[turbofan] Fix more -Wsign-compare warnings.

src/compiler/pipeline.cc

 // Copyright 2014 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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <memory>
 #include <sstream>
 
@@ skipping 256 matching lines @@
   void InitializeInstructionSequence(const CallDescriptor* descriptor) {
     DCHECK(sequence_ == nullptr);
     InstructionBlocks* instruction_blocks =
         InstructionSequence::InstructionBlocksFor(instruction_zone(),
                                                   schedule());
     sequence_ = new (instruction_zone()) InstructionSequence(
         info()->isolate(), instruction_zone(), instruction_blocks);
     if (descriptor && descriptor->RequiresFrameAsIncoming()) {
       sequence_->instruction_blocks()[0]->mark_needs_frame();
     } else {
-      DCHECK_EQ(0, descriptor->CalleeSavedFPRegisters());
-      DCHECK_EQ(0, descriptor->CalleeSavedRegisters());
+      DCHECK_EQ(0u, descriptor->CalleeSavedFPRegisters());
+      DCHECK_EQ(0u, descriptor->CalleeSavedRegisters());
     }
   }
 
   void InitializeFrameData(CallDescriptor* descriptor) {
     DCHECK(frame_ == nullptr);
     int fixed_frame_size = 0;
     if (descriptor != nullptr) {
       fixed_frame_size = descriptor->CalculateFixedFrameSize();
     }
     frame_ = new (instruction_zone()) Frame(fixed_frame_size);
@@ skipping 1706 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8