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llvm-mirror/include/llvm/Target/TargetInstrInfo.h
Evan Cheng 4c77fb5375 Add a if-conversion optimization that allows 'true' side of a diamond to be 
unpredicated. That is, turn
 subeq  r0, r1, #1
 addne  r0, r1, #1                                                                                                                                                                                                     
into
 sub    r0, r1, #1
 addne  r0, r1, #1

For targets where conditional instructions are always executed, this may be
beneficial. It may remove pseudo anti-dependency in out-of-order execution
CPUs. e.g.
 op    r1, ...
 str   r1, [r10]        ; end-of-life of r1 as div result
 cmp   r0, #65
 movne r1, #44  ; raw dependency on previous r1
 moveq r1, #12

If movne is unpredicated, then
 op    r1, ...
 str   r1, [r10]
 cmp   r0, #65
 mov   r1, #44  ; r1 written unconditionally
 moveq r1, #12

Both mov and moveq are no longer depdendent on the first instruction. This gives
the out-of-order execution engine more freedom to reorder them.

This has passed entire LLVM test suite. But it has not been enabled for any ARM
variant pending more performance evaluation.

rdar://8951196

llvm-svn: 146914
2011-12-19 22:01:30 +00:00

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41 KiB
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//===-- llvm/Target/TargetInstrInfo.h - Instruction 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 describes the target machine instruction set to the code generator.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETINSTRINFO_H
#define LLVM_TARGET_TARGETINSTRINFO_H
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
namespace llvm {
class InstrItineraryData;
class LiveVariables;
class MCAsmInfo;
class MachineMemOperand;
class MachineRegisterInfo;
class MDNode;
class MCInst;
class SDNode;
class ScheduleHazardRecognizer;
class SelectionDAG;
class ScheduleDAG;
class TargetRegisterClass;
class TargetRegisterInfo;
class BranchProbability;
template<class T> class SmallVectorImpl;
//---------------------------------------------------------------------------
///
/// TargetInstrInfo - Interface to description of machine instruction set
///
class TargetInstrInfo : public MCInstrInfo {
TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
public:
TargetInstrInfo(int CFSetupOpcode = -1, int CFDestroyOpcode = -1)
: CallFrameSetupOpcode(CFSetupOpcode),
CallFrameDestroyOpcode(CFDestroyOpcode) {
}
virtual ~TargetInstrInfo();
/// getRegClass - Givem a machine instruction descriptor, returns the register
/// class constraint for OpNum, or NULL.
const TargetRegisterClass *getRegClass(const MCInstrDesc &TID,
unsigned OpNum,
const TargetRegisterInfo *TRI) const;
/// isTriviallyReMaterializable - Return true if the instruction is trivially
/// rematerializable, meaning it has no side effects and requires no operands
/// that aren't always available.
bool isTriviallyReMaterializable(const MachineInstr *MI,
AliasAnalysis *AA = 0) const {
return MI->getOpcode() == TargetOpcode::IMPLICIT_DEF ||
(MI->getDesc().isRematerializable() &&
(isReallyTriviallyReMaterializable(MI, AA) ||
isReallyTriviallyReMaterializableGeneric(MI, AA)));
}
protected:
/// isReallyTriviallyReMaterializable - For instructions with opcodes for
/// which the M_REMATERIALIZABLE flag is set, this hook lets the target
/// specify whether the instruction is actually trivially rematerializable,
/// taking into consideration its operands. This predicate must return false
/// if the instruction has any side effects other than producing a value, or
/// if it requres any address registers that are not always available.
virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
AliasAnalysis *AA) const {
return false;
}
private:
/// isReallyTriviallyReMaterializableGeneric - For instructions with opcodes
/// for which the M_REMATERIALIZABLE flag is set and the target hook
/// isReallyTriviallyReMaterializable returns false, this function does
/// target-independent tests to determine if the instruction is really
/// trivially rematerializable.
bool isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
AliasAnalysis *AA) const;
public:
/// getCallFrameSetup/DestroyOpcode - These methods return the opcode of the
/// frame setup/destroy instructions if they exist (-1 otherwise). Some
/// targets use pseudo instructions in order to abstract away the difference
/// between operating with a frame pointer and operating without, through the
/// use of these two instructions.
