[csa] Add Unreachable() and use it after throw sites

src/compiler/raw-machine-assembler.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/raw-machine-assembler.h"
 
 #include "src/compiler/node-properties.h"
 #include "src/compiler/pipeline.h"
 #include "src/compiler/scheduler.h"
 #include "src/objects-inl.h"
@@ skipping 148 matching lines @@
 void RawMachineAssembler::PopAndReturn(Node* pop, Node* v1, Node* v2,
                                        Node* v3) {
   Node* values[] = {pop, v1, v2, v3};
   Node* ret = MakeNode(common()->Return(3), 4, values);
   schedule()->AddReturn(CurrentBlock(), ret);
   current_block_ = nullptr;
 }
 
 void RawMachineAssembler::DebugBreak() { AddNode(machine()->DebugBreak()); }
 
+void RawMachineAssembler::Unreachable() {
+  Node* values[] = {UndefinedConstant()};  // Unused.
+  Node* ret = MakeNode(common()->Throw(), 1, values);
+  schedule()->AddThrow(CurrentBlock(), ret);
+  current_block_ = nullptr;
+}
+
 void RawMachineAssembler::Comment(const char* msg) {
   AddNode(machine()->Comment(msg));
 }
 
 Node* RawMachineAssembler::CallN(CallDescriptor* desc, int input_count,
                                  Node* const* inputs) {
   DCHECK(!desc->NeedsFrameState());
   // +1 is for target.
   DCHECK_EQ(input_count, desc->ParameterCount() + 1);
   return AddNode(common()->Call(desc), input_count, inputs);
@@ skipping 155 matching lines @@
 
 RawMachineLabel::~RawMachineLabel() {
   // If this DCHECK fails, it means that the label has been bound but it's not
   // used, or the opposite. This would cause the register allocator to crash.
   DCHECK_EQ(bound_, used_);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8