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| <h3 class="section">4.10 <samp><span class="command">ld</span></samp> and the Altera Nios II</h3> |
| |
| <p><a name="index-Nios-II-call-relaxation-700"></a><a name="index-g_t_002d_002drelax-on-Nios-II-701"></a> |
| Call and immediate jump instructions on Nios II processors are limited to |
| transferring control to addresses in the same 256MB memory segment, |
| which may result in <samp><span class="command">ld</span></samp> giving |
| ‘<samp><span class="samp">relocation truncated to fit</span></samp>’ errors with very large programs. |
| The command-line option <samp><span class="option">--relax</span></samp> enables the generation of |
| trampolines that can access the entire 32-bit address space for calls |
| outside the normal <code>call</code> and <code>jmpi</code> address range. These |
| trampolines are inserted at section boundaries, so may not themselves |
| be reachable if an input section and its associated call trampolines are |
| larger than 256MB. |
| |
| <p>The <samp><span class="option">--relax</span></samp> option is enabled by default unless <samp><span class="option">-r</span></samp> |
| is also specified. You can disable trampoline generation by using the |
| <samp><span class="option">--no-relax</span></samp> linker option. You can also disable this optimization |
| locally by using the ‘<samp><span class="samp">set .noat</span></samp>’ directive in assembly-language |
| source files, as the linker-inserted trampolines use the <code>at</code> |
| register as a temporary. |
| |
| <p>Note that the linker <samp><span class="option">--relax</span></samp> option is independent of assembler |
| relaxation options, and that using the GNU assembler's <samp><span class="option">-relax-all</span></samp> |
| option interferes with the linker's more selective call instruction relaxation. |
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