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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `src/label.rs`."><title>label.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-b0742ba02757f159.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="juicebox_asm" data-themes="" data-resource-suffix="" data-rustdoc-version="1.83.0 (90b35a623 2024-11-26)" data-channel="1.83.0" data-search-js="search-f0d225181b97f9a4.js" data-settings-js="settings-805db61a62df4bd2.js" ><script src="../../static.files/storage-1d39b6787ed640ff.js"></script><script defer src="../../static.files/src-script-e66d777a5a92e9b2.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-f070b9041d14864c.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-0111fcff984fae8f.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer"></div><main><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">juicebox_asm/</div>label.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap"><div data-nosnippet><pre class="src-line-numbers">
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//! the emitted code.
</span><span class="kw">use </span>std::collections::HashSet;
<span class="doccomment">/// A label which is used as target for jump instructions.
///
/// ```rust
/// use juicebox_asm::{Asm, Label, Reg64};
/// use juicebox_asm::insn::{Mov, Jmp};
///
/// let mut lbl = Label::new();
/// let mut asm = Asm::new();
///
/// // Skip the mov instruction.
/// asm.jmp(&mut lbl);
/// asm.mov(Reg64::rax, Reg64::rax);
/// asm.bind(&mut lbl);
/// ```
///
/// # Panics
///
/// Panics if the label is dropped while not yet bound, or having unresolved relocations.
/// This is mainly a safety-guard to detect wrong usage.
</span><span class="kw">pub struct </span>Label {
<span class="doccomment">/// Location of the label. Will be set after the label is bound, else None.
</span>location: <span class="prelude-ty">Option</span><usize>,
<span class="doccomment">/// Offsets that must be patched with the label location.
</span>offsets: HashSet<usize>,
}
<span class="kw">impl </span>Label {
<span class="doccomment">/// Create a new `unbound` [Label].
</span><span class="kw">pub fn </span>new() -> Label {
Label {
location: <span class="prelude-val">None</span>,
offsets: HashSet::new(),
}
}
<span class="doccomment">/// Bind the label to the `location`, can only be bound once.
///
/// # Panics
///
/// Panics if the lable is already bound.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>bind(<span class="kw-2">&mut </span><span class="self">self</span>, loc: usize) {
<span class="comment">// A label can only be bound once!
</span><span class="macro">assert!</span>(!<span class="self">self</span>.is_bound());
<span class="self">self</span>.location = <span class="prelude-val">Some</span>(loc);
}
<span class="doccomment">/// Record an offset that must be patched with the label location.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>record_offset(<span class="kw-2">&mut </span><span class="self">self</span>, off: usize) {
<span class="self">self</span>.offsets.insert(off);
}
<span class="doccomment">/// Get the location of the lable if already bound, `None` else.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>location(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> {
<span class="self">self</span>.location
}
<span class="doccomment">/// Get the offsets which refer to the label. These are used to patch the jump instructions to
/// the label location.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>offsets_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span>HashSet<usize> {
<span class="kw-2">&mut </span><span class="self">self</span>.offsets
}
<span class="doccomment">/// Check whether the label is bound to a location.
</span><span class="kw">const fn </span>is_bound(<span class="kw-2">&</span><span class="self">self</span>) -> bool {
<span class="self">self</span>.location.is_some()
}
}
<span class="kw">impl </span>Drop <span class="kw">for </span>Label {
<span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) {
<span class="comment">// Ensure the label was bound when it is dropped.
</span><span class="macro">assert!</span>(<span class="self">self</span>.is_bound());
<span class="comment">// Ensure all offsets have been patched when the label is dropped.
</span><span class="macro">assert!</span>(<span class="self">self</span>.offsets.is_empty());
}
}
</code></pre></div></section></main></body></html>
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