[maglev] Add support for Symbol feedback on equality

Introduces a CheckSymbol to guard a reference equality for values in an
equality comparison with Symbol feedback.

Bug: v8:7700
Change-Id: Ieb012b292f2d955faf76e485e6636a2d293fa007
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3811500
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82219}

src/maglev/maglev-graph-builder.cc

@@ -513,7 +513,7 @@ void MaglevGraphBuilder::VisitCompareOperation() {
         //   return;
       }
       break;
-    case CompareOperationHint::kInternalizedString:
+    case CompareOperationHint::kInternalizedString: {
       DCHECK(kOperation == Operation::kEqual ||
              kOperation == Operation::kStrictEqual);
       ValueNode *left, *right;
@@ -529,6 +529,30 @@ void MaglevGraphBuilder::VisitCompareOperation() {
       }
       SetAccumulator(AddNewNode<TaggedEqual>({left, right}));
       return;
+    }
+    case CompareOperationHint::kSymbol: {
+      DCHECK(kOperation == Operation::kEqual ||
+             kOperation == Operation::kStrictEqual);
+      ValueNode *left, *right;
+      if (IsRegisterEqualToAccumulator(0)) {
+        left = right = LoadRegisterTagged(0);
+        AddNewNode<CheckHeapObject>({left});
+        AddNewNode<CheckSymbol>({left});
+      } else {
+        left = LoadRegisterTagged(0);
+        right = GetAccumulatorTagged();
+        AddNewNode<CheckHeapObject>({left});
+        AddNewNode<CheckSymbol>({left});
+        AddNewNode<CheckHeapObject>({right});
+        AddNewNode<CheckSymbol>({right});
+      }
+      if (TryBuildCompareOperation<BranchIfReferenceCompare>(kOperation, left,
+                                                             right)) {
+        return;
+      }
+      SetAccumulator(AddNewNode<TaggedEqual>({left, right}));
+      return;
+    }
     default:
       // Fallback to generic node.
       break;

src/maglev/maglev-graph-verifier.h

@@ -118,6 +118,7 @@ class MaglevGraphVerifier {
       case Opcode::kCheckSmi:
       case Opcode::kCheckNumber:
       case Opcode::kCheckString:
+      case Opcode::kCheckSymbol:
       case Opcode::kCheckedInternalizedString:
       // TODO(victorgomes): Can we check that the input is Boolean?
       case Opcode::kBranchIfToBooleanTrue:

src/maglev/maglev-ir.cc

@@ -1206,6 +1206,20 @@ void CheckHeapObject::GenerateCode(MaglevCodeGenState* code_gen_state,
 }
 void CheckHeapObject::PrintParams(std::ostream& os,
                                   MaglevGraphLabeller* graph_labeller) const {}
+void CheckSymbol::AllocateVreg(MaglevVregAllocationState* vreg_state) {
+  UseRegister(receiver_input());
+}
+void CheckSymbol::GenerateCode(MaglevCodeGenState* code_gen_state,
+                               const ProcessingState& state) {
+  Register object = ToRegister(receiver_input());
+  __ AssertNotSmi(object);
+  __ LoadMap(kScratchRegister, object);
+  __ CmpInstanceType(kScratchRegister, SYMBOL_TYPE);
+  EmitEagerDeoptIf(not_equal, code_gen_state, DeoptimizeReason::kNotASymbol,
+                   this);
+}
+void CheckSymbol::PrintParams(std::ostream& os,
+                              MaglevGraphLabeller* graph_labeller) const {}
 
 void CheckString::AllocateVreg(MaglevVregAllocationState* vreg_state) {
   UseRegister(receiver_input());

src/maglev/maglev-ir.h

@@ -183,6 +183,7 @@ class CompactInterpreterFrameState;
   V(CheckSmi)                         \
   V(CheckNumber)                      \
   V(CheckHeapObject)                  \
+  V(CheckSymbol)                      \
   V(CheckString)                      \
   V(CheckMapsWithMigration)           \
   V(StoreTaggedFieldNoWriteBarrier)   \
@@ -2320,6 +2321,22 @@ class CheckHeapObject : public FixedInputNodeT<1, CheckHeapObject> {
   void PrintParams(std::ostream&, MaglevGraphLabeller*) const;
 };
 
+class CheckSymbol : public FixedInputNodeT<1, CheckSymbol> {
+  using Base = FixedInputNodeT<1, CheckSymbol>;
+
+ public:
+  explicit CheckSymbol(uint64_t bitfield) : Base(bitfield) {}
+
+  static constexpr OpProperties kProperties = OpProperties::EagerDeopt();
+
+  static constexpr int kReceiverIndex = 0;
+  Input& receiver_input() { return input(kReceiverIndex); }
+
+  void AllocateVreg(MaglevVregAllocationState*);
+  void GenerateCode(MaglevCodeGenState*, const ProcessingState&);
+  void PrintParams(std::ostream&, MaglevGraphLabeller*) const;
+};
+
 class CheckString : public FixedInputNodeT<1, CheckString> {
   using Base = FixedInputNodeT<1, CheckString>;