//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Evan Cheng and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the machine register scavenger class. It can provide
// information such as unused register at any point in a machine basic block.
-// It also provides a mechanism to make registers availbale by evicting them
+// It also provides a mechanism to make registers available by evicting them
// to spill slots.
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_CODEGEN_REGISTER_SCAVENGING_H
-#define LLVM_CODEGEN_REGISTER_SCAVENGING_H
+#ifndef LLVM_CODEGEN_REGISTERSCAVENGING_H
+#define LLVM_CODEGEN_REGISTERSCAVENGING_H
-#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/ADT/BitVector.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
namespace llvm {
-class MRegisterInfo;
+class MachineRegisterInfo;
+class TargetRegisterInfo;
class TargetInstrInfo;
class TargetRegisterClass;
class RegScavenger {
+ const TargetRegisterInfo *TRI;
+ const TargetInstrInfo *TII;
+ MachineRegisterInfo* MRI;
MachineBasicBlock *MBB;
MachineBasicBlock::iterator MBBI;
- unsigned NumPhysRegs;
+ unsigned NumRegUnits;
- /// Tracking - True if RegScavenger is currently tracking the liveness of
- /// registers.
+ /// True if RegScavenger is currently tracking the liveness of registers.
bool Tracking;
- /// ScavengingFrameIndex - Special spill slot used for scavenging a register
- /// post register allocation.
- int ScavengingFrameIndex;
+ /// Information on scavenged registers (held in a spill slot).
+ struct ScavengedInfo {
+ ScavengedInfo(int FI = -1) : FrameIndex(FI), Reg(0), Restore(nullptr) {}
- /// ScavengedReg - If none zero, the specific register is currently being
- /// scavenged. That is, it is spilled to the special scavenging stack slot.
- unsigned ScavengedReg;
+ /// A spill slot used for scavenging a register post register allocation.
+ int FrameIndex;
- /// ScavengedRC - Register class of the scavenged register.
- ///
- const TargetRegisterClass *ScavengedRC;
+ /// If non-zero, the specific register is currently being
+ /// scavenged. That is, it is spilled to this scavenging stack slot.
+ unsigned Reg;
- /// RegStates - The current state of all the physical registers immediately
- /// before MBBI. One bit per physical register. If bit is set that means it's
- /// available, unset means the register is currently being used.
- BitVector RegStates;
+ /// The instruction that restores the scavenged register from stack.
+ const MachineInstr *Restore;
+ };
+
+ /// A vector of information on scavenged registers.
+ SmallVector<ScavengedInfo, 2> Scavenged;
+
+ /// The current state of each reg unit immediately before MBBI.
+ /// One bit per register unit. If bit is not set it means any
+ /// register containing that register unit is currently being used.
+ BitVector RegUnitsAvailable;
+
+ // These BitVectors are only used internally to forward(). They are members
+ // to avoid frequent reallocations.
+ BitVector KillRegUnits, DefRegUnits;
+ BitVector TmpRegUnits;
public:
RegScavenger()
- : MBB(NULL), NumPhysRegs(0), Tracking(false),
- ScavengingFrameIndex(-1), ScavengedReg(0), ScavengedRC(NULL) {};
-
- RegScavenger(MachineBasicBlock *mbb)
- : MBB(mbb), NumPhysRegs(0), Tracking(false),
- ScavengingFrameIndex(-1), ScavengedReg(0), ScavengedRC(NULL) {};
+ : MBB(nullptr), NumRegUnits(0), Tracking(false) {}
- /// enterBasicBlock - Start tracking liveness from the begin of the specific
- /// basic block.
+ /// Start tracking liveness from the begin of the specific basic block.
void enterBasicBlock(MachineBasicBlock *mbb);
- /// forward / backward - Move the internal MBB iterator and update register
- /// states.
+ /// Move the internal MBB iterator and update register states.
void forward();
- void backward();
- /// forward / backward - Move the internal MBB iterator and update register
- /// states until it has reached but not processed the specific iterator.
+ /// Move the internal MBB iterator and update register states until
+ /// it has processed the specific iterator.
void forward(MachineBasicBlock::iterator I) {
+ if (!Tracking && MBB->begin() != I) forward();
while (MBBI != I) forward();
}
- void backward(MachineBasicBlock::iterator I) {
- while (MBBI != I) backward();
+
+ /// Invert the behavior of forward() on the current instruction (undo the
+ /// changes to the available registers made by forward()).
+ void unprocess();
+
+ /// Unprocess instructions until you reach the provided iterator.
+ void unprocess(MachineBasicBlock::iterator I) {
+ while (MBBI != I) unprocess();
}
- /// skipTo - Move the internal MBB iterator but do not update register states.
- ///
- void skipTo(MachineBasicBlock::iterator I) { MBBI = I; }
+ /// Move the internal MBB iterator but do not update register states.
+ void skipTo(MachineBasicBlock::iterator I) {
+ if (I == MachineBasicBlock::iterator(nullptr))
+ Tracking = false;
+ MBBI = I;
+ }
- /// isReserved - Returns true if a register is reserved. It is never "unused".
- bool isReserved(unsigned Reg) const { return ReservedRegs[Reg]; }
+ MachineBasicBlock::iterator getCurrentPosition() const { return MBBI; }
- /// isUsed / isUsed - Test if a register is currently being used.
