Compiler: avoid creating Set in merge_if_vars #12433
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| then_var = then_vars[name]? | ||
| else_var = else_vars[name]? | ||
| next if then_var | ||
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| # Check whether the var didn't change at all | ||
| next if then_var.same?(else_var) | ||
| merge_if_var(name, node, cond_vars, then_var, else_var, before_then_vars, before_else_vars, then_unreachable, else_unreachable) |
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then_var must be nil after next. So I'm wondering if this tiny refactor might be a bit better? It just avoids fetching the actual then_var, because the value is not used.
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| then_var = then_vars[name]? | |
| else_var = else_vars[name]? | |
| next if then_var | |
| # Check whether the var didn't change at all | |
| next if then_var.same?(else_var) | |
| merge_if_var(name, node, cond_vars, then_var, else_var, before_then_vars, before_else_vars, then_unreachable, else_unreachable) | |
| next if then_vars.has_key?(name) | |
| merge_if_var(name, node, cond_vars, nil, else_var, before_then_vars, before_else_vars, then_unreachable, else_unreachable) |
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The diff looks very weird. I don't know why... Just ignore the first 5 deleted lines in the suggestion.
straight-shoota
approved these changes
Aug 31, 2022
asterite
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Sep 5, 2022
* Don't create `MetaVar` unless needed * Make check earlier to avoid extra Hash lookups * Even less extra Hash lookups * Compiler: avoid creating Set in merge_if_vars (#12433)
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Yes another optimization in
merge_if_vars. This one has a bit more impact: less memory allocated, and slightly better performance.When merging
ifvars we need to traverse all vars defined in thethenandelsebranches. We were doing this by creating a Set will all var names from both branches and then traversing that.However, it's more efficient if we first traverse the vars in
then. Then when traversing the vars inelsewe can skip that if we already traversed it in thethenbranch.