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<title>LLVM Assembly Language Reference Manual</title>
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<div class="doc_title"> LLVM Language Reference Manual </div>
<li><a href="#abstract">Abstract</a></li>
<li><a href="#introduction">Introduction</a></li>
<li><a href="#identifiers">Identifiers</a></li>
<li><a href="#t_primitive">Primitive Types</a>
<ol>
<li><a href="#t_classifications">Type Classifications</a></li>
<li><a href="#t_function">Function Type</a></li>
<li><a href="#t_pointer">Pointer Type</a></li>
<li><a href="#t_struct">Structure Type</a></li>
<!-- <li><a href="#t_packed" >Packed Type</a> -->
</ol>
</li>
</ol>
</li>
<li><a href="#highlevel">High Level Structure</a>
<ol>
<li><a href="#modulestructure">Module Structure</a></li>
<li><a href="#globalvars">Global Variables</a></li>
<li><a href="#functionstructure">Function Structure</a></li>
<li><a href="#instref">Instruction Reference</a>
<ol>
<li><a href="#terminators">Terminator Instructions</a>
<ol>
<li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
<li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
<li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
<li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
<li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
</ol>
</li>
<li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
<li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
<li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
<li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
<li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
<li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
<li><a href="#bitwiseops">Bitwise Binary Operations</a>
<ol>
<li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
<li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
<li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
<li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
<li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
<li><a href="#memoryops">Memory Access Operations</a>
<ol>
<li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
<li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
<li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
<li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
<li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
<li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
</ol>
</li>
<li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
<li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
<li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
<li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
<li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
<li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
<li><a href="#intrinsics">Intrinsic Functions</a>
<ol>
<li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
<ol>
<li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
<li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
<li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
<ol>
<li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
<li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
<li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_codegen">Code Generator Intrinsics</a>
<ol>
<li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
<li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_os">Operating System Intrinsics</a>
<ol>
<li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
<li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
<li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
<li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner
committed
<li><a href="#int_libc">Standard C Library Intrinsics</a>
<ol>
<li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
<li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
<li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
<li><a href="#i_isnan">'<tt>llvm.isnan</tt>' Intrinsic</a></li>
Chris Lattner
committed
</ol>
</li>
<li><a href="#int_debugger">Debugger intrinsics</a></li>
<div class="doc_author">
<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
</div>
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<div class="doc_section"> <a name="abstract">Abstract </a></div>
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<div class="doc_text">
<p>This document is a reference manual for the LLVM assembly language.
LLVM is an SSA based representation that provides type safety,
low-level operations, flexibility, and the capability of representing
'all' high-level languages cleanly. It is the common code
representation used throughout all phases of the LLVM compilation
strategy.</p>
</div>
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<div class="doc_section"> <a name="introduction">Introduction</a> </div>
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<div class="doc_text">
<p>The LLVM code representation is designed to be used in three
different forms: as an in-memory compiler IR, as an on-disk bytecode
representation (suitable for fast loading by a Just-In-Time compiler),
and as a human readable assembly language representation. This allows
LLVM to provide a powerful intermediate representation for efficient
compiler transformations and analysis, while providing a natural means
to debug and visualize the transformations. The three different forms
of LLVM are all equivalent. This document describes the human readable
representation and notation.</p>
<p>The LLVM representation aims to be a light-weight and low-level
while being expressive, typed, and extensible at the same time. It
aims to be a "universal IR" of sorts, by being at a low enough level
that high-level ideas may be cleanly mapped to it (similar to how
microprocessors are "universal IR's", allowing many source languages to
be mapped to them). By providing type information, LLVM can be used as
the target of optimizations: for example, through pointer analysis, it
can be proven that a C automatic variable is never accessed outside of
the current function... allowing it to be promoted to a simple SSA
value instead of a memory location.</p>
</div>
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<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
<div class="doc_text">
<p>It is important to note that this document describes 'well formed'
LLVM assembly language. There is a difference between what the parser
accepts and what is considered 'well formed'. For example, the
following instruction is syntactically okay, but not well formed:</p>
<pre>
%x = <a href="#i_add">add</a> int 1, %x
</pre>
<p>...because the definition of <tt>%x</tt> does not dominate all of
its uses. The LLVM infrastructure provides a verification pass that may
be used to verify that an LLVM module is well formed. This pass is
automatically run by the parser after parsing input assembly, and by
the optimizer before it outputs bytecode. The violations pointed out
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