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llvm-mirror/lib/Target/X86/X86InstrInfo.h
Simon Pilgrim 0ccb373260 [X86] Memory folding for commutative instructions (updated) 
This patch improves support for commutative instructions in the x86 memory folding implementation by attempting to fold a commuted version of the instruction if the original folding fails - if that folding fails as well the instruction is 're-commuted' back to its original order before returning.

Updated version of r219584 (reverted in r219595) - the commutation attempt now explicitly ensures that neither of the commuted source operands are tied to the destination operand / register, which was the source of all the regressions that occurred with the original patch attempt.

Added additional regression test case provided by Joerg Sonnenberger.

Differential Revision: http://reviews.llvm.org/D5818

llvm-svn: 220239
2014-10-20 22:14:22 +00:00

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//===-- X86InstrInfo.h - X86 Instruction 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 contains the X86 implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_X86_X86INSTRINFO_H
#define LLVM_LIB_TARGET_X86_X86INSTRINFO_H
#include "MCTargetDesc/X86BaseInfo.h"
#include "X86RegisterInfo.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Target/TargetInstrInfo.h"
#define GET_INSTRINFO_HEADER
#include "X86GenInstrInfo.inc"
namespace llvm {
class X86RegisterInfo;
class X86Subtarget;
namespace X86 {
// X86 specific condition code. These correspond to X86_*_COND in
// X86InstrInfo.td. They must be kept in synch.
enum CondCode {
COND_A = 0,
COND_AE = 1,
COND_B = 2,
COND_BE = 3,
COND_E = 4,
COND_G = 5,
COND_GE = 6,
COND_L = 7,
COND_LE = 8,
COND_NE = 9,
COND_NO = 10,
COND_NP = 11,
COND_NS = 12,
COND_O = 13,
COND_P = 14,
COND_S = 15,
LAST_VALID_COND = COND_S,
// Artificial condition codes. These are used by AnalyzeBranch
// to indicate a block terminated with two conditional branches to
// the same location. This occurs in code using FCMP_OEQ or FCMP_UNE,
// which can't be represented on x86 with a single condition. These
// are never used in MachineInstrs.
COND_NE_OR_P,
COND_NP_OR_E,
COND_INVALID
};
// Turn condition code into conditional branch opcode.
unsigned GetCondBranchFromCond(CondCode CC);
/// \brief Return a set opcode for the given condition and whether it has
/// a memory operand.
unsigned getSETFromCond(CondCode CC, bool HasMemoryOperand = false);
/// \brief Return a cmov opcode for the given condition, register size in
/// bytes, and operand type.
unsigned getCMovFromCond(CondCode CC, unsigned RegBytes,
bool HasMemoryOperand = false);
// Turn CMov opcode into condition code.
CondCode getCondFromCMovOpc(unsigned Opc);
/// GetOppositeBranchCondition - Return the inverse of the specified cond,
/// e.g. turning COND_E to COND_NE.
CondCode GetOppositeBranchCondition(CondCode CC);
} // end namespace X86;
/// isGlobalStubReference - Return true if the specified TargetFlag operand is
/// a reference to a stub for a global, not the global itself.
inline static bool isGlobalStubReference(unsigned char TargetFlag) {
switch (TargetFlag) {
case X86II::MO_DLLIMPORT: // dllimport stub.
case X86II::MO_GOTPCREL: // rip-relative GOT reference.
case X86II::MO_GOT: // normal GOT reference.
case X86II::MO_DARWIN_NONLAZY_PIC_BASE: // Normal $non_lazy_ptr ref.
case X86II::MO_DARWIN_NONLAZY: // Normal $non_lazy_ptr ref.
case X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE: // Hidden $non_lazy_ptr ref.
return true;
default:
return false;
}
}
/// isGlobalRelativeToPICBase - Return true if the specified global value
/// reference is relative to a 32-bit PIC base (X86ISD::GlobalBaseReg). If this
/// is true, the addressing mode has the PIC base register added in (e.g. EBX).
