📄 constraints.html
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Node:<a name="Constraints">Constraints</a>,
Next:<a rel="next" accesskey="n" href="Asm-Labels.html#Asm%20Labels">Asm Labels</a>,
Previous:<a rel="previous" accesskey="p" href="Extended-Asm.html#Extended%20Asm">Extended Asm</a>,
Up:<a rel="up" accesskey="u" href="C-Extensions.html#C%20Extensions">C Extensions</a>
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<h3 class="section">Constraints for <code>asm</code> Operands</h3>
<p>Here are specific details on what constraint letters you can use with
<code>asm</code> operands.
Constraints can say whether
an operand may be in a register, and which kinds of register; whether the
operand can be a memory reference, and which kinds of address; whether the
operand may be an immediate constant, and which possible values it may
have. Constraints can also require two operands to match.
<ul class="menu">
<li><a accesskey="1" href="Simple-Constraints.html#Simple%20Constraints">Simple Constraints</a>: Basic use of constraints.
<li><a accesskey="2" href="Multi-Alternative.html#Multi-Alternative">Multi-Alternative</a>: When an insn has two alternative constraint-patterns.
<li><a accesskey="3" href="Modifiers.html#Modifiers">Modifiers</a>: More precise control over effects of constraints.
<li><a accesskey="4" href="Machine-Constraints.html#Machine%20Constraints">Machine Constraints</a>: Special constraints for some particular machines.
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