LibJS: Work-in-progress JIT compiler :^)

Userland/Libraries/LibJS/Bytecode/BasicBlock.h

@@ -43,6 +43,16 @@ public:
 
     DeprecatedString const& name() const { return m_name; }
 
+    // ==============================================================
+    // FIXME: This is JIT state and shouldn't be part of BasicBlock itself.
+
+    // Offset into the instruction stream where this code block starts.
+    size_t offset { 0 };
+
+    // Offsets into the instruction stream where we have RIP-relative jump offsets to here that need patching.
+    Vector<size_t> jumps_to_here;
+    // ==============================================================
+
 private:
     explicit BasicBlock(DeprecatedString name);
 

Userland/Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -13,6 +13,7 @@
 #include <LibJS/Bytecode/Instruction.h>
 #include <LibJS/Bytecode/Interpreter.h>
 #include <LibJS/Bytecode/Op.h>
+#include <LibJS/JIT/Compiler.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/BigInt.h>
@@ -349,7 +350,16 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable& executa
     else
         push_call_frame(make<CallFrame>(), executable.number_of_registers);
 
-    run_bytecode();
+    if (auto native_executable = JIT::Compiler::compile(executable)) {
+        native_executable->run(vm());
+
+        for (size_t i = 0; i < vm().running_execution_context().local_variables.size(); ++i) {
+            dbgln("%{}: {}", i, vm().running_execution_context().local_variables[i]);
+        }
+
+    } else {
+        run_bytecode();
+    }
 
     dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter did run unit {:p}", &executable);
 

Userland/Libraries/LibJS/Bytecode/Interpreter.h

@@ -80,6 +80,9 @@ public:
 
     void visit_edges(Cell::Visitor&);
 
+    Span<Value> registers() { return m_current_call_frame; }
+    ReadonlySpan<Value> registers() const { return m_current_call_frame; }
+
 private:
     void run_bytecode();
 
@@ -93,9 +96,6 @@ private:
         return const_cast<Interpreter*>(this)->call_frame();
     }
 
-    Span<Value> registers() { return m_current_call_frame; }
-    ReadonlySpan<Value> registers() const { return m_current_call_frame; }
-
     void push_call_frame(Variant<NonnullOwnPtr<CallFrame>, CallFrame*>, size_t register_count);
     [[nodiscard]] Variant<NonnullOwnPtr<CallFrame>, CallFrame*> pop_call_frame();
 

Userland/Libraries/LibJS/Bytecode/Op.h

@@ -115,6 +115,8 @@ private:
         ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;            \
         DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const; \
                                                                                        \
+        Register lhs() const { return m_lhs_reg; }                                     \
+                                                                                       \
     private:                                                                           \
         Register m_lhs_reg;                                                            \
     };