| //===-- Thumb2SizeReduction.cpp - Thumb2 code size reduction pass -*- C++ -*-=// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "t2-reduce-size" |
| #include "ARM.h" |
| #include "ARMBaseInstrInfo.h" |
| #include "ARMBaseRegisterInfo.h" |
| #include "ARMSubtarget.h" |
| #include "MCTargetDesc/ARMAddressingModes.h" |
| #include "Thumb2InstrInfo.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/IR/Function.h" // To access Function attributes |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| using namespace llvm; |
| |
| STATISTIC(NumNarrows, "Number of 32-bit instrs reduced to 16-bit ones"); |
| STATISTIC(Num2Addrs, "Number of 32-bit instrs reduced to 2addr 16-bit ones"); |
| STATISTIC(NumLdSts, "Number of 32-bit load / store reduced to 16-bit ones"); |
| |
| static cl::opt<int> ReduceLimit("t2-reduce-limit", |
| cl::init(-1), cl::Hidden); |
| static cl::opt<int> ReduceLimit2Addr("t2-reduce-limit2", |
| cl::init(-1), cl::Hidden); |
| static cl::opt<int> ReduceLimitLdSt("t2-reduce-limit3", |
| cl::init(-1), cl::Hidden); |
| |
| namespace { |
| /// ReduceTable - A static table with information on mapping from wide |
| /// opcodes to narrow |
| struct ReduceEntry { |
| uint16_t WideOpc; // Wide opcode |
| uint16_t NarrowOpc1; // Narrow opcode to transform to |
| uint16_t NarrowOpc2; // Narrow opcode when it's two-address |
| uint8_t Imm1Limit; // Limit of immediate field (bits) |
| uint8_t Imm2Limit; // Limit of immediate field when it's two-address |
| unsigned LowRegs1 : 1; // Only possible if low-registers are used |
| unsigned LowRegs2 : 1; // Only possible if low-registers are used (2addr) |
| unsigned PredCC1 : 2; // 0 - If predicated, cc is on and vice versa. |
| // 1 - No cc field. |
| // 2 - Always set CPSR. |
| unsigned PredCC2 : 2; |
| unsigned PartFlag : 1; // 16-bit instruction does partial flag update |
| unsigned Special : 1; // Needs to be dealt with specially |
| unsigned AvoidMovs: 1; // Avoid movs with shifter operand (for Swift) |
| }; |
| |
| static const ReduceEntry ReduceTable[] = { |
| // Wide, Narrow1, Narrow2, imm1,imm2, lo1, lo2, P/C,PF,S,AM |
| { ARM::t2ADCrr, 0, ARM::tADC, 0, 0, 0, 1, 0,0, 0,0,0 }, |
| { ARM::t2ADDri, ARM::tADDi3, ARM::tADDi8, 3, 8, 1, 1, 0,0, 0,1,0 }, |
| { ARM::t2ADDrr, ARM::tADDrr, ARM::tADDhirr, 0, 0, 1, 0, 0,1, 0,0,0 }, |
| { ARM::t2ADDSri,ARM::tADDi3, ARM::tADDi8, 3, 8, 1, 1, 2,2, 0,1,0 }, |
| { ARM::t2ADDSrr,ARM::tADDrr, 0, 0, 0, 1, 0, 2,0, 0,1,0 }, |
| { ARM::t2ANDrr, 0, ARM::tAND, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| { ARM::t2ASRri, ARM::tASRri, 0, 5, 0, 1, 0, 0,0, 1,0,1 }, |
| { ARM::t2ASRrr, 0, ARM::tASRrr, 0, 0, 0, 1, 0,0, 1,0,1 }, |
| { ARM::t2BICrr, 0, ARM::tBIC, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| //FIXME: Disable CMN, as CCodes are backwards from compare expectations |
| //{ ARM::t2CMNrr, ARM::tCMN, 0, 0, 0, 1, 0, 2,0, 0,0,0 }, |
| { ARM::t2CMNzrr, ARM::tCMNz, 0, 0, 0, 1, 0, 2,0, 0,0,0 }, |
| { ARM::t2CMPri, ARM::tCMPi8, 0, 8, 0, 1, 0, 2,0, 0,0,0 }, |
| { ARM::t2CMPrr, ARM::tCMPhir, 0, 0, 0, 0, 0, 2,0, 0,1,0 }, |
| { ARM::t2EORrr, 0, ARM::tEOR, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| // FIXME: adr.n immediate offset must be multiple of 4. |
| //{ ARM::t2LEApcrelJT,ARM::tLEApcrelJT, 0, 0, 0, 1, 0, 1,0, 0,0,0 }, |
| { ARM::t2LSLri, ARM::tLSLri, 0, 5, 0, 1, 0, 0,0, 1,0,1 }, |
| { ARM::t2LSLrr, 0, ARM::tLSLrr, 0, 0, 0, 1, 0,0, 1,0,1 }, |
| { ARM::t2LSRri, ARM::tLSRri, 0, 5, 0, 1, 0, 0,0, 1,0,1 }, |
| { ARM::t2LSRrr, 0, ARM::tLSRrr, 0, 0, 0, 1, 0,0, 1,0,1 }, |
| // FIXME: tMOVi8 and tMVN also partially update CPSR but they are less |
| // likely to cause issue in the loop. As a size / performance workaround, |
| // they are not marked as such. |
| { ARM::t2MOVi, ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 0,0,0 }, |
| { ARM::t2MOVi16,ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 0,1,0 }, |
| // FIXME: Do we need the 16-bit 'S' variant? |
| { ARM::t2MOVr,ARM::tMOVr, 0, 0, 0, 0, 0, 1,0, 0,0,0 }, |
| { ARM::t2MUL, 0, ARM::tMUL, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| { ARM::t2MVNr, ARM::tMVN, 0, 0, 0, 1, 0, 0,0, 0,0,0 }, |
