| //===- HexagonNewValueJump.cpp - Hexagon Backend New Value Jump -----------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This implements NewValueJump pass in Hexagon. |
| // Ideally, we should merge this as a Peephole pass prior to register |
| // allocation, but because we have a spill in between the feeder and new value |
| // jump instructions, we are forced to write after register allocation. |
| // Having said that, we should re-attempt to pull this earlier at some point |
| // in future. |
| |
| // The basic approach looks for sequence of predicated jump, compare instruciton |
| // that genereates the predicate and, the feeder to the predicate. Once it finds |
| // all, it collapses compare and jump instruction into a new value jump |
| // intstructions. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/InitializePasses.h" |
| #include "Hexagon.h" |
| #include "HexagonInstrInfo.h" |
| #include "HexagonRegisterInfo.h" |
| #include "HexagonSubtarget.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/CodeGen/MachineBasicBlock.h" |
| #include "llvm/CodeGen/MachineBranchProbabilityInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/MachineOperand.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/CodeGen/TargetOpcodes.h" |
| #include "llvm/CodeGen/TargetRegisterInfo.h" |
| #include "llvm/CodeGen/TargetSubtargetInfo.h" |
| #include "llvm/IR/DebugLoc.h" |
| #include "llvm/MC/MCInstrDesc.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/BranchProbability.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <cassert> |
| #include <cstdint> |
| #include <iterator> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "hexagon-nvj" |
| |
| STATISTIC(NumNVJGenerated, "Number of New Value Jump Instructions created"); |
| |
| static cl::opt<int> DbgNVJCount("nvj-count", cl::init(-1), cl::Hidden, |
| cl::desc("Maximum number of predicated jumps to be converted to " |
| "New Value Jump")); |
| |
| static cl::opt<bool> DisableNewValueJumps("disable-nvjump", cl::Hidden, |
| cl::desc("Disable New Value Jumps")); |
| |
| namespace llvm { |
| |
| FunctionPass *createHexagonNewValueJump(); |
| void initializeHexagonNewValueJumpPass(PassRegistry&); |
| |
| } // end namespace llvm |
| |
| namespace { |
| |
| struct HexagonNewValueJump : public MachineFunctionPass { |
| static char ID; |
| |
| HexagonNewValueJump() : MachineFunctionPass(ID) {} |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.addRequired<MachineBranchProbabilityInfo>(); |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| StringRef getPassName() const override { return "Hexagon NewValueJump"; } |
| |
| bool runOnMachineFunction(MachineFunction &Fn) override; |
| |
| MachineFunctionProperties getRequiredProperties() const override { |
| return MachineFunctionProperties().set( |
| MachineFunctionProperties::Property::NoVRegs); |
| } |
| |
| private: |
| const HexagonInstrInfo *QII; |
| const HexagonRegisterInfo *QRI; |
| |
| /// A handle to the branch probability pass. |
| const MachineBranchProbabilityInfo *MBPI; |
| |
| bool isNewValueJumpCandidate(const MachineInstr &MI) const; |
| }; |
| |
| } // end anonymous namespace |
| |
| char HexagonNewValueJump::ID = 0; |
| |
| INITIALIZE_PASS_BEGIN(HexagonNewValueJump, "hexagon-nvj", |
| "Hexagon NewValueJump", false, false) |
| INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) |
| INITIALIZE_PASS_END(HexagonNewValueJump, "hexagon-nvj", |
| "Hexagon NewValueJump", false, false) |
| |
| // We have identified this II could be feeder to NVJ, |
| // verify that it can be. |
| static bool canBeFeederToNewValueJump(const HexagonInstrInfo *QII, |
| const TargetRegisterInfo *TRI, |
| MachineBasicBlock::iterator II, |
| MachineBasicBlock::iterator end, |
| MachineBasicBlock::iterator skip, |
| MachineFunction &MF) { |
| // Predicated instruction can not be feeder to NVJ. |
| if (QII->isPredicated(*II)) |
| return false; |
| |
| // Bail out if feederReg is a paired register (double regs in |
| // our case). One would think that we can check to see if a given |
