Introduce llvm-cov.

Add llvm-cov skeleton. It has initial support to read coverage info generated by GCOVProfiling.cpp. 
Today, you can do
prompt> clang a.c -ftest-coverage -fprofile-arcs -o a
prompt> ./a
prompt> llvm-cov -gcno a.gcno -gcda a.gcda 
a.c
 :	#include "a.h"
 :	
 :	int main() {
 :		int i = 0;
 :		if (i) {
1:			int j = 0;
1:			j = 1;
1:		} else {
 :			int k = 1;
 :			k = 2;
 :		}
1:		return 0;
 :	}
 :	
 :	




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140712 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-cov/llvm-cov.cpp b/tools/llvm-cov/llvm-cov.cpp
new file mode 100644
index 0000000..466deff
--- /dev/null
+++ b/tools/llvm-cov/llvm-cov.cpp
@@ -0,0 +1,83 @@
+//===- tools/llvm-cov/llvm-cov.cpp - LLVM coverage tool -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+// llvm-cov is a command line tools to analyze and report coverage information.
+//
+//
+//===----------------------------------------------------------------------===//
+
+#include "GCOVReader.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/MemoryObject.h"
+#include "llvm/Support/PrettyStackTrace.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/system_error.h"
+using namespace llvm;
+
+static cl::opt<bool>
+DumpGCOV("dump", cl::init(false), cl::desc("dump gcov file"));
+
+static cl::opt<std::string>
+InputGCNO("gcno", cl::desc("<input gcno file>"), cl::init(""));
+
+static cl::opt<std::string>
+InputGCDA("gcda", cl::desc("<input gcda file>"), cl::init(""));
+
+
+//===----------------------------------------------------------------------===//
+int main(int argc, char **argv) {
+  // Print a stack trace if we signal out.
+  sys::PrintStackTraceOnErrorSignal();
+  PrettyStackTraceProgram X(argc, argv);
+  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
+
+  cl::ParseCommandLineOptions(argc, argv, "llvm cov\n");
+
+
+  GCOVFile GF;
+  if (InputGCNO.empty())
+    errs() << " " << argv[0] << ": No gcov input file!\n";
+
+  OwningPtr<MemoryBuffer> Buff;
+  if (error_code ec = MemoryBuffer::getFileOrSTDIN(InputGCNO, Buff)) {
+    errs() << InputGCNO << ": " << ec.message() << "\n";
+    return 1;
+  }
+  GCOVBuffer GB(Buff.take());
+
+  if (!GF.read(GB)) {
+    errs() << "Invalid .gcno File!\n";
+    return 1;
+  }
+
+  if (!InputGCDA.empty()) {
+    OwningPtr<MemoryBuffer> Buff2;
+    if (error_code ec = MemoryBuffer::getFileOrSTDIN(InputGCDA, Buff2)) {
+      errs() << InputGCDA << ": " << ec.message() << "\n";
+      return 1;
+    }
+    GCOVBuffer GB2(Buff2.take());
+    
+    if (!GF.read(GB2)) {
+      errs() << "Invalid .gcda File!\n";
+      return 1;
+    }
+  }
+
+
+  if (DumpGCOV)
+    GF.dump();
+
+  FileInfo FI;
+  GF.collectLineCounts(FI);
+  return 0;
+}