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class="example-wrap"><div data-nosnippet><pre class="src-line-numbers"><a href="#1" id="1">1</a> <a href="#2" id="2">2</a> <a href="#3" id="3">3</a> <a href="#4" id="4">4</a> <a href="#5" id="5">5</a> <a href="#6" id="6">6</a> <a href="#7" id="7">7</a> <a href="#8" id="8">8</a> <a href="#9" id="9">9</a> <a href="#10" id="10">10</a> <a href="#11" id="11">11</a> <a href="#12" id="12">12</a> <a href="#13" id="13">13</a> <a href="#14" id="14">14</a> <a href="#15" id="15">15</a> <a href="#16" id="16">16</a> <a href="#17" id="17">17</a> <a href="#18" id="18">18</a> <a href="#19" id="19">19</a> <a href="#20" id="20">20</a> <a href="#21" id="21">21</a> <a href="#22" id="22">22</a> <a href="#23" id="23">23</a> <a href="#24" id="24">24</a> <a href="#25" id="25">25</a> <a href="#26" id="26">26</a> <a href="#27" id="27">27</a> <a href="#28" id="28">28</a> <a href="#29" id="29">29</a> <a href="#30" id="30">30</a> <a href="#31" id="31">31</a> <a href="#32" id="32">32</a> <a href="#33" id="33">33</a> 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Fibonacci example. //! //! Jit compile a function at runtime (generate native host code) to compute the fibonacci sequence //! to demonstrate the [`juicebox_asm`] crate. </span><span class="kw">use </span>juicebox_asm::insn::<span class="kw-2">*</span>; <span class="kw">use </span>juicebox_asm::Runtime; <span class="kw">use </span>juicebox_asm::{Asm, Imm64, Label, Reg64}; <span class="kw">const fn </span>fib_rs(n: u64) -> u64 { <span class="kw">match </span>n { <span class="number">0 </span>=> <span class="number">0</span>, <span class="number">1 </span>=> <span class="number">1</span>, <span class="kw">_ </span>=> fib_rs(n - <span class="number">2</span>) + fib_rs(n - <span class="number">1</span>), } } <span class="kw">fn </span>main() { <span class="kw">let </span><span class="kw-2">mut </span>asm = Asm::new(); <span class="kw">let </span><span class="kw-2">mut </span>lp = Label::new(); <span class="kw">let </span><span class="kw-2">mut </span>end = Label::new(); <span class="comment">// Reference implementation: // // int fib(int n) { // int tmp = 0; // int prv = 1; // int sum = 0; // loop: // if (n == 0) goto end; // tmp = sum; // sum += prv; // prv = tmp; // --n; // goto loop; // end: // return sum; // } // SystemV abi: // rdi -> first argument // rax -> return value </span><span class="kw">let </span>n = Reg64::rdi; <span class="kw">let </span>sum = Reg64::rax; <span class="kw">let </span>tmp = Reg64::rcx; <span class="kw">let </span>prv = Reg64::rbx; asm.mov(tmp, Imm64::from(<span class="number">0</span>)); asm.mov(prv, Imm64::from(<span class="number">1</span>)); asm.mov(sum, Imm64::from(<span class="number">0</span>)); asm.bind(<span class="kw-2">&mut </span>lp); asm.test(n, n); asm.jz(<span class="kw-2">&mut </span>end); asm.mov(tmp, sum); asm.add(sum, prv); asm.mov(prv, tmp); asm.dec(n); asm.jmp(<span class="kw-2">&mut </span>lp); asm.bind(<span class="kw-2">&mut </span>end); asm.ret(); <span class="comment">// Write out JIT code for visualization. // Disassemble for example with `ndisasm -b 64 jit.asm`. </span><span class="kw">let </span>code = asm.into_code(); std::fs::write(<span class="string">"jit.asm"</span>, <span class="kw-2">&</span>code).unwrap(); <span class="comment">// Move code into executable page and get function pointer to it. </span><span class="kw">let </span><span class="kw-2">mut </span>rt = Runtime::new(); <span class="kw">let </span>fib = <span class="kw">unsafe </span>{ rt.add_code::<<span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn</span>(u64) -> u64>(code) }; <span class="kw">for </span>n <span class="kw">in </span><span class="number">0</span>..<span class="number">15 </span>{ <span class="kw">let </span>fib_jit = fib(n); <span class="macro">println!</span>(<span class="string">"fib({}) = {}"</span>, n, fib_jit); <span class="macro">assert_eq!</span>(fib_jit, fib_rs(n)); } } </code></pre></div></section></main></body></html>