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//===-- RegisterAliasingTracker.h -------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Defines classes to keep track of register aliasing.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H
#define LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H
#include <memory>
#include <unordered_map>
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/PackedVector.h"
#include "llvm/MC/MCRegisterInfo.h"
namespace exegesis {
// Returns the registers that are aliased by the ones set in SourceBits.
llvm::BitVector getAliasedBits(const llvm::MCRegisterInfo &RegInfo,
const llvm::BitVector &SourceBits);
// Keeps track of a mapping from one register (or a register class) to its
// aliased registers.
//
// e.g.
// RegisterAliasingTracker Tracker(RegInfo, llvm::X86::EAX);
// Tracker.sourceBits() == { llvm::X86::EAX }
// Tracker.aliasedBits() == { llvm::X86::AL, llvm::X86::AH, llvm::X86::AX,
// llvm::X86::EAX,llvm::X86::HAX, llvm::X86::RAX }
// Tracker.getOrigin(llvm::X86::AL) == llvm::X86::EAX;
// Tracker.getOrigin(llvm::X86::BX) == -1;
struct RegisterAliasingTracker {
// Construct a tracker from an MCRegisterClass.
RegisterAliasingTracker(const llvm::MCRegisterInfo &RegInfo,
const llvm::BitVector &ReservedReg,
const llvm::MCRegisterClass &RegClass);
// Construct a tracker from an MCPhysReg.
RegisterAliasingTracker(const llvm::MCRegisterInfo &RegInfo,
const llvm::MCPhysReg Register);
const llvm::BitVector &sourceBits() const { return SourceBits; }
// Retrieves all the touched registers as a BitVector.
const llvm::BitVector &aliasedBits() const { return AliasedBits; }
// Returns the origin of this register or -1.
int getOrigin(llvm::MCPhysReg Aliased) const {
if (!AliasedBits[Aliased])
return -1;
return Origins[Aliased];
}
private:
RegisterAliasingTracker(const llvm::MCRegisterInfo &RegInfo);
RegisterAliasingTracker(const RegisterAliasingTracker &) = delete;
void FillOriginAndAliasedBits(const llvm::MCRegisterInfo &RegInfo,
const llvm::BitVector &OriginalBits);
llvm::BitVector SourceBits;
llvm::BitVector AliasedBits;
llvm::PackedVector<size_t, 10> Origins; // Max 1024 physical registers.
};
// A cache of existing trackers.
struct RegisterAliasingTrackerCache {
// RegInfo must outlive the cache.
RegisterAliasingTrackerCache(const llvm::MCRegisterInfo &RegInfo,
const llvm::BitVector &ReservedReg);
// Convenient function to retrieve a BitVector of the right size.
const llvm::BitVector &emptyRegisters() const { return EmptyRegisters; }
// Convenient function to retrieve the registers the function body can't use.
const llvm::BitVector &reservedRegisters() const { return ReservedReg; }
// Convenient function to retrieve the underlying MCRegInfo.
const llvm::MCRegisterInfo ®Info() const { return RegInfo; }
// Retrieves the RegisterAliasingTracker for this particular register.
const RegisterAliasingTracker &getRegister(llvm::MCPhysReg Reg) const;
// Retrieves the RegisterAliasingTracker for this particular register class.
const RegisterAliasingTracker &getRegisterClass(unsigned RegClassIndex) const;
private:
const llvm::MCRegisterInfo &RegInfo;
const llvm::BitVector ReservedReg;
const llvm::BitVector EmptyRegisters;
mutable std::unordered_map<unsigned, std::unique_ptr<RegisterAliasingTracker>>
Registers;
mutable std::unordered_map<unsigned, std::unique_ptr<RegisterAliasingTracker>>
RegisterClasses;
};
} // namespace exegesis
#endif // LLVM_TOOLS_LLVM_EXEGESIS_ALIASINGTRACKER_H
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