| // register cmpReg1 or cmpReg2 is a sub register of feederReg |
| // using -- if (QRI->isSubRegister(feederReg, cmpReg1) logic |
| // before the callsite of this function |
| // But we can not as it comes in the following fashion. |
| // %d0 = Hexagon_S2_lsr_r_p killed %d0, killed %r2 |
| // %r0 = KILL %r0, implicit killed %d0 |
| // %p0 = CMPEQri killed %r0, 0 |
| // Hence, we need to check if it's a KILL instruction. |
| if (II->getOpcode() == TargetOpcode::KILL) |
| return false; |
| |
| if (II->isImplicitDef()) |
| return false; |
| |
| if (QII->isSolo(*II)) |
| return false; |
| |
| if (QII->isFloat(*II)) |
| return false; |
| |
| // Make sure that the (unique) def operand is a register from IntRegs. |
| bool HadDef = false; |
| for (const MachineOperand &Op : II->operands()) { |
| if (!Op.isReg() || !Op.isDef()) |
| continue; |
| if (HadDef) |
| return false; |
| HadDef = true; |
| if (!Hexagon::IntRegsRegClass.contains(Op.getReg())) |
| return false; |
| } |
| assert(HadDef); |
| |
| // Make sure there is no 'def' or 'use' of any of the uses of |
| // feeder insn between its definition, this MI and jump, jmpInst |
| // skipping compare, cmpInst. |
| // Here's the example. |
| // r21=memub(r22+r24<<#0) |
| // p0 = cmp.eq(r21, #0) |
| // r4=memub(r3+r21<<#0) |
| // if (p0.new) jump:t .LBB29_45 |
| // Without this check, it will be converted into |
| // r4=memub(r3+r21<<#0) |
| // r21=memub(r22+r24<<#0) |
| // p0 = cmp.eq(r21, #0) |
| // if (p0.new) jump:t .LBB29_45 |
| // and result WAR hazards if converted to New Value Jump. |
| for (unsigned i = 0; i < II->getNumOperands(); ++i) { |
| if (II->getOperand(i).isReg() && |
| (II->getOperand(i).isUse() || II->getOperand(i).isDef())) { |
| MachineBasicBlock::iterator localII = II; |
| ++localII; |
| Register Reg = II->getOperand(i).getReg(); |
| for (MachineBasicBlock::iterator localBegin = localII; localBegin != end; |
| ++localBegin) { |
| if (localBegin == skip) |
| continue; |
| // Check for Subregisters too. |
| if (localBegin->modifiesRegister(Reg, TRI) || |
| localBegin->readsRegister(Reg, TRI)) |
| return false; |
| } |
| } |
| } |
| return true; |
| } |
| |
| // These are the common checks that need to performed |
| // to determine if |
| // 1. compare instruction can be moved before jump. |
| // 2. feeder to the compare instruction can be moved before jump. |
| static bool commonChecksToProhibitNewValueJump(bool afterRA, |
| MachineBasicBlock::iterator MII) { |
| // If store in path, bail out. |
| if (MII->mayStore()) |
| return false; |
| |
| // if call in path, bail out. |
| if (MII->isCall()) |
| return false; |
| |
| // if NVJ is running prior to RA, do the following checks. |
| if (!afterRA) { |
| // The following Target Opcode instructions are spurious |
| // to new value jump. If they are in the path, bail out. |
| // KILL sets kill flag on the opcode. It also sets up a |
| // single register, out of pair. |
| // %d0 = S2_lsr_r_p killed %d0, killed %r2 |
| // %r0 = KILL %r0, implicit killed %d0 |
| // %p0 = C2_cmpeqi killed %r0, 0 |
| // PHI can be anything after RA. |
| // COPY can remateriaze things in between feeder, compare and nvj. |
| if (MII->getOpcode() == TargetOpcode::KILL || |
| MII->getOpcode() == TargetOpcode::PHI || |
| MII->getOpcode() == TargetOpcode::COPY) |
| return false; |
| |
| // The following pseudo Hexagon instructions sets "use" and "def" |
| // of registers by individual passes in the backend. At this time, |
| // we don't know the scope of usage and definitions of these |
| // instructions. |
| if (MII->getOpcode() == Hexagon::LDriw_pred || |
| MII->getOpcode() == Hexagon::STriw_pred) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static bool canCompareBeNewValueJump(const HexagonInstrInfo *QII, |
| const TargetRegisterInfo *TRI, |
| MachineBasicBlock::iterator II, |
| unsigned pReg, |
| bool secondReg, |
| bool optLocation, |
| MachineBasicBlock::iterator end, |
| MachineFunction &MF) { |
| MachineInstr &MI = *II; |
| |
| // If the second operand of the compare is an imm, make sure it's in the |
