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added descriptions of vector extensions, info about vector literals and vector operations. 

llvm-svn: 148220
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Anton Yartsev 2012-01-15 16:22:24 +00:00
parent eaa262b5b8
commit e89856784c
1 changed files with 157 additions and 3 deletions
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clang/docs/LanguageExtensions.html
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@ -384,10 +384,11 @@ is used in the file argument.</p>
<h2 id="vectors">Vectors and Extended Vectors</h2>
<!-- ======================================================================= -->
<p>Supports the GCC vector extensions, plus some stuff like V[1].</p>
<p>Supports the GCC, OpenCL, AltiVec and NEON vector extensions.</p>
<p>Also supports <tt>ext_vector</tt>, which additionally support for V.xyzw
syntax and other tidbits as seen in OpenCL. An example is:</p>
OpenCL vector types are created using <tt>ext_vector_type</tt> attribute. It
support for V.xyzw syntax and other tidbits as seen in OpenCL. An example
is:</p>
<blockquote>
<pre>
@ -405,6 +406,159 @@ float4 foo(float2 a, float2 b) {
<p>Query for this feature with __has_extension(attribute_ext_vector_type).</p>
<p>Giving -faltivec option to clang enables support for AltiVec vector syntax
and functions. For example:</p>
<blockquote>
<pre>
vector float foo(vector int a) {
vector int b;
b = vec_add(a, a) + a;
return (vector float)b;
}
</pre>
</blockquote>
<p>NEON vector types are created using <tt>neon_vector_type</tt> and
<tt>neon_polyvector_type</tt> attributes. For example:</p>
<blockquote>
<pre>
typedef <b>__attribute__((neon_vector_type(8)))</b> int8_t int8x8_t;
typedef <b>__attribute__((neon_polyvector_type(16)))</b> poly8_t poly8x16_t;
int8x8_t foo(int8x8_t a) {
int8x8_t v;
v = a;
return v;
}
</pre>
</blockquote>
<!-- ======================================================================= -->
<h3><a name="vector_literals">Vector Literals</a></h3>
<!-- ======================================================================= -->
<p>Vector literals can be used to create vectors from a set of scalars, or
vectors. Either parentheses or braces form can be used. In the parentheses form
the number of literal values specified must be one, i.e. referring to a scalar
value, or must match the size of the vector type being created. If a single
scalar literal value is specified, the scalar literal value will be replicated
to all the components of the vector type. In the brackets form any number of
literals can be specified. For example:</p>
<blockquote>
<pre>
typedef int v4si __attribute__((__vector_size__(16)));
typedef float float4 __attribute__((ext_vector_type(4)));
typedef float float2 __attribute__((ext_vector_type(2)));
v4si vsi = (v4si){1, 2, 3, 4};
float4 vf = (float4)(1.0f, 2.0f, 3.0f, 4.0f);
vector int vi1 = (vector int)(1); // vi1 will be (1, 1, 1, 1).
vector int vi2 = (vector int){1}; // vi2 will be (1, 0, 0, 0).
vector int vi3 = (vector int)(1, 2); // error
vector int vi4 = (vector int){1, 2}; // vi4 will be (1, 2, 0, 0).
vector int vi5 = (vector int)(1, 2, 3, 4);
float4 vf = (float4)((float2)(1.0f, 2.0f), (float2)(3.0f, 4.0f));
</pre>
</blockquote>
<!-- ======================================================================= -->
<h3><a name="vector_operations">Vector Operations</a></h3>
<!-- ======================================================================= -->
<p>The table below shows the support for each operation by vector extension.
A dash indicates that an operation is not accepted according to a corresponding
specification.</p>
<table width="500" border="1" cellspacing="0">
<tr>
<th bgcolor="#ffddaa">Operator</th>
<th bgcolor="#ffddaa">OpenCL</th>
<th bgcolor="#ffddaa">AltiVec</th>
<th bgcolor="#ffddaa">GCC</th>
<th bgcolor="#ffddaa">NEON</th>
</tr>
<tr>
<td>[]</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
</tr>
<tr>
<td>unary operators +, -</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
</tr>
<tr>
<td>++, --</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
<td align="center">-</td>
</tr>
<tr>
<td>+, -, *, /, %</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
</tr>
<tr>
<td>bitwise operators &, |, ^, ~</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
</tr>
<tr>
<td>&gt&gt, &lt&lt</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
</tr>
<tr>
<td>!, &&,||</td>
<td align="center">no</td>
<td align="center">-</td>
<td align="center">-</td>
<td align="center">-</td>
</tr>
<tr>
<td>==,!=, >, <, >=, <=</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">-</td>
<td align="center">-</td>
</tr>
<tr>
<td>=</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
</tr>
<tr>
<td>:?</td>
<td align="center">yes</td>
<td align="center">-</td>
<td align="center">-</td>
<td align="center">-</td>
</tr>
<tr>
<td>sizeof</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
<td align="center">yes</td>
</tr>
</table>
<p>See also <a href="#__builtin_shufflevector">__builtin_shufflevector</a>.</p>
<!-- ======================================================================= -->