inline static bool isGlobalRelativeToPICBase(unsigned char TargetFlag) {
switch (TargetFlag) {
case X86II::MO_GOTOFF: // isPICStyleGOT: local global.
case X86II::MO_GOT: // isPICStyleGOT: other global.
case X86II::MO_PIC_BASE_OFFSET: // Darwin local global.
case X86II::MO_DARWIN_NONLAZY_PIC_BASE: // Darwin/32 external global.
case X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE: // Darwin/32 hidden global.
case X86II::MO_TLVP: // ??? Pretty sure..
return true;
default:
return false;
}
}
inline static bool isScale(const MachineOperand &MO) {
return MO.isImm() &&
(MO.getImm() == 1 || MO.getImm() == 2 ||
MO.getImm() == 4 || MO.getImm() == 8);
}
inline static bool isLeaMem(const MachineInstr *MI, unsigned Op) {
if (MI->getOperand(Op).isFI()) return true;
return Op+X86::AddrSegmentReg <= MI->getNumOperands() &&
MI->getOperand(Op+X86::AddrBaseReg).isReg() &&
isScale(MI->getOperand(Op+X86::AddrScaleAmt)) &&
MI->getOperand(Op+X86::AddrIndexReg).isReg() &&
(MI->getOperand(Op+X86::AddrDisp).isImm() ||
MI->getOperand(Op+X86::AddrDisp).isGlobal() ||
MI->getOperand(Op+X86::AddrDisp).isCPI() ||
MI->getOperand(Op+X86::AddrDisp).isJTI());
}
inline static bool isMem(const MachineInstr *MI, unsigned Op) {
if (MI->getOperand(Op).isFI()) return true;
return Op+X86::AddrNumOperands <= MI->getNumOperands() &&
MI->getOperand(Op+X86::AddrSegmentReg).isReg() &&
isLeaMem(MI, Op);
}
class X86InstrInfo final : public X86GenInstrInfo {
X86Subtarget &Subtarget;
const X86RegisterInfo RI;
/// RegOp2MemOpTable3Addr, RegOp2MemOpTable0, RegOp2MemOpTable1,
/// RegOp2MemOpTable2, RegOp2MemOpTable3 - Load / store folding opcode maps.
///
typedef DenseMap<unsigned,
std::pair<unsigned, unsigned> > RegOp2MemOpTableType;
RegOp2MemOpTableType RegOp2MemOpTable2Addr;
RegOp2MemOpTableType RegOp2MemOpTable0;
RegOp2MemOpTableType RegOp2MemOpTable1;
RegOp2MemOpTableType RegOp2MemOpTable2;
RegOp2MemOpTableType RegOp2MemOpTable3;
/// MemOp2RegOpTable - Load / store unfolding opcode map.
///
typedef DenseMap<unsigned,
std::pair<unsigned, unsigned> > MemOp2RegOpTableType;
MemOp2RegOpTableType MemOp2RegOpTable;
static void AddTableEntry(RegOp2MemOpTableType &R2MTable,
MemOp2RegOpTableType &M2RTable,
unsigned RegOp, unsigned MemOp, unsigned Flags);
virtual void anchor();
public:
explicit X86InstrInfo(X86Subtarget &STI);
/// getRegisterInfo - TargetInstrInfo is a superset of MRegister info. As
/// such, whenever a client has an instance of instruction info, it should
/// always be able to get register info as well (through this method).
///
const X86RegisterInfo &getRegisterInfo() const { return RI; }
/// 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.
bool isCoalescableExtInstr(const MachineInstr &MI,
unsigned &SrcReg, unsigned &DstReg,
unsigned &SubIdx) const override;
unsigned isLoadFromStackSlot(const MachineInstr *MI,
int &FrameIndex) const override;
/// isLoadFromStackSlotPostFE - Check for post-frame ptr elimination
/// stack locations as well. This uses a heuristic so it isn't
/// reliable for correctness.
unsigned isLoadFromStackSlotPostFE(const MachineInstr *MI,
int &FrameIndex) const override;
unsigned isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const override;
/// isStoreToStackSlotPostFE - Check for post-frame ptr elimination
/// stack locations as well. This uses a heuristic so it isn't
/// reliable for correctness.
