Add a viewCFGOnly function for debugging purposes.

include/swift/SIL/SILFunction.h

@@ -900,6 +900,9 @@ public:
   /// block inside.  This depends on there being a 'dot' and 'gv' program in
   /// your path.
   void viewCFG() const;
+  // Like the ViewCFG, but the graph does not show the basic block contents.
+  void viewCFGOnly() const;
+
 };
 
 inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,

lib/SIL/SILFunction.cpp

@@ -405,17 +405,28 @@ TargetFunction("view-cfg-only-for-function", llvm::cl::init(""),
                llvm::cl::desc("Only print out the cfg for this function"));
 #endif
 
-
-void SILFunction::viewCFG() const {
+namespace {
+void viewCFGHelper(const SILFunction* F, bool skipBBContents) {
 /// When asserts are disabled, this should be a NoOp.
 #ifndef NDEBUG
     // If we have a target function, only print that function out.
-    if (!TargetFunction.empty() && !(getName().str() == TargetFunction))
+    if (!TargetFunction.empty() && !(F->getName().str() == TargetFunction))
       return;
 
-  ViewGraph(const_cast<SILFunction *>(this), "cfg" + getName().str());
+    ViewGraph(const_cast<SILFunction *>(F), "cfg" + F->getName().str(),
+              /*shortNames=*/skipBBContents);
 #endif
 }
+}  // namespace
+
+void SILFunction::viewCFG() const {
+  viewCFGHelper(this, /*skipBBContents=*/false);
+}
+
+void SILFunction::viewCFGOnly() const {
+  viewCFGHelper(this, /*skipBBContents=*/true);
+}
+
 
 bool SILFunction::hasSelfMetadataParam() const {
   auto paramTypes = getConventions().getParameterSILTypes();