[turbofan] Fix -Wsign-compare warnings.

src/compiler/simd-scalar-lowering.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simd-scalar-lowering.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 119 matching lines @@
   }
   return result;
 }
 
 void SimdScalarLowering::LowerNode(Node* node) {
   SimdType rep_type = ReplacementType(node);
   switch (node->opcode()) {
     case IrOpcode::kStart: {
       int parameter_count = GetParameterCountAfterLowering();
       // Only exchange the node if the parameter count actually changed.
-      if (parameter_count != signature()->parameter_count()) {
+      if (parameter_count != static_cast<int>(signature()->parameter_count())) {
         int delta =
             parameter_count - static_cast<int>(signature()->parameter_count());
         int new_output_count = node->op()->ValueOutputCount() + delta;
         NodeProperties::ChangeOp(node, common()->Start(new_output_count));
       }
       break;
     }
     case IrOpcode::kParameter: {
       DCHECK(node->InputCount() == 1);
       // Only exchange the node if the parameter count actually changed. We do
       // not even have to do the default lowering because the the start node,
       // the only input of a parameter node, only changes if the parameter count
       // changes.
-      if (GetParameterCountAfterLowering() != signature()->parameter_count()) {
+      if (GetParameterCountAfterLowering() !=
+          static_cast<int>(signature()->parameter_count())) {
         int old_index = ParameterIndexOf(node->op());
         int new_index = GetParameterIndexAfterLowering(signature(), old_index);
         if (old_index == new_index) {
           NodeProperties::ChangeOp(node, common()->Parameter(new_index));
 
           Node* new_node[kMaxLanes];
           for (int i = 0; i < kMaxLanes; i++) {
             new_node[i] = nullptr;
           }
           new_node[0] = node;
           if (signature()->GetParam(old_index) ==
               MachineRepresentation::kSimd128) {
             for (int i = 1; i < kMaxLanes; i++) {
               new_node[i] = graph()->NewNode(common()->Parameter(new_index + i),
                                              graph()->start());
             }
           }
           ReplaceNode(node, new_node);
         }
       }
       break;
     }
     case IrOpcode::kReturn: {
       DefaultLowering(node);
       int new_return_count = GetReturnCountAfterLowering(signature());
-      if (signature()->return_count() != new_return_count) {
+      if (static_cast<int>(signature()->return_count()) != new_return_count) {
         NodeProperties::ChangeOp(node, common()->Return(new_return_count));
       }
       break;
     }
     case IrOpcode::kCall: {
       // TODO(turbofan): Make WASM code const-correct wrt. CallDescriptor.
       CallDescriptor* descriptor =
           const_cast<CallDescriptor*>(CallDescriptorOf(node->op()));
       if (DefaultLowering(node) ||
           (descriptor->ReturnCount() == 1 &&
@@ skipping 209 matching lines @@
       } else {
         UNREACHABLE();
       }
     }
     ReplaceNode(phi, rep_nodes);
   }
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8