add the 'alloc' metadata node to represent the size of offset of buffers pointed to by pointers.

This metadata can be attached to any instruction returning a pointer

llvm-svn: 158660

1 files changed, 44 insertions, 0 deletions

diff --git a/llvm/docs/LangRef.html b/llvm/docs/LangRef.html
index 9cb7e6392ab..2b81279b6e5 100644
--- a/llvm/docs/LangRef.html
+++ b/llvm/docs/LangRef.html
@@ -105,6 +105,7 @@
           <li><a href="#tbaa">'<tt>tbaa</tt>' Metadata</a></li>
           <li><a href="#fpmath">'<tt>fpmath</tt>' Metadata</a></li>
           <li><a href="#range">'<tt>range</tt>' Metadata</a></li>
+          <li><a href="#alloc">'<tt>alloc</tt>' Metadata</a></li>
         </ol>
       </li>
     </ol>
@@ -3077,6 +3078,49 @@ call void @llvm.dbg.value(metadata !24, i64 0, metadata !25)
 </pre>
 </div>
 </div>
+
+<!-- _______________________________________________________________________ -->
+<h4>
+  <a name="alloc">'<tt>alloc</tt>' Metadata</a>
+</h4>
+ 
+<div>
+
+<p><tt>alloc</tt> metadata may be attached to any instruction returning a
+   pointer. It can be used to express the size and offset relative to the
+   beginning of the buffer pointed by.</p>
+
+<blockquote>
+
+<p>The first parameter is a function that returns the size of the buffer, and
+   the second (optional) parameter is a function that returns the offset from
+   the beginning of the buffer. If the second parameter is not present or null,
+   the offset is assumed to be null. Both functions must be either readonly or
+   readnone.</p>
+<p><tt>alloc</tt> metadata can have additional parameters, which are passed to
+   the size and offset functions when they are evaluated. Therefore the size and
+   offset functions must have the same signature.</p>
+
+</blockquote>
+
+
+<p>Examples:</p>
+<div class="doc_code">
+<pre>
+  ; size of buffer allocated by this call is my_malloc_size(%s), and offset=0
+  %a = call my_malloc(%s), !alloc !{i32 (i32)* @my_malloc_size, null, i32 %s}
+
+  ; size of the buffer pointed by *ptr is size(%x), and offset=offset(%x)
+  %b = load i8** %foo, !alloc !{i32 (i32)* @size, i32 (i32)* @offset, i32 %x}
+
+  ; size of buffer allocated by this call is foo_size(), and offset=0
+  %a = call alloc_foo(%s), !alloc !0
+...
+!0 = metadata {i32 ()* @foo_size}
+</pre>
+</div>
+</div>
+
 </div>
 
 </div>