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//=== MC/MCRegisterInfo.h - Target Register Description ---------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file describes an abstract interface used to get information about a
// target machines register file. This information is used for a variety of
// purposed, especially register allocation.
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/ErrorHandling.h"
#include <cassert>
namespace llvm {
/// An unsigned integer type large enough to represent all physical registers,
/// but not necessarily virtual registers.
typedef uint16_t MCPhysReg;
/// MCRegisterClass - Base class of TargetRegisterClass.
class MCRegisterClass {
typedef const MCPhysReg* iterator;
typedef const MCPhysReg* const_iterator;
const char *Name;
const iterator RegsBegin;
const uint8_t *const RegSet;
const uint16_t RegsSize;
const uint16_t RegSetSize;
const uint16_t ID;
const uint16_t RegSize, Alignment; // Size & Alignment of register in bytes
const int8_t CopyCost;
const bool Allocatable;
/// getID() - Return the register class ID number.
unsigned getID() const { return ID; }
/// getName() - Return the register class name for debugging.
const char *getName() const { return Name; }
/// begin/end - Return all of the registers in this class.
iterator begin() const { return RegsBegin; }
iterator end() const { return RegsBegin + RegsSize; }
/// getNumRegs - Return the number of registers in this class.
unsigned getNumRegs() const { return RegsSize; }
/// getRegister - Return the specified register in the class.
unsigned getRegister(unsigned i) const {
assert(i < getNumRegs() && "Register number out of range!");
return RegsBegin[i];
/// contains - Return true if the specified register is included in this
/// register class. This does not include virtual registers.
bool contains(unsigned Reg) const {
unsigned InByte = Reg % 8;
unsigned Byte = Reg / 8;
if (Byte >= RegSetSize)
return false;
return (RegSet[Byte] & (1 << InByte)) != 0;
/// contains - Return true if both registers are in this class.
bool contains(unsigned Reg1, unsigned Reg2) const {
return contains(Reg1) && contains(Reg2);
/// getSize - Return the size of the register in bytes, which is also the size
/// of a stack slot allocated to hold a spilled copy of this register.
unsigned getSize() const { return RegSize; }
/// getAlignment - Return the minimum required alignment for a register of
/// this class.
unsigned getAlignment() const { return Alignment; }
/// getCopyCost - Return the cost of copying a value between two registers in
/// this class. A negative number means the register class is very expensive
/// to copy e.g. status flag register classes.
int getCopyCost() const { return CopyCost; }
/// isAllocatable - Return true if this register class may be used to create
/// virtual registers.
bool isAllocatable() const { return Allocatable; }
/// MCRegisterDesc - This record contains information about a particular
/// register. The SubRegs field is a zero terminated array of registers that
/// are sub-registers of the specific register, e.g. AL, AH are sub-registers
/// of AX. The SuperRegs field is a zero terminated array of registers that are
/// super-registers of the specific register, e.g. RAX, EAX, are
/// super-registers of AX.
struct MCRegisterDesc {
uint32_t Name; // Printable name for the reg (for debugging)
uint32_t SubRegs; // Sub-register set, described above
uint32_t SuperRegs; // Super-register set, described above
// Offset into MCRI::SubRegIndices of a list of sub-register indices for each
// sub-register in SubRegs.
uint32_t SubRegIndices;
// RegUnits - Points to the list of register units. The low 4 bits holds the
// Scale, the high bits hold an offset into DiffLists. See MCRegUnitIterator.
uint32_t RegUnits;
/// MCRegisterInfo base class - We assume that the target defines a static
/// array of MCRegisterDesc objects that represent all of the machine
/// registers that the target has. As such, we simply have to track a pointer
/// to this array so that we can turn register number into a register
/// descriptor.
