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LibJS: Make sure loop results are initialized

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This ensures that "while", do...while, "for" expressions have a
properly initialized result value even if the user terminated
the loop body via break or the loop body wasn't executed at all.
This commit is contained in:
Gunnar Beutner 2021-06-08 22:17:00 +02:00 • committed by Linus Groh
parent 624ceec04f
commit 5ff85abe8c
1 changed files with 12 additions and 0 deletions
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12
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -279,24 +279,32 @@ void AssignmentExpression::generate_bytecode(Bytecode::Generator& generator) con
void WhileStatement::generate_bytecode(Bytecode::Generator& generator) const void WhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{ {
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.begin_continuable_scope(); generator.begin_continuable_scope();
auto test_label = generator.make_label(); auto test_label = generator.make_label();
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
m_test->generate_bytecode(generator); m_test->generate_bytecode(generator);
auto& test_jump = generator.emit<Bytecode::Op::JumpIfFalse>(); auto& test_jump = generator.emit<Bytecode::Op::JumpIfFalse>();
m_body->generate_bytecode(generator); m_body->generate_bytecode(generator);
generator.emit<Bytecode::Op::Jump>(test_label); generator.emit<Bytecode::Op::Jump>(test_label);
test_jump.set_target(generator.make_label()); test_jump.set_target(generator.make_label());
generator.end_continuable_scope(); generator.end_continuable_scope();
generator.emit<Bytecode::Op::Load>(result_reg);
} }
void DoWhileStatement::generate_bytecode(Bytecode::Generator& generator) const void DoWhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{ {
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.begin_continuable_scope(); generator.begin_continuable_scope();
auto head_label = generator.make_label(); auto head_label = generator.make_label();
m_body->generate_bytecode(generator); m_body->generate_bytecode(generator);
generator.end_continuable_scope(); generator.end_continuable_scope();
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
m_test->generate_bytecode(generator); m_test->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpIfTrue>(head_label); generator.emit<Bytecode::Op::JumpIfTrue>(head_label);
generator.emit<Bytecode::Op::Load>(result_reg);
} }
void ForStatement::generate_bytecode(Bytecode::Generator& generator) const void ForStatement::generate_bytecode(Bytecode::Generator& generator) const
@ -306,8 +314,11 @@ void ForStatement::generate_bytecode(Bytecode::Generator& generator) const
if (m_init) if (m_init)
m_init->generate_bytecode(generator); m_init->generate_bytecode(generator);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.begin_continuable_scope(); generator.begin_continuable_scope();
auto jump_label = generator.make_label(); auto jump_label = generator.make_label();
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
if (m_test) { if (m_test) {
m_test->generate_bytecode(generator); m_test->generate_bytecode(generator);
test_jump = &generator.emit<Bytecode::Op::JumpIfFalse>(); test_jump = &generator.emit<Bytecode::Op::JumpIfFalse>();
@ -320,6 +331,7 @@ void ForStatement::generate_bytecode(Bytecode::Generator& generator) const
if (m_test) if (m_test)
test_jump->set_target(generator.make_label()); test_jump->set_target(generator.make_label());
generator.end_continuable_scope(); generator.end_continuable_scope();
generator.emit<Bytecode::Op::Load>(result_reg);
} }
void ObjectExpression::generate_bytecode(Bytecode::Generator& generator) const void ObjectExpression::generate_bytecode(Bytecode::Generator& generator) const