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103 lines
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<title>ARM-Relocations - Using as</title>
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<a name="ARM-Relocations"></a>
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<a name="ARM_002dRelocations"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="ARM_002dNeon_002dAlignment.html#ARM_002dNeon_002dAlignment">ARM-Neon-Alignment</a>,
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Previous: <a rel="previous" accesskey="p" href="ARM_002dRegs.html#ARM_002dRegs">ARM-Regs</a>,
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Up: <a rel="up" accesskey="u" href="ARM-Syntax.html#ARM-Syntax">ARM Syntax</a>
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<h5 class="subsubsection">9.4.2.4 ARM relocation generation</h5>
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<p><a name="index-data-relocations_002c-ARM-760"></a><a name="index-ARM-data-relocations-761"></a>Specific data relocations can be generated by putting the relocation name
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in parentheses after the symbol name. For example:
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<pre class="smallexample"> .word foo(TARGET1)
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</pre>
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<p>This will generate an ‘<samp><span class="samp">R_ARM_TARGET1</span></samp>’ relocation against the symbol
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<var>foo</var>.
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The following relocations are supported:
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<code>GOT</code>,
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<code>GOTOFF</code>,
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<code>TARGET1</code>,
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<code>TARGET2</code>,
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<code>SBREL</code>,
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<code>TLSGD</code>,
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<code>TLSLDM</code>,
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<code>TLSLDO</code>,
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<code>TLSDESC</code>,
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<code>TLSCALL</code>,
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<code>GOTTPOFF</code>,
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<code>GOT_PREL</code>
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and
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<code>TPOFF</code>.
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<p>For compatibility with older toolchains the assembler also accepts
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<code>(PLT)</code> after branch targets. On legacy targets this will
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generate the deprecated ‘<samp><span class="samp">R_ARM_PLT32</span></samp>’ relocation. On EABI
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targets it will encode either the ‘<samp><span class="samp">R_ARM_CALL</span></samp>’ or
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‘<samp><span class="samp">R_ARM_JUMP24</span></samp>’ relocation, as appropriate.
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<p><a name="index-MOVW-and-MOVT-relocations_002c-ARM-762"></a>Relocations for ‘<samp><span class="samp">MOVW</span></samp>’ and ‘<samp><span class="samp">MOVT</span></samp>’ instructions can be generated
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by prefixing the value with ‘<samp><span class="samp">#:lower16:</span></samp>’ and ‘<samp><span class="samp">#:upper16</span></samp>’
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respectively. For example to load the 32-bit address of foo into r0:
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<pre class="smallexample"> MOVW r0, #:lower16:foo
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MOVT r0, #:upper16:foo
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</pre>
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<p>Relocations ‘<samp><span class="samp">R_ARM_THM_ALU_ABS_G0_NC</span></samp>’, ‘<samp><span class="samp">R_ARM_THM_ALU_ABS_G1_NC</span></samp>’,
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‘<samp><span class="samp">R_ARM_THM_ALU_ABS_G2_NC</span></samp>’ and ‘<samp><span class="samp">R_ARM_THM_ALU_ABS_G3_NC</span></samp>’ can be
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generated by prefixing the value with ‘<samp><span class="samp">#:lower0_7:#</span></samp>’,
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‘<samp><span class="samp">#:lower8_15:#</span></samp>’, ‘<samp><span class="samp">#:upper0_7:#</span></samp>’ and ‘<samp><span class="samp">#:upper8_15:#</span></samp>’
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respectively. For example to load the 32-bit address of foo into r0:
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<pre class="smallexample"> MOVS r0, #:upper8_15:#foo
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LSLS r0, r0, #8
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ADDS r0, #:upper0_7:#foo
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LSLS r0, r0, #8
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ADDS r0, #:lower8_15:#foo
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LSLS r0, r0, #8
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ADDS r0, #:lower0_7:#foo
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</pre>
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