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//==-- llvm/Target/TargetSubtargetInfo.h - Target Information ----*- C++ -*-==//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file describes the subtarget options of a Target machine.
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/CodeGen.h"
namespace llvm {
class MachineFunction;
class MachineInstr;
class SDep;
class SUnit;
class TargetRegisterClass;
class TargetSchedModel;
struct MachineSchedPolicy;
template <typename T> class SmallVectorImpl;
/// TargetSubtargetInfo - Generic base class for all target subtargets. All
/// Target-specific options that control code generation and printing should
/// be exposed through a TargetSubtargetInfo-derived class.
class TargetSubtargetInfo : public MCSubtargetInfo {
TargetSubtargetInfo(const TargetSubtargetInfo&) LLVM_DELETED_FUNCTION;
void operator=(const TargetSubtargetInfo&) LLVM_DELETED_FUNCTION;
protected: // Can only create subclasses...
// AntiDepBreakMode - Type of anti-dependence breaking that should
// be performed before post-RA scheduling.
typedef SmallVectorImpl<const TargetRegisterClass*> RegClassVector;
virtual ~TargetSubtargetInfo();
/// Resolve a SchedClass at runtime, where SchedClass identifies an
/// MCSchedClassDesc with the isVariant property. This may return the ID of
/// another variant SchedClass, but repeated invocation must quickly terminate
/// in a nonvariant SchedClass.
virtual unsigned resolveSchedClass(unsigned SchedClass, const MachineInstr *MI,
const TargetSchedModel* SchedModel) const {
return 0;
/// \brief Temporary API to test migration to MI scheduler.
bool useMachineScheduler() const;
/// \brief True if the subtarget should run MachineScheduler after aggressive
/// coalescing.
/// This currently replaces the SelectionDAG scheduler with the "source" order
/// scheduler. It does not yet disable the postRA scheduler.
virtual bool enableMachineScheduler() const;
/// \brief True if the subtarget should run PostMachineScheduler.
/// This only takes effect if the target has configured the
/// PostMachineScheduler pass to run, or if the global cl::opt flag,
/// MISchedPostRA, is set.
virtual bool enablePostMachineScheduler() const;
/// \brief True if the subtarget should run the atomic expansion pass.
virtual bool enableAtomicExpandLoadLinked() const;
/// \brief Override generic scheduling policy within a region.
/// This is a convenient way for targets that don't provide any custom
/// scheduling heuristics (no custom MachineSchedStrategy) to make
/// changes to the generic scheduling policy.
virtual void overrideSchedPolicy(MachineSchedPolicy &Policy,
MachineInstr *begin,
MachineInstr *end,
unsigned NumRegionInstrs) const {}
// \brief Perform target specific adjustments to the latency of a schedule
// dependency.
virtual void adjustSchedDependency(SUnit *def, SUnit *use,
SDep& dep) const { }
// For use with PostRAScheduling: get the anti-dependence breaking that should
// be performed before post-RA scheduling.
virtual AntiDepBreakMode getAntiDepBreakMode() const {
// For use with PostRAScheduling: in CriticalPathRCs, return any register
// classes that should only be considered for anti-dependence breaking if they
// are on the critical path.
virtual void getCriticalPathRCs(RegClassVector &CriticalPathRCs) const {
return CriticalPathRCs.clear();
// For use with PostRAScheduling: get the minimum optimization level needed
// to enable post-RA scheduling.
virtual CodeGenOpt::Level getOptLevelToEnablePostRAScheduler() const {
return CodeGenOpt::Default;
/// \brief True if the subtarget should run the local reassignment
/// heuristic of the register allocator.
/// This heuristic may be compile time intensive, \p OptLevel provides
/// a finer grain to tune the register allocator.
virtual bool enableRALocalReassignment(CodeGenOpt::Level OptLevel) const;
/// \brief Enable use of alias analysis during code generation (during MI
/// scheduling, DAGCombine, etc.).
virtual bool useAA() const;
/// \brief Enable the use of the early if conversion pass.
virtual bool enableEarlyIfConversion() const { return false; }
/// \brief Reset the features for the subtarget.
virtual void resetSubtargetFeatures(const MachineFunction *MF) { }
} // End llvm namespace