[Harmony Wiki] Update of "Jitrino OPT/edge instrument" by Mikhail Fursov

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The following page has been changed by Mikhail Fursov:
http://wiki.apache.org/harmony/Jitrino_OPT/edge_instrument

New page:
''' 'edge_instrument' ''' - instruments HIR with extra instructions to collect edge profile information
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The optimization creates a map of counters and inserts counter increment instructions for every edge in Control Flow Graph. 
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The resulted map of counters is registered in [http://harmony.apache.org/subcomponents/drlvm/EM.html#PC edge profile collector].
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Once profile collector decides that method profile is ready it initiates method recompilation process.
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There are 2 ways of mapping of profile information to the methods IR:
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1) IR based profile mapping
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2) Bytecode based profile mapping
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To use IR based profile mapping compiler must ensure that the IR of the method is the same during instrumentation and [:Jitrino_OPT/edge_annotate: annotation] phases
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Bytecode based profile mapping is compiler independent. The 'key' for a counter is a 32-bit value composed from 16-bit offsets in bytecode: jump-offset and target-offset.