Reorganization: Move the Spiller out of VirtRegMap.cpp into its own files. No (intended) functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66720 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 312 insertions, 0 deletions

diff --git a/lib/CodeGen/Spiller.h b/lib/CodeGen/Spiller.h
new file mode 100644
index 0000000000..ae9565d4ac
--- /dev/null
+++ b/lib/CodeGen/Spiller.h
@@ -0,0 +1,312 @@
+//===-- llvm/CodeGen/Spiller.h - Spiller -*- C++ -*------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SPILLER_H
+#define LLVM_CODEGEN_SPILLER_H
+
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/IndexedMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "VirtRegMap.h"
+#include <map>
+
+namespace llvm {
+  
+  /// Spiller interface: Implementations of this interface assign spilled
+  /// virtual registers to stack slots, rewriting the code.
+  struct Spiller {
+    virtual ~Spiller();
+    virtual bool runOnMachineFunction(MachineFunction &MF,
+                                      VirtRegMap &VRM) = 0;
+  };
+
+  /// createSpiller - Create an return a spiller object, as specified on the
+  /// command line.
+  Spiller* createSpiller();
+  
+  // ************************************************************************ //
+  
+  // Simple Spiller Implementation
+  struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
+    bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
+  };
+  
+  // ************************************************************************ //
+  
+  /// AvailableSpills - As the local spiller is scanning and rewriting an MBB
+  /// from top down, keep track of which spills slots or remat are available in
+  /// each register.
+  ///
+  /// Note that not all physregs are created equal here.  In particular, some
+  /// physregs are reloads that we are allowed to clobber or ignore at any time.
+  /// Other physregs are values that the register allocated program is using
+  /// that we cannot CHANGE, but we can read if we like.  We keep track of this
+  /// on a per-stack-slot / remat id basis as the low bit in the value of the
+  /// SpillSlotsAvailable entries.  The predicate 'canClobberPhysReg()' checks
+  /// this bit and addAvailable sets it if.
+  class VISIBILITY_HIDDEN AvailableSpills {
+    const TargetRegisterInfo *TRI;
+    const TargetInstrInfo *TII;
+
+    // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled
+    // or remat'ed virtual register values that are still available, due to
+    // being loaded or stored to, but not invalidated yet.
+    std::map<int, unsigned> SpillSlotsOrReMatsAvailable;
+
+    // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable,
+    // indicating which stack slot values are currently held by a physreg.  This
+    // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a
+    // physreg is modified.
+    std::multimap<unsigned, int> PhysRegsAvailable;
+
+    void disallowClobberPhysRegOnly(unsigned PhysReg);
+
+    void ClobberPhysRegOnly(unsigned PhysReg);
+  public:
+    AvailableSpills(const TargetRegisterInfo *tri, const TargetInstrInfo *tii)
+      : TRI(tri), TII(tii) {
+    }
+
+    /// clear - Reset the state.
+    void clear() {
+      SpillSlotsOrReMatsAvailable.clear();
+      PhysRegsAvailable.clear();
+    }
+
+    const TargetRegisterInfo *getRegInfo() const { return TRI; }
+
+    /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is
+    /// available in a  physical register, return that PhysReg, otherwise
+    /// return 0.
+    unsigned getSpillSlotOrReMatPhysReg(int Slot) const {
+      std::map<int, unsigned>::const_iterator I =
+        SpillSlotsOrReMatsAvailable.find(Slot);
+      if (I != SpillSlotsOrReMatsAvailable.end()) {
+        return I->second >> 1;  // Remove the CanClobber bit.
+      }
+      return 0;
+    }
+
+    /// addAvailable - Mark that the specified stack slot / remat is available
+    /// in the specified physreg.  If CanClobber is true, the physreg can be
+    /// modified at any time without changing the semantics of the program.
+    void addAvailable(int SlotOrReMat, unsigned Reg, bool CanClobber = true) {
+      // If this stack slot is thought to be available in some other physreg, 
+      // remove its record.
