[csa] Clean up handling of type feedback variable.

This makes the code dealing with type feedback more concise and uniform
(at the cost of a few redundant comparisons).

Bug: 
Change-Id: If6b98bd1f0dddd392d7b00d65b600127bd30ff7e
Reviewed-on: https://chromium-review.googlesource.com/818984
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50035}

src/code-stub-assembler.h

@@ -1634,9 +1634,15 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   void ReportFeedbackUpdate(SloppyTNode<FeedbackVector> feedback_vector,
                             SloppyTNode<IntPtrT> slot_id, const char* reason);
 
-  // Combine the new feedback with the existing_feedback.
+  // Combine the new feedback with the existing_feedback. Do nothing if
+  // existing_feedback is nullptr.
+  void CombineFeedback(Variable* existing_feedback, int feedback);
   void CombineFeedback(Variable* existing_feedback, Node* feedback);
 
+  // Overwrite the existing feedback with new_feedback. Do nothing if
+  // existing_feedback is nullptr.
+  void OverwriteFeedback(Variable* existing_feedback, int new_feedback);
+
   // Check if a property name might require protector invalidation when it is
   // used for a property store or deletion.
   void CheckForAssociatedProtector(Node* name, Label* if_protector);
@@ -1931,12 +1937,10 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
       Node* context, Node* input, Object::Conversion mode,
       BigIntHandling bigint_handling = BigIntHandling::kThrow);
 
-  enum class Feedback { kCollect, kNone };
-  template <Feedback feedback>
   void TaggedToNumeric(Node* context, Node* value, Label* done,
-                       Variable* var_numeric, Variable* var_feedback = nullptr);
+                       Variable* var_numeric, Variable* var_feedback);
 
-  template <Feedback feedback, Object::Conversion conversion>
+  template <Object::Conversion conversion>
   void TaggedToWord32OrBigIntImpl(Node* context, Node* value, Label* if_number,
                                   Variable* var_word32,
                                   Label* if_bigint = nullptr,

src/globals.h

@@ -1301,8 +1301,8 @@ class CompareOperationFeedback {
     kInternalizedString = 0x8,
     kString = 0x18,
     kSymbol = 0x20,
+    kBigInt = 0x30,
     kReceiver = 0x40,
-    kBigInt = 0x80,
     kAny = 0xff
   };
 };

src/interpreter/interpreter-generator.cc

@@ -1245,8 +1245,7 @@ class UnaryNumericOpAssembler : public InterpreterAssembler {
       BIND(&if_bigint);
       {
         var_result.Bind(BigIntOp(value));
-        CombineFeedback(&var_feedback,
-                        SmiConstant(BinaryOperationFeedback::kBigInt));
+        CombineFeedback(&var_feedback, BinaryOperationFeedback::kBigInt);
         Goto(&end);
       }
 
@@ -1257,8 +1256,8 @@ class UnaryNumericOpAssembler : public InterpreterAssembler {
         // only reach this path on the first pass when the feedback is kNone.
         CSA_ASSERT(this, SmiEqual(var_feedback.value(),
                                   SmiConstant(BinaryOperationFeedback::kNone)));
-        var_feedback.Bind(
-            SmiConstant(BinaryOperationFeedback::kNumberOrOddball));
+        OverwriteFeedback(&var_feedback,
+                          BinaryOperationFeedback::kNumberOrOddball);
         var_value.Bind(LoadObjectField(value, Oddball::kToNumberOffset));
         Goto(&start);
       }
@@ -1270,7 +1269,7 @@ class UnaryNumericOpAssembler : public InterpreterAssembler {
         // only reach this path on the first pass when the feedback is kNone.
         CSA_ASSERT(this, SmiEqual(var_feedback.value(),
                                   SmiConstant(BinaryOperationFeedback::kNone)));
-        var_feedback.Bind(SmiConstant(BinaryOperationFeedback::kAny));
+        OverwriteFeedback(&var_feedback, BinaryOperationFeedback::kAny);
         var_value.Bind(
             CallBuiltin(Builtins::kNonNumberToNumeric, GetContext(), value));
         Goto(&start);
@@ -1279,8 +1278,7 @@ class UnaryNumericOpAssembler : public InterpreterAssembler {
 
     BIND(&do_float_op);
     {
-      CombineFeedback(&var_feedback,
-                      SmiConstant(BinaryOperationFeedback::kNumber));
+      CombineFeedback(&var_feedback, BinaryOperationFeedback::kNumber);
       var_result.Bind(
           AllocateHeapNumberWithValue(FloatOp(var_float_value.value())));
       Goto(&end);
@@ -1310,14 +1308,12 @@ class NegateAssemblerImpl : public UnaryNumericOpAssembler {
     GotoIf(SmiEqual(smi_value, SmiConstant(Smi::kMinValue)), &if_min_smi);
 
     // Else simply subtract operand from 0.
-    CombineFeedback(var_feedback,
-                    SmiConstant(BinaryOperationFeedback::kSignedSmall));
+    CombineFeedback(var_feedback, BinaryOperationFeedback::kSignedSmall);
     var_result.Bind(SmiSub(SmiConstant(0), smi_value));
     Goto(&end);
 
     BIND(&if_zero);
-    CombineFeedback(var_feedback,
-                    SmiConstant(BinaryOperationFeedback::kNumber));
+    CombineFeedback(var_feedback, BinaryOperationFeedback::kNumber);
     var_result.Bind(MinusZeroConstant());
     Goto(&end);
 
@@ -1412,8 +1408,7 @@ class IncDecAssembler : public UnaryNumericOpAssembler {
     }
 
     BIND(&if_notoverflow);
-    CombineFeedback(var_feedback,
-                    SmiConstant(BinaryOperationFeedback::kSignedSmall));
+    CombineFeedback(var_feedback, BinaryOperationFeedback::kSignedSmall);
     return BitcastWordToTaggedSigned(Projection(0, pair));
   }