///
int getCallFrameSetupOpcode() const { return CallFrameSetupOpcode; }
int getCallFrameDestroyOpcode() const { return CallFrameDestroyOpcode; }
/// isCoalescableExtInstr - Return true if the instruction is a "coalescable"
/// extension instruction. That is, it's like a copy where it's legal for the
/// source to overlap the destination. e.g. X86::MOVSX64rr32. If this returns
/// true, then it's expected the pre-extension value is available as a subreg
/// of the result register. This also returns the sub-register index in
/// SubIdx.
virtual bool isCoalescableExtInstr(const MachineInstr &MI,
unsigned &SrcReg, unsigned &DstReg,
unsigned &SubIdx) const {
return false;
}
/// isLoadFromStackSlot - If the specified machine instruction is a direct
/// load from a stack slot, return the virtual or physical register number of
/// the destination along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than loading from the stack slot.
virtual unsigned isLoadFromStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
return 0;
}
/// isLoadFromStackSlotPostFE - Check for post-frame ptr elimination
/// stack locations as well. This uses a heuristic so it isn't
/// reliable for correctness.
virtual unsigned isLoadFromStackSlotPostFE(const MachineInstr *MI,
int &FrameIndex) const {
return 0;
}
/// hasLoadFromStackSlot - If the specified machine instruction has
/// a load from a stack slot, return true along with the FrameIndex
/// of the loaded stack slot and the machine mem operand containing
/// the reference. If not, return false. Unlike
/// isLoadFromStackSlot, this returns true for any instructions that
/// loads from the stack. This is just a hint, as some cases may be
/// missed.
virtual bool hasLoadFromStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const {
return 0;
}
/// isStoreToStackSlot - If the specified machine instruction is a direct
/// store to a stack slot, return the virtual or physical register number of
/// the source reg along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than storing to the stack slot.
virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
return 0;
}
/// isStoreToStackSlotPostFE - Check for post-frame ptr elimination
/// stack locations as well. This uses a heuristic so it isn't
/// reliable for correctness.
virtual unsigned isStoreToStackSlotPostFE(const MachineInstr *MI,
int &FrameIndex) const {
return 0;
}
/// hasStoreToStackSlot - If the specified machine instruction has a
/// store to a stack slot, return true along with the FrameIndex of
/// the loaded stack slot and the machine mem operand containing the
/// reference. If not, return false. Unlike isStoreToStackSlot,
/// this returns true for any instructions that stores to the
/// stack. This is just a hint, as some cases may be missed.
virtual bool hasStoreToStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const {
return 0;
}
/// reMaterialize - Re-issue the specified 'original' instruction at the
/// specific location targeting a new destination register.
/// The register in Orig->getOperand(0).getReg() will be substituted by
/// DestReg:SubIdx. Any existing subreg index is preserved or composed with
/// SubIdx.
virtual void reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, unsigned SubIdx,
const MachineInstr *Orig,
const TargetRegisterInfo &TRI) const = 0;
/// scheduleTwoAddrSource - Schedule the copy / re-mat of the source of the
/// two-addrss instruction inserted by two-address pass.
virtual void scheduleTwoAddrSource(MachineInstr *SrcMI,
MachineInstr *UseMI,
const TargetRegisterInfo &TRI) const {
// Do nothing.
}
/// duplicate - Create a duplicate of the Orig instruction in MF. This is like
/// MachineFunction::CloneMachineInstr(), but the target may update operands
/// that are required to be unique.
///
/// The instruction must be duplicable as indicated by isNotDuplicable().
virtual MachineInstr *duplicate(MachineInstr *Orig,
MachineFunction &MF) const = 0;
/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
/// may be able to convert a two-address instruction into one or more true
/// three-address instructions on demand. This allows the X86 target (for
/// example) to convert ADD and SHL instructions into LEA instructions if they
/// would require register copies due to two-addressness.