+      ModifyStackSlotOrReMat(SlotOrReMat);
+
+      PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
+      SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) |
+                                                (unsigned)CanClobber;
+
+      if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
+        DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
+      else
+        DOUT << "Remembering SS#" << SlotOrReMat;
+      DOUT << " in physreg " << TRI->getName(Reg) << "\n";
+    }
+
+    /// canClobberPhysReg - Return true if the spiller is allowed to change the 
+    /// value of the specified stackslot register if it desires.  The specified
+    /// stack slot must be available in a physreg for this query to make sense.
+    bool canClobberPhysReg(int SlotOrReMat) const {
+      assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
+             "Value not available!");
+      return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
+    }
+
+    /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
+    /// stackslot register. The register is still available but is no longer
+    /// allowed to be modifed.
+    void disallowClobberPhysReg(unsigned PhysReg);
+
+    /// ClobberPhysReg - This is called when the specified physreg changes
+    /// value.  We use this to invalidate any info about stuff that lives in
+    /// it and any of its aliases.
+    void ClobberPhysReg(unsigned PhysReg);
+
+    /// ModifyStackSlotOrReMat - This method is called when the value in a stack
+    /// slot changes.  This removes information about which register the
+    /// previous value for this slot lives in (as the previous value is dead
+    /// now).
+    void ModifyStackSlotOrReMat(int SlotOrReMat);
+
+    /// AddAvailableRegsToLiveIn - Availability information is being kept coming
+    /// into the specified MBB. Add available physical registers as potential
+    /// live-in's. If they are reused in the MBB, they will be added to the
+    /// live-in set to make register scavenger and post-allocation scheduler.
+    void AddAvailableRegsToLiveIn(MachineBasicBlock &MBB, BitVector &RegKills,
+                                  std::vector<MachineOperand*> &KillOps);
+  };
+  
+  // ************************************************************************ //
+  
+  // ReusedOp - For each reused operand, we keep track of a bit of information,
+  // in case we need to rollback upon processing a new operand.  See comments
+  // below.
+  struct ReusedOp {
+    // The MachineInstr operand that reused an available value.
+    unsigned Operand;
+
+    // StackSlotOrReMat - The spill slot or remat id of the value being reused.
+    unsigned StackSlotOrReMat;
+
+    // PhysRegReused - The physical register the value was available in.
+    unsigned PhysRegReused;
+
+    // AssignedPhysReg - The physreg that was assigned for use by the reload.
+    unsigned AssignedPhysReg;
+    
+    // VirtReg - The virtual register itself.
+    unsigned VirtReg;
+
+    ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
+             unsigned vreg)
+      : Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
+        AssignedPhysReg(apr), VirtReg(vreg) {}
+  };
+  
+  /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
+  /// is reused instead of reloaded.
+  class VISIBILITY_HIDDEN ReuseInfo {
+    MachineInstr &MI;
+    std::vector<ReusedOp> Reuses;
+    BitVector PhysRegsClobbered;
+  public:
+    ReuseInfo(MachineInstr &mi, const TargetRegisterInfo *tri) : MI(mi) {
+      PhysRegsClobbered.resize(tri->getNumRegs());
+    }
+    
+    bool hasReuses() const {
+      return !Reuses.empty();
+    }
+    
+    /// addReuse - If we choose to reuse a virtual register that is already
+    /// available instead of reloading it, remember that we did so.
+    void addReuse(unsigned OpNo, unsigned StackSlotOrReMat,
+                  unsigned PhysRegReused, unsigned AssignedPhysReg,
+                  unsigned VirtReg) {
+      // If the reload is to the assigned register anyway, no undo will be
+      // required.
+      if (PhysRegReused == AssignedPhysReg) return;
+      
+      // Otherwise, remember this.
