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https://github.com/RGBCube/serenity
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LibJS/JIT: Implement static exception handling
This commit is contained in:
Evgeniy Baskov
Andreas Kling
parent
1341f4438d
commit
da45bd3fde
2 changed files with 39 additions and 181 deletions
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@ -360,146 +360,41 @@ void Compiler::compile_decrement(Bytecode::Op::Decrement const&)
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void Compiler::check_exception()
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{
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// if (!exception.is_empty()) goto m_exception_handler;
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load_vm_register(GPR0, Bytecode::Register::exception());
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m_assembler.mov(Assembler::Operand::Register(GPR1), Assembler::Operand::Imm(Value().encoded()));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR0),
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Assembler::Condition::NotEqualTo,
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Assembler::Operand::Register(GPR1),
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m_exception_handler);
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}
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void Compiler::handle_exception()
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{
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// if (!unwind_context.valid) return;
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Assembler::Label handle_exception {};
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m_assembler.mov(
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Assembler::Operand::Register(GPR0),
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 0));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR0),
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Assembler::Condition::NotEqualTo,
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Assembler::Operand::Imm(0),
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handle_exception);
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jump_to_exit();
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// handle_exception:
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handle_exception.link(m_assembler);
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// if (unwind_context.handler) {
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Assembler::Label no_handler {};
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m_assembler.mov(
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Assembler::Operand::Register(GPR0),
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 8));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR0),
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Assembler::Condition::EqualTo,
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Assembler::Operand::Imm(0),
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no_handler);
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// accumulator = exception;
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load_vm_register(GPR1, Bytecode::Register::exception());
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store_vm_register(Bytecode::Register::accumulator(), GPR1);
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// exception = Value();
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m_assembler.mov(
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Assembler::Operand::Register(GPR1),
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Assembler::Operand::Imm(Value().encoded()));
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store_vm_register(Bytecode::Register::exception(), GPR1);
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// unwind_context.handler = nullptr;
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m_assembler.mov(
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Assembler::Operand::Register(GPR1),
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Assembler::Operand::Imm(0));
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m_assembler.mov(
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 8),
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Assembler::Operand::Register(GPR1));
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// goto handler;
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m_assembler.jump(Assembler::Operand::Register(GPR0));
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// }
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// no_handler:
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no_handler.link(m_assembler);
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// if (unwind_context.finalizer) goto finalizer;
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Assembler::Label no_finalizer {};
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m_assembler.mov(
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Assembler::Operand::Register(GPR0),
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 16));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR0),
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Assembler::Condition::EqualTo,
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Assembler::Operand::Imm(0),
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no_finalizer);
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m_assembler.jump(Assembler::Operand::Register(GPR0));
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// no_finalizer:
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// NOTE: No catch and no finally!? Crash.
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no_finalizer.link(m_assembler);
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m_assembler.verify_not_reached();
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}
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void Compiler::push_unwind_context(bool valid, Optional<Bytecode::Label> const& handler, Optional<Bytecode::Label> const& finalizer)
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{
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// Put this on the stack, and then point UNWIND_CONTEXT_BASE at it.
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// struct {
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// u64 valid;
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// u64 handler;
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// u64 finalizer;
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// };
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if (finalizer.has_value()) {
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// push finalizer (patched later)
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m_assembler.mov(
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if (auto const* handler = current_block().handler(); handler) {
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Assembler::Label no_exception;
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR0),
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Assembler::Operand::Imm(0),
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Assembler::Patchable::Yes);
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block_data_for(finalizer.value().block()).absolute_references_to_here.append(m_assembler.m_output.size() - 8);
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m_assembler.push(Assembler::Operand::Register(GPR0));
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Assembler::Condition::EqualTo,
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Assembler::Operand::Register(GPR1),
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no_exception);
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store_vm_register(Bytecode::Register::accumulator(), GPR0);
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store_vm_register(Bytecode::Register::exception(), GPR1);
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m_assembler.jump(label_for(*handler));
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no_exception.link(m_assembler);
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} else if (auto const* finalizer = current_block().finalizer(); finalizer) {
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m_assembler.jump_if(Assembler::Operand::Register(GPR0),
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Assembler::Condition::NotEqualTo,
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Assembler::Operand::Register(GPR1),
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label_for(*finalizer));
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} else {
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m_assembler.push(Assembler::Operand::Imm(0));
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m_assembler.jump_if(Assembler::Operand::Register(GPR0),
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Assembler::Condition::NotEqualTo,
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Assembler::Operand::Register(GPR1),
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m_exit_label);
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}
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if (handler.has_value()) {
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// push handler (patched later)
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m_assembler.mov(
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Assembler::Operand::Register(GPR0),
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Assembler::Operand::Imm(0),
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Assembler::Patchable::Yes);
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block_data_for(handler.value().block()).absolute_references_to_here.append(m_assembler.m_output.size() - 8);