///
/// This method returns a null pointer if the transformation cannot be
/// performed, otherwise it returns the last new instruction.
///
virtual MachineInstr *
convertToThreeAddress(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
return 0;
}
/// commuteInstruction - If a target has any instructions that are
/// commutable but require converting to different instructions or making
/// non-trivial changes to commute them, this method can overloaded to do
/// that. The default implementation simply swaps the commutable operands.
/// If NewMI is false, MI is modified in place and returned; otherwise, a
/// new machine instruction is created and returned. Do not call this
/// method for a non-commutable instruction, but there may be some cases
/// where this method fails and returns null.
virtual MachineInstr *commuteInstruction(MachineInstr *MI,
bool NewMI = false) const = 0;
/// findCommutedOpIndices - If specified MI is commutable, return the two
/// operand indices that would swap value. Return false if the instruction
/// is not in a form which this routine understands.
virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
unsigned &SrcOpIdx2) const = 0;
/// produceSameValue - Return true if two machine instructions would produce
/// identical values. By default, this is only true when the two instructions
/// are deemed identical except for defs. If this function is called when the
/// IR is still in SSA form, the caller can pass the MachineRegisterInfo for
/// aggressive checks.
virtual bool produceSameValue(const MachineInstr *MI0,
const MachineInstr *MI1,
const MachineRegisterInfo *MRI = 0) const = 0;
/// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
/// true if it cannot be understood (e.g. it's a switch dispatch or isn't
/// implemented for a target). Upon success, this returns false and returns
/// with the following information in various cases:
///
/// 1. If this block ends with no branches (it just falls through to its succ)
/// just return false, leaving TBB/FBB null.
/// 2. If this block ends with only an unconditional branch, it sets TBB to be
/// the destination block.
/// 3. If this block ends with a conditional branch and it falls through to a
/// successor block, it sets TBB to be the branch destination block and a
/// list of operands that evaluate the condition. These operands can be
/// passed to other TargetInstrInfo methods to create new branches.
/// 4. If this block ends with a conditional branch followed by an
/// unconditional branch, it returns the 'true' destination in TBB, the
/// 'false' destination in FBB, and a list of operands that evaluate the
/// condition. These operands can be passed to other TargetInstrInfo
/// methods to create new branches.
///
/// Note that RemoveBranch and InsertBranch must be implemented to support
/// cases where this method returns success.
///
/// If AllowModify is true, then this routine is allowed to modify the basic
/// block (e.g. delete instructions after the unconditional branch).
///
virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify = false) const {
return true;
}
/// RemoveBranch - Remove the branching code at the end of the specific MBB.
/// This is only invoked in cases where AnalyzeBranch returns success. It
/// returns the number of instructions that were removed.
virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
return 0;
}
/// InsertBranch - Insert branch code into the end of the specified
/// MachineBasicBlock. The operands to this method are the same as those
/// returned by AnalyzeBranch. This is only invoked in cases where
/// AnalyzeBranch returns success. It returns the number of instructions
/// inserted.
///
/// It is also invoked by tail merging to add unconditional branches in
/// cases where AnalyzeBranch doesn't apply because there was no original
/// branch to analyze. At least this much must be implemented, else tail
/// merging needs to be disabled.
virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond,
DebugLoc DL) const {
assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
return 0;
}
/// ReplaceTailWithBranchTo - Delete the instruction OldInst and everything
/// after it, replacing it with an unconditional branch to NewDest. This is
/// used by the tail merging pass.
virtual void ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
MachineBasicBlock *NewDest) const = 0;
/// isLegalToSplitMBBAt - Return true if it's legal to split the given basic
/// block at the specified instruction (i.e. instruction would be the start
/// of a new basic block).
