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<tr class="row-even"><td>title: Functions</td>
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<p>Functions are represented by
<a class="reference external" href="llvm.core.Function.html">llvm.core.Function</a> objects. They are
contained within modules, and can be created either with the method
<tt class="docutils literal"><span class="pre">module_obj.add_function</span></tt> or the static constructor <tt class="docutils literal"><span class="pre">Function.new</span></tt>.
References to functions already present in a module can be retrieved via
<tt class="docutils literal"><span class="pre">module.get_function_named</span></tt> or by the static constructor method
<tt class="docutils literal"><span class="pre">Function.get</span></tt>. All functions in a module can be enumerated by
iterating over <tt class="docutils literal"><span class="pre">module_obj.functions</span></tt>.</p>
<div class="highlight-python"><pre># create a type, representing functions that take
an integer and return # a floating point value. ft = Type.function(
Type.float(), [ Type.int() ] )
# create a function of this type
f1 = module_obj.add_function(ft, "func1")
# or equivalently, like this:
f2 = Function.new(module_obj, ft, "func2")
# get a reference to an existing function
f3 = module_obj.get_function_named("func3")
# or like this:
f4 = Function.get(module_obj, "func4")
# list all function names in a module
for f in module_obj.functions: print f.name</pre>
</div>
<div class="section" id="intrinsic">
<h1>Intrinsic<a class="headerlink" href="#intrinsic" title="Permalink to this headline"></a></h1>
<p>References to intrinsic functions can be got via the static constructor
<tt class="docutils literal"><span class="pre">intrinsic</span></tt>. This returns a <tt class="docutils literal"><span class="pre">Function</span></tt> object, calling which is
equivalent to invoking the intrinsic. The <tt class="docutils literal"><span class="pre">intrinsic</span></tt> method has to be
called with a module object, an intrinsic ID (which is a numeric
constant) and a list of the types of arguments (which LLVM uses to
resolve overloaded intrinsic functions).</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># get a reference to the llvm.bswap intrinsic</span>
<span class="n">bswap</span> <span class="o">=</span> <span class="n">Function</span><span class="o">.</span><span class="n">intrinsic</span><span class="p">(</span><span class="n">mod</span><span class="p">,</span> <span class="n">INTR_BSWAP</span><span class="p">,</span> <span class="p">[</span><span class="n">Type</span><span class="o">.</span><span class="n">int</span><span class="p">()])</span>
<span class="c"># call it</span>
<span class="n">builder</span><span class="o">.</span><span class="n">call</span><span class="p">(</span><span class="n">bswap</span><span class="p">,</span> <span class="p">[</span><span class="n">value</span><span class="p">])</span>
</pre></div>
</div>
<p>Here, the constant <tt class="docutils literal"><span class="pre">INTR_BSWAP</span></tt>, available from <tt class="docutils literal"><span class="pre">llvm.core</span></tt>,
represents the LLVM intrinsic
<a class="reference external" href="http://www.llvm.org/docs/LangRef.html#int_bswap">llvm.bswap</a>. The
<tt class="docutils literal"><span class="pre">[Type.int()]</span></tt> selects the version of <tt class="docutils literal"><span class="pre">llvm.bswap</span></tt> that has a single
32-bit integer argument. The list of intrinsic IDs defined as integer
constants in <tt class="docutils literal"><span class="pre">llvm.core</span></tt>. These are:</p>
<p>{% include intrinsics.csv %}</p>
<p>There are also target-specific intrinsics (which correspond to that
target&#8217;s CPU instructions) available, but are omitted here for brevity.
Full list can be seen from
[<em>intrinsic_ids.py](https://github.com/numba/llvmpy/blob/master/llvm/</em>intrinsic_ids.py).
