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LibJS/Bytecode: Rewrite Jump-to-Return-or-End as just Return or End
Instead of wasting time jumping to a shared Return or End instruction, we can also emit a Return or End directly in many cases.
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parent
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commit
044539c60b
Notes:
sideshowbarker
2024-07-17 04:34:25 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/044539c60b Pull-request: https://github.com/SerenityOS/serenity/pull/24524
@ -340,9 +340,10 @@ CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::compile(VM& vm, ASTNo
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while (!it.at_end()) {
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auto& instruction = const_cast<Instruction&>(*it);
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// OPTIMIZATION: Don't emit jumps that just jump to the next block.
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if (instruction.type() == Instruction::Type::Jump) {
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auto& jump = static_cast<Bytecode::Op::Jump&>(instruction);
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// OPTIMIZATION: Don't emit jumps that just jump to the next block.
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if (jump.target().basic_block_index() == block->index() + 1) {
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if (basic_block_start_offsets.last() == bytecode.size()) {
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// This block is empty, just skip it.
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@ -351,6 +352,29 @@ CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::compile(VM& vm, ASTNo
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++it;
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continue;
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}
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// OPTIMIZATION: For jumps to a return-or-end-only block, we can emit a `Return` or `End` directly instead.
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auto& target_block = *generator.m_root_basic_blocks[jump.target().basic_block_index()];
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if (target_block.is_terminated()) {
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auto target_instruction_iterator = InstructionStreamIterator { target_block.instruction_stream() };
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auto& target_instruction = *target_instruction_iterator;
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if (target_instruction.type() == Instruction::Type::Return) {
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auto& return_instruction = static_cast<Bytecode::Op::Return const&>(target_instruction);
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Op::Return return_op(return_instruction.value());
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bytecode.append(reinterpret_cast<u8 const*>(&return_op), return_op.length());
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++it;
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continue;
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}
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if (target_instruction.type() == Instruction::Type::End) {
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auto& return_instruction = static_cast<Bytecode::Op::End const&>(target_instruction);
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Op::End end_op(return_instruction.value());
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bytecode.append(reinterpret_cast<u8 const*>(&end_op), end_op.length());
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++it;
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continue;
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}
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}
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}
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// OPTIMIZATION: For `JumpIf` where one of the targets is the very next block,
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