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1//===-- RegisterAliasingTracker.h -------------------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8///9/// \file10/// Defines classes to keep track of register aliasing.11///12//===----------------------------------------------------------------------===//13 14#ifndef LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H15#define LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H16 17#include <memory>18#include <unordered_map>19 20#include "llvm/ADT/BitVector.h"21#include "llvm/ADT/PackedVector.h"22#include "llvm/MC/MCRegisterInfo.h"23 24namespace llvm {25namespace exegesis {26 27// Returns the registers that are aliased by the ones set in SourceBits.28BitVector getAliasedBits(const MCRegisterInfo &RegInfo,29 const BitVector &SourceBits);30 31// Keeps track of a mapping from one register (or a register class) to its32// aliased registers.33//34// e.g.35// RegisterAliasingTracker Tracker(RegInfo, X86::EAX);36// Tracker.sourceBits() == { X86::EAX }37// Tracker.aliasedBits() == { X86::AL, X86::AH, X86::AX,38// X86::EAX,X86::HAX, X86::RAX }39// Tracker.getOrigin(X86::AL) == X86::EAX;40// Tracker.getOrigin(X86::BX) == -1;41struct RegisterAliasingTracker {42 // Construct a tracker from an MCRegisterClass.43 RegisterAliasingTracker(const MCRegisterInfo &RegInfo,44 const BitVector &ReservedReg,45 const MCRegisterClass &RegClass);46 47 // Construct a tracker from an MCRegister.48 RegisterAliasingTracker(const MCRegisterInfo &RegInfo,49 const MCRegister Register);50 51 const BitVector &sourceBits() const { return SourceBits; }52 53 // Retrieves all the touched registers as a BitVector.54 const BitVector &aliasedBits() const { return AliasedBits; }55 56 // Returns the origin of this register or -1.57 int getOrigin(MCPhysReg Aliased) const {58 if (!AliasedBits[Aliased])59 return -1;60 return Origins[Aliased];61 }62 63private:64 RegisterAliasingTracker(const MCRegisterInfo &RegInfo);65 RegisterAliasingTracker(const RegisterAliasingTracker &) = delete;66 67 void FillOriginAndAliasedBits(const MCRegisterInfo &RegInfo,68 const BitVector &OriginalBits);69 70 BitVector SourceBits;71 BitVector AliasedBits;72 PackedVector<size_t, 10> Origins; // Max 1024 physical registers.73};74 75// A cache of existing trackers.76struct RegisterAliasingTrackerCache {77 // RegInfo must outlive the cache.78 RegisterAliasingTrackerCache(const MCRegisterInfo &RegInfo,79 const BitVector &ReservedReg);80 81 // Convenient function to retrieve a BitVector of the right size.82 const BitVector &emptyRegisters() const { return EmptyRegisters; }83 84 // Convenient function to retrieve the registers the function body can't use.85 const BitVector &reservedRegisters() const { return ReservedReg; }86 87 // Convenient function to retrieve the underlying MCRegInfo.88 const MCRegisterInfo ®Info() const { return RegInfo; }89 90 // Retrieves the RegisterAliasingTracker for this particular register.91 const RegisterAliasingTracker &getRegister(MCRegister Reg) const;92 93 // Retrieves the RegisterAliasingTracker for this particular register class.94 const RegisterAliasingTracker &getRegisterClass(unsigned RegClassIndex) const;95 96private:97 const MCRegisterInfo &RegInfo;98 const BitVector ReservedReg;99 const BitVector EmptyRegisters;100 mutable std::unordered_map<unsigned, std::unique_ptr<RegisterAliasingTracker>>101 Registers;102 mutable std::unordered_map<unsigned, std::unique_ptr<RegisterAliasingTracker>>103 RegisterClasses;104};105 106// `a = a & ~b`, optimized for few bit sets in B and no allocation.107inline void remove(BitVector &A, const BitVector &B) {108 assert(A.size() == B.size());109 for (auto I : B.set_bits())110 A.reset(I);111}112 113// Returns a debug string for the list of registers.114std::string debugString(const MCRegisterInfo &RegInfo, const BitVector &Regs);115 116} // namespace exegesis117} // namespace llvm118 119#endif // LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H120