[turbofan] Implement OSR for outer loops.

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index 8e11e7c181af8fb17298ae0924760fed6e37a7ad..7def50e47aa069572228668614bcee6510ea9798 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -1062,7 +1062,7 @@ void RegisterAllocator::MeetRegisterConstraintsForLastInstructionInBlock(
       AllocateFixed(output, -1, false);
       // This value is produced on the stack, we never need to spill it.
       if (output->IsStackSlot()) {
-        DCHECK(output->index() < 0);
+        DCHECK(output->index() < frame_->GetSpillSlotCount());
         range->SetSpillOperand(output);
         range->SetSpillStartIndex(end);
         assigned = true;
@@ -1128,7 +1128,7 @@ void RegisterAllocator::MeetConstraintsBetween(Instruction* first,
 
           // This value is produced on the stack, we never need to spill it.
           if (first_output->IsStackSlot()) {
-            DCHECK(first_output->index() < 0);
+            DCHECK(first_output->index() < frame_->GetSpillSlotCount());
             range->SetSpillOperand(first_output);
             range->SetSpillStartIndex(gap_index - 1);
             assigned = true;