IPRA: Exit early on functions without calls

[MatzeB]

LGTM

[arsenm]

r311636

lib/CodeGen/RegUsageInfoPropagate.cpp

 /// is available then this pass will update the RegMask of the call instruction.
 /// This updated RegMask will be used by the register allocator while allocating
 /// the current MachineFunction.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/RegisterUsageInfo.h"
 #include "llvm/IR/Module.h"
 #include "llvm/PassAnalysisSupport.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"

 bool RegUsageInfoPropagationPass::runOnMachineFunction(MachineFunction &MF) {
   const Module *M = MF.getFunction()->getParent();
   PhysicalRegisterUsageInfo *PRUI = &getAnalysis<PhysicalRegisterUsageInfo>();
 
   DEBUG(dbgs() << " ++++++++++++++++++++ " << getPassName()
                << " ++++++++++++++++++++  \n");
   DEBUG(dbgs() << "MachineFunction : " << MF.getName() << "\n");
 
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  if (!MFI.hasCalls() && !MFI.hasTailCall())
+    return false;
+
   bool Changed = false;
 
   for (MachineBasicBlock &MBB : MF) {
     for (MachineInstr &MI : MBB) {
       if (!MI.isCall())
         continue;
       DEBUG(dbgs()
             << "Call Instruction Before Register Usage Info Propagation : \n");