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https://github.com/LadybirdBrowser/ladybird.git
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LibJS/Bytecode: Don't bother propagating completion values in functions
The last completion value in a function is not exposed to the language, since functions always either return something, or undefined. Given this, we can avoid emitting code that propagates the completion value from various statements, as long as we know we're generating code for a context where the completion value is not accessible. In practical terms, this means that function code gets to do less completion shuffling, while global and eval code has to keep doing it.
This commit is contained in:
Andreas Kling
parent
6c5e09557d
commit
9265385807
Notes:
sideshowbarker
2024-07-17 06:51:48 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/9265385807 Pull-request: https://github.com/SerenityOS/serenity/pull/24324
@ -800,8 +800,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> WhileStatement::generat
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auto& body_block = generator.make_block();
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auto& end_block = generator.make_block();
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auto result = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(result, generator.add_constant(js_undefined()));
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Optional<ScopedOperand> completion;
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if (generator.must_propagate_completion()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { test_block });
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@ -820,13 +823,15 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> WhileStatement::generat
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generator.end_continuable_scope();
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if (!generator.is_current_block_terminated()) {
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if (body.has_value())
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generator.emit<Bytecode::Op::Mov>(result, body.value());
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if (generator.must_propagate_completion()) {
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if (body.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, body.value());
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { test_block });
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}
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generator.switch_to_basic_block(end_block);
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return result;
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> DoWhileStatement::generate_bytecode(Bytecode::Generator& generator, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -849,8 +854,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> DoWhileStatement::gener
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auto& load_result_and_jump_to_end_block = generator.make_block();
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auto& end_block = generator.make_block();
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auto completion_value = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(completion_value, generator.add_constant(js_undefined()));
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Optional<ScopedOperand> completion;
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if (generator.must_propagate_completion()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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// jump to the body block
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { body_block });
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@ -870,8 +878,10 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> DoWhileStatement::gener
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generator.end_continuable_scope();
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if (!generator.is_current_block_terminated()) {
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if (body_result.has_value())
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generator.emit<Bytecode::Op::Mov>(completion_value, body_result.value());
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if (generator.must_propagate_completion()) {
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if (body_result.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, body_result.value());
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { test_block });
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}
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@ -879,7 +889,7 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> DoWhileStatement::gener
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { end_block });
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generator.switch_to_basic_block(end_block);
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return completion_value;
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> ForStatement::generate_bytecode(Bytecode::Generator& generator, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -2246,8 +2256,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> IfStatement::generate_b
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auto& false_block = generator.make_block();
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auto& end_block = generator.make_block();
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auto dst = choose_dst(generator, preferred_dst);
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generator.emit<Bytecode::Op::Mov>(dst, generator.add_constant(js_undefined()));
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Optional<ScopedOperand> completion;
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if (generator.must_propagate_completion()) {
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completion = choose_dst(generator, preferred_dst);
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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auto predicate = TRY(m_predicate->generate_bytecode(generator)).value();
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generator.emit_jump_if(
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@ -2256,10 +2269,12 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> IfStatement::generate_b
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Bytecode::Label { false_block });
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generator.switch_to_basic_block(true_block);
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auto consequent = TRY(m_consequent->generate_bytecode(generator, dst));
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auto consequent = TRY(m_consequent->generate_bytecode(generator, completion));
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if (!generator.is_current_block_terminated()) {
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if (consequent.has_value())
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generator.emit<Bytecode::Op::Mov>(dst, *consequent);
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if (generator.must_propagate_completion()) {
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if (consequent.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, *consequent);
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { end_block });
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}
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@ -2267,17 +2282,19 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> IfStatement::generate_b
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Optional<ScopedOperand> alternate;
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if (m_alternate) {
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alternate = TRY(m_alternate->generate_bytecode(generator, dst));
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alternate = TRY(m_alternate->generate_bytecode(generator, completion));
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}
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if (!generator.is_current_block_terminated()) {
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if (alternate.has_value())
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generator.emit<Bytecode::Op::Mov>(dst, *alternate);
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if (generator.must_propagate_completion()) {
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if (alternate.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, *alternate);
