that the latter doesn't
 131 escape <SAMP>`"'</SAMP> and <SAMP>`\'</SAMP> when printing strings.
 132
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