Add an option to specify function name when view/print CFG

[davidxl]

Summary

This is useful when a module contains large number of functions.

[davidxl]

ping.

[eraman]

LGTM with a change to the option description .

lib/Analysis/CFGPrinter.cpp

27

The description string doesn't need to have "The option to specify ...". Instead "Name of the function (or its substring) whose..." looks better to me.

lib/Analysis/CFGPrinter.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/CFGPrinter.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/FileSystem.h"
 using namespace llvm;
 
+static cl::opt<std::string> CFGFuncName(
+    "cfg-func-name", cl::Hidden,
+    cl::desc("The option to specify the name (or a substring of)"
+             " of the function whose CFG is viewed/printed."));
+
 namespace {
   struct CFGViewerLegacyPass : public FunctionPass {
     static char ID; // Pass identifcation, replacement for typeid
     CFGViewerLegacyPass() : FunctionPass(ID) {
       initializeCFGViewerLegacyPassPass(*PassRegistry::getPassRegistry());
     }
 
     bool runOnFunction(Function &F) override {

 
 PreservedAnalyses CFGOnlyViewerPass::run(Function &F,
                                          FunctionAnalysisManager &AM) {
   F.viewCFGOnly();
   return PreservedAnalyses::all();
 }
 
 static void writeCFGToDotFile(Function &F, bool CFGOnly = false) {
+  if (!CFGFuncName.empty() && !F.getName().contains(CFGFuncName))
+     return;
   std::string Filename = ("cfg." + F.getName() + ".dot").str();
   errs() << "Writing '" << Filename << "'...";
 
   std::error_code EC;
   raw_fd_ostream File(Filename, EC, sys::fs::F_Text);
 
   if (!EC)
     WriteGraph(File, (const Function*)&F, CFGOnly);

 }
 
 /// viewCFG - This function is meant for use from the debugger.  You can just
 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
 /// program, displaying the CFG of the current function.  This depends on there
 /// being a 'dot' and 'gv' program in your path.
 ///
 void Function::viewCFG() const {
+  if (!CFGFuncName.empty() && !getName().contains(CFGFuncName))
+     return;
   ViewGraph(this, "cfg" + getName());
 }
 
 /// viewCFGOnly - This function is meant for use from the debugger.  It works
 /// just like viewCFG, but it does not include the contents of basic blocks
 /// into the nodes, just the label.  If you are only interested in the CFG
 /// this can make the graph smaller.
 ///
 void Function::viewCFGOnly() const {
+  if (!CFGFuncName.empty() && !getName().contains(CFGFuncName))
+     return;
   ViewGraph(this, "cfg" + getName(), true);
 }
 
 FunctionPass *llvm::createCFGPrinterLegacyPassPass () {
   return new CFGPrinterLegacyPass();
 }
 
 FunctionPass *llvm::createCFGOnlyPrinterLegacyPassPass () {
   return new CFGOnlyPrinterLegacyPass();
 }