Define InitLLVM to do common initialization all at once.

We have a few functions that virtually all command wants to run on
process startup/shutdown. This patch adds InitLLVM class to do that
all at once, so that we don't need to copy-n-paste boilerplate code
to each llvm command's main() function.

Differential Revision: https://reviews.llvm.org/D45602

llvm-svn: 330046
diff --git a/llvm/tools/llvm-mca/llvm-mca.cpp b/llvm/tools/llvm-mca/llvm-mca.cpp
index 89900a4..a304d47 100644
--- a/llvm/tools/llvm-mca/llvm-mca.cpp
+++ b/llvm/tools/llvm-mca/llvm-mca.cpp
@@ -41,9 +41,8 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/PrettyStackTrace.h"
-#include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
@@ -276,9 +275,7 @@
 } // end of anonymous namespace
 
 int main(int argc, char **argv) {
-  sys::PrintStackTraceOnErrorSignal(argv[0]);
-  PrettyStackTraceProgram X(argc, argv);
-  llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
+  InitLLVM X(argc, argv);
 
   // Initialize targets and assembly parsers.
   llvm::InitializeAllTargetInfos();