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document the syntax of inline asm

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25624 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2006-01-25 23:47:57 +00:00
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docs/LangRef.html
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@ -55,6 +55,11 @@
<li><a href="#constantexprs">Constant Expressions</a>
</ol>
</li>
<li><a href="#othervalues">Other Values</a>
<ol>
<li><a href="#inlineasm">Inline Assembler Expressions</a>
</ol>
</li>
<li><a href="#instref">Instruction Reference</a>
<ol>
<li><a href="#terminators">Terminator Instructions</a>
@ -1144,6 +1149,56 @@ following is the syntax for constant expressions:</p>
</dl>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
<!-- *********************************************************************** -->
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="inlineasm">Inline Assembler Expressions</a>
</div>
<div class="doc_text">
<p>
LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
Module-Level Inline Assembly</a>) through the use of a special value. This
value represents the inline assembler as a string (containing the instructions
to emit), a list of operand constraints (stored as a string), and a flag that
indicates whether or not the inline asm expression has side effects. An example
inline assembler expression is:
</p>
<pre>
int(int) asm "bswap $0", "=r,r"
</pre>
<p>
Inline assembler expressions may <b>only</b> be used as the callee operand of
a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
</p>
<pre>
%X = call int asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(int %Y)
</pre>
<p>
Inline asms with side effects not visible in the constraint list must be marked
as having side effects. This is done through the use of the
'<tt>sideeffect</tt>' keyword, like so:
</p>
<pre>
call void asm sideeffect "eieio", ""()
</pre>
<p>TODO: The format of the asm and constraints string still need to be
documented here. Constraints on what can be done (e.g. duplication, moving, etc
need to be documented).
</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
<!-- *********************************************************************** -->