virtual bool isLegalToSplitMBBAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) const {
return true;
}
/// isProfitableToIfCvt - Return true if it's profitable to predicate
/// instructions with accumulated instruction latency of "NumCycles"
/// of the specified basic block, where the probability of the instructions
/// being executed is given by Probability, and Confidence is a measure
/// of our confidence that it will be properly predicted.
virtual
bool isProfitableToIfCvt(MachineBasicBlock &MBB, unsigned NumCyles,
unsigned ExtraPredCycles,
const BranchProbability &Probability) const {
return false;
}
/// isProfitableToIfCvt - Second variant of isProfitableToIfCvt, this one
/// checks for the case where two basic blocks from true and false path
/// of a if-then-else (diamond) are predicated on mutally exclusive
/// predicates, where the probability of the true path being taken is given
/// by Probability, and Confidence is a measure of our confidence that it
/// will be properly predicted.
virtual bool
isProfitableToIfCvt(MachineBasicBlock &TMBB,
unsigned NumTCycles, unsigned ExtraTCycles,
MachineBasicBlock &FMBB,
unsigned NumFCycles, unsigned ExtraFCycles,
const BranchProbability &Probability) const {
return false;
}
/// isProfitableToDupForIfCvt - Return true if it's profitable for
/// if-converter to duplicate instructions of specified accumulated
/// instruction latencies in the specified MBB to enable if-conversion.
/// The probability of the instructions being executed is given by
/// Probability, and Confidence is a measure of our confidence that it
/// will be properly predicted.
virtual bool
isProfitableToDupForIfCvt(MachineBasicBlock &MBB, unsigned NumCyles,
const BranchProbability &Probability) const {
return false;
}
/// isProfitableToUnpredicate - Return true if it's profitable to unpredicate
/// one side of a 'diamond', i.e. two sides of if-else predicated on mutually
/// exclusive predicates.
/// e.g.
/// subeq r0, r1, #1
/// addne r0, r1, #1
/// =>
/// sub r0, r1, #1
/// addne r0, r1, #1
///
/// This may be profitable is conditional instructions are always executed.
virtual bool isProfitableToUnpredicate(MachineBasicBlock &TMBB,
MachineBasicBlock &FMBB) const {
return false;
}
/// copyPhysReg - Emit instructions to copy a pair of physical registers.
virtual void copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
bool KillSrc) const {
assert(0 && "Target didn't implement TargetInstrInfo::copyPhysReg!");
}
/// storeRegToStackSlot - Store the specified register of the given register
/// class to the specified stack frame index. The store instruction is to be
/// added to the given machine basic block before the specified machine
/// instruction. If isKill is true, the register operand is the last use and
/// must be marked kill.
virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned SrcReg, bool isKill, int FrameIndex,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
}
/// loadRegFromStackSlot - Load the specified register of the given register
/// class from the specified stack frame index. The load instruction is to be
/// added to the given machine basic block before the specified machine
/// instruction.
virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, int FrameIndex,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
}
/// expandPostRAPseudo - This function is called for all pseudo instructions
/// that remain after register allocation. Many pseudo instructions are
/// created to help register allocation. This is the place to convert them
/// into real instructions. The target can edit MI in place, or it can insert
/// new instructions and erase MI. The function should return true if
/// anything was changed.
virtual bool expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
return false;
}
/// emitFrameIndexDebugValue - Emit a target-dependent form of
/// DBG_VALUE encoding the address of a frame index. Addresses would
/// normally be lowered the same way as other addresses on the target,
/// e.g. in load instructions. For targets that do not support this
/// the debug info is simply lost.
/// If you add this for a target you should handle this DBG_VALUE in the
/// target-specific AsmPrinter code as well; you will probably get invalid
/// assembly output if you don't.
virtual MachineInstr *emitFrameIndexDebugValue(MachineFunction &MF,
int FrameIx,
uint64_t Offset,
const MDNode *MDPtr,
DebugLoc dl) const {
return 0;
}
/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
/// slot into the specified machine instruction for the specified operand(s).
/// If this is possible, a new instruction is returned with the specified
/// operand folded, otherwise NULL is returned.
