LangRef.html

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<div class="doc_subsubsection">
  <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  call sbyte  (ushort address)* %llvm.readport(ushort &lt;address&gt;)
  call ubyte  (ushort address)* %llvm.readport(ushort &lt;address&gt;)
  call short  (ushort address)* %llvm.readport(ushort &lt;address&gt;)
  call ushort (ushort address)* %llvm.readport(ushort &lt;address&gt;)
  call int    (ushort address)* %llvm.readport(ushort &lt;address&gt;)
  call uint   (ushort address)* %llvm.readport(ushort &lt;address&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.readport</tt>' intrinsic reads data from the specified I/O port.
</p>

<h5>Arguments:</h5>

<p>
The argument to this intrinsic indicates the I/O address from which to read
the data.  The address is in the I/O address namespace; it is not a memory
location.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.readport</tt>' intrinsic reads data from the I/O port specified
by <i>address</i> and returns the value.  The address and return value must
be integers, but the size is dependent upon the platform upon which the
program is code generated.  For example, on x86, the address must be a
ushort, and the return value must be 8, 16, or 32 bits.
</p>

</div>

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<div class="doc_subsubsection">
  <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  call void (ushort address, sbyte value)* %llvm.writeport(ushort &lt;address&gt;, sbyte &lt;value&gt;)
  call void (ushort address, ubyte value)* %llvm.writeport(ushort &lt;address&gt;, ubyte &lt;value&gt;)
  call void (ushort address, short value)* %llvm.writeport(ushort &lt;address&gt;, short &lt;value&gt;)
  call void (ushort address, ushort value)* %llvm.writeport(ushort &lt;address&gt;, ushort &lt;value&gt;)
  call void (ushort address, int value)* %llvm.writeport(ushort &lt;address&gt;, int &lt;value&gt;)
  call void (ushort address, uint value)* %llvm.writeport(ushort &lt;address&gt;, uint &lt;value&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified I/O port.
</p>

<h5>Arguments:</h5>

<p>
The first argument to this intrinsic indicates the I/O address to which data
should be written.  The address is in the I/O address namespace; it is not a
memory location.
</p>

<p>
The second argument is the value to write to the I/O port.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
specified by <i>address</i>.  The address and value must be integers, but the
size is dependent upon the platform upon which the program is code generated.
For example, on x86, the address must be a ushort, and the value written must
be 8, 16, or 32 bits in length.
</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_libc">Standard C Library Intrinsics</a>
</div>

<div class="doc_text">
<p>
LLVM provides intrinsics for a few important standard C library functions.
These intrinsics allow source-language front-ends to pass information about the
alignment of the pointer arguments to the code generator, providing opportunity
for more efficient code generation.
</p>

</div>

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<div class="doc_subsubsection">
  <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  call void (sbyte*, sbyte*, uint, uint)* %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
                                                       uint &lt;len&gt;, uint &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
location to the destination location.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
does not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination, the second is a pointer to
the source.  The third argument is an (arbitrarily sized) integer argument
specifying the number of bytes to copy, and the fourth argument is the alignment
of the source and destination locations.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that the size of the copy is a multiple of the alignment
and that both the source and destination pointers are aligned to that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
location to the destination location, which are not allowed to overlap.  It
copies "len" bytes of memory over.  If the argument is known to be aligned to
some boundary, this can be specified as the fourth argument, otherwise it should
be set to 0 or 1.
</p>
</div>


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<div class="doc_subsubsection">
  <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  call void (sbyte*, sbyte*, uint, uint)* %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
                                                       uint &lt;len&gt;, uint &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>' 
intrinsic but allows the two memory locations to overlap.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
does not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination, the second is a pointer to
the source.  The third argument is an (arbitrarily sized) integer argument
specifying the number of bytes to copy, and the fourth argument is the alignment
of the source and destination locations.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that the size of the copy is a multiple of the alignment
and that both the source and destination pointers are aligned to that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
location to the destination location, which may overlap.  It
copies "len" bytes of memory over.  If the argument is known to be aligned to
some boundary, this can be specified as the fourth argument, otherwise it should
be set to 0 or 1.
</p>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  call void (sbyte*, ubyte, uint, uint)* %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
                                                      uint &lt;len&gt;, uint &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
byte value.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
does not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination to fill, the second is the
byte value to fill it with, the third argument is an (arbitrarily sized) integer
argument specifying the number of bytes to fill, and the fourth argument is the
known alignment of destination location.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that the size of the copy is a multiple of the alignment
and that the destination pointer is aligned to that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
destination location.  If the argument is known to be aligned to some boundary,
this can be specified as the fourth argument, otherwise it should be set to 0 or
1.
</p>
</div>


<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_debugger">Debugger Intrinsics</a>
</div>

<div class="doc_text">
<p>
The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
are described in the <a
href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
Debugging</a> document.
</p>
</div>


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