From 0768bf26230e3637ac045f3cf6b929cbfa3deed1 Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Sat, 28 Oct 2023 17:37:59 +0300
Subject: [PATCH] LibJS: Execute the finalizer when returning from a try block
 in the JIT

This fixes 1 of the 2 remaining failing test-js tests.
---
 Userland/Libraries/LibJS/JIT/Compiler.cpp | 44 +++++++++++++++++++++++
 Userland/Libraries/LibJS/JIT/Compiler.h   |  1 +
 2 files changed, 45 insertions(+)

diff --git a/Userland/Libraries/LibJS/JIT/Compiler.cpp b/Userland/Libraries/LibJS/JIT/Compiler.cpp
index a844e98e9f..3dcfcabbe6 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.cpp
+++ b/Userland/Libraries/LibJS/JIT/Compiler.cpp
@@ -566,6 +566,32 @@ JS_ENUMERATE_COMMON_UNARY_OPS(DO_COMPILE_COMMON_UNARY_OP)
 void Compiler::compile_return(Bytecode::Op::Return const&)
 {
     load_vm_register(GPR0, Bytecode::Register::accumulator());
+
+    // check for finalizer
+    // if (!unwind_context.valid) goto normal_return;
+    auto normal_return = m_assembler.make_label();
+    m_assembler.mov(
+        Assembler::Operand::Register(GPR1),
+        Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 0));
+    m_assembler.jump_if_equal(
+        Assembler::Operand::Register(GPR1),
+        Assembler::Operand::Imm(0),
+        normal_return);
+
+    // if (!unwind_context.finalizer) goto normal_return;
+    m_assembler.mov(
+        Assembler::Operand::Register(GPR1),
+        Assembler::Operand::Mem64BaseAndOffset(UNWIND_CONTEXT_BASE, 16));
+    m_assembler.jump_if_equal(
+        Assembler::Operand::Register(GPR1),
+        Assembler::Operand::Imm(0),
+        normal_return);
+
+    store_vm_register(Bytecode::Register::saved_return_value(), GPR0);
+    m_assembler.jump(Assembler::Operand::Register(GPR1));
+
+    // normal_return:
+    normal_return.link(m_assembler);
     store_vm_register(Bytecode::Register::return_value(), GPR0);
     m_assembler.exit();
 }
@@ -933,6 +959,21 @@ void Compiler::compile_set_variable(Bytecode::Op::SetVariable const& op)
     check_exception();
 }
 
+void Compiler::compile_continue_pending_unwind(Bytecode::Op::ContinuePendingUnwind const& op)
+{
+    // re-throw the exception if we reached the end of the finally block and there was no catch block to handle it
+    check_exception();
+
+    // if (!saved_return_value.is_empty()) goto resume_block;
+    load_vm_register(GPR0, Bytecode::Register::saved_return_value());
+    m_assembler.mov(Assembler::Operand::Register(GPR1), Assembler::Operand::Imm(Value().encoded()));
+    m_assembler.jump_if_not_equal(Assembler::Operand::Register(GPR0), Assembler::Operand::Register(GPR1), label_for(op.resume_target().block()));
+
+    // finish the pending return from the try block
+    store_vm_register(Bytecode::Register::return_value(), GPR0);
+    m_assembler.exit();
+}
+
 static void cxx_create_lexical_environment(VM& vm)
 {
     auto make_and_swap_envs = [&](auto& old_environment) {
@@ -1088,6 +1129,9 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
             case Bytecode::Instruction::Type::LessThan:
                 compiler.compile_less_than(static_cast<Bytecode::Op::LessThan const&>(op));
                 break;
+            case Bytecode::Instruction::Type::ContinuePendingUnwind:
+                compiler.compile_continue_pending_unwind(static_cast<Bytecode::Op::ContinuePendingUnwind const&>(op));
+                break;
 
 #    define DO_COMPILE_COMMON_BINARY_OP(TitleCaseName, snake_case_name)                          \
     case Bytecode::Instruction::Type::TitleCaseName:                                             \
diff --git a/Userland/Libraries/LibJS/JIT/Compiler.h b/Userland/Libraries/LibJS/JIT/Compiler.h
index 64935812d8..168282ae0e 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.h
+++ b/Userland/Libraries/LibJS/JIT/Compiler.h
@@ -112,6 +112,7 @@ private:
     void compile_call(Bytecode::Op::Call const&);
     void compile_typeof_variable(Bytecode::Op::TypeofVariable const&);
     void compile_set_variable(Bytecode::Op::SetVariable const&);
+    void compile_continue_pending_unwind(Bytecode::Op::ContinuePendingUnwind const&);
 
     void store_vm_register(Bytecode::Register, Assembler::Reg);
     void load_vm_register(Assembler::Reg, Bytecode::Register);