/// The new instruction is inserted before MI, and the client is responsible
/// for removing the old instruction.
MachineInstr* foldMemoryOperand(MachineBasicBlock::iterator MI,
const SmallVectorImpl<unsigned> &Ops,
int FrameIndex) const;
/// foldMemoryOperand - Same as the previous version except it allows folding
/// of any load and store from / to any address, not just from a specific
/// stack slot.
MachineInstr* foldMemoryOperand(MachineBasicBlock::iterator MI,
const SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const;
protected:
/// foldMemoryOperandImpl - Target-dependent implementation for
/// foldMemoryOperand. Target-independent code in foldMemoryOperand will
/// take care of adding a MachineMemOperand to the newly created instruction.
virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
const SmallVectorImpl<unsigned> &Ops,
int FrameIndex) const {
return 0;
}
/// foldMemoryOperandImpl - Target-dependent implementation for
/// foldMemoryOperand. Target-independent code in foldMemoryOperand will
/// take care of adding a MachineMemOperand to the newly created instruction.
virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
const SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const {
return 0;
}
public:
/// canFoldMemoryOperand - Returns true for the specified load / store if
/// folding is possible.
virtual
bool canFoldMemoryOperand(const MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops) const =0;
/// unfoldMemoryOperand - Separate a single instruction which folded a load or
/// a store or a load and a store into two or more instruction. If this is
/// possible, returns true as well as the new instructions by reference.
virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
SmallVectorImpl<MachineInstr*> &NewMIs) const{
return false;
}
virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
SmallVectorImpl<SDNode*> &NewNodes) const {
return false;
}
/// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
/// instruction after load / store are unfolded from an instruction of the
/// specified opcode. It returns zero if the specified unfolding is not
/// possible. If LoadRegIndex is non-null, it is filled in with the operand
/// index of the operand which will hold the register holding the loaded
/// value.
virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
bool UnfoldLoad, bool UnfoldStore,
unsigned *LoadRegIndex = 0) const {
return 0;
}
/// areLoadsFromSameBasePtr - This is used by the pre-regalloc scheduler
/// to determine if two loads are loading from the same base address. It
/// should only return true if the base pointers are the same and the
/// only differences between the two addresses are the offset. It also returns
/// the offsets by reference.
virtual bool areLoadsFromSameBasePtr(SDNode *Load1, SDNode *Load2,
int64_t &Offset1, int64_t &Offset2) const {
return false;
}
/// shouldScheduleLoadsNear - This is a used by the pre-regalloc scheduler to
/// determine (in conjunction with areLoadsFromSameBasePtr) if two loads should
/// be scheduled togther. On some targets if two loads are loading from
/// addresses in the same cache line, it's better if they are scheduled
/// together. This function takes two integers that represent the load offsets
/// from the common base address. It returns true if it decides it's desirable
/// to schedule the two loads together. "NumLoads" is the number of loads that
/// have already been scheduled after Load1.
virtual bool shouldScheduleLoadsNear(SDNode *Load1, SDNode *Load2,
int64_t Offset1, int64_t Offset2,
unsigned NumLoads) const {
return false;
}
/// ReverseBranchCondition - Reverses the branch condition of the specified
/// condition list, returning false on success and true if it cannot be
/// reversed.
virtual
bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
return true;
}
/// insertNoop - Insert a noop into the instruction stream at the specified
/// point.
virtual void insertNoop(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const;
/// getNoopForMachoTarget - Return the noop instruction to use for a noop.
virtual void getNoopForMachoTarget(MCInst &NopInst) const {
// Default to just using 'nop' string.
}
/// isPredicated - Returns true if the instruction is already predicated.
