[llvm-commits] [llvm] r151908 - /llvm/trunk/docs/GarbageCollection.html

Fri Mar 2 03:30:51 PST 2012

Author: jialiu
Date: Fri Mar  2 05:30:51 2012
New Revision: 151908

URL: http://llvm.org/viewvc/llvm-project?rev=151908&view=rev
Log:
add llvm.gcroot into GarbageCollection.html, patch bylost lostfreeman at gmail.com.

Modified:
    llvm/trunk/docs/GarbageCollection.html

Modified: llvm/trunk/docs/GarbageCollection.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/GarbageCollection.html?rev=151908&r1=151907&r2=151908&view=diff
==============================================================================

--- llvm/trunk/docs/GarbageCollection.html (original)
+++ llvm/trunk/docs/GarbageCollection.html Fri Mar  2 05:30:51 2012
@@ -1,4 +1,4 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+ï»¿<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
                       "http://www.w3.org/TR/html4/strict.dtd">
 <html>
 <head>
@@ -429,7 +429,8 @@
 <p>The <tt>llvm.gcroot</tt> intrinsic is used to inform LLVM that a stack
 variable references an object on the heap and is to be tracked for garbage
 collection. The exact impact on generated code is specified by a <a
-href="#plugin">compiler plugin</a>.</p>
+href="#plugin">compiler plugin</a>. All calls to <tt>llvm.gcroot</tt> <b>must</b> reside
+ inside the first basic block.</p>
 
 <p>A compiler which uses mem2reg to raise imperative code using <tt>alloca</tt>
 into SSA form need only add a call to <tt>@llvm.gcroot</tt> for those variables
@@ -437,7 +438,9 @@
 
 <p>It is also important to mark intermediate values with <tt>llvm.gcroot</tt>.
 For example, consider <tt>h(f(), g())</tt>. Beware leaking the result of
-<tt>f()</tt> in the case that <tt>g()</tt> triggers a collection.</p>
+<tt>f()</tt> in the case that <tt>g()</tt> triggers a collection. Note, that
+stack variables must be initialized and marked with <tt>llvm.gcroot</tt> in
+function's prologue.</p>
 
 <p>The first argument <b>must</b> be a value referring to an alloca instruction
 or a bitcast of an alloca. The second contains a pointer to metadata that