/// Note this class is designed to be a base class of TargetRegisterInfo, which
/// is the interface used by codegen. However, specific targets *should never*
/// specialize this class. MCRegisterInfo should only contain getters to access
/// TableGen generated physical register data. It must not be extended with
/// virtual methods.
class MCRegisterInfo {
typedef const MCRegisterClass *regclass_iterator;
/// DwarfLLVMRegPair - Emitted by tablegen so Dwarf<->LLVM reg mappings can be
/// performed with a binary search.
struct DwarfLLVMRegPair {
unsigned FromReg;
unsigned ToReg;
bool operator<(DwarfLLVMRegPair RHS) const { return FromReg < RHS.FromReg; }
/// SubRegCoveredBits - Emitted by tablegen: bit range covered by a subreg
/// index, -1 in any being invalid.
struct SubRegCoveredBits {
uint16_t Offset;
uint16_t Size;
const MCRegisterDesc *Desc; // Pointer to the descriptor array
unsigned NumRegs; // Number of entries in the array
unsigned RAReg; // Return address register
unsigned PCReg; // Program counter register
const MCRegisterClass *Classes; // Pointer to the regclass array
unsigned NumClasses; // Number of entries in the array
unsigned NumRegUnits; // Number of regunits.
const MCPhysReg (*RegUnitRoots)[2]; // Pointer to regunit root table.
const MCPhysReg *DiffLists; // Pointer to the difflists array
const char *RegStrings; // Pointer to the string table.
const uint16_t *SubRegIndices; // Pointer to the subreg lookup
// array.
const SubRegCoveredBits *SubRegIdxRanges; // Pointer to the subreg covered
// bit ranges array.
unsigned NumSubRegIndices; // Number of subreg indices.
const uint16_t *RegEncodingTable; // Pointer to array of register
// encodings.
unsigned L2DwarfRegsSize;
unsigned EHL2DwarfRegsSize;
unsigned Dwarf2LRegsSize;
unsigned EHDwarf2LRegsSize;
const DwarfLLVMRegPair *L2DwarfRegs; // LLVM to Dwarf regs mapping
const DwarfLLVMRegPair *EHL2DwarfRegs; // LLVM to Dwarf regs mapping EH
const DwarfLLVMRegPair *Dwarf2LRegs; // Dwarf to LLVM regs mapping
const DwarfLLVMRegPair *EHDwarf2LRegs; // Dwarf to LLVM regs mapping EH
DenseMap<unsigned, int> L2SEHRegs; // LLVM to SEH regs mapping
/// DiffListIterator - Base iterator class that can traverse the
/// differentially encoded register and regunit lists in DiffLists.
/// Don't use this class directly, use one of the specialized sub-classes
/// defined below.
class DiffListIterator {
uint16_t Val;
const MCPhysReg *List;
/// Create an invalid iterator. Call init() to point to something useful.
DiffListIterator() : Val(0), List(nullptr) {}
/// init - Point the iterator to InitVal, decoding subsequent values from
/// DiffList. The iterator will initially point to InitVal, sub-classes are
/// responsible for skipping the seed value if it is not part of the list.
void init(MCPhysReg InitVal, const MCPhysReg *DiffList) {
Val = InitVal;
List = DiffList;
/// advance - Move to the next list position, return the applied
/// differential. This function does not detect the end of the list, that
/// is the caller's responsibility (by checking for a 0 return value).
unsigned advance() {
assert(isValid() && "Cannot move off the end of the list.");
MCPhysReg D = *List++;
Val += D;
return D;
/// isValid - returns true if this iterator is not yet at the end.
bool isValid() const { return List; }
/// Dereference the iterator to get the value at the current position.
unsigned operator*() const { return Val; }
/// Pre-increment to move to the next position.
void operator++() {
// The end of the list is encoded as a 0 differential.
if (!advance())
List = nullptr;
// These iterators are allowed to sub-class DiffListIterator and access
// internal list pointers.
friend class MCSubRegIterator;
friend class MCSuperRegIterator;
friend class MCRegUnitIterator;
friend class MCRegUnitRootIterator;
/// \brief Initialize MCRegisterInfo, called by TableGen
/// auto-generated routines. *DO NOT USE*.