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { end_block });
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}
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generator.switch_to_basic_block(end_block);
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return dst;
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> ContinueStatement::generate_bytecode(Bytecode::Generator& generator, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -2508,7 +2525,7 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> TryStatement::generate_
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Bytecode::BasicBlock* next_block { nullptr };
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Optional<ScopedOperand> dst;
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Optional<ScopedOperand> completion;
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if (m_finalizer) {
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// FIXME: See notes in Op.h->ScheduleJump
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@ -2564,9 +2581,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> TryStatement::generate_
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}));
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auto handler_result = TRY(m_handler->body().generate_bytecode(generator));
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if (handler_result.has_value() && !generator.is_current_block_terminated()) {
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dst = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*dst, *handler_result);
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if (generator.must_propagate_completion()) {
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if (handler_result.has_value() && !generator.is_current_block_terminated()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, *handler_result);
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}
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}
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handler_target = Bytecode::Label { handler_block };
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@ -2608,9 +2627,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> TryStatement::generate_
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generator.switch_to_basic_block(target_block);
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auto block_result = TRY(m_block->generate_bytecode(generator));
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if (!generator.is_current_block_terminated()) {
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if (block_result.has_value()) {
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dst = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*dst, *block_result);
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if (generator.must_propagate_completion()) {
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if (block_result.has_value()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, *block_result);
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}
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}
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if (m_finalizer) {
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@ -2630,9 +2651,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> TryStatement::generate_
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generator.end_boundary(Bytecode::Generator::BlockBoundaryType::Unwind);
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generator.switch_to_basic_block(next_block ? *next_block : saved_block);
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if (!dst.has_value())
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return generator.add_constant(js_undefined());
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return dst;
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if (generator.must_propagate_completion()) {
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if (!completion.has_value())
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return generator.add_constant(js_undefined());
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}
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> SwitchStatement::generate_bytecode(Bytecode::Generator& generator, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -2645,8 +2668,11 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> SwitchStatement::genera
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{
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Bytecode::Generator::SourceLocationScope scope(generator, *this);
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auto dst = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(dst, generator.add_constant(js_undefined()));
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Optional<ScopedOperand> completion;
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if (generator.must_propagate_completion()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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auto discriminant = TRY(m_discriminant->generate_bytecode(generator)).value();
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Vector<Bytecode::BasicBlock&> case_blocks;
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@ -2699,10 +2725,12 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> SwitchStatement::genera
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auto result = TRY(statement->generate_bytecode(generator));
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if (generator.is_current_block_terminated())
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break;
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if (result.has_value())
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generator.emit<Bytecode::Op::Mov>(dst, *result);
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else
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generator.emit<Bytecode::Op::Mov>(dst, generator.add_constant(js_undefined()));
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if (generator.must_propagate_completion()) {
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if (result.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, *result);
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else
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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}
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if (!generator.is_current_block_terminated()) {
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auto next_block = current_block;
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@ -2722,7 +2750,7 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> SwitchStatement::genera
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if (did_create_lexical_environment)
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generator.end_variable_scope();
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return dst;
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> SuperExpression::generate_bytecode(Bytecode::Generator&, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -3026,8 +3054,11 @@ static Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> for_in_of_body_e
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bool has_lexical_binding = false;
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// 3. Let V be undefined.
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auto completion_value = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(completion_value, generator.add_constant(js_undefined()));
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Optional<ScopedOperand> completion;
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if (generator.must_propagate_completion()) {
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completion = generator.allocate_register();
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generator.emit<Bytecode::Op::Mov>(*completion, generator.add_constant(js_undefined()));
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}
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// 4. Let destructuring be IsDestructuring of lhs.
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auto destructuring = head_result.is_destructuring;
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@ -3229,14 +3260,16 @@ static Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> for_in_of_body_e
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// The body can contain an unconditional block terminator (e.g. return, throw), so we have to check for that before generating the Jump.
