[turbofan] Emit explicit checkpoint before operations.

src/compiler/bytecode-graph-builder.cc

Index: src/compiler/bytecode-graph-builder.cc
diff --git a/src/compiler/bytecode-graph-builder.cc b/src/compiler/bytecode-graph-builder.cc
index 50cc15c2a9b5869d825bc89f38ff44dcbac51489..42e416598a2253942eaa718ed22a34e346cefeeb 100644
--- a/src/compiler/bytecode-graph-builder.cc
+++ b/src/compiler/bytecode-graph-builder.cc
@@ -109,6 +109,11 @@ class BytecodeGraphBuilder::FrameStateBeforeAndAfter {
         id_before, OutputFrameStateCombine::Ignore());
     id_after_ = BailoutId(id_before.ToInt() +
                           builder->bytecode_iterator().current_bytecode_size());
+    // Create an explicit checkpoint node for before the operation.
+    Node* node = builder_->NewNode(builder_->common()->Checkpoint());
+    DCHECK_EQ(IrOpcode::kDead,
+              NodeProperties::GetFrameStateInput(node, 0)->opcode());
+    NodeProperties::ReplaceFrameStateInput(node, 0, frame_state_before_);
   }
 
   ~FrameStateBeforeAndAfter() {
@@ -136,6 +141,7 @@ class BytecodeGraphBuilder::FrameStateBeforeAndAfter {
 
     if (count >= 2) {
       // Add the frame state for before the operation.
+      // TODO(mstarzinger): Get rid of frame state input before!
       DCHECK_EQ(IrOpcode::kDead,
                 NodeProperties::GetFrameStateInput(node, 1)->opcode());
       NodeProperties::ReplaceFrameStateInput(node, 1, frame_state_before_);