void InitMCRegisterInfo(const MCRegisterDesc *D, unsigned NR, unsigned RA,
unsigned PC,
const MCRegisterClass *C, unsigned NC,
const MCPhysReg (*RURoots)[2],
unsigned NRU,
const MCPhysReg *DL,
const char *Strings,
const uint16_t *SubIndices,
unsigned NumIndices,
const SubRegCoveredBits *SubIdxRanges,
const uint16_t *RET) {
Desc = D;
NumRegs = NR;
RAReg = RA;
PCReg = PC;
Classes = C;
DiffLists = DL;
RegStrings = Strings;
NumClasses = NC;
RegUnitRoots = RURoots;
NumRegUnits = NRU;
SubRegIndices = SubIndices;
NumSubRegIndices = NumIndices;
SubRegIdxRanges = SubIdxRanges;
RegEncodingTable = RET;
/// \brief Used to initialize LLVM register to Dwarf
/// register number mapping. Called by TableGen auto-generated routines.
/// *DO NOT USE*.
void mapLLVMRegsToDwarfRegs(const DwarfLLVMRegPair *Map, unsigned Size,
bool isEH) {
if (isEH) {
EHL2DwarfRegs = Map;
EHL2DwarfRegsSize = Size;
} else {
L2DwarfRegs = Map;
L2DwarfRegsSize = Size;
/// \brief Used to initialize Dwarf register to LLVM
/// register number mapping. Called by TableGen auto-generated routines.
/// *DO NOT USE*.
void mapDwarfRegsToLLVMRegs(const DwarfLLVMRegPair *Map, unsigned Size,
bool isEH) {
if (isEH) {
EHDwarf2LRegs = Map;
EHDwarf2LRegsSize = Size;
} else {
Dwarf2LRegs = Map;
Dwarf2LRegsSize = Size;
/// mapLLVMRegToSEHReg - Used to initialize LLVM register to SEH register
/// number mapping. By default the SEH register number is just the same
/// as the LLVM register number.
/// FIXME: TableGen these numbers. Currently this requires target specific
/// initialization code.
void mapLLVMRegToSEHReg(unsigned LLVMReg, int SEHReg) {
L2SEHRegs[LLVMReg] = SEHReg;
/// \brief This method should return the register where the return
/// address can be found.
unsigned getRARegister() const {
return RAReg;
/// Return the register which is the program counter.
unsigned getProgramCounter() const {
return PCReg;
const MCRegisterDesc &operator[](unsigned RegNo) const {
assert(RegNo < NumRegs &&
"Attempting to access record for invalid register number!");
return Desc[RegNo];
/// \brief Provide a get method, equivalent to [], but more useful with a
/// pointer to this object.
const MCRegisterDesc &get(unsigned RegNo) const {
return operator[](RegNo);
/// \brief Returns the physical register number of sub-register "Index"
/// for physical register RegNo. Return zero if the sub-register does not
/// exist.
unsigned getSubReg(unsigned Reg, unsigned Idx) const;
/// \brief Return a super-register of the specified register
/// Reg so its sub-register of index SubIdx is Reg.
unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx,
const MCRegisterClass *RC) const;
/// \brief For a given register pair, return the sub-register index
/// if the second register is a sub-register of the first. Return zero
/// otherwise.
unsigned getSubRegIndex(unsigned RegNo, unsigned SubRegNo) const;
/// \brief Get the size of the bit range covered by a sub-register index.
/// If the index isn't continuous, return the sum of the sizes of its parts.
/// If the index is used to access subregisters of different sizes, return -1.
unsigned getSubRegIdxSize(unsigned Idx) const;
/// \brief Get the offset of the bit range covered by a sub-register index.
/// If an Offset doesn't make sense (the index isn't continuous, or is used to
/// access sub-registers at different offsets), return -1.
unsigned getSubRegIdxOffset(unsigned Idx) const;
/// \brief Return the human-readable symbolic target-specific name for the
/// specified physical register.
const char *getName(unsigned RegNo) const {
return RegStrings + get(RegNo).Name;
/// \brief Return the number of registers this target has (useful for
/// sizing arrays holding per register information)
unsigned getNumRegs() const {
return NumRegs;
/// \brief Return the number of sub-register indices
/// understood by the target. Index 0 is reserved for the no-op sub-register,
/// while 1 to getNumSubRegIndices() - 1 represent real sub-registers.
