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LibJS: Implement bytecode generation for switch

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This commit is contained in:
Marcin Gasperowicz 2021-06-11 00:36:16 +02:00 • committed by Andreas Kling
parent fbb54efd28
commit a64089092f
2 changed files with 59 additions and 0 deletions
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1
Userland/Libraries/LibJS/AST.h
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@ -1309,6 +1309,7 @@ public:
virtual void dump(int indent) const override; virtual void dump(int indent) const override;
virtual Value execute(Interpreter&, GlobalObject&) const override; virtual Value execute(Interpreter&, GlobalObject&) const override;
virtual void generate_bytecode(Bytecode::Generator&) const override;
private: private:
NonnullRefPtr<Expression> m_discriminant; NonnullRefPtr<Expression> m_discriminant;

58
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -2,10 +2,12 @@
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org> * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Linus Groh <linusg@serenityos.org> * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org> * Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
* Copyright (c) 2021, Marcin Gasperowicz <xnooga@gmail.com>
* *
* SPDX-License-Identifier: BSD-2-Clause * SPDX-License-Identifier: BSD-2-Clause
*/ */
#include <AK/Format.h>
#include <LibJS/AST.h> #include <LibJS/AST.h>
#include <LibJS/Bytecode/Generator.h> #include <LibJS/Bytecode/Generator.h>
#include <LibJS/Bytecode/Instruction.h> #include <LibJS/Bytecode/Instruction.h>
@ -968,4 +970,60 @@ void TryStatement::generate_bytecode(Bytecode::Generator& generator) const
generator.switch_to_basic_block(next_block ? *next_block : saved_block); generator.switch_to_basic_block(next_block ? *next_block : saved_block);
} }
void SwitchStatement::generate_bytecode(Bytecode::Generator& generator) const
{
auto discriminant_reg = generator.allocate_register();
m_discriminant->generate_bytecode(generator);
generator.emit<Bytecode::Op::Store>(discriminant_reg);
Vector<Bytecode::BasicBlock&> case_blocks;
Bytecode::BasicBlock* default_block { nullptr };
Bytecode::BasicBlock* next_test_block = &generator.make_block();
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *next_test_block }, {});
for (auto& switch_case : m_cases) {
auto& case_block = generator.make_block();
if (switch_case.test()) {
generator.switch_to_basic_block(*next_test_block);
switch_case.test()->generate_bytecode(generator);
generator.emit<Bytecode::Op::TypedEquals>(discriminant_reg);
next_test_block = &generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(Bytecode::Label { case_block }, Bytecode::Label { *next_test_block });
} else {
default_block = &case_block;
}
case_blocks.append(case_block);
}
generator.switch_to_basic_block(*next_test_block);
auto& end_block = generator.make_block();
if (default_block != nullptr) {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *default_block }, {});
} else {
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { end_block }, {});
}
auto current_block = case_blocks.begin();
generator.begin_breakable_scope(Bytecode::Label { end_block });
for (auto& switch_case : m_cases) {
generator.switch_to_basic_block(*current_block);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
for (auto& statement : switch_case.consequent()) {
statement.generate_bytecode(generator);
}
if (!generator.is_current_block_terminated()) {
auto next_block = current_block;
next_block++;
if (next_block.is_end()) {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { end_block }, {});
} else {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *next_block }, {});
}
}
current_block++;
}
generator.end_breakable_scope();
generator.switch_to_basic_block(end_block);
}
} }