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LibJS: Support for (x in obj) iteration in bytecode VM

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We were mistakenly treating these as `for (x of obj)`. By reorganizing
the code a little bit, we actually support both kinds of iteration with
less duplication. :^)

Fixes 17 tests in test262.
This commit is contained in:
Andreas Kling 2022-10-19 17:42:54 +02:00
parent 249350a7a3
commit 29935fe943
1 changed files with 34 additions and 53 deletions
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37
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -2077,6 +2077,7 @@ static Bytecode::CodeGenerationErrorOr<ForInOfHeadEvaluationResult> for_in_of_he
{
ForInOfHeadEvaluationResult result {};
bool entered_lexical_scope = false;
if (auto* ast_ptr = lhs.get_pointer<NonnullRefPtr<ASTNode>>(); ast_ptr && is<VariableDeclaration>(**ast_ptr)) {
// Runtime Semantics: ForInOfLoopEvaluation, for any of:
// ForInOfStatement : for ( var ForBinding in Expression ) Statement
@ -2092,7 +2093,7 @@ static Bytecode::CodeGenerationErrorOr<ForInOfHeadEvaluationResult> for_in_of_he
// NOTE: 'uninitializedBoundNames' refers to the lexical bindings (i.e. Const/Let) present in the second and last form.
// 2. If uninitializedBoundNames is not an empty List, then
bool entered_lexical_scope = false;
if (variable_declaration.declaration_kind() != DeclarationKind::Var) {
entered_lexical_scope = true;
// a. Assert: uninitializedBoundNames has no duplicate entries.
@ -2108,6 +2109,13 @@ static Bytecode::CodeGenerationErrorOr<ForInOfHeadEvaluationResult> for_in_of_he
// d. Set the running execution context's LexicalEnvironment to newEnv.
// NOTE: Done by CreateEnvironment.
}
} else {
// Runtime Semantics: ForInOfLoopEvaluation, for any of:
// ForInOfStatement : for ( LeftHandSideExpression in Expression ) Statement
// ForInOfStatement : for ( LeftHandSideExpression of AssignmentExpression ) Statement
result.lhs_kind = LHSKind::Assignment;
}
// 3. Let exprRef be the result of evaluating expr.
TRY(rhs->generate_bytecode(generator));
@ -2154,33 +2162,6 @@ static Bytecode::CodeGenerationErrorOr<ForInOfHeadEvaluationResult> for_in_of_he
// d. Return ? GetIterator(exprValue, iteratorHint).
generator.emit<Bytecode::Op::GetIterator>();
}
} else {
// Runtime Semantics: ForInOfLoopEvaluation, for any of:
// ForInOfStatement : for ( LeftHandSideExpression in Expression ) Statement
// ForInOfStatement : for ( LeftHandSideExpression of AssignmentExpression ) Statement
// Skip everything except steps 3, 5 and 7 (see above true branch for listing).
result.lhs_kind = LHSKind::Assignment;
// 3. Let exprRef be the result of evaluating expr.
TRY(rhs->generate_bytecode(generator));
// 5. Let exprValue be ? GetValue(exprRef).
// NOTE: No need to store this anywhere.
// a. Assert: iterationKind is iterate or async-iterate.
// b. If iterationKind is async-iterate, let iteratorHint be async.
if (iteration_kind == IterationKind::AsyncIterate) {
return Bytecode::CodeGenerationError {
rhs.ptr(),
"Unimplemented iteration mode: AsyncIterate"sv,
};
}
// c. Else, let iteratorHint be sync.
// d. Return ? GetIterator(exprValue, iteratorHint).
generator.emit<Bytecode::Op::GetIterator>();
}
return result;
}