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perf: optimize imports that are not mutated or reassigned #8948

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Merged
dummdidumm merged 6 commits into from
Jul 18, 2023
Merged

perf: optimize imports that are not mutated or reassigned #8948

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dc78491
perf: don't count primitive const values as dependencies
benmccann Jul 10, 2023
d703dca
merge master
benmccann Jul 10, 2023
a0393b2
don't need to check if value is object as it won't be literal
benmccann Jul 10, 2023
73586aa
look at whether the variable was mutated or reassigned instead
benmccann Jul 10, 2023
e55c891
Merge branch 'master' into const
benmccann Jul 16, 2023
2d18307
changeset
benmccann Jul 18, 2023
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15 changes: 13 additions & 2 deletions packages/svelte/src/compiler/compile/Component.js
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Original file line number Diff line number Diff line change
Expand Up @@ -772,12 +772,23 @@ export default class Component {
}
const writable =
node.type === 'VariableDeclaration' && (node.kind === 'var' || node.kind === 'let');
const imported = node.type.startsWith('Import');

let immutable = false;
if (node.type === 'VariableDeclaration' && node.kind === 'const') {
immutable = true;
for (const declaration of node.declarations) {
if (declaration.init.type !== 'Literal' || typeof declaration.init.value === 'object') {
immutable = false;
}
}
}

this.add_var(node, {
name,
initialised: instance_scope.initialised_declarations.has(name),
imported: node.type.startsWith('Import'),
writable,
imported
immutable
});
this.node_for_declaration.set(name, node);
});
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2 changes: 1 addition & 1 deletion packages/svelte/src/compiler/compile/internal_exports.js
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7 changes: 5 additions & 2 deletions packages/svelte/src/compiler/compile/nodes/shared/Expression.js
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,8 @@ export default class Expression {

/** @type {Array<import('estree').Node | import('estree').Node[]>} */
declarations = [];
/** */

/** @type {boolean} */
uses_context = false;

/** @type {import('estree').Node} */
Expand Down Expand Up @@ -128,7 +129,7 @@ export default class Expression {
.forEach((name) => dependencies.add(name));
}
} else {
if (!lazy) {
if (!lazy && !component.var_lookup.get(name)?.immutable) {
dependencies.add(name);
}
component.add_reference(node, name);
Expand Down Expand Up @@ -231,6 +232,8 @@ export default class Expression {
if (this.manipulated) return this.manipulated;
const { component, declarations, scope_map: map, template_scope, owner } = this;
let scope = this.scope;

/** @type {import('estree').FunctionExpression | import('estree').ArrowFunctionExpression | null} */
let function_expression;

/** @type {Set<string>} */
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1 change: 1 addition & 0 deletions packages/svelte/src/compiler/interfaces.d.ts
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Expand Up @@ -383,6 +383,7 @@ export interface Var {
writable?: boolean;

// used internally, but not exposed
immutable?: boolean;
global?: boolean;
internal?: boolean; // event handlers, bindings
initialised?: boolean;
Expand Down