See the <a class="reference external" href="http://www.llvm.org/docs/LangRef.html">LLVM Language
Reference</a> for more information
on the intrinsics, and the
<a class="reference external" href="https://github.com/numba/llvmpy/blob/master/test/intrinsic.py">test</a>
directory in the source distribution for more examples. The intrinsic ID
can be retrieved from a function object with the read-only property
<tt class="docutils literal"><span class="pre">intrinsic_id</span></tt>.</p>
<blockquote>
<div><p><strong>Auto-generation of Intrinsic IDs</strong></p>
<p>A script (tool/intrgen.py in source tree) generates the intrinsic
IDs automatically. This is necessary when compiling llvmpy with a
different version of LLVM.</p>
</div></blockquote>
</div>
<div class="section" id="calling-convention-callconv">
<h1>Calling Convention # {#callconv}<a class="headerlink" href="#calling-convention-callconv" title="Permalink to this headline"></a></h1>
<p>The function&#8217;s calling convention can be set using the
<tt class="docutils literal"><span class="pre">calling_convention</span></tt> property. The following (integer) constants
defined in <tt class="docutils literal"><span class="pre">llvm.core</span></tt> can be used as values:</p>
<p>Value | Equivalent LLVM Assembly Keyword |
&#8212;&#8212;|&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-| <tt class="docutils literal"><span class="pre">CC_C</span></tt> | <tt class="docutils literal"><span class="pre">ccc</span></tt> |
<tt class="docutils literal"><span class="pre">CC_FASTCALL</span></tt> | <tt class="docutils literal"><span class="pre">fastcc</span></tt> | <tt class="docutils literal"><span class="pre">CC_COLDCALL</span></tt> | <tt class="docutils literal"><span class="pre">coldcc</span></tt> |
<tt class="docutils literal"><span class="pre">CC_X86_STDCALL</span></tt> | <tt class="docutils literal"><span class="pre">x86_stdcallcc</span></tt> | <tt class="docutils literal"><span class="pre">CC_X86_FASTCALL</span></tt> |
<tt class="docutils literal"><span class="pre">x86_fastcallcc</span></tt> |</p>
<p>See the <a class="reference external" href="http://www.llvm.org/docs/LangRef.html#callingconv">LLVM docs</a>
for more information on each. Backend-specific numbered conventions can
be directly passed as integers.</p>
<p>An arbitrary string identifying which garbage collector to use can be
set or got with the property <tt class="docutils literal"><span class="pre">collector</span></tt>.</p>
<p>The value objects corresponding to the arguments of a function can be
got using the read-only property <tt class="docutils literal"><span class="pre">args</span></tt>. These can be iterated over,
and also be indexed via integers. An example:</p>
<div class="highlight-python"><pre># list all argument names and types for arg in
fn.args: print arg.name, "of type", arg.type
# change the name of the first argument
fn.args[0].name = "objptr"</pre>
</div>
<p>Basic blocks (see later) are contained within functions. When newly
created, a function has no basic blocks. They have to be added
explicitly, using the <tt class="docutils literal"><span class="pre">append_basic_block</span></tt> method, which adds a new,
empty basic block as the last one in the function. The first basic block
of the function can be retrieved using the <tt class="docutils literal"><span class="pre">get_entry_basic_block</span></tt>
method. The existing basic blocks can be enumerated by iterating over
using the read-only property <tt class="docutils literal"><span class="pre">basic_blocks</span></tt>. The number of basic
blocks can be got via <tt class="docutils literal"><span class="pre">basic_block_count</span></tt> method. Note that
<tt class="docutils literal"><span class="pre">get_entry_basic_block</span></tt> is slightly faster than <tt class="docutils literal"><span class="pre">basic_blocks[0]</span></tt>
and so is <tt class="docutils literal"><span class="pre">basic_block_count</span></tt>, over <tt class="docutils literal"><span class="pre">len(f.basic_blocks)</span></tt>.</p>
<div class="highlight-python"><pre># add a basic block b1 =
fn.append_basic_block("entry")
# get the first one
b2 = fn.get_entry_basic_block() b2 = fn.basic_mdblocks[0] # slower
than previous method
# print names of all basic blocks
for b in fn.basic_blocks: print b.name
# get number of basic blocks
n = fn.basic_block_count n = len(fn.basic_blocks) # slower than
previous method</pre>
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<li><a class="reference internal" href="#">Intrinsic</a></li>
<li><a class="reference internal" href="#calling-convention-callconv">Calling Convention # {#callconv}</a></li>
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