| { ARM::t2ORRrr, 0, ARM::tORR, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| { ARM::t2REV, ARM::tREV, 0, 0, 0, 1, 0, 1,0, 0,0,0 }, |
| { ARM::t2REV16, ARM::tREV16, 0, 0, 0, 1, 0, 1,0, 0,0,0 }, |
| { ARM::t2REVSH, ARM::tREVSH, 0, 0, 0, 1, 0, 1,0, 0,0,0 }, |
| { ARM::t2RORrr, 0, ARM::tROR, 0, 0, 0, 1, 0,0, 1,0,0 }, |
| { ARM::t2RSBri, ARM::tRSB, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2RSBSri,ARM::tRSB, 0, 0, 0, 1, 0, 2,0, 0,1,0 }, |
| { ARM::t2SBCrr, 0, ARM::tSBC, 0, 0, 0, 1, 0,0, 0,0,0 }, |
| { ARM::t2SUBri, ARM::tSUBi3, ARM::tSUBi8, 3, 8, 1, 1, 0,0, 0,0,0 }, |
| { ARM::t2SUBrr, ARM::tSUBrr, 0, 0, 0, 1, 0, 0,0, 0,0,0 }, |
| { ARM::t2SUBSri,ARM::tSUBi3, ARM::tSUBi8, 3, 8, 1, 1, 2,2, 0,0,0 }, |
| { ARM::t2SUBSrr,ARM::tSUBrr, 0, 0, 0, 1, 0, 2,0, 0,0,0 }, |
| { ARM::t2SXTB, ARM::tSXTB, 0, 0, 0, 1, 0, 1,0, 0,1,0 }, |
| { ARM::t2SXTH, ARM::tSXTH, 0, 0, 0, 1, 0, 1,0, 0,1,0 }, |
| { ARM::t2TSTrr, ARM::tTST, 0, 0, 0, 1, 0, 2,0, 0,0,0 }, |
| { ARM::t2UXTB, ARM::tUXTB, 0, 0, 0, 1, 0, 1,0, 0,1,0 }, |
| { ARM::t2UXTH, ARM::tUXTH, 0, 0, 0, 1, 0, 1,0, 0,1,0 }, |
| |
| // FIXME: Clean this up after splitting each Thumb load / store opcode |
| // into multiple ones. |
| { ARM::t2LDRi12,ARM::tLDRi, ARM::tLDRspi, 5, 8, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRs, ARM::tLDRr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRBi12,ARM::tLDRBi, 0, 5, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRBs, ARM::tLDRBr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRHi12,ARM::tLDRHi, 0, 5, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRHs, ARM::tLDRHr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRSBs,ARM::tLDRSB, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2LDRSHs,ARM::tLDRSH, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRi12,ARM::tSTRi, ARM::tSTRspi, 5, 8, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRs, ARM::tSTRr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRBi12,ARM::tSTRBi, 0, 5, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRBs, ARM::tSTRBr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRHi12,ARM::tSTRHi, 0, 5, 0, 1, 0, 0,0, 0,1,0 }, |
| { ARM::t2STRHs, ARM::tSTRHr, 0, 0, 0, 1, 0, 0,0, 0,1,0 }, |
| |
| { ARM::t2LDMIA, ARM::tLDMIA, 0, 0, 0, 1, 1, 1,1, 0,1,0 }, |
| { ARM::t2LDMIA_RET,0, ARM::tPOP_RET, 0, 0, 1, 1, 1,1, 0,1,0 }, |
| { ARM::t2LDMIA_UPD,ARM::tLDMIA_UPD,ARM::tPOP,0, 0, 1, 1, 1,1, 0,1,0 }, |
| // ARM::t2STM (with no basereg writeback) has no Thumb1 equivalent |
| { ARM::t2STMIA_UPD,ARM::tSTMIA_UPD, 0, 0, 0, 1, 1, 1,1, 0,1,0 }, |
| { ARM::t2STMDB_UPD, 0, ARM::tPUSH, 0, 0, 1, 1, 1,1, 0,1,0 } |
| }; |
| |
| class Thumb2SizeReduce : public MachineFunctionPass { |
| public: |
| static char ID; |
| Thumb2SizeReduce(); |
| |
| const Thumb2InstrInfo *TII; |
| const ARMSubtarget *STI; |
| |
| virtual bool runOnMachineFunction(MachineFunction &MF); |
| |
| virtual const char *getPassName() const { |
| return "Thumb2 instruction size reduction pass"; |
| } |
| |
| private: |
| /// ReduceOpcodeMap - Maps wide opcode to index of entry in ReduceTable. |
| DenseMap<unsigned, unsigned> ReduceOpcodeMap; |
| |
| bool canAddPseudoFlagDep(MachineInstr *Def, MachineInstr *Use, |
| bool IsSelfLoop); |
| |
| bool VerifyPredAndCC(MachineInstr *MI, const ReduceEntry &Entry, |
| bool is2Addr, ARMCC::CondCodes Pred, |
| bool LiveCPSR, bool &HasCC, bool &CCDead); |
| |
| bool ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry); |
| |
| bool ReduceSpecial(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, bool LiveCPSR, |
| MachineInstr *CPSRDef, bool IsSelfLoop); |
| |
| /// ReduceTo2Addr - Reduce a 32-bit instruction to a 16-bit two-address |
| /// instruction. |
| bool ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop); |
| |
| /// ReduceToNarrow - Reduce a 32-bit instruction to a 16-bit |
| /// non-two-address instruction. |
| bool ReduceToNarrow(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop); |
| |
| /// ReduceMI - Attempt to reduce MI, return true on success. |
| bool ReduceMI(MachineBasicBlock &MBB, MachineInstr *MI, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop); |
| |
| /// ReduceMBB - Reduce width of instructions in the specified basic block. |
