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Diffstat (limited to 'src/main/scala/firrtl/analyses/InstanceGraph.scala')
| -rw-r--r-- | src/main/scala/firrtl/analyses/InstanceGraph.scala | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/main/scala/firrtl/analyses/InstanceGraph.scala b/src/main/scala/firrtl/analyses/InstanceGraph.scala index 7b60b110..ddd5eb8b 100644 --- a/src/main/scala/firrtl/analyses/InstanceGraph.scala +++ b/src/main/scala/firrtl/analyses/InstanceGraph.scala @@ -15,6 +15,15 @@ import firrtl.annotations.TargetToken._ * * @constructor constructs an instance graph from a Circuit * @param c the Circuit to analyze + * @note The current implementation has some performance problems, which is why [[InstanceKeyGraph]] + * exists and should be preferred for new use cases. Eventually the old class will be deprecated + * in favor of the new implementation. + * The performance problems in the old implementation stem from the fact that DefInstance is used as the + * key to the underlying Map. DefInstance contains the type of the module besides the module and instance names. + * This type is not needed as it can be inferred from the module name. If the module name is the same, + * the type will be the same and vice versa. + * Hashing and comparing deep bundle types however is inefficient which can manifest in slower then necessary + * lookups and insertions. */ class InstanceGraph(c: Circuit) { |