unsigned isStoreToStackSlotPostFE(const MachineInstr *MI,
int &FrameIndex) const override;
bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
AliasAnalysis *AA) const override;
void reMaterialize(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
unsigned DestReg, unsigned SubIdx,
const MachineInstr *Orig,
const TargetRegisterInfo &TRI) const override;
/// Given an operand within a MachineInstr, insert preceding code to put it
/// into the right format for a particular kind of LEA instruction. This may
/// involve using an appropriate super-register instead (with an implicit use
/// of the original) or creating a new virtual register and inserting COPY
/// instructions to get the data into the right class.
///
/// Reference parameters are set to indicate how caller should add this
/// operand to the LEA instruction.
bool classifyLEAReg(MachineInstr *MI, const MachineOperand &Src,
unsigned LEAOpcode, bool AllowSP,
unsigned &NewSrc, bool &isKill,
bool &isUndef, MachineOperand &ImplicitOp) const;
/// 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 a true
/// three-address instruction 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 new instruction.
///
MachineInstr *convertToThreeAddress(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI,
LiveVariables *LV) const override;
/// commuteInstruction - We have a few instructions that must be hacked on to
/// commute them.
///
MachineInstr *commuteInstruction(MachineInstr *MI, bool NewMI) const override;
bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
unsigned &SrcOpIdx2) const override;
// Branch analysis.
bool isUnpredicatedTerminator(const MachineInstr* MI) const override;
bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const override;
unsigned RemoveBranch(MachineBasicBlock &MBB) const override;
unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond,
DebugLoc DL) const override;
bool canInsertSelect(const MachineBasicBlock&,
const SmallVectorImpl<MachineOperand> &Cond,
unsigned, unsigned, int&, int&, int&) const override;
void insertSelect(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI, DebugLoc DL,
unsigned DstReg,
const SmallVectorImpl<MachineOperand> &Cond,
unsigned TrueReg, unsigned FalseReg) const override;
void copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
bool KillSrc) const override;
void storeRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned SrcReg, bool isKill, int FrameIndex,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const override;
void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill,
SmallVectorImpl<MachineOperand> &Addr,
const TargetRegisterClass *RC,
MachineInstr::mmo_iterator MMOBegin,
MachineInstr::mmo_iterator MMOEnd,
SmallVectorImpl<MachineInstr*> &NewMIs) const;
void loadRegFromStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, int FrameIndex,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const override;
void loadRegFromAddr(MachineFunction &MF, unsigned DestReg,
SmallVectorImpl<MachineOperand> &Addr,
const TargetRegisterClass *RC,
MachineInstr::mmo_iterator MMOBegin,
MachineInstr::mmo_iterator MMOEnd,
SmallVectorImpl<MachineInstr*> &NewMIs) const;
bool expandPostRAPseudo(MachineBasicBlock::iterator MI) const override;
/// foldMemoryOperand - If this target supports it, fold a load or store of
/// the specified stack slot into the specified machine instruction for the
/// specified operand(s). If this is possible, the target should perform the
/// folding and return true, otherwise it should return false. If it folds
/// the instruction, it is likely that the MachineInstruction the iterator
/// references has been changed.
MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
const SmallVectorImpl<unsigned> &Ops,
int FrameIndex) const override;
/// 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* foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
const SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const override;
/// canFoldMemoryOperand - Returns true if the specified load / store is
/// folding is possible.
bool canFoldMemoryOperand(const MachineInstr*,
const SmallVectorImpl<unsigned> &) const override;
/// 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.
bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
SmallVectorImpl<MachineInstr*> &NewMIs) const override;
bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
SmallVectorImpl<SDNode*> &NewNodes) const override;
/// 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.
unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
bool UnfoldLoad, bool UnfoldStore,
unsigned *LoadRegIndex = nullptr) const override;
/// 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.
bool areLoadsFromSameBasePtr(SDNode *Load1, SDNode *Load2, int64_t &Offset1,
int64_t &Offset2) const override;
/// 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.
