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//===- CodeGenRegisters.h - Register and RegisterClass Info -----*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines structures to encapsulate information gleaned from the
// target register and register class definitions.
#include "SetTheory.h"
#include "llvm/TableGen/Record.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/ErrorHandling.h"
#include <cstdlib>
#include <map>
#include <string>
#include <set>
#include <vector>
namespace llvm {
class CodeGenRegBank;
/// CodeGenSubRegIndex - Represents a sub-register index.
class CodeGenSubRegIndex {
Record *const TheDef;
const unsigned EnumValue;
CodeGenSubRegIndex(Record *R, unsigned Enum);
const std::string &getName() const;
std::string getNamespace() const;
std::string getQualifiedName() const;
// Order CodeGenSubRegIndex pointers by EnumValue.
struct Less {
bool operator()(const CodeGenSubRegIndex *A,
const CodeGenSubRegIndex *B) const {
assert(A && B);
return A->EnumValue < B->EnumValue;
// Map of composite subreg indices.
typedef std::map<CodeGenSubRegIndex*, CodeGenSubRegIndex*, Less> CompMap;
// Returns the subreg index that results from composing this with Idx.
// Returns NULL if this and Idx don't compose.
CodeGenSubRegIndex *compose(CodeGenSubRegIndex *Idx) const {
CompMap::const_iterator I = Composed.find(Idx);
return I == Composed.end() ? 0 : I->second;
// Add a composite subreg index: this+A = B.
// Return a conflicting composite, or NULL
CodeGenSubRegIndex *addComposite(CodeGenSubRegIndex *A,
CodeGenSubRegIndex *B) {
std::pair<CompMap::iterator, bool> Ins =
Composed.insert(std::make_pair(A, B));
return (Ins.second || Ins.first->second == B) ? 0 : Ins.first->second;
// Update the composite maps of components specified in 'ComposedOf'.
void updateComponents(CodeGenRegBank&);
// Clean out redundant composite mappings.
void cleanComposites();
// Return the map of composites.
const CompMap &getComposites() const { return Composed; }
CompMap Composed;
/// CodeGenRegister - Represents a register definition.
struct CodeGenRegister {
Record *TheDef;
unsigned EnumValue;
unsigned CostPerUse;
bool CoveredBySubRegs;
// Map SubRegIndex -> Register.
typedef std::map<CodeGenSubRegIndex*, CodeGenRegister*,
CodeGenSubRegIndex::Less> SubRegMap;
CodeGenRegister(Record *R, unsigned Enum);
const std::string &getName() const;
// Get a map of sub-registers computed lazily.
// This includes unique entries for all sub-sub-registers.
const SubRegMap &getSubRegs(CodeGenRegBank&);
const SubRegMap &getSubRegs() const {
assert(SubRegsComplete && "Must precompute sub-registers");
return SubRegs;
// Add sub-registers to OSet following a pre-order defined by the .td file.
void addSubRegsPreOrder(SetVector<const CodeGenRegister*> &OSet,
CodeGenRegBank&) const;
// List of super-registers in topological order, small to large.
typedef std::vector<const CodeGenRegister*> SuperRegList;
// Get the list of super-registers. This is valid after getSubReg
// visits all registers during RegBank construction.
const SuperRegList &getSuperRegs() const {
assert(SubRegsComplete && "Must precompute sub-registers");
return SuperRegs;
// List of register units in ascending order.
typedef SmallVector<unsigned, 16> RegUnitList;
// Get the list of register units.
// This is only valid after getSubRegs() completes.
const RegUnitList &getRegUnits() const { return RegUnits; }
// Inherit register units from subregisters.
// Return true if the RegUnits changed.
bool inheritRegUnits(CodeGenRegBank &RegBank);
// Adopt a register unit for pressure tracking.
