[turbofan] Avoid some non-const reference arguments

... by making them const or converting them to pointers.

Bug: v8:9429
Change-Id: If4a7832944f5dc35cec04c11087499a552a7469a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1700073
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62705}

src/compiler/diamond.h

@@ -33,16 +33,13 @@ struct Diamond {
   }
 
   // Place {this} after {that} in control flow order.
-  void Chain(Diamond& that) {  // NOLINT(runtime/references)
-    branch->ReplaceInput(1, that.merge);
-  }
+  void Chain(Diamond const& that) { branch->ReplaceInput(1, that.merge); }
 
   // Place {this} after {that} in control flow order.
   void Chain(Node* that) { branch->ReplaceInput(1, that); }
 
   // Nest {this} into either the if_true or if_false branch of {that}.
-  void Nest(Diamond& that,  // NOLINT(runtime/references)
-            bool if_true) {
+  void Nest(Diamond const& that, bool if_true) {
     if (if_true) {
       branch->ReplaceInput(1, that.if_true);
       that.merge->ReplaceInput(0, merge);

src/compiler/int64-lowering.cc

@@ -145,16 +145,16 @@ int Int64Lowering::GetParameterCountAfterLowering(
       signature, static_cast<int>(signature->parameter_count()));
 }
 
-void Int64Lowering::GetIndexNodes(Node* index, Node*& index_low,
-                                  Node*& index_high) {
+void Int64Lowering::GetIndexNodes(Node* index, Node** index_low,
+                                  Node** index_high) {
 #if defined(V8_TARGET_LITTLE_ENDIAN)
-  index_low = index;
-  index_high = graph()->NewNode(machine()->Int32Add(), index,
-                                graph()->NewNode(common()->Int32Constant(4)));
+  *index_low = index;
+  *index_high = graph()->NewNode(machine()->Int32Add(), index,
+                                 graph()->NewNode(common()->Int32Constant(4)));
 #elif defined(V8_TARGET_BIG_ENDIAN)
-  index_low = graph()->NewNode(machine()->Int32Add(), index,
-                               graph()->NewNode(common()->Int32Constant(4)));
-  index_high = index;
+  *index_low = graph()->NewNode(machine()->Int32Add(), index,
+                                graph()->NewNode(common()->Int32Constant(4)));
+  *index_high = index;
 #endif
 }
 
@@ -185,7 +185,7 @@ void Int64Lowering::LowerNode(Node* node) {
         Node* index = node->InputAt(1);
         Node* index_low;
         Node* index_high;
-        GetIndexNodes(index, index_low, index_high);
+        GetIndexNodes(index, &index_low, &index_high);
         const Operator* load_op;
 
         if (node->opcode() == IrOpcode::kLoad) {
@@ -235,7 +235,7 @@ void Int64Lowering::LowerNode(Node* node) {
         Node* index = node->InputAt(1);
         Node* index_low;
         Node* index_high;
-        GetIndexNodes(index, index_low, index_high);
+        GetIndexNodes(index, &index_low, &index_high);
         Node* value = node->InputAt(2);
         DCHECK(HasReplacementLow(value));
         DCHECK(HasReplacementHigh(value));

src/compiler/int64-lowering.h

@@ -59,9 +59,7 @@ class V8_EXPORT_PRIVATE Int64Lowering {
   bool HasReplacementHigh(Node* node);
   Node* GetReplacementHigh(Node* node);
   void PreparePhiReplacement(Node* phi);
-  void GetIndexNodes(Node* index,
-                     Node*& index_low,    // NOLINT(runtime/references)
-                     Node*& index_high);  // NOLINT(runtime/references)
+  void GetIndexNodes(Node* index, Node** index_low, Node** index_high);
   void ReplaceNodeWithProjections(Node* node);
   void LowerMemoryBaseAndIndex(Node* node);
 

src/compiler/load-elimination.cc

@@ -419,14 +419,15 @@ bool LoadElimination::AbstractState::Equals(AbstractState const* that) const {
 }
 
 void LoadElimination::AbstractState::FieldsMerge(
-    AbstractFields& this_fields, AbstractFields const& that_fields,
+    AbstractFields* this_fields, AbstractFields const& that_fields,
     Zone* zone) {
-  for (size_t i = 0; i < this_fields.size(); ++i) {
-    if (this_fields[i]) {
+  for (size_t i = 0; i < this_fields->size(); ++i) {
+    AbstractField const*& this_field = (*this_fields)[i];
+    if (this_field) {
       if (that_fields[i]) {
-        this_fields[i] = this_fields[i]->Merge(that_fields[i], zone);
+        this_field = this_field->Merge(that_fields[i], zone);
       } else {
-        this_fields[i] = nullptr;
+        this_field = nullptr;
       }
     }
   }
@@ -442,8 +443,8 @@ void LoadElimination::AbstractState::Merge(AbstractState const* that,
   }
 
   // Merge the information we have about the fields.
-  FieldsMerge(this->fields_, that->fields_, zone);
-  FieldsMerge(this->const_fields_, that->const_fields_, zone);
+  FieldsMerge(&this->fields_, that->fields_, zone);
+  FieldsMerge(&this->const_fields_, that->const_fields_, zone);
 
   // Merge the information we have about the maps.
   if (this->maps_) {

src/compiler/load-elimination.h

@@ -233,7 +233,7 @@ class V8_EXPORT_PRIVATE LoadElimination final
 
     bool FieldsEquals(AbstractFields const& this_fields,
                       AbstractFields const& that_fields) const;
-    void FieldsMerge(AbstractFields& this_fields,  // NOLINT(runtime/references)
+    void FieldsMerge(AbstractFields* this_fields,
                      AbstractFields const& that_fields, Zone* zone);
 
     AbstractElements const* elements_ = nullptr;