[WIP] NumberToString operator in TF.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index d72fc827591350c7b4283b89ee861cb23bb340d8..7e93dc512519788e4bdc87b8392168722421563b 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -2028,6 +2028,44 @@ class RepresentationSelector {
         if (lower()) DeferReplacement(node, node->InputAt(0));
         return;
       }
+      case IrOpcode::kNumberToString: {
+        Type* const rhs_type = TypeOf(node->InputAt(1));
+        VisitBinop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
+        if (lower()) {
+          if (rhs_type->Is(type_cache_.kSingletonTen)) {
+            // NumberToString(x, #10) => Call(NumberToStringStub, x, no-context)
+            Operator::Properties properties = Operator::kEliminatable;
+            Callable callable =
+                CodeFactory::NumberToString(jsgraph_->isolate());
+            CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
+            CallDescriptor* desc = Linkage::GetStubCallDescriptor(
+                jsgraph_->isolate(), jsgraph_->zone(), callable.descriptor(), 0,
+                flags, properties);
+            node->InsertInput(jsgraph_->zone(), 0,
+                              jsgraph_->HeapConstant(callable.code()));
+            node->ReplaceInput(2, jsgraph_->NoContextConstant());
+            node->AppendInput(jsgraph_->zone(), jsgraph_->graph()->start());
+            NodeProperties::ChangeOp(node, jsgraph_->common()->Call(desc));
+          } else {
+            // NumberToString(x, y) => %NumberToString(x, y, no-context)
+            Operator::Properties properties = Operator::kEliminatable;
+            CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
+            Runtime::FunctionId id = Runtime::kNumberToString;
+            CallDescriptor* desc = Linkage::GetRuntimeCallDescriptor(
+                jsgraph_->zone(), id, 2, properties, flags);
+            node->InsertInput(jsgraph_->zone(), 0,
+                              jsgraph_->CEntryStubConstant(1));
+            node->AppendInput(jsgraph_->zone(),
+                              jsgraph_->ExternalConstant(
+                                  ExternalReference(id, jsgraph_->isolate())));
+            node->AppendInput(jsgraph_->zone(), jsgraph_->Int32Constant(2));
+            node->AppendInput(jsgraph_->zone(), jsgraph_->NoContextConstant());
+            node->AppendInput(jsgraph_->zone(), jsgraph_->graph()->start());
+            NodeProperties::ChangeOp(node, jsgraph_->common()->Call(desc));
+          }
+        }
+        return;
+      }
       case IrOpcode::kReferenceEqual: {
         VisitBinop(node, UseInfo::AnyTagged(), MachineRepresentation::kBit);
         if (lower()) {