[turbofan] Fix more -Wsign-compare warnings.

src/compiler/arm64/unwinding-info-writer-arm64.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/arm64/unwinding-info-writer-arm64.h"
 #include "src/compiler/instruction.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 void UnwindingInfoWriter::BeginInstructionBlock(int pc_offset,
                                                 const InstructionBlock* block) {
   if (!enabled()) return;
 
   block_will_exit_ = false;
 
-  DCHECK_LT(block->rpo_number().ToInt(), block_initial_states_.size());
+  DCHECK_LT(block->rpo_number().ToInt(),
+            static_cast<int>(block_initial_states_.size()));
   const BlockInitialState* initial_state =
       block_initial_states_[block->rpo_number().ToInt()];
   if (initial_state) {
     if (initial_state->saved_lr_ != saved_lr_) {
       eh_frame_writer_.AdvanceLocation(pc_offset);
       if (initial_state->saved_lr_) {
         eh_frame_writer_.RecordRegisterSavedToStack(lr, kPointerSize);
       } else {
         eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
       }
       saved_lr_ = initial_state->saved_lr_;
     }
   } else {
     // The entry block always lacks an explicit initial state.
     // The exit block may lack an explicit state, if it is only reached by
     //   the block ending in a ret.
     // All the other blocks must have an explicit initial state.
     DCHECK(block->predecessors().empty() || block->successors().empty());
   }
 }
 
 void UnwindingInfoWriter::EndInstructionBlock(const InstructionBlock* block) {
   if (!enabled() || block_will_exit_) return;
 
   for (const RpoNumber& successor : block->successors()) {
     int successor_index = successor.ToInt();
-    DCHECK_LT(successor_index, block_initial_states_.size());
+    DCHECK_LT(successor_index, static_cast<int>(block_initial_states_.size()));
     const BlockInitialState* existing_state =
         block_initial_states_[successor_index];
 
     // If we already had an entry for this BB, check that the values are the
     // same we are trying to insert.
     if (existing_state) {
       DCHECK_EQ(existing_state->saved_lr_, saved_lr_);
     } else {
       block_initial_states_[successor_index] =
           new (zone_) BlockInitialState(saved_lr_);
@@ skipping 44 matching lines @@
   if (!enabled()) return;
 
   eh_frame_writer_.AdvanceLocation(pc_offset);
   eh_frame_writer_.SetBaseAddressRegisterAndOffset(fp, 0);
   eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8