//
// 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 {
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;
- /// ScavengeRestore - Instruction that restores the scavenged register from
- /// stack.
- const MachineInstr *ScavengeRestore;
+ /// The instruction that restores the scavenged register from stack.
+ const MachineInstr *Restore;
+ };
- /// CalleeSavedrRegs - A bitvector of callee saved registers for the target.
- ///
- BitVector CalleeSavedRegs;
+ /// A vector of information on scavenged registers.
+ SmallVector<ScavengedInfo, 2> Scavenged;
- /// ReservedRegs - A bitvector of reserved registers.
- ///
- BitVector ReservedRegs;
+ /// 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;
- /// RegsAvailable - 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 RegsAvailable;
+ // 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) {}
+ : 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);
- /// initRegState - allow resetting register state info for multiple
- /// passes over/within the same function.
- void initRegState();
-
- /// forward - Move the internal MBB iterator and update register states.
+ /// Move the internal MBB iterator and update register states.
void forward();
- /// forward - Move the internal MBB iterator and update register states until
+ /// 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();
}
- /// skipTo - Move the internal MBB iterator but do not update register states.
- ///
- void skipTo(MachineBasicBlock::iterator I) { MBBI = I; }
+ /// 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();
+ }
+
+ /// 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;
+ }
- /// getRegsUsed - return all registers currently in use in used.
- void getRegsUsed(BitVector &used, bool includeReserved);
+ MachineBasicBlock::iterator getCurrentPosition() const { return MBBI; }
- /// getRegsAvailable - Return all available registers in the register class
- /// in Mask.
+ /// Return if a specific register is currently used.
+ bool isRegUsed(unsigned Reg, bool includeReserved = true) const;
+
+ /// Return all available registers in the register class in Mask.
BitVector getRegsAvailable(const TargetRegisterClass *RC);
- /// FindUnusedReg - Find a unused register of the specified register class.
+ /// Find an unused register of the specified register class.
/// Return 0 if none is found.
unsigned FindUnusedReg(const TargetRegisterClass *RegClass) const;
- /// setScavengingFrameIndex / getScavengingFrameIndex - accessor and setter of
- /// ScavengingFrameIndex.
- void setScavengingFrameIndex(int FI) { ScavengingFrameIndex = FI; }
- int getScavengingFrameIndex() const { return ScavengingFrameIndex; }
+ /// 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);
+ }
- /// scavengeRegister - Make a register of the specific register class
+ /// 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.
return scavengeRegister(RegClass, MBBI, SPAdj);
}
- /// setUsed - Tell the scavenger a register is used.
- ///
- void setUsed(unsigned Reg);
+ /// Tell the scavenger a register is used.
+ void setRegUsed(unsigned Reg, LaneBitmask LaneMask = ~0u);
private:
- /// isReserved - Returns true if a register is reserved. It is never "unused".
- bool isReserved(unsigned Reg) const { return ReservedRegs.test(Reg); }
-
- /// isUsed / isUnused - Test if a register is currently being used.
- ///
- bool isUsed(unsigned Reg) const { return !RegsAvailable.test(Reg); }
- bool isUnused(unsigned Reg) const { return RegsAvailable.test(Reg); }
+ /// Returns true if a register is reserved. It is never "unused".
+ bool isReserved(unsigned Reg) const { return MRI->isReserved(Reg); }
- /// isAliasUsed - Is Reg or an alias currently in use?
- bool isAliasUsed(unsigned Reg) const;
-
- /// setUsed / setUnused - Mark the state of one or a number of registers.
+ /// setUsed / setUnused - Mark the state of one or a number of register units.
///
- void setUsed(BitVector &Regs) {
- RegsAvailable &= ~Regs;
+ void setUsed(BitVector &RegUnits) {
+ RegUnitsAvailable.reset(RegUnits);
}
- void setUnused(BitVector &Regs) {
- RegsAvailable |= Regs;
+ void setUnused(BitVector &RegUnits) {
+ RegUnitsAvailable |= RegUnits;
}
- /// Add Reg and all its sub-registers to BV.
- void addRegWithSubRegs(BitVector &BV, unsigned Reg);
+ /// Processes the current instruction and fill the KillRegUnits and
+ /// DefRegUnits bit vectors.
+ void determineKillsAndDefs();
- /// Add Reg and its aliases to BV.
- void addRegWithAliases(BitVector &BV, unsigned Reg);
+ /// Add all Reg Units that Reg contains to BV.
+ void addRegUnits(BitVector &BV, unsigned Reg);
- /// findSurvivorReg - Return the candidate register that is unused for the
- /// longest after StartMI. UseMI is set to the instruction where the search
- /// stopped.
+ /// 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,
unsigned InstrLimit,
MachineBasicBlock::iterator &UseMI);
+ /// Allow resetting register state info for multiple
+ /// passes over/within the same function.
+ void initRegState();
};
} // End llvm namespace
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