[turbofan] Added --csa-trap-on-node option that helps debugging graph verification issues.

src/code-stub-assembler.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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
 
 using compiler::Node;
 
+CodeStubAssembler::CodeStubAssembler(compiler::CodeAssemblerState* state)
+    : compiler::CodeAssembler(state) {
+  if (DEBUG_BOOL && FLAG_csa_trap_on_node != nullptr) {
+    HandleBreakOnNode();
+  }
+}
+
+void CodeStubAssembler::HandleBreakOnNode() {
+  // FLAG_csa_trap_on_node should be in a form "STUB,NODE" where STUB is a
+  // string specifying the name of a stub and NODE is number specifying node id.
+  const char* name = state()->name();
+  size_t name_length = strlen(name);
+  if (strncmp(FLAG_csa_trap_on_node, name, name_length) != 0) {
+    // Different name.
+    return;
+  }
+  size_t option_length = strlen(FLAG_csa_trap_on_node);
+  if (option_length < name_length + 2 ||
+      FLAG_csa_trap_on_node[name_length] != ',') {
+    // Option is too short.
+    return;
+  }
+  const char* start = &FLAG_csa_trap_on_node[name_length + 1];
+  char* end;
+  int node_id = static_cast<int>(strtol(start, &end, 10));
+  if (start == end) {
+    // Bad node id.
+    return;
+  }
+  BreakOnNode(node_id);
+}
+
 void CodeStubAssembler::Assert(const NodeGenerator& codition_body,
                                const char* message, const char* file,
                                int line) {
 #if defined(DEBUG)
   Label ok(this);
   Label not_ok(this, Label::kDeferred);
   if (message != nullptr && FLAG_code_comments) {
     Comment("[ Assert: %s", message);
   } else {
     Comment("[ Assert");
@@ skipping 8257 matching lines @@
                        Heap::kUndefinedValueRootIndex);
   StoreObjectFieldRoot(result, PromiseReactionJobInfo::kDebugNameOffset,
                        Heap::kUndefinedValueRootIndex);
   StoreObjectFieldNoWriteBarrier(result, PromiseReactionJobInfo::kContextOffset,
                                  context);
   return result;
 }
 
 }  // namespace internal
 }  // namespace v8