adding missing header
HSAIL: fixed Windows build
simplification in FixedNodeProbabilityCache
use NodeClass.Position when matching graphs, rearrange MatchableNode annotations, improve error reporting
share position computations in MatchStatements
Added write barriers for LoweredAtomicReadAndWriteNode.
Merge.
added CollectionsProvider and NodeCollectionsProvider and replaced (almost) all allocations of IdentityHashMaps to go through these providers