[turbofan] Eliminate a non-const reference argument in scheduler

Bug: v8:9429
Change-Id: I48ae73fbd32b0ea4694bea738c42e34bd921c3c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1700074
Auto-Submit: Georg Neis <neis@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62700}

src/compiler/scheduler.cc

@@ -728,12 +728,10 @@ class SpecialRPONumberer : public ZoneObject {
     }
   };
 
-  int Push(
-      ZoneVector<SpecialRPOStackFrame>& stack,  // NOLINT(runtime/references)
-      int depth, BasicBlock* child, int unvisited) {
+  int Push(int depth, BasicBlock* child, int unvisited) {
     if (child->rpo_number() == unvisited) {
-      stack[depth].block = child;
-      stack[depth].index = 0;
+      stack_[depth].block = child;
+      stack_[depth].index = 0;
       child->set_rpo_number(kBlockOnStack);
       return depth + 1;
     }
@@ -781,7 +779,7 @@ class SpecialRPONumberer : public ZoneObject {
     DCHECK_LT(previous_block_count_, schedule_->BasicBlockCount());
     stack_.resize(schedule_->BasicBlockCount() - previous_block_count_);
     previous_block_count_ = schedule_->BasicBlockCount();
-    int stack_depth = Push(stack_, 0, entry, kBlockUnvisited1);
+    int stack_depth = Push(0, entry, kBlockUnvisited1);
     int num_loops = static_cast<int>(loops_.size());
 
     while (stack_depth > 0) {
@@ -803,7 +801,7 @@ class SpecialRPONumberer : public ZoneObject {
         } else {
           // Push the successor onto the stack.
           DCHECK_EQ(kBlockUnvisited1, succ->rpo_number());
-          stack_depth = Push(stack_, stack_depth, succ, kBlockUnvisited1);
+          stack_depth = Push(stack_depth, succ, kBlockUnvisited1);
         }
       } else {
         // Finished with all successors; pop the stack and add the block.
@@ -828,7 +826,7 @@ class SpecialRPONumberer : public ZoneObject {
       // edges that lead out of loops. Visits each block once, but linking loop
       // sections together is linear in the loop size, so overall is
       // O(|B| + max(loop_depth) * max(|loop|))
-      stack_depth = Push(stack_, 0, entry, kBlockUnvisited2);
+      stack_depth = Push(0, entry, kBlockUnvisited2);
       while (stack_depth > 0) {
         SpecialRPOStackFrame* frame = &stack_[stack_depth - 1];
         BasicBlock* block = frame->block;
@@ -875,7 +873,7 @@ class SpecialRPONumberer : public ZoneObject {
             loop->AddOutgoing(zone_, succ);
           } else {
             // Push the successor onto the stack.
-            stack_depth = Push(stack_, stack_depth, succ, kBlockUnvisited2);
+            stack_depth = Push(stack_depth, succ, kBlockUnvisited2);
             if (HasLoopNumber(succ)) {
               // Push the inner loop onto the loop stack.
               DCHECK(GetLoopNumber(succ) < num_loops);