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s390-Literal-Pool-Entries.html 5.6KB

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  62. <a name="Literal-Pool-Entries"></a>
  63. <h4 class="subsubsection">9.41.3.8 Literal Pool Entries</h4>
  64. <a name="index-literal-pool-entries_002c-s390"></a>
  65. <a name="index-s390-literal-pool-entries"></a>
  66. <p>A literal pool is a collection of values. To access the values a pointer
  67. to the literal pool is loaded to a register, the literal pool register.
  68. Usually, register %r13 is used as the literal pool register
  69. (<a href="s390-Register.html#s390-Register">s390 Register</a>). Literal pool entries are created by adding the
  70. suffix :lit1, :lit2, :lit4, or :lit8 to the end of an expression for an
  71. instruction operand. The expression is added to the literal pool and the
  72. operand is replaced with the offset to the literal in the literal pool.
  73. </p>
  74. <dl compact="compact">
  75. <dt><code>:lit1</code></dt>
  76. <dd><p>The literal pool entry is created as an 8-bit value. An operand modifier
  77. must not be used for the original expression.
  78. </p></dd>
  79. <dt><code>:lit2</code></dt>
  80. <dd><p>The literal pool entry is created as a 16 bit value. The operand modifier
  81. @got may be used in the original expression. The term &lsquo;<samp>x@got:lit2</samp>&rsquo;
  82. will put the got offset for the global symbol x to the literal pool as
  83. 16 bit value.
  84. </p></dd>
  85. <dt><code>:lit4</code></dt>
  86. <dd><p>The literal pool entry is created as a 32-bit value. The operand modifier
  87. @got and @plt may be used in the original expression. The term
  88. &lsquo;<samp>x@got:lit4</samp>&rsquo; will put the got offset for the global symbol x to the
  89. literal pool as a 32-bit value. The term &lsquo;<samp>x@plt:lit4</samp>&rsquo; will put the
  90. plt offset for the global symbol x to the literal pool as a 32-bit value.
  91. </p></dd>
  92. <dt><code>:lit8</code></dt>
  93. <dd><p>The literal pool entry is created as a 64-bit value. The operand modifier
  94. @got and @plt may be used in the original expression. The term
  95. &lsquo;<samp>x@got:lit8</samp>&rsquo; will put the got offset for the global symbol x to the
  96. literal pool as a 64-bit value. The term &lsquo;<samp>x@plt:lit8</samp>&rsquo; will put the
  97. plt offset for the global symbol x to the literal pool as a 64-bit value.
  98. </p></dd>
  99. </dl>
  100. <p>The assembler directive &lsquo;<samp>.ltorg</samp>&rsquo; is used to emit all literal pool
  101. entries to the current position.
  102. </p>
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