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  20. <title>Insn Attributes (GNU Compiler Collection (GCC) Internals)</title>
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  67. <a name="Instruction-Attributes"></a>
  68. <h3 class="section">17.19 Instruction Attributes</h3>
  69. <a name="index-insn-attributes"></a>
  70. <a name="index-instruction-attributes"></a>
  71. <p>In addition to describing the instruction supported by the target machine,
  72. the <samp>md</samp> file also defines a group of <em>attributes</em> and a set of
  73. values for each. Every generated insn is assigned a value for each attribute.
  74. One possible attribute would be the effect that the insn has on the machine&rsquo;s
  75. condition code. This attribute can then be used by <code>NOTICE_UPDATE_CC</code>
  76. to track the condition codes.
  77. </p>
  78. <table class="menu" border="0" cellspacing="0">
  79. <tr><td align="left" valign="top">&bull; <a href="Defining-Attributes.html#Defining-Attributes" accesskey="1">Defining Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifying attributes and their values.
  80. </td></tr>
  81. <tr><td align="left" valign="top">&bull; <a href="Expressions.html#Expressions" accesskey="2">Expressions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Valid expressions for attribute values.
  82. </td></tr>
  83. <tr><td align="left" valign="top">&bull; <a href="Tagging-Insns.html#Tagging-Insns" accesskey="3">Tagging Insns</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Assigning attribute values to insns.
  84. </td></tr>
  85. <tr><td align="left" valign="top">&bull; <a href="Attr-Example.html#Attr-Example" accesskey="4">Attr Example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">An example of assigning attributes.
  86. </td></tr>
  87. <tr><td align="left" valign="top">&bull; <a href="Insn-Lengths.html#Insn-Lengths" accesskey="5">Insn Lengths</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Computing the length of insns.
  88. </td></tr>
  89. <tr><td align="left" valign="top">&bull; <a href="Constant-Attributes.html#Constant-Attributes" accesskey="6">Constant Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Defining attributes that are constant.
  90. </td></tr>
  91. <tr><td align="left" valign="top">&bull; <a href="Mnemonic-Attribute.html#Mnemonic-Attribute" accesskey="7">Mnemonic Attribute</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Obtain the instruction mnemonic as attribute value.
  92. </td></tr>
  93. <tr><td align="left" valign="top">&bull; <a href="Delay-Slots.html#Delay-Slots" accesskey="8">Delay Slots</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Defining delay slots required for a machine.
  94. </td></tr>
  95. <tr><td align="left" valign="top">&bull; <a href="Processor-pipeline-description.html#Processor-pipeline-description" accesskey="9">Processor pipeline description</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifying information for insn scheduling.
  96. </td></tr>
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