For PR797:

Make sys::Program::ExecuteAndWait not throw exceptions and update any
affected code. It now return -9999 to signal that the program couldn't be
executed. Only one case (in bugpoint) actually examines the result code.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29785 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/GraphWriter.cpp

@@ -59,7 +59,9 @@ void llvm::DisplayGraph(const sys::Path &Filename) {
     args.push_back(PSFilename.c_str());
     args.push_back(0);
     
-    sys::Program::ExecuteAndWait(gv, &args[0]);
+    if (sys::Program::ExecuteAndWait(gv, &args[0])) {
+      std::cerr << "Error viewing graph: 'gv' not in path?\n";
+    }
   }
   PSFilename.eraseFromDisk();
 #elif HAVE_DOTTY