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LibJS: Generate bytecode for do...while statements :^)

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This was quite straightforward using the same label/jump machinery that
we added for while statements.

The main addition here is a new JumpIfTrue bytecode instruction.
This commit is contained in:
Andreas Kling 2021-06-04 12:20:44 +02:00
parent bd1a5e282a
commit f2863b5a89
4 changed files with 45 additions and 0 deletions
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1
Userland/Libraries/LibJS/AST.h
View file

@ -391,6 +391,7 @@ public:
virtual Value execute(Interpreter&, GlobalObject&) const override;
virtual void dump(int indent) const override;
virtual Optional<Bytecode::Register> generate_bytecode(Bytecode::Generator&) const override;
private:
NonnullRefPtr<Expression> m_test;

10
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
View file

@ -105,4 +105,14 @@ Optional<Bytecode::Register> WhileStatement::generate_bytecode(Bytecode::Generat
return body_result_reg;
}
Optional<Bytecode::Register> DoWhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{
auto head_label = generator.make_label();
auto body_result_reg = m_body->generate_bytecode(generator);
auto test_result_reg = m_test->generate_bytecode(generator);
VERIFY(test_result_reg.has_value());
generator.emit<Bytecode::Op::JumpIfTrue>(*test_result_reg, head_label);
return body_result_reg;
}
}

15
Userland/Libraries/LibJS/Bytecode/Op.cpp
View file

@ -64,6 +64,14 @@ void JumpIfFalse::execute(Bytecode::Interpreter& interpreter) const
interpreter.jump(m_target.value());
}
void JumpIfTrue::execute(Bytecode::Interpreter& interpreter) const
{
VERIFY(m_target.has_value());
auto result = interpreter.reg(m_result);
if (result.as_bool())
interpreter.jump(m_target.value());
}
String Load::to_string() const
{
return String::formatted("Load dst:{}, value:{}", m_dst, m_value.to_string_without_side_effects());
@ -116,4 +124,11 @@ String JumpIfFalse::to_string() const
return String::formatted("JumpIfFalse result:{}, target:<empty>", m_result);
}
String JumpIfTrue::to_string() const
{
if (m_target.has_value())
return String::formatted("JumpIfTrue result:{}, target:{}", m_result, m_target.value());
return String::formatted("JumpIfTrue result:{}, target:<empty>", m_result);
}
}

19
Userland/Libraries/LibJS/Bytecode/Op.h
View file

@ -193,4 +193,23 @@ private:
Optional<Label> m_target;
};
class JumpIfTrue final : public Instruction {
public:
explicit JumpIfTrue(Register result, Optional<Label> target = {})
: m_result(result)
, m_target(move(target))
{
}
void set_target(Optional<Label> target) { m_target = move(target); }
virtual ~JumpIfTrue() override { }
virtual void execute(Bytecode::Interpreter&) const override;
virtual String to_string() const override;
private:
Register m_result;
Optional<Label> m_target;
};
}