src: remove ScopeInfo/SharedInfo fields

* `kScriptOffset` is never present (it's replaced by
  `kScriptOrDebugInfoOffset`)
* `kScopeInfoOffset` also no longer present. Simplify the resulting
  branch.
* `kStackLocalCountOffset` is no longer present, making
  `kEmbeddedParamAndStackLocals` always false. Remove some dead code as
  a result.

Author: kvakil

src/llv8-constants.cc

@@ -192,7 +192,6 @@ void SharedInfo::Load() {
   kInferredNameOffset =
       LoadConstant("class_SharedFunctionInfo__inferred_name__String",
                    "class_SharedFunctionInfo__function_identifier__Object");
-  kScriptOffset = LoadConstant("class_SharedFunctionInfo__script__Object");
   kScriptOrDebugInfoOffset = LoadConstant(
       {"class_SharedFunctionInfo__script_or_debug_info__Object",
        "class_SharedFunctionInfo__script_or_debug_info__HeapObject"});
@@ -212,18 +211,9 @@ void SharedInfo::Load() {
         "class_SharedFunctionInfo__formal_parameter_count__SMI");
   }
 
-  // NOTE: Could potentially be -1 on v4 and v5 node, should check in llv8
-  kScopeInfoOffset =
-      LoadConstant("class_SharedFunctionInfo__scope_info__ScopeInfo");
-
-  kStartPositionMask = LoadConstant("sharedfunctioninfo_start_position_mask");
-  kStartPositionShift = LoadConstant("sharedfunctioninfo_start_position_shift");
-
-  if (kStartPositionShift == -1) {
-    // TODO(indutny): check version?
-    kStartPositionShift = 2;
-    kStartPositionMask = ~((1 << kStartPositionShift) - 1);
-  }
+  // TODO: this should use postmortem data.
+  kStartPositionShift = 2;
+  kStartPositionMask = ~((1 << kStartPositionShift) - 1);
 
   if (LoadConstant("class_SharedFunctionInfo__compiler_hints__int") == -1 &&
       kNameOrScopeInfoOffset == -1)
@@ -251,8 +241,6 @@ void Code::Load() {
 
 void ScopeInfo::Load() {
   kParameterCountOffset = LoadConstant("scopeinfo_idx_nparams");
-  kStackLocalCountOffset = LoadConstant("scopeinfo_idx_nstacklocals");
-  kEmbeddedParamAndStackLocals = kStackLocalCountOffset != -1;
   kContextLocalCountOffset = LoadConstant("scopeinfo_idx_ncontextlocals");
   kVariablePartIndex = LoadConstant("scopeinfo_idx_first_vars");
   // Prior to Node.js v16, ScopeInfo inherited from FixedArray. In release

src/llv8-constants.h

@@ -158,12 +158,10 @@ class SharedInfo : public Module {
   int64_t kNameOrScopeInfoOffset;
   int64_t kNameOffset;
   int64_t kInferredNameOffset;
-  int64_t kScriptOffset;
   Constant<int64_t> kScriptOrDebugInfoOffset;
   int64_t kStartPositionOffset;
   int64_t kEndPositionOffset;
   int64_t kParameterCountOffset;
-  int64_t kScopeInfoOffset;
   int64_t kFunctionDataOffset;
 
   int64_t kStartPositionMask;
@@ -202,9 +200,7 @@ class ScopeInfo : public Module {
   CONSTANTS_DEFAULT_METHODS(ScopeInfo);
 
   int64_t kParameterCountOffset;
-  int64_t kStackLocalCountOffset;
   int64_t kContextLocalCountOffset;
-  bool kEmbeddedParamAndStackLocals;
   int64_t kVariablePartIndex;
   bool kIsFixedArray;
 

src/llv8-inl.h

@@ -481,11 +481,8 @@ ACCESSOR(SharedFunctionInfo, function_data, shared_info()->kFunctionDataOffset,
 ACCESSOR(SharedFunctionInfo, name, shared_info()->kNameOffset, String)
 ACCESSOR(SharedFunctionInfo, inferred_name, shared_info()->kInferredNameOffset,
          Value)
-ACCESSOR(SharedFunctionInfo, script, shared_info()->kScriptOffset, Script)
 SAFE_ACCESSOR(SharedFunctionInfo, script_or_debug_info,
               shared_info()->kScriptOrDebugInfoOffset, HeapObject)
-ACCESSOR(SharedFunctionInfo, scope_info, shared_info()->kScopeInfoOffset,
-         HeapObject)
 ACCESSOR(SharedFunctionInfo, name_or_scope_info,
          shared_info()->kNameOrScopeInfoOffset, HeapObject)
 
