perf(parser): register import / export statements in module record directly
#12807
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…d directly (#12807) Currently when parsing a list of statements in `parse_directives_and_statements`, we: 1. Check on every turn of the loop whether the statement is a `ModuleDeclaration`, and whether at top level. 2. If so, we call `ModuleRecordBuilder::visit_module_declaration`. 3. `visit_module_declaration` branches again on the type of the `ModuleDeclaration`. Instead, remove `ModuleRecordBuilder::visit_module_declaration` method, and instead call individual methods of `ModuleRecordBuilder` for each type of declaration directly, when parsing that particular declaration. This removes the need to check *every* statement in the loop in `parse_directives_and_statements` just in case it's a module declaration. Gives a small perf boost (+0.2%) on parser benchmarks. Might be a little bit more in real world, as this removes an unpredictable branch, which CodSpeed doesn't measure.
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…12808) We currently store the `default` keyword for `ExportDefaultDeclaration` as a `ModuleExportName`. This is overkill because the name is always, by definition, `default`. The only place the `Span` of `default` keyword is used is in `ModuleRecordBuilder`. So essentially storing the span in AST is using the AST as temporary storage - it's only put there so that `ModuleRecordBuilder` can pull it out again. After #12807, we can just pass the span direct to `ModuleRecordBuilder`, and so remove the need for it to be in the AST at all. So we can remove the whole field. This reduces size of `ExportDefaultDeclaration` from 80 bytes to 24. That has very limited impact, because each file can only have 1 `export default` statement. But still... less is more! It also removes erroneous code in both isolated declarations and transformer, which both just gave the keyword an empty span. I think the fact that everywhere that does use this field uses it wrongly is good justification for its removal! (alternative to #12803)
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…d directly (oxc-project#12807) Currently when parsing a list of statements in `parse_directives_and_statements`, we: 1. Check on every turn of the loop whether the statement is a `ModuleDeclaration`, and whether at top level. 2. If so, we call `ModuleRecordBuilder::visit_module_declaration`. 3. `visit_module_declaration` branches again on the type of the `ModuleDeclaration`. Instead, remove `ModuleRecordBuilder::visit_module_declaration` method, and instead call individual methods of `ModuleRecordBuilder` for each type of declaration directly, when parsing that particular declaration. This removes the need to check *every* statement in the loop in `parse_directives_and_statements` just in case it's a module declaration. Gives a small perf boost (+0.2%) on parser benchmarks. Might be a little bit more in real world, as this removes an unpredictable branch, which CodSpeed doesn't measure.
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…xc-project#12808) We currently store the `default` keyword for `ExportDefaultDeclaration` as a `ModuleExportName`. This is overkill because the name is always, by definition, `default`. The only place the `Span` of `default` keyword is used is in `ModuleRecordBuilder`. So essentially storing the span in AST is using the AST as temporary storage - it's only put there so that `ModuleRecordBuilder` can pull it out again. After oxc-project#12807, we can just pass the span direct to `ModuleRecordBuilder`, and so remove the need for it to be in the AST at all. So we can remove the whole field. This reduces size of `ExportDefaultDeclaration` from 80 bytes to 24. That has very limited impact, because each file can only have 1 `export default` statement. But still... less is more! It also removes erroneous code in both isolated declarations and transformer, which both just gave the keyword an empty span. I think the fact that everywhere that does use this field uses it wrongly is good justification for its removal! (alternative to oxc-project#12803)
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Currently when parsing a list of statements in
parse_directives_and_statements, we:ModuleDeclaration, and whether at top level.ModuleRecordBuilder::visit_module_declaration.visit_module_declarationbranches again on the type of theModuleDeclaration.Instead, remove
ModuleRecordBuilder::visit_module_declarationmethod, and instead call individual methods ofModuleRecordBuilderfor each type of declaration directly, when parsing that particular declaration.This removes the need to check every statement in the loop in
parse_directives_and_statementsjust in case it's a module declaration.Gives a small perf boost (+0.2%) on parser benchmarks. Might be a little bit more in real world, as this removes an unpredictable branch, which CodSpeed doesn't measure.