///
virtual bool isPredicated(const MachineInstr *MI) const {
return false;
}
/// isUnpredicatedTerminator - Returns true if the instruction is a
/// terminator instruction that has not been predicated.
virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const = 0;
/// PredicateInstruction - Convert the instruction into a predicated
/// instruction. It returns true if the operation was successful.
virtual
bool PredicateInstruction(MachineInstr *MI,
const SmallVectorImpl<MachineOperand> &Pred) const = 0;
/// SubsumesPredicate - Returns true if the first specified predicate
/// subsumes the second, e.g. GE subsumes GT.
virtual
bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
const SmallVectorImpl<MachineOperand> &Pred2) const {
return false;
}
/// DefinesPredicate - If the specified instruction defines any predicate
/// or condition code register(s) used for predication, returns true as well
/// as the definition predicate(s) by reference.
virtual bool DefinesPredicate(MachineInstr *MI,
std::vector<MachineOperand> &Pred) const {
return false;
}
/// isPredicable - Return true if the specified instruction can be predicated.
/// By default, this returns true for every instruction with a
/// PredicateOperand.
virtual bool isPredicable(MachineInstr *MI) const {
return MI->getDesc().isPredicable();
}
/// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
/// instruction that defines the specified register class.
virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
return true;
}
/// isSchedulingBoundary - Test if the given instruction should be
/// considered a scheduling boundary. This primarily includes labels and
/// terminators.
virtual bool isSchedulingBoundary(const MachineInstr *MI,
const MachineBasicBlock *MBB,
const MachineFunction &MF) const = 0;
/// Measure the specified inline asm to determine an approximation of its
/// length.
virtual unsigned getInlineAsmLength(const char *Str,
const MCAsmInfo &MAI) const;
/// CreateTargetHazardRecognizer - Allocate and return a hazard recognizer to
/// use for this target when scheduling the machine instructions before
/// register allocation.
virtual ScheduleHazardRecognizer*
CreateTargetHazardRecognizer(const TargetMachine *TM,
const ScheduleDAG *DAG) const = 0;
/// CreateTargetPostRAHazardRecognizer - Allocate and return a hazard
/// recognizer to use for this target when scheduling the machine instructions
/// after register allocation.
virtual ScheduleHazardRecognizer*
CreateTargetPostRAHazardRecognizer(const InstrItineraryData*,
const ScheduleDAG *DAG) const = 0;
/// AnalyzeCompare - For a comparison instruction, return the source register
/// in SrcReg and the value it compares against in CmpValue. Return true if
/// the comparison instruction can be analyzed.
virtual bool AnalyzeCompare(const MachineInstr *MI,
unsigned &SrcReg, int &Mask, int &Value) const {
return false;
}
/// OptimizeCompareInstr - See if the comparison instruction can be converted
/// into something more efficient. E.g., on ARM most instructions can set the
/// flags register, obviating the need for a separate CMP.
virtual bool OptimizeCompareInstr(MachineInstr *CmpInstr,
unsigned SrcReg, int Mask, int Value,
const MachineRegisterInfo *MRI) const {
return false;
}
/// FoldImmediate - 'Reg' is known to be defined by a move immediate
/// instruction, try to fold the immediate into the use instruction.
virtual bool FoldImmediate(MachineInstr *UseMI, MachineInstr *DefMI,
unsigned Reg, MachineRegisterInfo *MRI) const {
return false;
}
/// getNumMicroOps - Return the number of u-operations the given machine
/// instruction will be decoded to on the target cpu.
virtual unsigned getNumMicroOps(const InstrItineraryData *ItinData,
const MachineInstr *MI) const;
/// isZeroCost - Return true for pseudo instructions that don't consume any
/// machine resources in their current form. These are common cases that the
/// scheduler should consider free, rather than conservatively handling them
/// as instructions with no itinerary.
bool isZeroCost(unsigned Opcode) const {
return Opcode <= TargetOpcode::COPY;
}
/// getOperandLatency - Compute and return the use operand latency of a given
/// pair of def and use.