// A unit is adopted iff its unit number is >= NumNativeRegUnits.
void adoptRegUnit(unsigned RUID) { RegUnits.push_back(RUID); }
// Get the sum of this register's register unit weights.
unsigned getWeight(const CodeGenRegBank &RegBank) const;
// Order CodeGenRegister pointers by EnumValue.
struct Less {
bool operator()(const CodeGenRegister *A,
const CodeGenRegister *B) const {
assert(A && B);
return A->EnumValue < B->EnumValue;
// Canonically ordered set.
typedef std::set<const CodeGenRegister*, Less> Set;
bool SubRegsComplete;
SubRegMap SubRegs;
SuperRegList SuperRegs;
RegUnitList RegUnits;
class CodeGenRegisterClass {
CodeGenRegister::Set Members;
// Allocation orders. Order[0] always contains all registers in Members.
std::vector<SmallVector<Record*, 16> > Orders;
// Bit mask of sub-classes including this, indexed by their EnumValue.
BitVector SubClasses;
// List of super-classes, topologocally ordered to have the larger classes
// first. This is the same as sorting by EnumValue.
SmallVector<CodeGenRegisterClass*, 4> SuperClasses;
Record *TheDef;
std::string Name;
// For a synthesized class, inherit missing properties from the nearest
// super-class.
void inheritProperties(CodeGenRegBank&);
// Map SubRegIndex -> sub-class. This is the largest sub-class where all
// registers have a SubRegIndex sub-register.
DenseMap<CodeGenSubRegIndex*, CodeGenRegisterClass*> SubClassWithSubReg;
// Map SubRegIndex -> set of super-reg classes. This is all register
// classes SuperRC such that:
// R:SubRegIndex in this RC for all R in SuperRC.
SmallPtrSet<CodeGenRegisterClass*, 8> > SuperRegClasses;
unsigned EnumValue;
std::string Namespace;
std::vector<MVT::SimpleValueType> VTs;
unsigned SpillSize;
unsigned SpillAlignment;
int CopyCost;
bool Allocatable;
// Map SubRegIndex -> RegisterClass
DenseMap<Record*,Record*> SubRegClasses;
std::string AltOrderSelect;
// Return the Record that defined this class, or NULL if the class was
// created by TableGen.
Record *getDef() const { return TheDef; }
const std::string &getName() const { return Name; }
std::string getQualifiedName() const;
const std::vector<MVT::SimpleValueType> &getValueTypes() const {return VTs;}
unsigned getNumValueTypes() const { return VTs.size(); }
MVT::SimpleValueType getValueTypeNum(unsigned VTNum) const {
if (VTNum < VTs.size())
return VTs[VTNum];
llvm_unreachable("VTNum greater than number of ValueTypes in RegClass!");
// Return true if this this class contains the register.
bool contains(const CodeGenRegister*) const;
// Returns true if RC is a subclass.
// RC is a sub-class of this class if it is a valid replacement for any
// instruction operand where a register of this classis required. It must
// satisfy these conditions:
// 1. All RC registers are also in this.
// 2. The RC spill size must not be smaller than our spill size.
// 3. RC spill alignment must be compatible with ours.
bool hasSubClass(const CodeGenRegisterClass *RC) const {
return SubClasses.test(RC->EnumValue);
// getSubClassWithSubReg - Returns the largest sub-class where all
// registers have a SubIdx sub-register.
getSubClassWithSubReg(CodeGenSubRegIndex *SubIdx) const {
return SubClassWithSubReg.lookup(SubIdx);
void setSubClassWithSubReg(CodeGenSubRegIndex *SubIdx,
CodeGenRegisterClass *SubRC) {
SubClassWithSubReg[SubIdx] = SubRC;
// getSuperRegClasses - Returns a bit vector of all register classes
// containing only SubIdx super-registers of this class.
void getSuperRegClasses(CodeGenSubRegIndex *SubIdx, BitVector &Out) const;
// addSuperRegClass - Add a class containing only SudIdx super-registers.
void addSuperRegClass(CodeGenSubRegIndex *SubIdx,
CodeGenRegisterClass *SuperRC) {
// getSubClasses - Returns a constant BitVector of subclasses indexed by
// EnumValue.
// The SubClasses vector includs an entry for this class.
const BitVector &getSubClasses() const { return SubClasses; }
// getSuperClasses - Returns a list of super classes ordered by EnumValue.
// The array does not include an entry for this class.
ArrayRef<CodeGenRegisterClass*> getSuperClasses() const {
return SuperClasses;
// Returns an ordered list of class members.
// The order of registers is the same as in the .td file.
