[runtime] Adds kScopeInfoMaxInlinedLocalNamesSize

kScopeInfoMaxInlinedLocalNamesSize is a threshold for inlined storage,
otherwise local names will be stored in a hash table.

Bug: v8:12315
Change-Id: Ibfa5bec5222c9e60765c3663707623544895ec0f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3386601Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78622}

src/common/globals.h

@@ -1153,6 +1153,11 @@ inline std::ostream& operator<<(std::ostream& os, CreateArgumentsType type) {
   UNREACHABLE();
 }
 
+// TODO(victorgomes, v8:12315): Local names are currently always inlined, so we
+// choose the maximum int value as threshold.
+constexpr int kScopeInfoMaxInlinedLocalNamesSize =
+    std::numeric_limits<int>::max();
+
 enum ScopeType : uint8_t {
   CLASS_SCOPE,     // The scope introduced by a class.
   EVAL_SCOPE,      // The top-level scope for an eval source.

src/objects/scope-info-inl.h

@@ -32,6 +32,10 @@ int ScopeInfo::ContextLocalCount() const { return context_local_count(); }
 
 ObjectSlot ScopeInfo::data_start() { return RawField(OffsetOfElementAt(0)); }
 
+bool ScopeInfo::HasInlinedLocalNames() const {
+  return ContextLocalCount() < kScopeInfoMaxInlinedLocalNamesSize;
+}
+
 }  // namespace internal
 }  // namespace v8
 

src/objects/scope-info.h

@@ -141,10 +141,7 @@ class ScopeInfo : public TorqueGeneratedScopeInfo<ScopeInfo, HeapObject> {
   SourceTextModuleInfo ModuleDescriptorInfo() const;
 
   // Return true if the local names are inlined in the scope info object.
-  bool HasInlinedLocalNames() const {
-    // TODO(victorgomes, v8:12315): Currently, local names are always inlined.
-    return true;
-  }
+  inline bool HasInlinedLocalNames() const;
 
   // Return the name of the given context local.
   String ContextLocalName(int var) const;

src/objects/scope-info.tq

@@ -97,6 +97,9 @@ struct ModuleVariable {
   properties: SmiTagged<VariableProperties>;
 }
 
+const kMaxInlinedLocalNamesSize:
+    constexpr int32 generates 'kScopeInfoMaxInlinedLocalNamesSize';
+
 @generateBodyDescriptor
 extern class ScopeInfo extends HeapObject {
   const flags: SmiTagged<ScopeFlags>;
@@ -108,10 +111,11 @@ extern class ScopeInfo extends HeapObject {
   // context.
   const context_local_count: Smi;
 
-  // Contains the names of local variables and parameters that are allocated
-  // in the context. They are stored in increasing order of the context slot
-  // index starting with Context::MIN_CONTEXT_SLOTS.
-  context_local_names[context_local_count]: String;
+  // Contains the names of inlined local variables and parameters that are
+  // allocated in the context. They are stored in increasing order of the
+  // context slot index starting with Context::MIN_CONTEXT_SLOTS.
+  context_local_names[Convert<intptr>(context_local_count) < kMaxInlinedLocalNamesSize ? context_local_count : 0]:
+      String;
 
   // Contains the variable modes and initialization flags corresponding to
   // the context locals in ContextLocalNames.

src/torque/runtime-macro-shims.h

@@ -21,6 +21,7 @@ inline intptr_t ChangeInt32ToIntPtr(int32_t i) { return i; }
 inline uintptr_t ChangeUint32ToWord(uint32_t u) { return u; }
 inline intptr_t IntPtrAdd(intptr_t a, intptr_t b) { return a + b; }
 inline intptr_t IntPtrMul(intptr_t a, intptr_t b) { return a * b; }
+inline bool IntPtrLessThan(intptr_t a, intptr_t b) { return a < b; }
 inline intptr_t Signed(uintptr_t u) { return static_cast<intptr_t>(u); }
 template <typename Smi>
 inline int32_t SmiUntag(Smi s) {

tools/debug_helper/debug-macro-shims.h

@@ -66,6 +66,10 @@ inline Value<intptr_t> IntPtrMul(d::MemoryAccessor accessor, intptr_t a,
                                  intptr_t b) {
   return {d::MemoryAccessResult::kOk, a * b};
 }
+inline Value<bool> IntPtrLessThan(d::MemoryAccessor accessor, intptr_t a,
+                                  intptr_t b) {
+  return {d::MemoryAccessResult::kOk, a < b};
+}
 inline Value<intptr_t> Signed(d::MemoryAccessor accessor, uintptr_t u) {
   return {d::MemoryAccessResult::kOk, static_cast<intptr_t>(u)};
 }