dart2js: compile metadata lazily in the lazy emitter.
In the lazy emitter evaluates the metadata lazily at first access.
Does this by keeping two arrays. The first one containing the unparsed expressions. The second one containing the evaluated expressions.
R=sra@google.com
Review URL: https://codereview.chromium.org//1137883002
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@45726 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/pkg/compiler/lib/src/js_emitter/new_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/new_emitter/emitter.dart
index 78e6886..aeeddc3 100644
--- a/pkg/compiler/lib/src/js_emitter/new_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/new_emitter/emitter.dart
@@ -171,9 +171,7 @@
return js.js.expressionTemplateFor("('$isPrefix' + #) in #.prototype");
case JsBuiltin.getMetadata:
- String metadataAccess =
- _emitter.generateEmbeddedGlobalAccessString(METADATA);
- return js.js.expressionTemplateFor("$metadataAccess[#]");
+ return _emitter.templateForReadMetadata;
case JsBuiltin.getType:
return _emitter.templateForReadType;
diff --git a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
index a61c38d..ebeb1df 100644
--- a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
@@ -452,18 +452,57 @@
return js.js.expressionTemplateFor('$readMetadataTypeName(#)');
}
+ static final String readMetadataName = "readLazyMetadata";
+ static final String lazyMetadataName = "lazy_$METADATA";
+
+ js.Statement get readMetadataFunction {
+ // Types are non-evaluated and must be compiled at first use.
+ // Compiled strings are guaranteed not to be strings, and it's thus safe
+ // to use a type-test to determine if a type has already been compiled.
+ return js.js.statement('''function $readMetadataName(index) {
+ var lazyMetadata = #lazyMetadataAccess[index];
+ if (typeof lazyMetadata == 'string') {
+ #metadataAccess[index] = expressionCompile(lazyMetadata);
+ #lazyMetadataAccess[index] = null;
+ }
+ return #metadataAccess[index];
+ }''', {
+ "lazyMetadataAccess": generateEmbeddedGlobalAccess(lazyMetadataName),
+ "metadataAccess": generateEmbeddedGlobalAccess(METADATA)
+ });
+ }
+
+ js.Template get templateForReadMetadata {
+ // TODO(floitsch): make sure that no local variable shadows the access to
+ // the readMetadata function.
+ return js.js.expressionTemplateFor('$readMetadataName(#)');
+ }
+
List<js.Property> emitMetadata(Program program) {
+ // Unparses all given js-expressions (suitable for `expressionCompile`) and
+ // returns the result in a js-array.
+ // If the given [expressions] is null returns the empty js-array.
+ js.ArrayInitializer unparseExpressions(List<js.Expression> expressions) {
+ if (expressions == null) expressions = <js.Expression>[];
+ List<js.LiteralString> unparsedExpressions = expressions
+ .map((expr) => unparse(compiler, expr, protectForEval: false))
+ .toList();
+ return new js.ArrayInitializer(unparsedExpressions);
+ }
+
List<js.Property> metadataGlobals = <js.Property>[];
- metadataGlobals.add(new js.Property(
- js.string(METADATA), new js.ArrayInitializer(program.metadata)));
+
+ js.ArrayInitializer unparsedMetadata = unparseExpressions(program.metadata);
+ metadataGlobals.add(new js.Property(js.string(lazyMetadataName),
+ unparsedMetadata));
+ metadataGlobals.add(new js.Property(js.string(METADATA),
+ new js.ArrayInitializer([])));
+
List<js.Expression> types =
program.metadataTypes[program.fragments.first.outputUnit];
- if (types == null) types = <js.Expression>[];
- List<js.LiteralString> unparsedTypes = types
- .map((type) => unparse(compiler, type, protectForEval: false))
- .toList();
- js.ArrayInitializer typesArray = new js.ArrayInitializer(unparsedTypes);
- metadataGlobals.add(new js.Property(js.string(TYPES), typesArray));
+ metadataGlobals.add(new js.Property(js.string(TYPES),
+ unparseExpressions(types)));
+
return metadataGlobals;
}