| bool ReduceMBB(MachineBasicBlock &MBB); |
| |
| bool OptimizeSize; |
| bool MinimizeSize; |
| }; |
| char Thumb2SizeReduce::ID = 0; |
| } |
| |
| Thumb2SizeReduce::Thumb2SizeReduce() : MachineFunctionPass(ID) { |
| OptimizeSize = MinimizeSize = false; |
| for (unsigned i = 0, e = array_lengthof(ReduceTable); i != e; ++i) { |
| unsigned FromOpc = ReduceTable[i].WideOpc; |
| if (!ReduceOpcodeMap.insert(std::make_pair(FromOpc, i)).second) |
| assert(false && "Duplicated entries?"); |
| } |
| } |
| |
| static bool HasImplicitCPSRDef(const MCInstrDesc &MCID) { |
| for (const uint16_t *Regs = MCID.getImplicitDefs(); *Regs; ++Regs) |
| if (*Regs == ARM::CPSR) |
| return true; |
| return false; |
| } |
| |
| /// canAddPseudoFlagDep - For A9 (and other out-of-order) implementations, |
| /// the 's' 16-bit instruction partially update CPSR. Abort the |
| /// transformation to avoid adding false dependency on last CPSR setting |
| /// instruction which hurts the ability for out-of-order execution engine |
| /// to do register renaming magic. |
| /// This function checks if there is a read-of-write dependency between the |
| /// last instruction that defines the CPSR and the current instruction. If there |
| /// is, then there is no harm done since the instruction cannot be retired |
| /// before the CPSR setting instruction anyway. |
| /// Note, we are not doing full dependency analysis here for the sake of compile |
| /// time. We're not looking for cases like: |
| /// r0 = muls ... |
| /// r1 = add.w r0, ... |
| /// ... |
| /// = mul.w r1 |
| /// In this case it would have been ok to narrow the mul.w to muls since there |
| /// are indirect RAW dependency between the muls and the mul.w |
| bool |
| Thumb2SizeReduce::canAddPseudoFlagDep(MachineInstr *Def, MachineInstr *Use, |
| bool FirstInSelfLoop) { |
| // Disable the check for -Oz (aka OptimizeForSizeHarder). |
| if (MinimizeSize || !STI->avoidCPSRPartialUpdate()) |
| return false; |
| |
| if (!Def) |
| // If this BB loops back to itself, conservatively avoid narrowing the |
| // first instruction that does partial flag update. |
| return FirstInSelfLoop; |
| |
| SmallSet<unsigned, 2> Defs; |
| for (unsigned i = 0, e = Def->getNumOperands(); i != e; ++i) { |
| const MachineOperand &MO = Def->getOperand(i); |
| if (!MO.isReg() || MO.isUndef() || MO.isUse()) |
| continue; |
| unsigned Reg = MO.getReg(); |
| if (Reg == 0 || Reg == ARM::CPSR) |
| continue; |
| Defs.insert(Reg); |
| } |
| |
| for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) { |
| const MachineOperand &MO = Use->getOperand(i); |
| if (!MO.isReg() || MO.isUndef() || MO.isDef()) |
| continue; |
| unsigned Reg = MO.getReg(); |
| if (Defs.count(Reg)) |
| return false; |
| } |
| |
| // No read-after-write dependency. The narrowing will add false dependency. |
| return true; |
| } |
| |
| bool |
| Thumb2SizeReduce::VerifyPredAndCC(MachineInstr *MI, const ReduceEntry &Entry, |
| bool is2Addr, ARMCC::CondCodes Pred, |
| bool LiveCPSR, bool &HasCC, bool &CCDead) { |
| if ((is2Addr && Entry.PredCC2 == 0) || |
| (!is2Addr && Entry.PredCC1 == 0)) { |
| if (Pred == ARMCC::AL) { |
| // Not predicated, must set CPSR. |
| if (!HasCC) { |
| // Original instruction was not setting CPSR, but CPSR is not |
| // currently live anyway. It's ok to set it. The CPSR def is |
| // dead though. |
| if (!LiveCPSR) { |
| HasCC = true; |
| CCDead = true; |
| return true; |
| } |
| return false; |
| } |
| } else { |
| // Predicated, must not set CPSR. |
| if (HasCC) |
| return false; |
| } |
| } else if ((is2Addr && Entry.PredCC2 == 2) || |
| (!is2Addr && Entry.PredCC1 == 2)) { |
| /// Old opcode has an optional def of CPSR. |
| if (HasCC) |
| return true; |
| // If old opcode does not implicitly define CPSR, then it's not ok since |
| // these new opcodes' CPSR def is not meant to be thrown away. e.g. CMP. |
| if (!HasImplicitCPSRDef(MI->getDesc())) |
| return false; |
| HasCC = true; |
| } else { |
| // 16-bit instruction does not set CPSR. |
| if (HasCC) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static bool VerifyLowRegs(MachineInstr *MI) { |
| unsigned Opc = MI->getOpcode(); |
| bool isPCOk = (Opc == ARM::t2LDMIA_RET || Opc == ARM::t2LDMIA || |
| Opc == ARM::t2LDMDB || Opc == ARM::t2LDMIA_UPD || |
| Opc == ARM::t2LDMDB_UPD); |
| bool isLROk = (Opc == ARM::t2STMIA_UPD || Opc == ARM::t2STMDB_UPD); |
| bool isSPOk = isPCOk || isLROk; |
| for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { |
| const MachineOperand &MO = MI->getOperand(i); |
| if (!MO.isReg() || MO.isImplicit()) |
| continue; |
| unsigned Reg = MO.getReg(); |
| if (Reg == 0 || Reg == ARM::CPSR) |
| continue; |
| if (isPCOk && Reg == ARM::PC) |
| continue; |
| if (isLROk && Reg == ARM::LR) |
| continue; |
| if (Reg == ARM::SP) { |
| if (isSPOk) |
| continue; |
| if (i == 1 && (Opc == ARM::t2LDRi12 || Opc == ARM::t2STRi12)) |
| // Special case for these ldr / str with sp as base register. |
| continue; |
| } |
| if (!isARMLowRegister(Reg)) |
| return false; |
| } |
| return true; |
| } |
| |
| bool |
| Thumb2SizeReduce::ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry) { |
| if (ReduceLimitLdSt != -1 && ((int)NumLdSts >= ReduceLimitLdSt)) |
| return false; |
| |
| unsigned Scale = 1; |
| bool HasImmOffset = false; |
| bool HasShift = false; |
| bool HasOffReg = true; |
| bool isLdStMul = false; |
| unsigned Opc = Entry.NarrowOpc1; |
| unsigned OpNum = 3; // First 'rest' of operands. |
| uint8_t ImmLimit = Entry.Imm1Limit; |
| |
| switch (Entry.WideOpc) { |
| default: |
| llvm_unreachable("Unexpected Thumb2 load / store opcode!"); |
| case ARM::t2LDRi12: |
| case ARM::t2STRi12: |
| if (MI->getOperand(1).getReg() == ARM::SP) { |
| Opc = Entry.NarrowOpc2; |
| ImmLimit = Entry.Imm2Limit; |
| HasOffReg = false; |
| } |
| |
| Scale = 4; |
| HasImmOffset = true; |
| HasOffReg = false; |
| break; |
| case ARM::t2LDRBi12: |
| case ARM::t2STRBi12: |
| HasImmOffset = true; |
| HasOffReg = false; |
| break; |
| case ARM::t2LDRHi12: |
| case ARM::t2STRHi12: |
| Scale = 2; |
| HasImmOffset = true; |
| HasOffReg = false; |
| break; |
| case ARM::t2LDRs: |
| case ARM::t2LDRBs: |
| case ARM::t2LDRHs: |
| case ARM::t2LDRSBs: |
| case ARM::t2LDRSHs: |
| case ARM::t2STRs: |
| case ARM::t2STRBs: |
| case ARM::t2STRHs: |
| HasShift = true; |
| OpNum = 4; |
| break; |
| case ARM::t2LDMIA: |
| case ARM::t2LDMDB: { |
| unsigned BaseReg = MI->getOperand(0).getReg(); |
| if (!isARMLowRegister(BaseReg) || Entry.WideOpc != ARM::t2LDMIA) |
| return false; |
| |
| // For the non-writeback version (this one), the base register must be |
| // one of the registers being loaded. |
| bool isOK = false; |
| for (unsigned i = 4; i < MI->getNumOperands(); ++i) { |
| if (MI->getOperand(i).getReg() == BaseReg) { |
| isOK = true; |
| break; |
| } |
| } |
| |
| if (!isOK) |
| return false; |
| |
| OpNum = 0; |
| isLdStMul = true; |
| break; |
| } |
| case ARM::t2LDMIA_RET: { |
| unsigned BaseReg = MI->getOperand(1).getReg(); |
| if (BaseReg != ARM::SP) |
| return false; |
| Opc = Entry.NarrowOpc2; // tPOP_RET |
| OpNum = 2; |
| isLdStMul = true; |
| break; |
| } |
| case ARM::t2LDMIA_UPD: |
| case ARM::t2LDMDB_UPD: |
| case ARM::t2STMIA_UPD: |
| case ARM::t2STMDB_UPD: { |
| OpNum = 0; |
| |
| unsigned BaseReg = MI->getOperand(1).getReg(); |
| if (BaseReg == ARM::SP && |
| (Entry.WideOpc == ARM::t2LDMIA_UPD || |
| Entry.WideOpc == ARM::t2STMDB_UPD)) { |
| Opc = Entry.NarrowOpc2; // tPOP or tPUSH |
| OpNum = 2; |
| } else if (!isARMLowRegister(BaseReg) || |
| (Entry.WideOpc != ARM::t2LDMIA_UPD && |
| Entry.WideOpc != ARM::t2STMIA_UPD)) { |
| return false; |
| } |
| |
| isLdStMul = true; |
| break; |
| } |
| } |
| |
| unsigned OffsetReg = 0; |
| bool OffsetKill = false; |
| if (HasShift) { |
| OffsetReg = MI->getOperand(2).getReg(); |
| OffsetKill = MI->getOperand(2).isKill(); |
| |
| if (MI->getOperand(3).getImm()) |
| // Thumb1 addressing mode doesn't support shift. |
| return false; |
| } |
| |
| unsigned OffsetImm = 0; |
| if (HasImmOffset) { |
| OffsetImm = MI->getOperand(2).getImm(); |
| unsigned MaxOffset = ((1 << ImmLimit) - 1) * Scale; |
| |
| if ((OffsetImm & (Scale - 1)) || OffsetImm > MaxOffset) |
| // Make sure the immediate field fits. |
| return false; |
| } |
| |
| // Add the 16-bit load / store instruction. |
| DebugLoc dl = MI->getDebugLoc(); |
| MachineInstrBuilder MIB = BuildMI(MBB, MI, dl, TII->get(Opc)); |
| if (!isLdStMul) { |
| MIB.addOperand(MI->getOperand(0)); |
| MIB.addOperand(MI->getOperand(1)); |
| |
| if (HasImmOffset) |
| MIB.addImm(OffsetImm / Scale); |
| |
| assert((!HasShift || OffsetReg) && "Invalid so_reg load / store address!"); |
| |
| if (HasOffReg) |
| MIB.addReg(OffsetReg, getKillRegState(OffsetKill)); |
| } |
| |
| // Transfer the rest of operands. |
| for (unsigned e = MI->getNumOperands(); OpNum != e; ++OpNum) |
| MIB.addOperand(MI->getOperand(OpNum)); |
| |
| // Transfer memoperands. |
| MIB->setMemRefs(MI->memoperands_begin(), MI->memoperands_end()); |
| |
| // Transfer MI flags. |
| MIB.setMIFlags(MI->getFlags()); |
| |
| DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB); |
| |
| MBB.erase_instr(MI); |
| ++NumLdSts; |
| return true; |
| } |
| |
| bool |
| Thumb2SizeReduce::ReduceSpecial(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop) { |
| unsigned Opc = MI->getOpcode(); |
| if (Opc == ARM::t2ADDri) { |
| // If the source register is SP, try to reduce to tADDrSPi, otherwise |
| // it's a normal reduce. |
| if (MI->getOperand(1).getReg() != ARM::SP) { |
| if (ReduceTo2Addr(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop)) |
| return true; |
| return ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| } |
| // Try to reduce to tADDrSPi. |
| unsigned Imm = MI->getOperand(2).getImm(); |
| // The immediate must be in range, the destination register must be a low |
| // reg, the predicate must be "always" and the condition flags must not |
| // be being set. |
| if (Imm & 3 || Imm > 1020) |
| return false; |
| if (!isARMLowRegister(MI->getOperand(0).getReg())) |
| return false; |
| if (MI->getOperand(3).getImm() != ARMCC::AL) |
| return false; |
| const MCInstrDesc &MCID = MI->getDesc(); |
| if (MCID.hasOptionalDef() && |
| MI->getOperand(MCID.getNumOperands()-1).getReg() == ARM::CPSR) |
| return false; |
| |
| MachineInstrBuilder MIB = BuildMI(MBB, MI, MI->getDebugLoc(), |
| TII->get(ARM::tADDrSPi)) |
| .addOperand(MI->getOperand(0)) |
| .addOperand(MI->getOperand(1)) |
| .addImm(Imm / 4); // The tADDrSPi has an implied scale by four. |
| AddDefaultPred(MIB); |
| |
| // Transfer MI flags. |
| MIB.setMIFlags(MI->getFlags()); |
| |
| DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " <<*MIB); |
| |
| MBB.erase_instr(MI); |
| ++NumNarrows; |
| return true; |
| } |
| |
| if (Entry.LowRegs1 && !VerifyLowRegs(MI)) |
| return false; |
| |
| if (MI->mayLoad() || MI->mayStore()) |
| return ReduceLoadStore(MBB, MI, Entry); |
| |
| switch (Opc) { |
| default: break; |
| case ARM::t2ADDSri: |
| case ARM::t2ADDSrr: { |
| unsigned PredReg = 0; |
| if (getInstrPredicate(MI, PredReg) == ARMCC::AL) { |
| switch (Opc) { |
| default: break; |
| case ARM::t2ADDSri: { |
| if (ReduceTo2Addr(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop)) |
| return true; |
| // fallthrough |
| } |
| case ARM::t2ADDSrr: |
| return ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| } |
| } |
| break; |
| } |
| case ARM::t2RSBri: |
| case ARM::t2RSBSri: |
| case ARM::t2SXTB: |
| case ARM::t2SXTH: |
| case ARM::t2UXTB: |
| case ARM::t2UXTH: |
| if (MI->getOperand(2).getImm() == 0) |
| return ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| break; |
| case ARM::t2MOVi16: |
| // Can convert only 'pure' immediate operands, not immediates obtained as |
| // globals' addresses. |
| if (MI->getOperand(1).isImm()) |
| return ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| break; |
| case ARM::t2CMPrr: { |
| // Try to reduce to the lo-reg only version first. Why there are two |
| // versions of the instruction is a mystery. |
| // It would be nice to just have two entries in the master table that |
| // are prioritized, but the table assumes a unique entry for each |
| // source insn opcode. So for now, we hack a local entry record to use. |
| static const ReduceEntry NarrowEntry = |
| { ARM::t2CMPrr,ARM::tCMPr, 0, 0, 0, 1, 1,2, 0, 0,1,0 }; |
| if (ReduceToNarrow(MBB, MI, NarrowEntry, LiveCPSR, CPSRDef, IsSelfLoop)) |
| return true; |
