polish: skip creating extra reference for safely re-used node#10720
Merged
nicolo-ribaudo merged 2 commits intobabel:masterfrom Nov 16, 2019
Merged
polish: skip creating extra reference for safely re-used node#10720nicolo-ribaudo merged 2 commits intobabel:masterfrom
nicolo-ribaudo merged 2 commits intobabel:masterfrom
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| scope.push({ id: ref }); | ||
| let ref, assignment; | ||
| // skip creating extra reference when `left` is semantically safe to re-use | ||
| if (t.isIdentifier(node.left)) { |
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What about using isConstantExpression, or maybe better maybeGenerateMemoised?
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Good idea! I end up with maybeGenerateMemoised because it is rare that the left is a literal --even if it is, creating a reference other than inlining this literal should costs less bytes in most situations, given that we generate [_]+ as identifier name for literals.
JLHwung
commented
Nov 15, 2019
| ref = node.left; | ||
| assignment = t.cloneNode(node.left); | ||
| } else { | ||
| assignment = t.assignmentExpression("=", ref, node.left); |
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if ref is non-null, it is always cloned from node.left.
jridgewell
approved these changes
Nov 15, 2019
nicolo-ribaudo
approved these changes
Nov 15, 2019
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nicolo-ribaudo
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We need to figure out why CircleCI isn't running for your PRs
This was referenced Dec 12, 2019
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In this PR we skip creating extra reference when the
leftof??is a static reference, which is safely to reused when later unfolding into conditional comparison.Compared to the master branch, this PR generate less code for the common case
var bar = foo ?? "bar"Before:
After: