[llvm-commits] CVS: llvm/docs/LangRef.html

[Andrew Lenharth]

Changes in directory llvm/docs:

LangRef.html updated: 1.116 -> 1.117
---
Log message:

continued readcyclecounter support

---
Diffs of the changes:  (+35 -1)

 LangRef.html |   36 +++++++++++++++++++++++++++++++++++-
 1 files changed, 35 insertions(+), 1 deletion(-)


Index: llvm/docs/LangRef.html
diff -u llvm/docs/LangRef.html:1.116 llvm/docs/LangRef.html:1.117
--- llvm/docs/LangRef.html:1.116	Thu Nov 10 20:15:27 2005
+++ llvm/docs/LangRef.html	Fri Nov 11 10:46:55 2005
@@ -128,6 +128,7 @@
           <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>'   Intrinsic</a></li>
           <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
           <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
+          <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
         </ol>
       </li>
       <li><a href="#int_os">Operating System Intrinsics</a>
@@ -2811,6 +2812,39 @@
 
 </div>
 
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+  <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+  declare ulong %llvm.readcyclecounter( )
+</pre>
+
+<h5>Overview:</h5>
+
+
+<p>
+The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle 
+counter register (or similar low latency, high accuracy clocks) on those targets
+that support it.  On X86, it should map to RDTSC.  On Alpha, it should map to RPCC.
+As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
+should only be used for small timings.  
+</p>
+
+<h5>Semantics:</h5>
+
+<p>
+When directly supported, reading the cycle counter should not modify any memory.  
+Implementations are allowed to either return a application specific value or a
+system wide value.  On backends without support, this is lowered to a constant 0.
+</p>
+
+</div>
+
 
 <!-- ======================================================================= -->
 <div class="doc_subsection">
@@ -3388,7 +3422,7 @@
 
   <a href="mailto:sabre at nondot.org">Chris Lattner</a><br>
   <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
-  Last modified: $Date: 2005/11/11 02:15:27 $
+  Last modified: $Date: 2005/11/11 16:46:55 $
 </address>
 </body>
 </html>