| return ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| } |
| } |
| return false; |
| } |
| |
| bool |
| Thumb2SizeReduce::ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop) { |
| |
| if (ReduceLimit2Addr != -1 && ((int)Num2Addrs >= ReduceLimit2Addr)) |
| return false; |
| |
| if (!MinimizeSize && !OptimizeSize && Entry.AvoidMovs && |
| STI->avoidMOVsShifterOperand()) |
| // Don't issue movs with shifter operand for some CPUs unless we |
| // are optimizing / minimizing for size. |
| return false; |
| |
| unsigned Reg0 = MI->getOperand(0).getReg(); |
| unsigned Reg1 = MI->getOperand(1).getReg(); |
| // t2MUL is "special". The tied source operand is second, not first. |
| if (MI->getOpcode() == ARM::t2MUL) { |
| unsigned Reg2 = MI->getOperand(2).getReg(); |
| // Early exit if the regs aren't all low regs. |
| if (!isARMLowRegister(Reg0) || !isARMLowRegister(Reg1) |
| || !isARMLowRegister(Reg2)) |
| return false; |
| if (Reg0 != Reg2) { |
| // If the other operand also isn't the same as the destination, we |
| // can't reduce. |
| if (Reg1 != Reg0) |
| return false; |
| // Try to commute the operands to make it a 2-address instruction. |
| MachineInstr *CommutedMI = TII->commuteInstruction(MI); |
| if (!CommutedMI) |
| return false; |
| } |
| } else if (Reg0 != Reg1) { |
| // Try to commute the operands to make it a 2-address instruction. |
| unsigned CommOpIdx1, CommOpIdx2; |
| if (!TII->findCommutedOpIndices(MI, CommOpIdx1, CommOpIdx2) || |
| CommOpIdx1 != 1 || MI->getOperand(CommOpIdx2).getReg() != Reg0) |
| return false; |
| MachineInstr *CommutedMI = TII->commuteInstruction(MI); |
| if (!CommutedMI) |
| return false; |
| } |
| if (Entry.LowRegs2 && !isARMLowRegister(Reg0)) |
| return false; |
| if (Entry.Imm2Limit) { |
| unsigned Imm = MI->getOperand(2).getImm(); |
| unsigned Limit = (1 << Entry.Imm2Limit) - 1; |
| if (Imm > Limit) |
| return false; |
| } else { |
| unsigned Reg2 = MI->getOperand(2).getReg(); |
| if (Entry.LowRegs2 && !isARMLowRegister(Reg2)) |
| return false; |
| } |
| |
| // Check if it's possible / necessary to transfer the predicate. |
| const MCInstrDesc &NewMCID = TII->get(Entry.NarrowOpc2); |
| unsigned PredReg = 0; |
| ARMCC::CondCodes Pred = getInstrPredicate(MI, PredReg); |
| bool SkipPred = false; |
| if (Pred != ARMCC::AL) { |
| if (!NewMCID.isPredicable()) |
| // Can't transfer predicate, fail. |
| return false; |
| } else { |
| SkipPred = !NewMCID.isPredicable(); |
| } |
| |
| bool HasCC = false; |
| bool CCDead = false; |
| const MCInstrDesc &MCID = MI->getDesc(); |
| if (MCID.hasOptionalDef()) { |
| unsigned NumOps = MCID.getNumOperands(); |
| HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR); |
| if (HasCC && MI->getOperand(NumOps-1).isDead()) |
| CCDead = true; |
| } |
| if (!VerifyPredAndCC(MI, Entry, true, Pred, LiveCPSR, HasCC, CCDead)) |
| return false; |
| |
| // Avoid adding a false dependency on partial flag update by some 16-bit |
| // instructions which has the 's' bit set. |
| if (Entry.PartFlag && NewMCID.hasOptionalDef() && HasCC && |
| canAddPseudoFlagDep(CPSRDef, MI, IsSelfLoop)) |
| return false; |
| |
| // Add the 16-bit instruction. |
| DebugLoc dl = MI->getDebugLoc(); |
| MachineInstrBuilder MIB = BuildMI(MBB, MI, dl, NewMCID); |
| MIB.addOperand(MI->getOperand(0)); |
| if (NewMCID.hasOptionalDef()) { |
| if (HasCC) |
| AddDefaultT1CC(MIB, CCDead); |
| else |
| AddNoT1CC(MIB); |
| } |
| |
| // Transfer the rest of operands. |
| unsigned NumOps = MCID.getNumOperands(); |
| for (unsigned i = 1, e = MI->getNumOperands(); i != e; ++i) { |
| if (i < NumOps && MCID.OpInfo[i].isOptionalDef()) |
| continue; |
| if (SkipPred && MCID.OpInfo[i].isPredicate()) |
| continue; |
| MIB.addOperand(MI->getOperand(i)); |
| } |
| |
| // Transfer MI flags. |
| MIB.setMIFlags(MI->getFlags()); |
| |
| DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB); |
| |
| MBB.erase_instr(MI); |
| ++Num2Addrs; |
| return true; |
| } |
| |
| bool |
| Thumb2SizeReduce::ReduceToNarrow(MachineBasicBlock &MBB, MachineInstr *MI, |
| const ReduceEntry &Entry, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop) { |
| if (ReduceLimit != -1 && ((int)NumNarrows >= ReduceLimit)) |
| return false; |
| |
| if (!MinimizeSize && !OptimizeSize && Entry.AvoidMovs && |
| STI->avoidMOVsShifterOperand()) |
| // Don't issue movs with shifter operand for some CPUs unless we |
| // are optimizing / minimizing for size. |
| return false; |
| |
| unsigned Limit = ~0U; |
| if (Entry.Imm1Limit) |
| Limit = (1 << Entry.Imm1Limit) - 1; |
| |
| const MCInstrDesc &MCID = MI->getDesc(); |
| for (unsigned i = 0, e = MCID.getNumOperands(); i != e; ++i) { |
| if (MCID.OpInfo[i].isPredicate()) |
| continue; |
| const MachineOperand &MO = MI->getOperand(i); |
| if (MO.isReg()) { |
| unsigned Reg = MO.getReg(); |
| if (!Reg || Reg == ARM::CPSR) |
| continue; |
| if (Entry.LowRegs1 && !isARMLowRegister(Reg)) |
| return false; |
| } else if (MO.isImm() && |
| !MCID.OpInfo[i].isPredicate()) { |
| if (((unsigned)MO.getImm()) > Limit) |
| return false; |
| } |
| } |
| |
| // Check if it's possible / necessary to transfer the predicate. |
| const MCInstrDesc &NewMCID = TII->get(Entry.NarrowOpc1); |
| unsigned PredReg = 0; |
| ARMCC::CondCodes Pred = getInstrPredicate(MI, PredReg); |
| bool SkipPred = false; |
| if (Pred != ARMCC::AL) { |
| if (!NewMCID.isPredicable()) |
| // Can't transfer predicate, fail. |
| return false; |
| } else { |
| SkipPred = !NewMCID.isPredicable(); |
| } |
| |
| bool HasCC = false; |
| bool CCDead = false; |
| if (MCID.hasOptionalDef()) { |
| unsigned NumOps = MCID.getNumOperands(); |
| HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR); |
| if (HasCC && MI->getOperand(NumOps-1).isDead()) |
| CCDead = true; |
| } |
| if (!VerifyPredAndCC(MI, Entry, false, Pred, LiveCPSR, HasCC, CCDead)) |
| return false; |
| |
| // Avoid adding a false dependency on partial flag update by some 16-bit |
| // instructions which has the 's' bit set. |
| if (Entry.PartFlag && NewMCID.hasOptionalDef() && HasCC && |
| canAddPseudoFlagDep(CPSRDef, MI, IsSelfLoop)) |
| return false; |
| |
| // Add the 16-bit instruction. |
| DebugLoc dl = MI->getDebugLoc(); |
| MachineInstrBuilder MIB = BuildMI(MBB, MI, dl, NewMCID); |
| MIB.addOperand(MI->getOperand(0)); |
| if (NewMCID.hasOptionalDef()) { |
| if (HasCC) |
| AddDefaultT1CC(MIB, CCDead); |
| else |
| AddNoT1CC(MIB); |
| } |
| |
| // Transfer the rest of operands. |
| unsigned NumOps = MCID.getNumOperands(); |
| for (unsigned i = 1, e = MI->getNumOperands(); i != e; ++i) { |
| if (i < NumOps && MCID.OpInfo[i].isOptionalDef()) |
| continue; |
| if ((MCID.getOpcode() == ARM::t2RSBSri || |
| MCID.getOpcode() == ARM::t2RSBri || |
| MCID.getOpcode() == ARM::t2SXTB || |
| MCID.getOpcode() == ARM::t2SXTH || |
| MCID.getOpcode() == ARM::t2UXTB || |
| MCID.getOpcode() == ARM::t2UXTH) && i == 2) |
| // Skip the zero immediate operand, it's now implicit. |
| continue; |
| bool isPred = (i < NumOps && MCID.OpInfo[i].isPredicate()); |
| if (SkipPred && isPred) |
| continue; |
| const MachineOperand &MO = MI->getOperand(i); |
| if (MO.isReg() && MO.isImplicit() && MO.getReg() == ARM::CPSR) |
| // Skip implicit def of CPSR. Either it's modeled as an optional |
| // def now or it's already an implicit def on the new instruction. |
| continue; |
| MIB.addOperand(MO); |
| } |
| if (!MCID.isPredicable() && NewMCID.isPredicable()) |
| AddDefaultPred(MIB); |
| |
| // Transfer MI flags. |
| MIB.setMIFlags(MI->getFlags()); |
| |
| DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB); |
| |
| MBB.erase_instr(MI); |
| ++NumNarrows; |
| return true; |
| } |
| |
| static bool UpdateCPSRDef(MachineInstr &MI, bool LiveCPSR, bool &DefCPSR) { |
| bool HasDef = false; |
| for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { |
| const MachineOperand &MO = MI.getOperand(i); |
| if (!MO.isReg() || MO.isUndef() || MO.isUse()) |
| continue; |
| if (MO.getReg() != ARM::CPSR) |
| continue; |
| |
| DefCPSR = true; |
| if (!MO.isDead()) |
| HasDef = true; |
| } |
| |
| return HasDef || LiveCPSR; |
| } |
| |
| static bool UpdateCPSRUse(MachineInstr &MI, bool LiveCPSR) { |
| for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { |
| const MachineOperand &MO = MI.getOperand(i); |
| if (!MO.isReg() || MO.isUndef() || MO.isDef()) |
| continue; |
| if (MO.getReg() != ARM::CPSR) |
| continue; |
| assert(LiveCPSR && "CPSR liveness tracking is wrong!"); |
| if (MO.isKill()) { |
| LiveCPSR = false; |
| break; |
| } |
| } |
| |
| return LiveCPSR; |
| } |
| |
| bool Thumb2SizeReduce::ReduceMI(MachineBasicBlock &MBB, MachineInstr *MI, |
| bool LiveCPSR, MachineInstr *CPSRDef, |
| bool IsSelfLoop) { |
| unsigned Opcode = MI->getOpcode(); |
| DenseMap<unsigned, unsigned>::iterator OPI = ReduceOpcodeMap.find(Opcode); |
| if (OPI == ReduceOpcodeMap.end()) |
| return false; |
| const ReduceEntry &Entry = ReduceTable[OPI->second]; |
| |
| // Don't attempt normal reductions on "special" cases for now. |
| if (Entry.Special) |
| return ReduceSpecial(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop); |
| |
| // Try to transform to a 16-bit two-address instruction. |
| if (Entry.NarrowOpc2 && |
| ReduceTo2Addr(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop)) |
| return true; |
| |
| // Try to transform to a 16-bit non-two-address instruction. |
| if (Entry.NarrowOpc1 && |
| ReduceToNarrow(MBB, MI, Entry, LiveCPSR, CPSRDef, IsSelfLoop)) |
| return true; |
| |
| return false; |
| } |
| |
| bool Thumb2SizeReduce::ReduceMBB(MachineBasicBlock &MBB) { |
| bool Modified = false; |
| |
| // Yes, CPSR could be livein. |
| bool LiveCPSR = MBB.isLiveIn(ARM::CPSR); |
| MachineInstr *CPSRDef = 0; |
| MachineInstr *BundleMI = 0; |
| |
| // If this BB loops back to itself, conservatively avoid narrowing the |
| // first instruction that does partial flag update. |
| bool IsSelfLoop = MBB.isSuccessor(&MBB); |
| MachineBasicBlock::instr_iterator MII = MBB.instr_begin(),E = MBB.instr_end(); |
| MachineBasicBlock::instr_iterator NextMII; |
| for (; MII != E; MII = NextMII) { |
| NextMII = llvm::next(MII); |
| |
| MachineInstr *MI = &*MII; |
| if (MI->isBundle()) { |
| BundleMI = MI; |
| continue; |
| } |
| |
| LiveCPSR = UpdateCPSRUse(*MI, LiveCPSR); |
| |
| // Does NextMII belong to the same bundle as MI? |
| bool NextInSameBundle = NextMII != E && NextMII->isBundledWithPred(); |
| |
| if (ReduceMI(MBB, MI, LiveCPSR, CPSRDef, IsSelfLoop)) { |
| Modified = true; |
| MachineBasicBlock::instr_iterator I = prior(NextMII); |
| MI = &*I; |
| // Removing and reinserting the first instruction in a bundle will break |
| // up the bundle. Fix the bundling if it was broken. |
| if (NextInSameBundle && !NextMII->isBundledWithPred()) |
| NextMII->bundleWithPred(); |
| } |
| |
| if (!NextInSameBundle && MI->isInsideBundle()) { |
| // FIXME: Since post-ra scheduler operates on bundles, the CPSR kill |
| // marker is only on the BUNDLE instruction. Process the BUNDLE |
| // instruction as we finish with the bundled instruction to work around |
| // the inconsistency. |
| if (BundleMI->killsRegister(ARM::CPSR)) |
| LiveCPSR = false; |
| MachineOperand *MO = BundleMI->findRegisterDefOperand(ARM::CPSR); |
| if (MO && !MO->isDead()) |
| LiveCPSR = true; |
| } |
| |
| bool DefCPSR = false; |
| LiveCPSR = UpdateCPSRDef(*MI, LiveCPSR, DefCPSR); |
| if (MI->isCall()) { |
| // Calls don't really set CPSR. |
| CPSRDef = 0; |
| IsSelfLoop = false; |
| } else if (DefCPSR) { |
| // This is the last CPSR defining instruction. |
| CPSRDef = MI; |
| IsSelfLoop = false; |
| } |
| } |
| |
| return Modified; |
| } |
| |
| bool Thumb2SizeReduce::runOnMachineFunction(MachineFunction &MF) { |
| const TargetMachine &TM = MF.getTarget(); |
| TII = static_cast<const Thumb2InstrInfo*>(TM.getInstrInfo()); |
| STI = &TM.getSubtarget<ARMSubtarget>(); |
| |
| // Optimizing / minimizing size? |
| AttributeSet FnAttrs = MF.getFunction()->getAttributes(); |
| OptimizeSize = FnAttrs.hasAttribute(AttributeSet::FunctionIndex, |
| Attribute::OptimizeForSize); |
| MinimizeSize = FnAttrs.hasAttribute(AttributeSet::FunctionIndex, |
| Attribute::MinSize); |
| |
| bool Modified = false; |
| for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) |
| Modified |= ReduceMBB(*I); |
| return Modified; |
| } |
| |
| /// createThumb2SizeReductionPass - Returns an instance of the Thumb2 size |
| /// reduction pass. |
| FunctionPass *llvm::createThumb2SizeReductionPass() { |
| return new Thumb2SizeReduce(); |
| } |
