Stop tracking unused registers in VirtRegMap.

The information was only used by the register allocator in
StackSlotColoring.

llvm-svn: 144482

Author: stoklund

llvm/lib/CodeGen/StackSlotColoring.cpp

@@ -49,11 +49,8 @@ namespace {
   class StackSlotColoring : public MachineFunctionPass {
     bool ColorWithRegs;
     LiveStacks* LS;
-    VirtRegMap* VRM;
     MachineFrameInfo *MFI;
-    MachineRegisterInfo *MRI;
     const TargetInstrInfo  *TII;
-    const TargetRegisterInfo *TRI;
     const MachineLoopInfo *loopInfo;
 
     // SSIntervals - Spill slot intervals.
@@ -414,21 +411,16 @@ bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
     });
 
   MFI = MF.getFrameInfo();
-  MRI = &MF.getRegInfo(); 
   TII = MF.getTarget().getInstrInfo();
-  TRI = MF.getTarget().getRegisterInfo();
   LS = &getAnalysis<LiveStacks>();
-  VRM = &getAnalysis<VirtRegMap>();
   loopInfo = &getAnalysis<MachineLoopInfo>();
 
   bool Changed = false;
 
   unsigned NumSlots = LS->getNumIntervals();
-  if (NumSlots < 2) {
-    if (NumSlots == 0 || !VRM->HasUnusedRegisters())
-      // Nothing to do!
-      return false;
-  }
+  if (NumSlots == 0)
+    // Nothing to do!
+    return false;
 
   // If there are calls to setjmp or sigsetjmp, don't perform stack slot
   // coloring. The stack could be modified before the longjmp is executed,

llvm/lib/CodeGen/VirtRegMap.cpp

@@ -221,41 +221,6 @@ void VirtRegMap::RemoveMachineInstrFromMaps(MachineInstr *MI) {
   EmergencySpillMap.erase(MI);
 }
 
-/// FindUnusedRegisters - Gather a list of allocatable registers that
-/// have not been allocated to any virtual register.
-bool VirtRegMap::FindUnusedRegisters(LiveIntervals* LIs) {
-  unsigned NumRegs = TRI->getNumRegs();
-  UnusedRegs.reset();
-  UnusedRegs.resize(NumRegs);
-
-  BitVector Used(NumRegs);
-  for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
-    unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
-    if (Virt2PhysMap[Reg] != (unsigned)VirtRegMap::NO_PHYS_REG)
-      Used.set(Virt2PhysMap[Reg]);
-  }
-
-  BitVector Allocatable = TRI->getAllocatableSet(*MF);
-  bool AnyUnused = false;
-  for (unsigned Reg = 1; Reg < NumRegs; ++Reg) {
-    if (Allocatable[Reg] && !Used[Reg] && !LIs->hasInterval(Reg)) {
-      bool ReallyUnused = true;
-      for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) {
-        if (Used[*AS] || LIs->hasInterval(*AS)) {
-          ReallyUnused = false;
-          break;
-        }
-      }
-      if (ReallyUnused) {
-        AnyUnused = true;
-        UnusedRegs.set(Reg);
-      }
-    }
-  }
-
-  return AnyUnused;
-}
-
 void VirtRegMap::rewrite(SlotIndexes *Indexes) {
   DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
                << "********** Function: "

llvm/lib/CodeGen/VirtRegMap.h

@@ -132,9 +132,6 @@ namespace llvm {
     /// the register is implicitly defined.
     BitVector ImplicitDefed;
 
-    /// UnusedRegs - A list of physical registers that have not been used.
-    BitVector UnusedRegs;
-
     /// createSpillSlot - Allocate a spill slot for RC from MFI.
     unsigned createSpillSlot(const TargetRegisterClass *RC);
 
@@ -475,39 +472,6 @@ namespace llvm {
     /// the folded instruction map and spill point map.
     void RemoveMachineInstrFromMaps(MachineInstr *MI);
 
-    /// FindUnusedRegisters - Gather a list of allocatable registers that
-    /// have not been allocated to any virtual register.
-    bool FindUnusedRegisters(LiveIntervals* LIs);
-
-    /// HasUnusedRegisters - Return true if there are any allocatable registers
-    /// that have not been allocated to any virtual register.
-    bool HasUnusedRegisters() const {
-      return !UnusedRegs.none();
-    }
-
-    /// setRegisterUsed - Remember the physical register is now used.
-    void setRegisterUsed(unsigned Reg) {
-      UnusedRegs.reset(Reg);
-    }
-
-    /// isRegisterUnused - Return true if the physical register has not been
-    /// used.
-    bool isRegisterUnused(unsigned Reg) const {
-      return UnusedRegs[Reg];
-    }
-
-    /// getFirstUnusedRegister - Return the first physical register that has not
-    /// been used.
-    unsigned getFirstUnusedRegister(const TargetRegisterClass *RC) {
-      int Reg = UnusedRegs.find_first();
-      while (Reg != -1) {
-        if (allocatableRCRegs[RC][Reg])
-          return (unsigned)Reg;
-        Reg = UnusedRegs.find_next(Reg);
-      }
-      return 0;
-    }
-
     /// rewrite - Rewrite all instructions in MF to use only physical registers
     /// by mapping all virtual register operands to their assigned physical
     /// registers.