//===- LiveIntervalCalc.h - Calculate live intervals -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// The LiveIntervalCalc class is an extension of LiveRangeCalc targeted to the
// computation and modification of the LiveInterval variants of LiveRanges.
// LiveIntervals are meant to track liveness of registers and stack slots and
// LiveIntervalCalc adds to LiveRangeCalc all the machinery required to
// construct the liveness of virtual registers tracked by a LiveInterval.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_LIVEINTERVALCALC_H
#define LLVM_CODEGEN_LIVEINTERVALCALC_H
#include "llvm/CodeGen/LiveRangeCalc.h"
namespace llvm {
template <class NodeT> class DomTreeNodeBase;
using MachineDomTreeNode = DomTreeNodeBase<MachineBasicBlock>;
class LiveIntervalCalc : public LiveRangeCalc {
/// Extend the live range of @p LR to reach all uses of Reg.
///
/// If @p LR is a main range, or if @p LI is null, then all uses must be
/// jointly dominated by the definitions from @p LR. If @p LR is a subrange
/// of the live interval @p LI, corresponding to lane mask @p LaneMask,
/// all uses must be jointly dominated by the definitions from @p LR
/// together with definitions of other lanes where @p LR becomes undefined
/// (via <def,read-undef> operands).
/// If @p LR is a main range, the @p LaneMask should be set to ~0, i.e.
/// LaneBitmask::getAll().
void extendToUses(LiveRange &LR, Register Reg, LaneBitmask LaneMask,
LiveInterval *LI = nullptr);
public:
LiveIntervalCalc() = default;
/// createDeadDefs - Create a dead def in LI for every def operand of Reg.
/// Each instruction defining Reg gets a new VNInfo with a corresponding
/// minimal live range.
void createDeadDefs(LiveRange &LR, Register Reg);
/// Extend the live range of @p LR to reach all uses of Reg.
///
/// All uses must be jointly dominated by existing liveness. PHI-defs are
/// inserted as needed to preserve SSA form.
void extendToUses(LiveRange &LR, MCRegister PhysReg) {
extendToUses(LR, PhysReg, LaneBitmask::getAll());
}
/// Calculates liveness for the register specified in live interval @p LI.
/// Creates subregister live ranges as needed if subreg liveness tracking is
/// enabled.
void calculate(LiveInterval &LI, bool TrackSubRegs);
/// For live interval \p LI with correct SubRanges construct matching
/// information for the main live range. Expects the main live range to not
/// have any segments or value numbers.
void constructMainRangeFromSubranges(LiveInterval &LI);
};
} // end namespace llvm
#endif // LLVM_CODEGEN_LIVEINTERVALCALC_H