/// In most cases, the static scheduling itinerary was enough to determine the
/// operand latency. But it may not be possible for instructions with variable
/// number of defs / uses.
virtual int getOperandLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *UseMI, unsigned UseIdx) const;
virtual int getOperandLatency(const InstrItineraryData *ItinData,
SDNode *DefNode, unsigned DefIdx,
SDNode *UseNode, unsigned UseIdx) const = 0;
/// getOutputLatency - Compute and return the output dependency latency of a
/// a given pair of defs which both target the same register. This is usually
/// one.
virtual unsigned getOutputLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *DepMI) const {
return 1;
}
/// getInstrLatency - Compute the instruction latency of a given instruction.
/// If the instruction has higher cost when predicated, it's returned via
/// PredCost.
virtual int getInstrLatency(const InstrItineraryData *ItinData,
const MachineInstr *MI,
unsigned *PredCost = 0) const;
virtual int getInstrLatency(const InstrItineraryData *ItinData,
SDNode *Node) const = 0;
/// isHighLatencyDef - Return true if this opcode has high latency to its
/// result.
virtual bool isHighLatencyDef(int opc) const { return false; }
/// hasHighOperandLatency - Compute operand latency between a def of 'Reg'
/// and an use in the current loop, return true if the target considered
/// it 'high'. This is used by optimization passes such as machine LICM to
/// determine whether it makes sense to hoist an instruction out even in
/// high register pressure situation.
virtual
bool hasHighOperandLatency(const InstrItineraryData *ItinData,
const MachineRegisterInfo *MRI,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *UseMI, unsigned UseIdx) const {
return false;
}
/// hasLowDefLatency - Compute operand latency of a def of 'Reg', return true
/// if the target considered it 'low'.
virtual
bool hasLowDefLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI, unsigned DefIdx) const;
/// verifyInstruction - Perform target specific instruction verification.
virtual
bool verifyInstruction(const MachineInstr *MI, StringRef &ErrInfo) const {
return true;
}
/// getExecutionDomain - Return the current execution domain and bit mask of
/// possible domains for instruction.
///
/// Some micro-architectures have multiple execution domains, and multiple
/// opcodes that perform the same operation in different domains. For
/// example, the x86 architecture provides the por, orps, and orpd
/// instructions that all do the same thing. There is a latency penalty if a
/// register is written in one domain and read in another.
///
/// This function returns a pair (domain, mask) containing the execution
/// domain of MI, and a bit mask of possible domains. The setExecutionDomain
/// function can be used to change the opcode to one of the domains in the
/// bit mask. Instructions whose execution domain can't be changed should
/// return a 0 mask.
///
/// The execution domain numbers don't have any special meaning except domain
/// 0 is used for instructions that are not associated with any interesting
/// execution domain.
///
virtual std::pair<uint16_t, uint16_t>
getExecutionDomain(const MachineInstr *MI) const {
return std::make_pair(0, 0);
}
/// setExecutionDomain - Change the opcode of MI to execute in Domain.
///
/// The bit (1 << Domain) must be set in the mask returned from
/// getExecutionDomain(MI).
///
virtual void setExecutionDomain(MachineInstr *MI, unsigned Domain) const {}
/// getPartialRegUpdateClearance - Returns the preferred minimum clearance
/// before an instruction with an unwanted partial register update.
///
/// Some instructions only write part of a register, and implicitly need to
/// read the other parts of the register. This may cause unwanted stalls
/// preventing otherwise unrelated instructions from executing in parallel in
/// an out-of-order CPU.
///
/// For example, the x86 instruction cvtsi2ss writes its result to bits
/// [31:0] of the destination xmm register. Bits [127:32] are unaffected, so
/// the instruction needs to wait for the old value of the register to become
/// available:
///
/// addps %xmm1, %xmm0
/// movaps %xmm0, (%rax)
/// cvtsi2ss %rbx, %xmm0
///
/// In the code above, the cvtsi2ss instruction needs to wait for the addps
/// instruction before it can issue, even though the high bits of %xmm0
/// probably aren't needed.
///
/// This hook returns the preferred clearance before MI, measured in
/// instructions. Other defs of MI's operand OpNum are avoided in the last N
/// instructions before MI. It should only return a positive value for
/// unwanted dependencies. If the old bits of the defined register have
/// useful values, or if MI is determined to otherwise read the dependency,
/// the hook should return 0.