bool shouldScheduleLoadsNear(SDNode *Load1, SDNode *Load2,
int64_t Offset1, int64_t Offset2,
unsigned NumLoads) const override;
bool shouldScheduleAdjacent(MachineInstr* First,
MachineInstr *Second) const override;
void getNoopForMachoTarget(MCInst &NopInst) const override;
bool
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const override;
/// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
/// instruction that defines the specified register class.
bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const override;
/// isSafeToClobberEFLAGS - Return true if it's safe insert an instruction tha
/// would clobber the EFLAGS condition register. Note the result may be
/// conservative. If it cannot definitely determine the safety after visiting
/// a few instructions in each direction it assumes it's not safe.
bool isSafeToClobberEFLAGS(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const;
static bool isX86_64ExtendedReg(const MachineOperand &MO) {
if (!MO.isReg()) return false;
return X86II::isX86_64ExtendedReg(MO.getReg());
}
/// getGlobalBaseReg - Return a virtual register initialized with the
/// the global base register value. Output instructions required to
/// initialize the register in the function entry block, if necessary.
///
unsigned getGlobalBaseReg(MachineFunction *MF) const;
std::pair<uint16_t, uint16_t>
getExecutionDomain(const MachineInstr *MI) const override;
void setExecutionDomain(MachineInstr *MI, unsigned Domain) const override;
unsigned
getPartialRegUpdateClearance(const MachineInstr *MI, unsigned OpNum,
const TargetRegisterInfo *TRI) const override;
unsigned getUndefRegClearance(const MachineInstr *MI, unsigned &OpNum,
const TargetRegisterInfo *TRI) const override;
void breakPartialRegDependency(MachineBasicBlock::iterator MI, unsigned OpNum,
const TargetRegisterInfo *TRI) const override;
MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
unsigned OpNum,
const SmallVectorImpl<MachineOperand> &MOs,
unsigned Size, unsigned Alignment,
bool AllowCommute) const;
void
getUnconditionalBranch(MCInst &Branch,
const MCSymbolRefExpr *BranchTarget) const override;
void getTrap(MCInst &MI) const override;
bool isHighLatencyDef(int opc) const override;
bool hasHighOperandLatency(const InstrItineraryData *ItinData,
const MachineRegisterInfo *MRI,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *UseMI,
unsigned UseIdx) const override;
/// analyzeCompare - For a comparison instruction, return the source registers
/// in SrcReg and SrcReg2 if having two register operands, and the value it
/// compares against in CmpValue. Return true if the comparison instruction
/// can be analyzed.
bool analyzeCompare(const MachineInstr *MI, unsigned &SrcReg,
unsigned &SrcReg2, int &CmpMask,
int &CmpValue) const override;
/// optimizeCompareInstr - Check if there exists an earlier instruction that
/// operates on the same source operands and sets flags in the same way as
/// Compare; remove Compare if possible.
bool optimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg,
unsigned SrcReg2, int CmpMask, int CmpValue,
const MachineRegisterInfo *MRI) const override;
/// optimizeLoadInstr - Try to remove the load by folding it to a register
/// operand at the use. We fold the load instructions if and only if the
/// def and use are in the same BB. We only look at one load and see
/// whether it can be folded into MI. FoldAsLoadDefReg is the virtual register
/// defined by the load we are trying to fold. DefMI returns the machine
/// instruction that defines FoldAsLoadDefReg, and the function returns
/// the machine instruction generated due to folding.
MachineInstr* optimizeLoadInstr(MachineInstr *MI,
const MachineRegisterInfo *MRI,
unsigned &FoldAsLoadDefReg,
MachineInstr *&DefMI) const override;
private:
MachineInstr * convertToThreeAddressWithLEA(unsigned MIOpc,
MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI,
LiveVariables *LV) const;
/// isFrameOperand - Return true and the FrameIndex if the specified
/// operand and follow operands form a reference to the stack frame.
bool isFrameOperand(const MachineInstr *MI, unsigned int Op,
int &FrameIndex) const;
};
} // End llvm namespace
#endif
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