unsigned getNumSubRegIndices() const {
return NumSubRegIndices;
/// \brief Return the number of (native) register units in the
/// target. Register units are numbered from 0 to getNumRegUnits() - 1. They
/// can be accessed through MCRegUnitIterator defined below.
unsigned getNumRegUnits() const {
return NumRegUnits;
/// \brief Map a target register to an equivalent dwarf register
/// number. Returns -1 if there is no equivalent value. The second
/// parameter allows targets to use different numberings for EH info and
/// debugging info.
int getDwarfRegNum(unsigned RegNum, bool isEH) const;
/// \brief Map a dwarf register back to a target register.
int getLLVMRegNum(unsigned RegNum, bool isEH) const;
/// \brief Map a target register to an equivalent SEH register
/// number. Returns LLVM register number if there is no equivalent value.
int getSEHRegNum(unsigned RegNum) const;
regclass_iterator regclass_begin() const { return Classes; }
regclass_iterator regclass_end() const { return Classes+NumClasses; }
unsigned getNumRegClasses() const {
return (unsigned)(regclass_end()-regclass_begin());
/// \brief Returns the register class associated with the enumeration
/// value. See class MCOperandInfo.
const MCRegisterClass& getRegClass(unsigned i) const {
assert(i < getNumRegClasses() && "Register Class ID out of range");
return Classes[i];
/// \brief Returns the encoding for RegNo
uint16_t getEncodingValue(unsigned RegNo) const {
assert(RegNo < NumRegs &&
"Attempting to get encoding for invalid register number!");
return RegEncodingTable[RegNo];
/// \brief Returns true if RegB is a sub-register of RegA.
bool isSubRegister(unsigned RegA, unsigned RegB) const {
return isSuperRegister(RegB, RegA);
/// \brief Returns true if RegB is a super-register of RegA.
bool isSuperRegister(unsigned RegA, unsigned RegB) const;
/// \brief Returns true if RegB is a sub-register of RegA or if RegB == RegA.
bool isSubRegisterEq(unsigned RegA, unsigned RegB) const {
return isSuperRegisterEq(RegB, RegA);
/// \brief Returns true if RegB is a super-register of RegA or if
/// RegB == RegA.
bool isSuperRegisterEq(unsigned RegA, unsigned RegB) const {
return RegA == RegB || isSuperRegister(RegA, RegB);
// Register List Iterators
// MCRegisterInfo provides lists of super-registers, sub-registers, and
// aliasing registers. Use these iterator classes to traverse the lists.
/// MCSubRegIterator enumerates all sub-registers of Reg.
/// If IncludeSelf is set, Reg itself is included in the list.
class MCSubRegIterator : public MCRegisterInfo::DiffListIterator {
MCSubRegIterator(unsigned Reg, const MCRegisterInfo *MCRI,
bool IncludeSelf = false) {
init(Reg, MCRI->DiffLists + MCRI->get(Reg).SubRegs);
// Initially, the iterator points to Reg itself.
if (!IncludeSelf)
/// MCSuperRegIterator enumerates all super-registers of Reg.
/// If IncludeSelf is set, Reg itself is included in the list.
class MCSuperRegIterator : public MCRegisterInfo::DiffListIterator {
MCSuperRegIterator() {}
MCSuperRegIterator(unsigned Reg, const MCRegisterInfo *MCRI,
bool IncludeSelf = false) {
init(Reg, MCRI->DiffLists + MCRI->get(Reg).SuperRegs);
// Initially, the iterator points to Reg itself.
if (!IncludeSelf)
// Definition for isSuperRegister. Put it down here since it needs the
// iterator defined above in addition to the MCRegisterInfo class itself.
inline bool MCRegisterInfo::isSuperRegister(unsigned RegA, unsigned RegB) const{
for (MCSuperRegIterator I(RegA, this); I.isValid(); ++I)
if (*I == RegB)
return true;
return false;
// Register Units
// Register units are used to compute register aliasing. Every register has at
// least one register unit, but it can have more. Two registers overlap if and
// only if they have a common register unit.
// A target with a complicated sub-register structure will typically have many
// fewer register units than actual registers. MCRI::getNumRegUnits() returns
// the number of register units in the target.