+      Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused, 
+                                AssignedPhysReg, VirtReg));
+    }
+
+    void markClobbered(unsigned PhysReg) {
+      PhysRegsClobbered.set(PhysReg);
+    }
+
+    bool isClobbered(unsigned PhysReg) const {
+      return PhysRegsClobbered.test(PhysReg);
+    }
+    
+    /// GetRegForReload - We are about to emit a reload into PhysReg.  If there
+    /// is some other operand that is using the specified register, either pick
+    /// a new register to use, or evict the previous reload and use this reg. 
+    unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
+                             AvailableSpills &Spills,
+                             std::vector<MachineInstr*> &MaybeDeadStores,
+                             SmallSet<unsigned, 8> &Rejected,
+                             BitVector &RegKills,
+                             std::vector<MachineOperand*> &KillOps,
+                             VirtRegMap &VRM);
+
+    /// GetRegForReload - Helper for the above GetRegForReload(). Add a
+    /// 'Rejected' set to remember which registers have been considered and
+    /// rejected for the reload. This avoids infinite looping in case like
+    /// this:
+    /// t1 := op t2, t3
+    /// t2 <- assigned r0 for use by the reload but ended up reuse r1
+    /// t3 <- assigned r1 for use by the reload but ended up reuse r0
+    /// t1 <- desires r1
+    ///       sees r1 is taken by t2, tries t2's reload register r0
+    ///       sees r0 is taken by t3, tries t3's reload register r1
+    ///       sees r1 is taken by t2, tries t2's reload register r0 ...
+    unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
+                             AvailableSpills &Spills,
+                             std::vector<MachineInstr*> &MaybeDeadStores,
+                             BitVector &RegKills,
+                             std::vector<MachineOperand*> &KillOps,
+                             VirtRegMap &VRM) {
+      SmallSet<unsigned, 8> Rejected;
+      return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
+                             RegKills, KillOps, VRM);
+    }
+  };
+  
+  // ************************************************************************ //
+  
+  /// LocalSpiller - This spiller does a simple pass over the machine basic
+  /// block to attempt to keep spills in registers as much as possible for
+  /// blocks that have low register pressure (the vreg may be spilled due to
+  /// register pressure in other blocks).
+  class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
+    MachineRegisterInfo *RegInfo;
+    const TargetRegisterInfo *TRI;
+    const TargetInstrInfo *TII;
+    DenseMap<MachineInstr*, unsigned> DistanceMap;
+  public:
+    bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM);
+  private:
+    void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
+                          unsigned Reg, BitVector &RegKills,
+                          std::vector<MachineOperand*> &KillOps);
+    bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
+                           MachineBasicBlock::iterator &MII,
+                           std::vector<MachineInstr*> &MaybeDeadStores,
+                           AvailableSpills &Spills, BitVector &RegKills,
+                           std::vector<MachineOperand*> &KillOps,
+                           VirtRegMap &VRM);
+    bool CommuteToFoldReload(MachineBasicBlock &MBB,
+                             MachineBasicBlock::iterator &MII,
+                             unsigned VirtReg, unsigned SrcReg, int SS,
+                             AvailableSpills &Spills,
+                             BitVector &RegKills,
+                             std::vector<MachineOperand*> &KillOps,
+                             const TargetRegisterInfo *TRI,
+                             VirtRegMap &VRM);
+    void SpillRegToStackSlot(MachineBasicBlock &MBB,
+                             MachineBasicBlock::iterator &MII,
+                             int Idx, unsigned PhysReg, int StackSlot,
+                             const TargetRegisterClass *RC,
+                             bool isAvailable, MachineInstr *&LastStore,
+                             AvailableSpills &Spills,
+                             SmallSet<MachineInstr*, 4> &ReMatDefs,
+                             BitVector &RegKills,
+                             std::vector<MachineOperand*> &KillOps,
+                             VirtRegMap &VRM);
+    void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
+                    AvailableSpills &Spills,
+                    BitVector &RegKills, std::vector<MachineOperand*> &KillOps);
+  };
+}
+
+#endif
\ No newline at end of file