[PEI] Simplify handling of targets with no phys regs. NFC

[thegameg]

Summary

Make doSpillCalleeSavedRegs a member function, instead of passing most of the members of PEI as arguments.

[MatzeB]

LGTM. I wish we wouldn't use std::functions here at all and instead something like a base class with two subclasses, but that is for another patch.

[thegameg]

Reverted in r308581.

[thegameg]

Rebased and commited in rL317309.

llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp

 #include "llvm/Target/TargetSubtargetInfo.h"
 #include <climits>
 
 using namespace llvm;
 
 #define DEBUG_TYPE "prologepilog"
 
 typedef SmallVector<MachineBasicBlock *, 4> MBBVector;
-static void doSpillCalleeSavedRegs(MachineFunction &MF, RegScavenger *RS,
-                                   unsigned &MinCSFrameIndex,
-                                   unsigned &MaxCXFrameIndex,
-                                   const MBBVector &SaveBlocks,
-                                   const MBBVector &RestoreBlocks);
-
 namespace {
 class PEI : public MachineFunctionPass {
 public:
   static char ID;
   PEI() : MachineFunctionPass(ID) {
     initializePEIPass(*PassRegistry::getPassRegistry());
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override;
 
   MachineFunctionProperties getRequiredProperties() const override {
     MachineFunctionProperties MFP;
     if (UsesCalleeSaves)
       MFP.set(MachineFunctionProperties::Property::NoVRegs);
     return MFP;
   }
 
   /// runOnMachineFunction - Insert prolog/epilog code and replace abstract
   /// frame indexes with appropriate references.
   ///
   bool runOnMachineFunction(MachineFunction &Fn) override;
 
 private:
-  std::function<void(MachineFunction &MF, RegScavenger *RS,
-                     unsigned &MinCSFrameIndex, unsigned &MaxCSFrameIndex,
-                     const MBBVector &SaveBlocks,
-                     const MBBVector &RestoreBlocks)>
-      SpillCalleeSavedRegisters;
+  std::function<void(MachineFunction &MF)> SpillCalleeSavedRegisters;
   std::function<void(MachineFunction &MF, RegScavenger &RS)>
       ScavengeFrameVirtualRegs;
 
   bool UsesCalleeSaves = false;
 
   RegScavenger *RS;
 
   // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved
private:
   bool FrameIndexVirtualScavenging;
 
   // Flag to control whether the scavenger should be passed even though
   // FrameIndexVirtualScavenging is used.
   bool FrameIndexEliminationScavenging;
 
   void calculateCallFrameInfo(MachineFunction &Fn);
   void calculateSaveRestoreBlocks(MachineFunction &Fn);
-
+  void doSpillCalleeSavedRegs(MachineFunction &MF);
   void calculateFrameObjectOffsets(MachineFunction &Fn);
   void replaceFrameIndices(MachineFunction &Fn);
   void replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn,
                            int &SPAdj);
   void insertPrologEpilogCode(MachineFunction &Fn);
 };
 } // namespace
 

 
 /// runOnMachineFunction - Insert prolog/epilog code and replace abstract
 /// frame indexes with appropriate references.
 ///
 bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   if (!SpillCalleeSavedRegisters) {
     const TargetMachine &TM = Fn.getTarget();
     if (!TM.usesPhysRegsForPEI()) {
-      SpillCalleeSavedRegisters = [](MachineFunction &, RegScavenger *,
-                                     unsigned &, unsigned &, const MBBVector &,
-                                     const MBBVector &) {};
+      SpillCalleeSavedRegisters = [](MachineFunction &) {};
       ScavengeFrameVirtualRegs = [](MachineFunction &, RegScavenger &) {};
     } else {
-      SpillCalleeSavedRegisters = doSpillCalleeSavedRegs;
+      SpillCalleeSavedRegisters = [this](MachineFunction &Fn) {
+        this->doSpillCalleeSavedRegs(Fn);
+      };
       ScavengeFrameVirtualRegs = scavengeFrameVirtualRegs;
       UsesCalleeSaves = true;
     }
   }
 
   const Function* F = Fn.getFunction();
   const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
   const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
 
   RS = TRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : nullptr;
   FrameIndexVirtualScavenging = TRI->requiresFrameIndexScavenging(Fn);
   FrameIndexEliminationScavenging = (RS && !FrameIndexVirtualScavenging) ||
     TRI->requiresFrameIndexReplacementScavenging(Fn);
 
   // Calculate the MaxCallFrameSize and AdjustsStack variables for the
   // function's frame information. Also eliminates call frame pseudo
   // instructions.
   calculateCallFrameInfo(Fn);
 
   // Determine placement of CSR spill/restore code and prolog/epilog code:
   // place all spills in the entry block, all restores in return blocks.
   calculateSaveRestoreBlocks(Fn);
 
   // Handle CSR spilling and restoring, for targets that need it.
-  SpillCalleeSavedRegisters(Fn, RS, MinCSFrameIndex, MaxCSFrameIndex,
-                            SaveBlocks, RestoreBlocks);
+  SpillCalleeSavedRegisters(Fn);
 
   // Allow the target machine to make final modifications to the function
   // before the frame layout is finalized.
   TFI->processFunctionBeforeFrameFinalized(Fn, RS);
 
   // Calculate actual frame offsets for all abstract stack objects...
   calculateFrameObjectOffsets(Fn);
 
for (const CalleeSavedInfo &CI : reverse(CSI)) {
       assert(I != RestoreBlock.begin() &&
              "loadRegFromStackSlot didn't insert any code!");
       // Insert in reverse order.  loadRegFromStackSlot can insert
       // multiple instructions.
     }
   }
 }
 
-static void doSpillCalleeSavedRegs(MachineFunction &Fn, RegScavenger *RS,
-                                   unsigned &MinCSFrameIndex,
-                                   unsigned &MaxCSFrameIndex,
-                                   const MBBVector &SaveBlocks,
-                                   const MBBVector &RestoreBlocks) {
+void PEI::doSpillCalleeSavedRegs(MachineFunction &Fn) {
   const Function *F = Fn.getFunction();
   const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
   MachineFrameInfo &MFI = Fn.getFrameInfo();
   ArrayRef<CalleeSavedInfo> CSI = MFI.getCalleeSavedInfo();
   MinCSFrameIndex = std::numeric_limits<unsigned>::max();
   MaxCSFrameIndex = 0;
 
   // Determine which of the registers in the callee save list should be saved.