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add llvm.gcroot into GarbageCollection.html, patch bylost lostfreeman@gmail.com.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151908 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jia Liu 2012-03-02 11:30:51 +00:00
parent dc62a90696
commit 08bc33dcbb
1 changed files with 6 additions and 3 deletions
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9
docs/GarbageCollection.html
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@ -1,4 +1,4 @@
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
@ -429,7 +429,8 @@ programs that use different garbage collection algorithms (or none at all).</p>
<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 @@ which a pointers into the GC heap.</p>
<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