manupa-arm commented on a change in pull request #5143: [RELAY] Re-wrote the
Graph Partitioner to support multiple outputs
URL: https://github.com/apache/incubator-tvm/pull/5143#discussion_r398522710
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File path: src/relay/transforms/partition_graph.cc
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@@ -102,61 +89,71 @@ class AnnotationChecker : public ExprVisitor {
bool found_end_{false};
};
-/*! \brief This class partitions the expr labeled with begin and end annoations
+/*! \brief This class partitions the expr labeled with begin and end
annotations
* into function containing multiple regions. Each region is labeled with
* a compiler attribute so that it will be handled by any compilers that are
not
* in the TVM stack.
*
- * TODO(@zhiics) This following algorithm is not adequate to handle all cases,
- * i.e. multiple `compiler_end` nodes.
+ * Input : A Relay module that have functions with disjoint annotated regions
+ * using compiler_begin and compiler_end. There could be multiple
outputs.
+ *
+ * Output : A Relay module with global functions for such disjoint annotated
regions
+ * with calls inserted at the respective location
+ *
+ * Dependencies : RegionSet Utility class.
+ *
+ * Methodology :
+ * 1) The RegionSet utility class is able to construct a collection of
+ * nodes that are bound by a given annotation -- here we use
compiler_begin
+ * and compiler_end
+ * 2) Initially, for each function in the module RegionSets are populated.
+ * 3) Then, Vistor pass is traversed until a compiler_end node is
encountered
+ * that belongs to a "region".
+ * 4) When the first compiler_end of a given annotated region is found, a
function is
+ * formed and inserted.
+ * a) if the region has multiple outputs, a Tuple node (capturing all
outputs)
+ * is returned.
+ * 5) Thereafter, if we encounter an another output of the same annotated
region,
+ * it is important to note that the function is already formed.
Therefore, it will
+ * lookup the function and add a TupleGetItemNode.
+ * a) We will use the location index of "rets" of each "Region" of
RegionSet
+ * as TupleGetItemNode index.
+ * 6) Therefore, functions will be created for all annotated regions. The
name for each
+ * global function is created using "Region" id and the compiler name.
+ *
+ * Expected Usecase :
+ * This pass is intended to run as the last pass in a series of passes as
follows :
+ * 1) Annotate Supported Single Ops - annotated each single op with
supported backends.
Review comment:
Removed the use-case segment. This is not needed now; as things are still in
discussion as how this pass would potentially fit in the bigger picture.
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