@@ -521,8 +518,6 @@ Value SharedFunctionInfo::GetInferredName(Error& err) {
 }
 
 HeapObject SharedFunctionInfo::GetScopeInfo(Error& err) {
-  if (v8()->shared_info()->kNameOrScopeInfoOffset == -1) return scope_info(err);
-
   HeapObject maybe_scope_info = name_or_scope_info(err);
   if (!String::IsString(v8(), maybe_scope_info, err)) return maybe_scope_info;
 
@@ -531,10 +526,6 @@ HeapObject SharedFunctionInfo::GetScopeInfo(Error& err) {
 }
 
 Script SharedFunctionInfo::GetScript(Error& err) {
-  if (!v8()->shared_info()->kScriptOrDebugInfoOffset.Loaded()) {
-    return script(err);
-  }
-
   HeapObject maybe_script = script_or_debug_info(err);
   if (maybe_script.IsScript(err)) return maybe_script;
 
@@ -1096,18 +1087,6 @@ inline Smi ScopeInfo::ParameterCount(Error& err) {
       err);
 }
 
-inline Smi ScopeInfo::StackLocalCount(Error& err) {
-  if (v8()->scope_info()->kStackLocalCountOffset == -1) {
-    return Smi(v8(), 0);
-  }
-  int64_t data_offset =
-      v8()->scope_info()->kIsFixedArray ? v8()->fixed_array()->kDataOffset : 0;
-  return HeapObject::LoadFieldValue<Smi>(
-      data_offset + v8()->scope_info()->kStackLocalCountOffset *
-                        v8()->common()->kPointerSize,
-      err);
-}
-
 inline Smi ScopeInfo::ContextLocalCount(Error& err) {
   int64_t data_offset = v8()->scope_info()->kIsFixedArray
                             ? v8()->fixed_array()->kDataOffset
@@ -1120,16 +1099,6 @@ inline Smi ScopeInfo::ContextLocalCount(Error& err) {
 
 inline int ScopeInfo::ContextLocalIndex(Error& err) {
   int context_local_index = v8()->scope_info()->kVariablePartIndex;
-
-  if (v8()->scope_info()->kEmbeddedParamAndStackLocals) {
-    Smi param_count = ParameterCount(err);
-    if (err.Fail()) return -1;
-    context_local_index += param_count.GetValue() + 1;
-
-    Smi stack_local = StackLocalCount(err);
-    if (err.Fail()) return -1;
-    context_local_index += stack_local.GetValue();
-  }
   return context_local_index;
 }
 

src/llv8.h

@@ -217,11 +217,9 @@ class SharedFunctionInfo : public HeapObject {
 
  private:
   inline String name(Error& err);
-  inline Script script(Error& err);
   inline HeapObject script_or_debug_info(Error& err);
   inline Value inferred_name(Error& err);
   inline Value function_data(Error& err);
-  inline HeapObject scope_info(Error& err);
   inline HeapObject name_or_scope_info(Error& err);
 };
 
@@ -520,7 +518,6 @@ class ScopeInfo : public HeapObject {
   };
 
   inline Smi ParameterCount(Error& err);
-  inline Smi StackLocalCount(Error& err);
   inline Smi ContextLocalCount(Error& err);
   inline int ContextLocalIndex(Error& err);
   inline PositionInfo MaybePositionInfo(Error& err);

src/printer.cc

@@ -203,11 +203,6 @@ std::string Printer::Stringify(v8::FixedArray fixed_array, Error& err) {
 
 template <>
 std::string Printer::Stringify(v8::Context ctx, Error& err) {
-  // Not enough postmortem information, return bare minimum
-  if (llv8_->shared_info()->kScopeInfoOffset == -1 &&
-      llv8_->shared_info()->kNameOrScopeInfoOffset == -1)
-    return std::string();
-
   std::string res = "<Context";
 
   if (!options_.detailed) {