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Add new "memory use marker" intrinsics. These indicate lifetimes and invariant

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sections of memory objects.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83953 91177308-0d34-0410-b5e6-96231b3b80d8
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Nick Lewycky
2009-10-13 07:03:23 +00:00
parent 6e4bdfc229
commit cc271861da
3 changed files with 183 additions and 0 deletions
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@@ -273,6 +273,14 @@
<li><a href="#int_atomic_load_umin"><tt>llvm.atomic.load.umin</tt></a></li>
</ol>
</li>
<li><a href="#int_memorymarkers">Memory Use Markers</a>
<ol>
<li><a href="#int_lifetime_start"><tt>llvm.lifetime.start</tt></a></li>
<li><a href="#int_lifetime_end"><tt>llvm.lifetime.end</tt></a></li>
<li><a href="#int_invariant_start"><tt>llvm.invariant.start</tt></a></li>
<li><a href="#int_invariant_end"><tt>llvm.invariant.end</tt></a></li>
</ol>
</li>
<li><a href="#int_general">General intrinsics</a>
<ol>
<li><a href="#int_var_annotation">
@@ -6980,6 +6988,129 @@ LLVM</a>.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="int_memorymarkers">Memory Use Markers</a>
</div>
<div class="doc_text">
<p>This class of intrinsics exists to information about the lifetime of memory
objects and ranges where variables are immutable.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="int_lifetime_start">'<tt>llvm.lifetime.start</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
declare void @llvm.lifetime.start(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.lifetime.start</tt>' intrinsic specifies the start of a memory
object's lifetime.</p>
<h5>Arguments:</h5>
<p>The first argument is a the size of the object, or -1 if it is variable
sized. The second argument is a pointer to the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that before this point in the code, the value of the
memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
never be used and has an undefined value. A load from the pointer that is
preceded by this intrinsic can be replaced with
<tt>'<a href="#undefvalues">undef</a>'</tt>.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="int_lifetime_end">'<tt>llvm.lifetime.end</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
declare void @llvm.lifetime.end(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.lifetime.end</tt>' intrinsic specifies the end of a memory
object's lifetime.</p>
<h5>Arguments:</h5>
<p>The first argument is a the size of the object, or -1 if it is variable
sized. The second argument is a pointer to the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that after this point in the code, the value of the
memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
never be used and has an undefined value. Any stores into the memory object
following this intrinsic may be removed as dead.
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="int_invariant_start">'<tt>llvm.invariant.start</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
declare {}* @llvm.invariant.start(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;) readonly
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.invariant.start</tt>' intrinsic specifies that the contents of
a memory object will not change.</p>
<h5>Arguments:</h5>
<p>The first argument is a the size of the object, or -1 if it is variable
sized. The second argument is a pointer to the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that until an <tt>llvm.invariant.end</tt> that uses
the return value, the referenced memory location is constant and
unchanging.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="int_invariant_end">'<tt>llvm.invariant.end</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
declare void @llvm.invariant.end({}* &lt;start&gt;, i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.invariant.end</tt>' intrinsic specifies that the contents of
a memory object are mutable.</p>
<h5>Arguments:</h5>
<p>The first argument is the matching <tt>llvm.invariant.start</tt> intrinsic.
The second argument is a the size of the object, or -1 if it is variable
sized and the third argument is a pointer to the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that the memory is mutable again.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="int_general">General Intrinsics</a>