[opaque pointer type] Pass GlobalAlias the actual pointer type rather than decomposin...

[oota-llvm.git] / docs / GarbageCollection.rst

diff --git a/docs/GarbageCollection.rst b/docs/GarbageCollection.rst
index b5a3b1f527b9d1d624b1dc0262660c7e7b418840..a1557fcdb0994f993ac76b3b256f5be013ce85e1 100644 (file)
--- a/docs/GarbageCollection.rst
+++ b/docs/GarbageCollection.rst
@@ -247,9 +247,9 @@ Using ``llvm.gcwrite``
 
 The ``llvm.gcroot`` 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 :ref:`compiler plugin
-<plugin>`.  All calls to ``llvm.gcroot`` **must** reside inside the first basic
-block.
+The exact impact on generated code is specified by the Function's selected 
+:ref:`GC strategy <plugin>`.  All calls to ``llvm.gcroot`` **must** reside 
+inside the first basic block.
 
 The first argument **must** be a value referring to an alloca instruction or a
 bitcast of an alloca.  The second contains a pointer to metadata that should be
@@ -386,8 +386,10 @@ greater performance impact since pointer reads are more frequent than writes.
 
 .. _plugin:
 
-Built In Collectors
-====================
+.. _builtin-gc-strategies:
+
+Built In GC Strategies
+======================
 
 LLVM includes built in support for several varieties of garbage collectors.  
 
@@ -501,7 +503,19 @@ The Statepoint Example GC
   F.setGC("statepoint-example");
 
 This GC provides an example of how one might use the infrastructure provided 
-by ``gc.statepoint``.  
+by ``gc.statepoint``. This example GC is compatible with the 
+:ref:`PlaceSafepoints` and :ref:`RewriteStatepointsForGC` utility passes 
+which simplify ``gc.statepoint`` sequence insertion. If you need to build a 
+custom GC strategy around the ``gc.statepoints`` mechanisms, it is recommended
+that you use this one as a starting point.
+
+This GC strategy does not support read or write barriers.  As a result, these 
+intrinsics are lowered to normal loads and stores.
+
+The stack map format generated by this GC strategy can be found in the 
+:ref:`stackmap-section` using a format documented :ref:`here 
+<statepoint-stackmap-format>`. This format is intended to be the standard 
+format supported by LLVM going forward.
 
 
 Custom GC Strategies