// MCRegUnitIterator enumerates a list of register units for Reg. The list is
// in ascending numerical order.
class MCRegUnitIterator : public MCRegisterInfo::DiffListIterator {
/// MCRegUnitIterator - Create an iterator that traverses the register units
/// in Reg.
MCRegUnitIterator() {}
MCRegUnitIterator(unsigned Reg, const MCRegisterInfo *MCRI) {
assert(Reg && "Null register has no regunits");
// Decode the RegUnits MCRegisterDesc field.
unsigned RU = MCRI->get(Reg).RegUnits;
unsigned Scale = RU & 15;
unsigned Offset = RU >> 4;
// Initialize the iterator to Reg * Scale, and the List pointer to
// DiffLists + Offset.
init(Reg * Scale, MCRI->DiffLists + Offset);
// That may not be a valid unit, we need to advance by one to get the real
// unit number. The first differential can be 0 which would normally
// terminate the list, but since we know every register has at least one
// unit, we can allow a 0 differential here.
// Each register unit has one or two root registers. The complete set of
// registers containing a register unit is the union of the roots and their
// super-registers. All registers aliasing Unit can be visited like this:
// for (MCRegUnitRootIterator RI(Unit, MCRI); RI.isValid(); ++RI) {
// for (MCSuperRegIterator SI(*RI, MCRI, true); SI.isValid(); ++SI)
// visit(*SI);
// }
/// MCRegUnitRootIterator enumerates the root registers of a register unit.
class MCRegUnitRootIterator {
uint16_t Reg0;
uint16_t Reg1;
MCRegUnitRootIterator() : Reg0(0), Reg1(0) {}
MCRegUnitRootIterator(unsigned RegUnit, const MCRegisterInfo *MCRI) {
assert(RegUnit < MCRI->getNumRegUnits() && "Invalid register unit");
Reg0 = MCRI->RegUnitRoots[RegUnit][0];
Reg1 = MCRI->RegUnitRoots[RegUnit][1];
/// \brief Dereference to get the current root register.
unsigned operator*() const {
return Reg0;
/// \brief Check if the iterator is at the end of the list.
bool isValid() const {
return Reg0;
/// \brief Preincrement to move to the next root register.
void operator++() {
assert(isValid() && "Cannot move off the end of the list.");
Reg0 = Reg1;
Reg1 = 0;
/// MCRegAliasIterator enumerates all registers aliasing Reg. If IncludeSelf is
/// set, Reg itself is included in the list. This iterator does not guarantee
/// any ordering or that entries are unique.
class MCRegAliasIterator {
unsigned Reg;
const MCRegisterInfo *MCRI;
bool IncludeSelf;
MCRegUnitIterator RI;
MCRegUnitRootIterator RRI;
MCSuperRegIterator SI;
MCRegAliasIterator(unsigned Reg, const MCRegisterInfo *MCRI,
bool IncludeSelf)
: Reg(Reg), MCRI(MCRI), IncludeSelf(IncludeSelf) {
// Initialize the iterators.
for (RI = MCRegUnitIterator(Reg, MCRI); RI.isValid(); ++RI) {
for (RRI = MCRegUnitRootIterator(*RI, MCRI); RRI.isValid(); ++RRI) {
for (SI = MCSuperRegIterator(*RRI, MCRI, true); SI.isValid(); ++SI) {
if (!(!IncludeSelf && Reg == *SI))
bool isValid() const {
return RI.isValid();
unsigned operator*() const {
assert (SI.isValid() && "Cannot dereference an invalid iterator.");
return *SI;
void advance() {
// Assuming SI is valid.
if (SI.isValid()) return;
if (RRI.isValid()) {
SI = MCSuperRegIterator(*RRI, MCRI, true);
if (RI.isValid()) {
RRI = MCRegUnitRootIterator(*RI, MCRI);
SI = MCSuperRegIterator(*RRI, MCRI, true);
void operator++() {
assert(isValid() && "Cannot move off the end of the list.");
do advance();
while (!IncludeSelf && isValid() && *SI == Reg);
} // End llvm namespace