CodeGenRegisters.h   [plain text]

//===- 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.
//
//===----------------------------------------------------------------------===//

#ifndef CODEGEN_REGISTERS_H
#define CODEGEN_REGISTERS_H

#include "Record.h"
#include "SetTheory.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
#include <cstdlib>
#include <map>
#include <string>
#include <set>
#include <vector>

namespace llvm {
  class CodeGenRegBank;

  /// CodeGenRegister - Represents a register definition.
  struct CodeGenRegister {
    Record *TheDef;
    unsigned EnumValue;
    unsigned CostPerUse;

    // Map SubRegIndex -> Register.
    typedef std::map<Record*, CodeGenRegister*, LessRecord> 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<CodeGenRegister*> &OSet) const;

    // List of super-registers in topological order, small to large.
    typedef std::vector<CodeGenRegister*> SuperRegList;

    // Get the list of super-registers.
    // This is only valid after computeDerivedInfo has visited all registers.
    const SuperRegList &getSuperRegs() const {
      assert(SubRegsComplete && "Must precompute sub-registers");
      return SuperRegs;
    }

    // Order CodeGenRegister pointers by EnumValue.
    struct Less {
      bool operator()(const CodeGenRegister *A,
                      const CodeGenRegister *B) const {
        return A->EnumValue < B->EnumValue;
      }
    };

    // Canonically ordered set.
    typedef std::set<const CodeGenRegister*, Less> Set;

  private:
    bool SubRegsComplete;
    SubRegMap SubRegs;
    SuperRegList SuperRegs;
  };


  class CodeGenRegisterClass {
    CodeGenRegister::Set Members;
    const std::vector<Record*> *Elements;
    std::vector<SmallVector<Record*, 16> > AltOrders;
  public:
    Record *TheDef;
    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;

    const std::string &getName() 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];
      assert(0 && "VTNum greater than number of ValueTypes in RegClass!");
      abort();
    }

    // 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;

    // 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 {
      if (No == 0)
        return *Elements;
      else
        return AltOrders[No - 1];
    }

    // Return the total number of allocation orders available.
    unsigned getNumOrders() const { return 1 + AltOrders.size(); }

    CodeGenRegisterClass(CodeGenRegBank&, Record *R);
  };

  // CodeGenRegBank - Represent a target's registers and the relations between
  // them.
  class CodeGenRegBank {
    RecordKeeper &Records;
    SetTheory Sets;

    std::vector<Record*> SubRegIndices;
    unsigned NumNamedIndices;
    std::vector<CodeGenRegister*> Registers;
    DenseMap<Record*, CodeGenRegister*> Def2Reg;

    std::vector<CodeGenRegisterClass> RegClasses;
    DenseMap<Record*, CodeGenRegisterClass*> Def2RC;

    // Composite SubRegIndex instances.
    // Map (SubRegIndex, SubRegIndex) -> SubRegIndex.
    typedef DenseMap<std::pair<Record*, Record*>, Record*> CompositeMap;
    CompositeMap Composite;

    // Populate the Composite map from sub-register relationships.
    void computeComposites();

  public:
    CodeGenRegBank(RecordKeeper&);

    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.
    const std::vector<Record*> &getSubRegIndices() { return SubRegIndices; }
    unsigned getNumNamedIndices() { return NumNamedIndices; }

    // Map a SubRegIndex Record to its enum value.
    unsigned getSubRegIndexNo(Record *idx);

    // Find or create a sub-register index representing the A+B composition.
    Record *getCompositeSubRegIndex(Record *A, Record *B, bool create = false);

    const std::vector<CodeGenRegister*> &getRegisters() { return Registers; }

    // Find a register from its Record def.
    CodeGenRegister *getReg(Record*);

    const std::vector<CodeGenRegisterClass> &getRegClasses() {
      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);

    // 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);
  };
}

#endif