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| <title>Using as: s390 Operand Modifier</title> |
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| Next: <a href="s390-Instruction-Marker.html#s390-Instruction-Marker" accesskey="n" rel="next">s390 Instruction Marker</a>, Previous: <a href="s390-Aliases.html#s390-Aliases" accesskey="p" rel="prev">s390 Aliases</a>, Up: <a href="s390-Syntax.html#s390-Syntax" accesskey="u" rel="up">s390 Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Instruction-Operand-Modifier"></a> |
| <h4 class="subsubsection">9.38.3.6 Instruction Operand Modifier</h4> |
| <a name="index-instruction-operand-modifier_002c-s390"></a> |
| <a name="index-s390-instruction-operand-modifier"></a> |
| |
| <p>If a symbol modifier is attached to a symbol in an expression for an |
| instruction operand field, the symbol term is replaced with a reference |
| to an object in the global offset table (GOT) or the procedure linkage |
| table (PLT). The following expressions are allowed: |
| ‘<samp>symbol@modifier + constant</samp>’, |
| ‘<samp>symbol@modifier + label + constant</samp>’, and |
| ‘<samp>symbol@modifier - label + constant</samp>’. |
| The term ‘<samp>symbol</samp>’ is the symbol that will be entered into the GOT or |
| PLT, ‘<samp>label</samp>’ is a local label, and ‘<samp>constant</samp>’ is an arbitrary |
| expression that the assembler can evaluate to a constant value. |
| </p> |
| <p>The term ‘<samp>(symbol + constant1)@modifier +/- label + constant2</samp>’ |
| is also accepted but a warning message is printed and the term is |
| converted to ‘<samp>symbol@modifier +/- label + constant1 + constant2</samp>’. |
| </p> |
| <dl compact="compact"> |
| <dt><code>@got</code></dt> |
| <dt><code>@got12</code></dt> |
| <dd><p>The @got modifier can be used for displacement fields, 16-bit immediate |
| fields and 32-bit pc-relative immediate fields. The @got12 modifier is |
| synonym to @got. The symbol is added to the GOT. For displacement |
| fields and 16-bit immediate fields the symbol term is replaced with |
| the offset from the start of the GOT to the GOT slot for the symbol. |
| For a 32-bit pc-relative field the pc-relative offset to the GOT |
| slot from the current instruction address is used. |
| </p></dd> |
| <dt><code>@gotent</code></dt> |
| <dd><p>The @gotent modifier can be used for 32-bit pc-relative immediate fields. |
| The symbol is added to the GOT and the symbol term is replaced with |
| the pc-relative offset from the current instruction to the GOT slot for the |
| symbol. |
| </p></dd> |
| <dt><code>@gotoff</code></dt> |
| <dd><p>The @gotoff modifier can be used for 16-bit immediate fields. The symbol |
| term is replaced with the offset from the start of the GOT to the |
| address of the symbol. |
| </p></dd> |
| <dt><code>@gotplt</code></dt> |
| <dd><p>The @gotplt modifier can be used for displacement fields, 16-bit immediate |
| fields, and 32-bit pc-relative immediate fields. A procedure linkage |
| table entry is generated for the symbol and a jump slot for the symbol |
| is added to the GOT. For displacement fields and 16-bit immediate |
| fields the symbol term is replaced with the offset from the start of the |
| GOT to the jump slot for the symbol. For a 32-bit pc-relative field |
| the pc-relative offset to the jump slot from the current instruction |
| address is used. |
| </p></dd> |
| <dt><code>@plt</code></dt> |
| <dd><p>The @plt modifier can be used for 16-bit and 32-bit pc-relative immediate |
| fields. A procedure linkage table entry is generated for the symbol. |
| The symbol term is replaced with the relative offset from the current |
| instruction to the PLT entry for the symbol. |
| </p></dd> |
| <dt><code>@pltoff</code></dt> |
| <dd><p>The @pltoff modifier can be used for 16-bit immediate fields. The symbol |
| term is replaced with the offset from the start of the PLT to the address |
| of the symbol. |
| </p></dd> |
| <dt><code>@gotntpoff</code></dt> |
| <dd><p>The @gotntpoff modifier can be used for displacement fields. The symbol |
| is added to the static TLS block and the negated offset to the symbol |
| in the static TLS block is added to the GOT. The symbol term is replaced |
| with the offset to the GOT slot from the start of the GOT. |
| </p></dd> |
| <dt><code>@indntpoff</code></dt> |
| <dd><p>The @indntpoff modifier can be used for 32-bit pc-relative immediate |
| fields. The symbol is added to the static TLS block and the negated offset |
| to the symbol in the static TLS block is added to the GOT. The symbol term |
| is replaced with the pc-relative offset to the GOT slot from the current |
| instruction address. |
| </p></dd> |
| </dl> |
| |
| <p>For more information about the thread local storage modifiers |
| ‘<samp>gotntpoff</samp>’ and ‘<samp>indntpoff</samp>’ see the ELF extension documentation |
| ‘<samp>ELF Handling For Thread-Local Storage</samp>’. |
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| Next: <a href="s390-Instruction-Marker.html#s390-Instruction-Marker" accesskey="n" rel="next">s390 Instruction Marker</a>, Previous: <a href="s390-Aliases.html#s390-Aliases" accesskey="p" rel="prev">s390 Aliases</a>, Up: <a href="s390-Syntax.html#s390-Syntax" accesskey="u" rel="up">s390 Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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