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

llvm-svn: 151908
This commit is contained in:
Jia Liu 2012-03-02 11:30:51 +00:00
parent 80998e7618
commit d9605a6582
1 changed files with 6 additions and 3 deletions
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9
llvm/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"> "http://www.w3.org/TR/html4/strict.dtd">
<html> <html>
<head> <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 <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 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 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> <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 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>. <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 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 <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 or a bitcast of an alloca. The second contains a pointer to metadata that