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https://issues.apache.org/jira/browse/SYSTEMML-1935?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias Boehm closed SYSTEMML-1935.
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Resolution: Done
Assignee: Matthias Boehm
Fix Version/s: SystemML 1.0
> Improve rewrite for merging statement blocks
> --------------------------------------------
>
> Key: SYSTEMML-1935
> URL: https://issues.apache.org/jira/browse/SYSTEMML-1935
> Project: SystemML
> Issue Type: Task
> Reporter: Matthias Boehm
> Assignee: Matthias Boehm
> Fix For: SystemML 1.0
>
>
> There are two shortcomings of the (recently introduced) rewrite on merging
> statement block sequences.
> * Order of statement block rewrites: Currently, we apply HOP DAG rewrites and
> statement block rewrites recursively over the entire program. For statement
> block rewrites, we first apply sequence rewrites and then individual block
> rewrites. However, this misses opportunities when an individual block rewrite
> such as branch-removal expands for example an if to a sequence of blocks.
> * Missing dead code elimination: When merging statement blocks, we connect
> transient writes and transient reads and add roots if they are not existing
> transient writes. However, we should explicitly check the live out set in
> order to eliminate dead code that does not need to be computed (e.g.,
> originating from branch-removal and sequence merge)
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