// No = 0 is the default allocation order, No = 1 is the first alternative.
ArrayRef<Record*> getOrder(unsigned No = 0) const {
return Orders[No];
// Return the total number of allocation orders available.
unsigned getNumOrders() const { return Orders.size(); }
// Get the set of registers. This set contains the same registers as
// getOrder(0).
const CodeGenRegister::Set &getMembers() const { return Members; }
// Populate a unique sorted list of units from a register set.
void buildRegUnitSet(std::vector<unsigned> &RegUnits) const;
CodeGenRegisterClass(CodeGenRegBank&, Record *R);
// A key representing the parts of a register class used for forming
// sub-classes. Note the ordering provided by this key is not the same as
// the topological order used for the EnumValues.
struct Key {
const CodeGenRegister::Set *Members;
unsigned SpillSize;
unsigned SpillAlignment;
Key(const Key &O)
: Members(O.Members),
SpillAlignment(O.SpillAlignment) {}
Key(const CodeGenRegister::Set *M, unsigned S = 0, unsigned A = 0)
: Members(M), SpillSize(S), SpillAlignment(A) {}
Key(const CodeGenRegisterClass &RC)
: Members(&RC.getMembers()),
SpillAlignment(RC.SpillAlignment) {}
// Lexicographical order of (Members, SpillSize, SpillAlignment).
bool operator<(const Key&) const;
// Create a non-user defined register class.
CodeGenRegisterClass(StringRef Name, Key Props);
// Called by CodeGenRegBank::CodeGenRegBank().
static void computeSubClasses(CodeGenRegBank&);
// Each RegUnitSet is a sorted vector with a name.
struct RegUnitSet {
typedef std::vector<unsigned>::const_iterator iterator;
std::string Name;
std::vector<unsigned> Units;
// CodeGenRegBank - Represent a target's registers and the relations between
// them.
class CodeGenRegBank {
RecordKeeper &Records;
SetTheory Sets;
// SubRegIndices.
std::vector<CodeGenSubRegIndex*> SubRegIndices;
DenseMap<Record*, CodeGenSubRegIndex*> Def2SubRegIdx;
unsigned NumNamedIndices;
// Registers.
std::vector<CodeGenRegister*> Registers;
DenseMap<Record*, CodeGenRegister*> Def2Reg;
unsigned NumNativeRegUnits;
unsigned NumRegUnits; // # native + adopted register units.
// Map each register unit to a weight (for register pressure).
// Includes native and adopted register units.
std::vector<unsigned> RegUnitWeights;
// Register classes.
std::vector<CodeGenRegisterClass*> RegClasses;
DenseMap<Record*, CodeGenRegisterClass*> Def2RC;
typedef std::map<CodeGenRegisterClass::Key, CodeGenRegisterClass*> RCKeyMap;
RCKeyMap Key2RC;
// Remember each unique set of register units. Initially, this contains a
// unique set for each register class. Simliar sets are coalesced with
// pruneUnitSets and new supersets are inferred during computeRegUnitSets.
std::vector<RegUnitSet> RegUnitSets;
// Map RegisterClass index to the index of the RegUnitSet that contains the
// class's units and any inferred RegUnit supersets.
std::vector<std::vector<unsigned> > RegClassUnitSets;
// Add RC to *2RC maps.
void addToMaps(CodeGenRegisterClass*);
// Create a synthetic sub-class if it is missing.
CodeGenRegisterClass *getOrCreateSubClass(const CodeGenRegisterClass *RC,
const CodeGenRegister::Set *Membs,
StringRef Name);
// Infer missing register classes.
void computeInferredRegisterClasses();
void inferCommonSubClass(CodeGenRegisterClass *RC);
void inferSubClassWithSubReg(CodeGenRegisterClass *RC);
void inferMatchingSuperRegClass(CodeGenRegisterClass *RC,
unsigned FirstSubRegRC = 0);
// Iteratively prune unit sets.
void pruneUnitSets();
// Compute a weight for each register unit created during getSubRegs.
void computeRegUnitWeights();
// Create a RegUnitSet for each RegClass and infer superclasses.
void computeRegUnitSets();
// Populate the Composite map from sub-register relationships.
void computeComposites();
SetTheory &getSets() { return Sets; }
// Sub-register indices. The first NumNamedIndices are defined by the user
// in the .td files. The rest are synthesized such that all sub-registers
// have a unique name.
