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//===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- C++ -*--------===//
// The LLVM Compiler Infrastructure
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
// This file implements a virtual register map. This maps virtual registers to
// physical registers and virtual registers to stack slots. It is created and
// updated by a register allocator and then used by a machine code rewriter that
// adds spill code and rewrites virtual into physical register references.
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/IndexedMap.h"
#include "llvm/Support/Streams.h"
#include <map>
namespace llvm {
class MachineInstr;
class MachineFunction;
class TargetInstrInfo;
class VirtRegMap {
enum {
NO_STACK_SLOT = (1L << 30)-1,
MAX_STACK_SLOT = (1L << 18)-1
enum ModRef { isRef = 1, isMod = 2, isModRef = 3 };
typedef std::multimap<MachineInstr*,
std::pair<unsigned, ModRef> > MI2VirtMapTy;
const TargetInstrInfo &TII;
MachineFunction &MF;
/// Virt2PhysMap - This is a virtual to physical register
/// mapping. Each virtual register is required to have an entry in
/// it; even spilled virtual registers (the register mapped to a
/// spilled register is the temporary used to load it from the
/// stack).
IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2PhysMap;
/// Virt2StackSlotMap - This is virtual register to stack slot
/// mapping. Each spilled virtual register has an entry in it
/// which corresponds to the stack slot this register is spilled
/// at.
IndexedMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap;
IndexedMap<int, VirtReg2IndexFunctor> Virt2ReMatIdMap;
/// MI2VirtMap - This is MachineInstr to virtual register
/// mapping. In the case of memory spill code being folded into
/// instructions, we need to know which virtual register was
/// read/written by this instruction.
MI2VirtMapTy MI2VirtMap;
/// ReMatMap - This is virtual register to re-materialized instruction
/// mapping. Each virtual register whose definition is going to be
/// re-materialized has an entry in it.
IndexedMap<MachineInstr*, VirtReg2IndexFunctor> ReMatMap;
/// ReMatId - Instead of assigning a stack slot to a to be rematerialized
/// virtual register, an unique id is being assigned. This keeps track of
/// the highest id used so far. Note, this starts at (1<<18) to avoid
/// conflicts with stack slot numbers.
int ReMatId;
VirtRegMap(const VirtRegMap&); // DO NOT IMPLEMENT
void operator=(const VirtRegMap&); // DO NOT IMPLEMENT
explicit VirtRegMap(MachineFunction &mf);
void grow();
/// @brief returns true if the specified virtual register is
/// mapped to a physical register
bool hasPhys(unsigned virtReg) const {
return getPhys(virtReg) != NO_PHYS_REG;
/// @brief returns the physical register mapped to the specified
/// virtual register
unsigned getPhys(unsigned virtReg) const {
return Virt2PhysMap[virtReg];
/// @brief creates a mapping for the specified virtual register to
/// the specified physical register
void assignVirt2Phys(unsigned virtReg, unsigned physReg) {
assert(MRegisterInfo::isVirtualRegister(virtReg) &&
assert(Virt2PhysMap[virtReg] == NO_PHYS_REG &&
"attempt to assign physical register to already mapped "
"virtual register");
Virt2PhysMap[virtReg] = physReg;
/// @brief clears the specified virtual register's, physical
/// register mapping
void clearVirt(unsigned virtReg) {
assert(Virt2PhysMap[virtReg] != NO_PHYS_REG &&
"attempt to clear a not assigned virtual register");
Virt2PhysMap[virtReg] = NO_PHYS_REG;
/// @brief clears all virtual to physical register mappings
void clearAllVirt() {
/// @brief returns true is the specified virtual register is not
/// mapped to a stack slot or rematerialized.
bool isAssignedReg(unsigned virtReg) const {
return getStackSlot(virtReg) == NO_STACK_SLOT &&
getReMatId(virtReg) == NO_STACK_SLOT;
/// @brief returns the stack slot mapped to the specified virtual
/// register
int getStackSlot(unsigned virtReg) const {
return Virt2StackSlotMap[virtReg];
/// @brief returns the rematerialization id mapped to the specified virtual
/// register
int getReMatId(unsigned virtReg) const {
return Virt2ReMatIdMap[virtReg];
/// @brief create a mapping for the specifed virtual register to
/// the next available stack slot
int assignVirt2StackSlot(unsigned virtReg);
/// @brief create a mapping for the specified virtual register to
/// the specified stack slot
void assignVirt2StackSlot(unsigned virtReg, int frameIndex);
/// @brief assign an unique re-materialization id to the specified
/// virtual register.
int assignVirtReMatId(unsigned virtReg);
/// @brief assign an unique re-materialization id to the specified
/// virtual register.
void assignVirtReMatId(unsigned virtReg, int id);
/// @brief returns true if the specified virtual register is being
/// re-materialized.
bool isReMaterialized(unsigned virtReg) const {
return ReMatMap[virtReg] != NULL;
/// @brief returns the original machine instruction being re-issued
/// to re-materialize the specified virtual register.
MachineInstr *getReMaterializedMI(unsigned virtReg) const {
return ReMatMap[virtReg];
/// @brief records the specified virtual register will be
/// re-materialized and the original instruction which will be re-issed
/// for this purpose. If parameter all is true, then all uses of the
/// registers are rematerialized and it's safe to delete the definition.
void setVirtIsReMaterialized(unsigned virtReg, MachineInstr *def) {
ReMatMap[virtReg] = def;
/// @brief Updates information about the specified virtual register's value
/// folded into newMI machine instruction. The OpNum argument indicates the
/// operand number of OldMI that is folded.
void virtFolded(unsigned VirtReg, MachineInstr *OldMI, unsigned OpNum,
MachineInstr *NewMI);
/// @brief returns the virtual registers' values folded in memory
/// operands of this instruction
std::pair<MI2VirtMapTy::const_iterator, MI2VirtMapTy::const_iterator>
getFoldedVirts(MachineInstr* MI) const {
return MI2VirtMap.equal_range(MI);
/// RemoveFromFoldedVirtMap - If the specified machine instruction is in
/// the folded instruction map, remove its entry from the map.
void RemoveFromFoldedVirtMap(MachineInstr *MI) {
void print(std::ostream &OS) const;
void print(std::ostream *OS) const { if (OS) print(*OS); }
void dump() const;
inline std::ostream *operator<<(std::ostream *OS, const VirtRegMap &VRM) {
return OS;
inline std::ostream &operator<<(std::ostream &OS, const VirtRegMap &VRM) {
return OS;
/// 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();
} // End llvm namespace