- ///
- bool isUsed(unsigned Reg) const { return !RegStates[Reg]; }
- bool isUnused(unsigned Reg) const { return RegStates[Reg]; }
+ /// Return if a specific register is currently used.
+ bool isRegUsed(unsigned Reg, bool includeReserved = true) const;
- /// setUsed / setUnused - Mark the state of one or a number of registers.
- ///
- void setUsed(unsigned Reg) { RegStates.reset(Reg); }
- void setUsed(BitVector Regs) { RegStates &= ~Regs; }
- void setUnused(unsigned Reg) { RegStates.set(Reg); }
- void setUnused(BitVector Regs) { RegStates |= Regs; }
-
- /// FindUnusedReg - Find a unused register of the specified register class
- /// from the specified set of registers. It return 0 is none is found.
- unsigned FindUnusedReg(const TargetRegisterClass *RegClass,
- const BitVector &Candidates) const;
-
- /// FindUnusedReg - Find a unused register of the specified register class.
- /// Exclude callee saved registers if directed. It return 0 is none is found.
- unsigned FindUnusedReg(const TargetRegisterClass *RegClass,
- bool ExCalleeSaved = false) const;
-
- /// setScavengingFrameIndex / getScavengingFrameIndex - accessor and setter of
- /// ScavengingFrameIndex.
- void setScavengingFrameIndex(int FI) { ScavengingFrameIndex = FI; }
- int getScavengingFrameIndex() const { return ScavengingFrameIndex; }
-
- /// scavengeRegister - Make a register of the specific register class
- /// available and do the appropriate bookkeeping. Returns the scavenged
- /// register.
+ /// Return all available registers in the register class in Mask.
+ BitVector getRegsAvailable(const TargetRegisterClass *RC);
+
+ /// Find an unused register of the specified register class.
+ /// Return 0 if none is found.
+ unsigned FindUnusedReg(const TargetRegisterClass *RegClass) const;
+
+ /// Add a scavenging frame index.
+ void addScavengingFrameIndex(int FI) {
+ Scavenged.push_back(ScavengedInfo(FI));
+ }
+
+ /// Query whether a frame index is a scavenging frame index.
+ bool isScavengingFrameIndex(int FI) const {
+ for (SmallVectorImpl<ScavengedInfo>::const_iterator I = Scavenged.begin(),
+ IE = Scavenged.end(); I != IE; ++I)
+ if (I->FrameIndex == FI)
+ return true;
+
+ return false;
+ }
+
+ /// Get an array of scavenging frame indices.
+ void getScavengingFrameIndices(SmallVectorImpl<int> &A) const {
+ for (SmallVectorImpl<ScavengedInfo>::const_iterator I = Scavenged.begin(),
+ IE = Scavenged.end(); I != IE; ++I)
+ if (I->FrameIndex >= 0)
+ A.push_back(I->FrameIndex);
+ }
+
+ /// Make a register of the specific register class
+ /// available and do the appropriate bookkeeping. SPAdj is the stack
+ /// adjustment due to call frame, it's passed along to eliminateFrameIndex().
+ /// Returns the scavenged register.
unsigned scavengeRegister(const TargetRegisterClass *RegClass,
- MachineBasicBlock::iterator I);
- unsigned scavengeRegister(const TargetRegisterClass *RegClass) {
- return scavengeRegister(RegClass, MBBI);
+ MachineBasicBlock::iterator I, int SPAdj);
+ unsigned scavengeRegister(const TargetRegisterClass *RegClass, int SPAdj) {
+ return scavengeRegister(RegClass, MBBI, SPAdj);
}
+ /// Tell the scavenger a register is used.
+ void setRegUsed(unsigned Reg, LaneBitmask LaneMask = ~0u);
private:
- const MRegisterInfo *RegInfo;
- const TargetInstrInfo *TII;
+ /// Returns true if a register is reserved. It is never "unused".
+ bool isReserved(unsigned Reg) const { return MRI->isReserved(Reg); }
- /// CalleeSavedrRegs - A bitvector of callee saved registers for the target.
+ /// setUsed / setUnused - Mark the state of one or a number of register units.
///
- BitVector CalleeSavedRegs;
+ void setUsed(BitVector &RegUnits) {
+ RegUnitsAvailable.reset(RegUnits);
+ }
+ void setUnused(BitVector &RegUnits) {
+ RegUnitsAvailable |= RegUnits;
+ }
- /// ReservedRegs - A bitvector of reserved registers.
- ///
- BitVector ReservedRegs;
+ /// Processes the current instruction and fill the KillRegUnits and
+ /// DefRegUnits bit vectors.
+ void determineKillsAndDefs();
- /// restoreScavengedReg - Restore scavenged by loading it back from the
- /// emergency spill slot. Mark it used.
- void restoreScavengedReg();
+ /// Add all Reg Units that Reg contains to BV.
+ void addRegUnits(BitVector &BV, unsigned Reg);
+
+ /// Return the candidate register that is unused for the longest after
+ /// StartMI. UseMI is set to the instruction where the search stopped.
+ ///
+ /// No more than InstrLimit instructions are inspected.
+ unsigned findSurvivorReg(MachineBasicBlock::iterator StartMI,
+ BitVector &Candidates,
+ unsigned InstrLimit,
+ MachineBasicBlock::iterator &UseMI);
+
+ /// Allow resetting register state info for multiple
+ /// passes over/within the same function.
+ void initRegState();
};
-
+
} // End llvm namespace
#endif
projects / oota-llvm.git / blobdiff