ArrayRef<CodeGenSubRegIndex*> getSubRegIndices() { return SubRegIndices; }
unsigned getNumNamedIndices() { return NumNamedIndices; }
// Find a SubRegIndex form its Record def.
CodeGenSubRegIndex *getSubRegIdx(Record*);
// Find or create a sub-register index representing the A+B composition.
CodeGenSubRegIndex *getCompositeSubRegIndex(CodeGenSubRegIndex *A,
CodeGenSubRegIndex *B);
const std::vector<CodeGenRegister*> &getRegisters() { return Registers; }
// Find a register from its Record def.
CodeGenRegister *getReg(Record*);
// Get a Register's index into the Registers array.
unsigned getRegIndex(const CodeGenRegister *Reg) const {
return Reg->EnumValue - 1;
// Create a new non-native register unit that can be adopted by a register
// to increase its pressure. Note that NumNativeRegUnits is not increased.
unsigned newRegUnit(unsigned Weight) {
if (!RegUnitWeights.empty()) {
assert(Weight && "should only add allocatable units");
RegUnitWeights[NumRegUnits] = Weight;
return NumRegUnits++;
// Native units are the singular unit of a leaf register. Register aliasing
// is completely characterized by native units. Adopted units exist to give
// register additional weight but don't affect aliasing.
bool isNativeUnit(unsigned RUID) {
return RUID < NumNativeRegUnits;
ArrayRef<CodeGenRegisterClass*> getRegClasses() const {
return RegClasses;
// Find a register class from its def.
CodeGenRegisterClass *getRegClass(Record*);
/// getRegisterClassForRegister - Find the register class that contains the
/// specified physical register. If the register is not in a register
/// class, return null. If the register is in multiple classes, and the
/// classes have a superset-subset relationship and the same set of types,
/// return the superclass. Otherwise return null.
const CodeGenRegisterClass* getRegClassForRegister(Record *R);
// Get a register unit's weight. Zero for unallocatable registers.
unsigned getRegUnitWeight(unsigned RUID) const {
return RegUnitWeights[RUID];
// Get the sum of unit weights.
unsigned getRegUnitSetWeight(const std::vector<unsigned> &Units) const {
unsigned Weight = 0;
for (std::vector<unsigned>::const_iterator
I = Units.begin(), E = Units.end(); I != E; ++I)
Weight += getRegUnitWeight(*I);
return Weight;
// Increase a RegUnitWeight.
void increaseRegUnitWeight(unsigned RUID, unsigned Inc) {
RegUnitWeights[RUID] += Inc;
// Get the number of register pressure dimensions.
unsigned getNumRegPressureSets() const { return RegUnitSets.size(); }
// Get a set of register unit IDs for a given dimension of pressure.
RegUnitSet getRegPressureSet(unsigned Idx) const {
return RegUnitSets[Idx];
// Get a list of pressure set IDs for a register class. Liveness of a
// register in this class impacts each pressure set in this list by the
// weight of the register. An exact solution requires all registers in a
// class to have the same class, but it is not strictly guaranteed.
ArrayRef<unsigned> getRCPressureSetIDs(unsigned RCIdx) const {
return RegClassUnitSets[RCIdx];
// Computed derived records such as missing sub-register indices.
void computeDerivedInfo();
// Compute full overlap sets for every register. These sets include the
// rarely used aliases that are neither sub nor super-registers.
// Map[R1].count(R2) is reflexive and symmetric, but not transitive.
// If R1 is a sub-register of R2, Map[R1] is a subset of Map[R2].
void computeOverlaps(std::map<const CodeGenRegister*,
CodeGenRegister::Set> &Map);
// Compute the set of registers completely covered by the registers in Regs.
// The returned BitVector will have a bit set for each register in Regs,
// all sub-registers, and all super-registers that are covered by the
// registers in Regs.
// This is used to compute the mask of call-preserved registers from a list
// of callee-saves.
BitVector computeCoveredRegisters(ArrayRef<Record*> Regs);