///
/// The unwanted dependency may be handled by:
///
/// 1. Allocating the same register for an MI def and use. That makes the
/// unwanted dependency identical to a required dependency.
///
/// 2. Allocating a register for the def that has no defs in the previous N
/// instructions.
///
/// 3. Calling breakPartialRegDependency() with the same arguments. This
/// allows the target to insert a dependency breaking instruction.
///
virtual unsigned
getPartialRegUpdateClearance(const MachineInstr *MI, unsigned OpNum,
const TargetRegisterInfo *TRI) const {
// The default implementation returns 0 for no partial register dependency.
return 0;
}
/// breakPartialRegDependency - Insert a dependency-breaking instruction
/// before MI to eliminate an unwanted dependency on OpNum.
///
/// If it wasn't possible to avoid a def in the last N instructions before MI
/// (see getPartialRegUpdateClearance), this hook will be called to break the
/// unwanted dependency.
///
/// On x86, an xorps instruction can be used as a dependency breaker:
///
/// addps %xmm1, %xmm0
/// movaps %xmm0, (%rax)
/// xorps %xmm0, %xmm0
/// cvtsi2ss %rbx, %xmm0
///
/// An <imp-kill> operand should be added to MI if an instruction was
/// inserted. This ties the instructions together in the post-ra scheduler.
///
virtual void
breakPartialRegDependency(MachineBasicBlock::iterator MI, unsigned OpNum,
const TargetRegisterInfo *TRI) const {}
private:
int CallFrameSetupOpcode, CallFrameDestroyOpcode;
};
/// TargetInstrInfoImpl - This is the default implementation of
/// TargetInstrInfo, which just provides a couple of default implementations
/// for various methods. This separated out because it is implemented in
/// libcodegen, not in libtarget.
class TargetInstrInfoImpl : public TargetInstrInfo {
protected:
TargetInstrInfoImpl(int CallFrameSetupOpcode = -1,
int CallFrameDestroyOpcode = -1)
: TargetInstrInfo(CallFrameSetupOpcode, CallFrameDestroyOpcode) {}
public:
virtual void ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
MachineBasicBlock *NewDest) const;
virtual MachineInstr *commuteInstruction(MachineInstr *MI,
bool NewMI = false) const;
virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
unsigned &SrcOpIdx2) const;
virtual bool canFoldMemoryOperand(const MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops) const;
virtual bool hasLoadFromStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const;
virtual bool hasStoreToStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const;
virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
virtual bool PredicateInstruction(MachineInstr *MI,
const SmallVectorImpl<MachineOperand> &Pred) const;
virtual void reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, unsigned SubReg,
const MachineInstr *Orig,
const TargetRegisterInfo &TRI) const;
virtual MachineInstr *duplicate(MachineInstr *Orig,
MachineFunction &MF) const;
virtual bool produceSameValue(const MachineInstr *MI0,
const MachineInstr *MI1,
const MachineRegisterInfo *MRI) const;
virtual bool isSchedulingBoundary(const MachineInstr *MI,
const MachineBasicBlock *MBB,
const MachineFunction &MF) const;
using TargetInstrInfo::getOperandLatency;
virtual int getOperandLatency(const InstrItineraryData *ItinData,
SDNode *DefNode, unsigned DefIdx,
SDNode *UseNode, unsigned UseIdx) const;
using TargetInstrInfo::getInstrLatency;
virtual int getInstrLatency(const InstrItineraryData *ItinData,
SDNode *Node) const;
bool usePreRAHazardRecognizer() const;
virtual ScheduleHazardRecognizer *
CreateTargetHazardRecognizer(const TargetMachine*, const ScheduleDAG*) const;
virtual ScheduleHazardRecognizer *
CreateTargetPostRAHazardRecognizer(const InstrItineraryData*,
const ScheduleDAG*) const;
};
} // End llvm namespace
#endif
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