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m_assembler.push(Assembler::Operand::Register(GPR0));
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} else {
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m_assembler.push(Assembler::Operand::Imm(0));
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}
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// push valid
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m_assembler.push(Assembler::Operand::Imm(valid));
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// UNWIND_CONTEXT_BASE = STACK_POINTER
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m_assembler.mov(
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Assembler::Operand::Register(UNWIND_CONTEXT_BASE),
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Assembler::Operand::Register(STACK_POINTER));
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// align stack pointer
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m_assembler.sub(Assembler::Operand::Register(STACK_POINTER), Assembler::Operand::Imm(8));
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}
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void Compiler::pop_unwind_context()
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{
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m_assembler.add(Assembler::Operand::Register(STACK_POINTER), Assembler::Operand::Imm(32));
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m_assembler.add(Assembler::Operand::Register(UNWIND_CONTEXT_BASE), Assembler::Operand::Imm(32));
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}
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void Compiler::compile_enter_unwind_context(Bytecode::Op::EnterUnwindContext const& op)
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{
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push_unwind_context(true, op.handler_target(), op.finalizer_target());
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m_assembler.jump(label_for(op.entry_point().block()));
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}
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void Compiler::compile_leave_unwind_context(Bytecode::Op::LeaveUnwindContext const&)
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{
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pop_unwind_context();
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/* Nothing */
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}
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void Compiler::compile_throw(Bytecode::Op::Throw const&)
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@ -668,35 +563,13 @@ void Compiler::compile_return(Bytecode::Op::Return const&)
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{
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load_vm_register(GPR0, Bytecode::Register::accumulator());
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// check for finalizer
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// if (!unwind_context.valid) goto normal_return;
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Assembler::Label normal_return {};
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m_assembler.mov(
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Assembler::Operand::Register(GPR1),
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 0));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR1),
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Assembler::Condition::EqualTo,
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Assembler::Operand::Imm(0),
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normal_return);
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// if (!unwind_context.finalizer) goto normal_return;
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m_assembler.mov(
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Assembler::Operand::Register(GPR1),
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Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 16));
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m_assembler.jump_if(
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Assembler::Operand::Register(GPR1),
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Assembler::Condition::EqualTo,
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Assembler::Operand::Imm(0),
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normal_return);
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store_vm_register(Bytecode::Register::saved_return_value(), GPR0);
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m_assembler.jump(Assembler::Operand::Register(GPR1));
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// normal_return:
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normal_return.link(m_assembler);
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store_vm_register(Bytecode::Register::return_value(), GPR0);
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jump_to_exit();
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if (auto const* finalizer = current_block().finalizer(); finalizer) {
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store_vm_register(Bytecode::Register::saved_return_value(), GPR0);
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m_assembler.jump(label_for(*finalizer));
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} else {
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store_vm_register(Bytecode::Register::return_value(), GPR0);
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jump_to_exit();
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}
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}
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static Value cxx_new_string(VM& vm, DeprecatedString const& string)
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@ -1800,10 +1673,9 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
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Assembler::Operand::Register(LOCALS_ARRAY_BASE),
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Assembler::Operand::Register(ARG2));
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compiler.push_unwind_context(false, {}, {});
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for (auto& block : bytecode_executable.basic_blocks) {
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compiler.block_data_for(*block).start_offset = compiler.m_output.size();
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compiler.set_current_block(*block);
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auto it = Bytecode::InstructionStreamIterator(block->instruction_stream());
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while (!it.at_end()) {
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auto const& op = *it;
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@ -1831,11 +1703,6 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
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compiler.m_exit_label.link(compiler.m_assembler);
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compiler.m_assembler.exit();
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if (!compiler.m_exception_handler.jump_slot_offsets_in_instruction_stream.is_empty()) {
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compiler.m_exception_handler.link(compiler.m_assembler);
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compiler.handle_exception();
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}
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auto* executable_memory = mmap(nullptr, compiler.m_output.size(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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if (executable_memory == MAP_FAILED) {
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dbgln("mmap: {}", strerror(errno));
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@ -1844,21 +1711,7 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
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for (auto& block : bytecode_executable.basic_blocks) {
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auto& block_data = compiler.block_data_for(*block);
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block_data.label.link_to(compiler.m_assembler, block_data.start_offset);
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// Patch up all the absolute references
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for (auto& absolute_reference : block_data.absolute_references_to_here) {
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auto offset = bit_cast<u64>(executable_memory) + block_data.start_offset;
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compiler.m_output[absolute_reference + 0] = (offset >> 0) & 0xff;
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compiler.m_output[absolute_reference + 1] = (offset >> 8) & 0xff;
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compiler.m_output[absolute_reference + 2] = (offset >> 16) & 0xff;
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compiler.m_output[absolute_reference + 3] = (offset >> 24) & 0xff;
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compiler.m_output[absolute_reference + 4] = (offset >> 32) & 0xff;
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compiler.m_output[absolute_reference + 5] = (offset >> 40) & 0xff;
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compiler.m_output[absolute_reference + 6] = (offset >> 48) & 0xff;
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compiler.m_output[absolute_reference + 7] = (offset >> 56) & 0xff;
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}
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}
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if constexpr (DUMP_JIT_MACHINE_CODE_TO_STDOUT) {
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