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if (!generator.is_current_block_terminated()) {
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if (result.has_value())
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generator.emit<Bytecode::Op::Mov>(completion_value, *result);
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if (generator.must_propagate_completion()) {
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if (result.has_value())
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generator.emit<Bytecode::Op::Mov>(*completion, *result);
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}
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generator.emit<Bytecode::Op::Jump>(Bytecode::Label { loop_update });
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}
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generator.switch_to_basic_block(loop_end);
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return completion_value;
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return completion;
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}
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Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> ForInStatement::generate_bytecode(Bytecode::Generator& generator, [[maybe_unused]] Optional<ScopedOperand> preferred_dst) const
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@ -17,13 +17,14 @@
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namespace JS::Bytecode {
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Generator::Generator(VM& vm)
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Generator::Generator(VM& vm, MustPropagateCompletion must_propagate_completion)
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: m_vm(vm)
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, m_string_table(make<StringTable>())
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, m_identifier_table(make<IdentifierTable>())
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, m_regex_table(make<RegexTable>())
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, m_constants(vm.heap())
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, m_accumulator(*this, Operand(Register::accumulator()))
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, m_must_propagate_completion(must_propagate_completion == MustPropagateCompletion::Yes)
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{
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}
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@ -190,9 +191,9 @@ CodeGenerationErrorOr<void> Generator::emit_function_declaration_instantiation(E
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return {};
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}
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CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::emit_function_body_bytecode(VM& vm, ASTNode const& node, FunctionKind enclosing_function_kind, GCPtr<ECMAScriptFunctionObject const> function)
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CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::emit_function_body_bytecode(VM& vm, ASTNode const& node, FunctionKind enclosing_function_kind, GCPtr<ECMAScriptFunctionObject const> function, MustPropagateCompletion must_propagate_completion)
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{
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Generator generator(vm);
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Generator generator(vm, must_propagate_completion);
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generator.switch_to_basic_block(generator.make_block());
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SourceLocationScope scope(generator, node);
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@ -429,7 +430,7 @@ CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::generate_from_ast_nod
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CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::generate_from_function(VM& vm, ECMAScriptFunctionObject const& function)
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{
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return emit_function_body_bytecode(vm, function.ecmascript_code(), function.kind(), &function);
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return emit_function_body_bytecode(vm, function.ecmascript_code(), function.kind(), &function, MustPropagateCompletion::No);
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}
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void Generator::grow(size_t additional_size)
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@ -33,6 +33,11 @@ public:
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Block,
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};
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enum class MustPropagateCompletion {
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No,
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Yes,
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};
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static CodeGenerationErrorOr<NonnullGCPtr<Executable>> generate_from_ast_node(VM&, ASTNode const&, FunctionKind = FunctionKind::Normal);
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static CodeGenerationErrorOr<NonnullGCPtr<Executable>> generate_from_function(VM&, ECMAScriptFunctionObject const& function);
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@ -302,10 +307,12 @@ public:
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[[nodiscard]] bool is_finished() const { return m_finished; }
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[[nodiscard]] bool must_propagate_completion() const { return m_must_propagate_completion; }
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private:
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VM& m_vm;
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static CodeGenerationErrorOr<NonnullGCPtr<Executable>> emit_function_body_bytecode(VM&, ASTNode const&, FunctionKind, GCPtr<ECMAScriptFunctionObject const>);
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static CodeGenerationErrorOr<NonnullGCPtr<Executable>> emit_function_body_bytecode(VM&, ASTNode const&, FunctionKind, GCPtr<ECMAScriptFunctionObject const>, MustPropagateCompletion = MustPropagateCompletion::Yes);
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enum class JumpType {
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Continue,
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@ -314,7 +321,7 @@ private:
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void generate_scoped_jump(JumpType);
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void generate_labelled_jump(JumpType, DeprecatedFlyString const& label);
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explicit Generator(VM&);
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Generator(VM&, MustPropagateCompletion);
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~Generator() = default;
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void grow(size_t);
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@ -353,6 +360,7 @@ private:
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HashTable<u32> m_initialized_locals;
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bool m_finished { false };
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bool m_must_propagate_completion { true };
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};
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}
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