LibJS: Add file & line number to bytecode VM stack traces :^)

This works by adding source start/end offset to every bytecode
instruction. In the future we can make this more efficient by keeping
a map of bytecode ranges to source ranges in the Executable instead,
but let's just get traces working first.

Co-Authored-By: Andrew Kaster <akaster@serenityos.org>

Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp

@@ -152,6 +152,7 @@ ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(Value this_argu
 
     // Non-standard
     callee_context.arguments.extend(move(arguments_list));
+    callee_context.instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
 
     // 2. Let calleeContext be PrepareForOrdinaryCall(F, undefined).
     // NOTE: We throw if the end of the native stack is reached, so unlike in the spec this _does_ need an exception check.
@@ -221,6 +222,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> ECMAScriptFunctionObject::internal_const
 
     // Non-standard
     callee_context.arguments.extend(move(arguments_list));
+    callee_context.instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
 
     // 4. Let calleeContext be PrepareForOrdinaryCall(F, newTarget).
     // NOTE: We throw if the end of the native stack is reached, so unlike in the spec this _does_ need an exception check.

Userland/Libraries/LibJS/Runtime/Error.cpp

@@ -83,9 +83,12 @@ void Error::populate_stack()
         if (function_name.is_empty())
             function_name = "<unknown>"sv;
 
+        UnrealizedSourceRange range = {};
+        if (context->instruction_stream_iterator.has_value())
+            range = context->instruction_stream_iterator->source_range();
         TracebackFrame frame {
             .function_name = move(function_name),
-            .source_range_storage = context->source_range,
+            .source_range_storage = range,
         };
 
         m_traceback.append(move(frame));

Userland/Libraries/LibJS/Runtime/ExecutionContext.cpp

@@ -33,7 +33,7 @@ ExecutionContext ExecutionContext::copy() const
     copy.lexical_environment = lexical_environment;
     copy.variable_environment = variable_environment;
     copy.private_environment = private_environment;
-    copy.source_range = source_range;
+    copy.instruction_stream_iterator = instruction_stream_iterator;
     copy.function_name = function_name;
     copy.this_value = this_value;
     copy.is_strict_mode = is_strict_mode;

Userland/Libraries/LibJS/Runtime/ExecutionContext.h

@@ -10,6 +10,7 @@
 
 #include <AK/DeprecatedFlyString.h>
 #include <AK/WeakPtr.h>
+#include <LibJS/Bytecode/Instruction.h>
 #include <LibJS/Forward.h>
 #include <LibJS/Heap/MarkedVector.h>
 #include <LibJS/Module.h>
@@ -43,7 +44,7 @@ public:
     // Non-standard: This points at something that owns this ExecutionContext, in case it needs to be protected from GC.
     GCPtr<Cell> context_owner;
 
-    UnrealizedSourceRange source_range;
+    Optional<Bytecode::InstructionStreamIterator&> instruction_stream_iterator;
     DeprecatedFlyString function_name;
     Value this_value;
     MarkedVector<Value> arguments;

Userland/Libraries/LibJS/Runtime/NativeFunction.cpp

@@ -6,6 +6,7 @@
  */
 
 #include <LibJS/AST.h>
+#include <LibJS/Bytecode/Interpreter.h>
 #include <LibJS/Runtime/FunctionEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/NativeFunction.h>
@@ -128,9 +129,9 @@ ThrowCompletionOr<Value> NativeFunction::internal_call(Value this_argument, Mark
     // Note: This is already the default value.
 
     // 8. Perform any necessary implementation-defined initialization of calleeContext.
-
     callee_context.this_value = this_argument;
     callee_context.arguments.extend(move(arguments_list));
+    callee_context.instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
 
     callee_context.lexical_environment = caller_context.lexical_environment;
     callee_context.variable_environment = caller_context.variable_environment;
@@ -192,8 +193,8 @@ ThrowCompletionOr<NonnullGCPtr<Object>> NativeFunction::internal_construct(Marke
     // Note: This is already the default value.
 
     // 8. Perform any necessary implementation-defined initialization of calleeContext.
-
     callee_context.arguments.extend(move(arguments_list));
+    callee_context.instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
 
     callee_context.lexical_environment = caller_context.lexical_environment;
     callee_context.variable_environment = caller_context.variable_environment;

Userland/Libraries/LibJS/Runtime/VM.cpp

@@ -746,8 +746,8 @@ void VM::dump_backtrace() const
 {
     for (ssize_t i = m_execution_context_stack.size() - 1; i >= 0; --i) {
         auto& frame = m_execution_context_stack[i];
-        if (frame->source_range.source_code) {
-            auto source_range = frame->source_range.realize();
+        if (frame->instruction_stream_iterator->source_code()) {
+            auto source_range = frame->instruction_stream_iterator->source_range().realize();
             dbgln("-> {} @ {}:{},{}", frame->function_name, source_range.filename(), source_range.start.line, source_range.start.column);
         } else {
             dbgln("-> {}", frame->function_name);