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Cleanup the cast section, add the select instruction

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12307 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2004-03-12 05:50:16 +00:00
parent 6551ea98b2
commit cc37aae854
1 changed files with 95 additions and 21 deletions
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@ -80,6 +80,7 @@
<ol>
<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>
@ -1506,38 +1507,111 @@ came from in the last <a href="#terminators">terminator</a> instruction.</p>
<h5>Example:</h5>
<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_cast">'<tt>cast .. to</tt>'
Instruction</a> </div>
<div class="doc_subsubsection">
<a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre> &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
<pre>
&lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>cast</tt>' instruction is used as the primitive means to
convert integers to floating point, change data type sizes, and break
type safety (by casting pointers).</p>
<p>
The '<tt>cast</tt>' instruction is used as the primitive means to convert
integers to floating point, change data type sizes, and break type safety (by
casting pointers).
</p>
<h5>Arguments:</h5>
<p>The '<tt>cast</tt>' instruction takes a value to cast, which must be
a first class value, and a type to cast it to, which must also be a <a
href="#t_firstclass">first class</a> type.</p>
<p>
The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
class value, and a type to cast it to, which must also be a <a
href="#t_firstclass">first class</a> type.
</p>
<h5>Semantics:</h5>
<p>This instruction follows the C rules for explicit casts when
determining how the data being cast must change to fit in its new
container.</p>
<p>When casting to bool, any value that would be considered true in the
context of a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>'
values, all else are '<tt>false</tt>'.</p>
<p>When extending an integral value from a type of one signness to
another (for example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value
is sign-extended if the <b>source</b> value is signed, and
zero-extended if the source value is unsigned. <tt>bool</tt> values
are always zero extended into either zero or one.</p>
<p>
This instruction follows the C rules for explicit casts when determining how the
data being cast must change to fit in its new container.
</p>
<p>
When casting to bool, any value that would be considered true in the context of
a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
all else are '<tt>false</tt>'.
</p>
<p>
When extending an integral value from a type of one signness to another (for
example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
<b>source</b> value is signed, and zero-extended if the source value is
unsigned. <tt>bool</tt> values are always zero extended into either zero or
one.
</p>
<h5>Example:</h5>
<pre> %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
<pre>
%X = cast int 257 to ubyte <i>; yields ubyte:1</i>
%Y = cast int 123 to bool <i>; yields bool:true</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="i_select">'<tt>select</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
&lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
</pre>
<h5>Overview:</h5>
<p>
The '<tt>select</tt>' instruction is used to choose one value based on a
condition, without branching.
</p>
<h5>Arguments:</h5>
<p>
The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
</p>
<h5>Semantics:</h5>
<p>
If the boolean condition evaluates to true, the instruction returns the first
value argument, otherwise it returns the second value argument.
</p>
<h5>Example:</h5>
<pre>
%X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
Instruction</a> </div>