| // range specified by the arch. |
| if (!secondReg) { |
| const MachineOperand &Op2 = MI.getOperand(2); |
| if (!Op2.isImm()) |
| return false; |
| |
| int64_t v = Op2.getImm(); |
| bool Valid = false; |
| |
| switch (MI.getOpcode()) { |
| case Hexagon::C2_cmpeqi: |
| case Hexagon::C4_cmpneqi: |
| case Hexagon::C2_cmpgti: |
| case Hexagon::C4_cmpltei: |
| Valid = (isUInt<5>(v) || v == -1); |
| break; |
| case Hexagon::C2_cmpgtui: |
| case Hexagon::C4_cmplteui: |
| Valid = isUInt<5>(v); |
| break; |
| case Hexagon::S2_tstbit_i: |
| case Hexagon::S4_ntstbit_i: |
| Valid = (v == 0); |
| break; |
| } |
| |
| if (!Valid) |
| return false; |
| } |
| |
| unsigned cmpReg1, cmpOp2 = 0; // cmpOp2 assignment silences compiler warning. |
| cmpReg1 = MI.getOperand(1).getReg(); |
| |
| if (secondReg) { |
| cmpOp2 = MI.getOperand(2).getReg(); |
| |
| // If the same register appears as both operands, we cannot generate a new |
| // value compare. Only one operand may use the .new suffix. |
| if (cmpReg1 == cmpOp2) |
| return false; |
| |
| // Make sure that the second register is not from COPY |
| // at machine code level, we don't need this, but if we decide |
| // to move new value jump prior to RA, we would be needing this. |
| MachineRegisterInfo &MRI = MF.getRegInfo(); |
| if (!Register::isPhysicalRegister(cmpOp2)) { |
| MachineInstr *def = MRI.getVRegDef(cmpOp2); |
| if (def->getOpcode() == TargetOpcode::COPY) |
| return false; |
| } |
| } |
| |
| // Walk the instructions after the compare (predicate def) to the jump, |
| // and satisfy the following conditions. |
| ++II; |
| for (MachineBasicBlock::iterator localII = II; localII != end; ++localII) { |
| if (localII->isDebugInstr()) |
| continue; |
| |
| // Check 1. |
| // If "common" checks fail, bail out. |
| if (!commonChecksToProhibitNewValueJump(optLocation, localII)) |
| return false; |
| |
| // Check 2. |
| // If there is a def or use of predicate (result of compare), bail out. |
| if (localII->modifiesRegister(pReg, TRI) || |
| localII->readsRegister(pReg, TRI)) |
| return false; |
| |
| // Check 3. |
| // If there is a def of any of the use of the compare (operands of compare), |
| // bail out. |
| // Eg. |
| // p0 = cmp.eq(r2, r0) |
| // r2 = r4 |
| // if (p0.new) jump:t .LBB28_3 |
| if (localII->modifiesRegister(cmpReg1, TRI) || |
| (secondReg && localII->modifiesRegister(cmpOp2, TRI))) |
| return false; |
| } |
| return true; |
| } |
| |
| // Given a compare operator, return a matching New Value Jump compare operator. |
| // Make sure that MI here is included in isNewValueJumpCandidate. |
| static unsigned getNewValueJumpOpcode(MachineInstr *MI, int reg, |
| bool secondRegNewified, |
| MachineBasicBlock *jmpTarget, |
| const MachineBranchProbabilityInfo |
| *MBPI) { |
| bool taken = false; |
| MachineBasicBlock *Src = MI->getParent(); |
| const BranchProbability Prediction = |
| MBPI->getEdgeProbability(Src, jmpTarget); |
| |
| if (Prediction >= BranchProbability(1,2)) |
| taken = true; |
| |
| switch (MI->getOpcode()) { |
| case Hexagon::C2_cmpeq: |
| return taken ? Hexagon::J4_cmpeq_t_jumpnv_t |
| : Hexagon::J4_cmpeq_t_jumpnv_nt; |
| |
| case Hexagon::C2_cmpeqi: |
| if (reg >= 0) |
| return taken ? Hexagon::J4_cmpeqi_t_jumpnv_t |
| : Hexagon::J4_cmpeqi_t_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpeqn1_t_jumpnv_t |
| : Hexagon::J4_cmpeqn1_t_jumpnv_nt; |
| |
| case Hexagon::C4_cmpneqi: |
| if (reg >= 0) |
| return taken ? Hexagon::J4_cmpeqi_f_jumpnv_t |
| : Hexagon::J4_cmpeqi_f_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpeqn1_f_jumpnv_t : |
| Hexagon::J4_cmpeqn1_f_jumpnv_nt; |
| |
| case Hexagon::C2_cmpgt: |
| if (secondRegNewified) |
| return taken ? Hexagon::J4_cmplt_t_jumpnv_t |
| : Hexagon::J4_cmplt_t_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgt_t_jumpnv_t |
| : Hexagon::J4_cmpgt_t_jumpnv_nt; |
| |
| case Hexagon::C2_cmpgti: |
| if (reg >= 0) |
| return taken ? Hexagon::J4_cmpgti_t_jumpnv_t |
| : Hexagon::J4_cmpgti_t_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgtn1_t_jumpnv_t |
| : Hexagon::J4_cmpgtn1_t_jumpnv_nt; |
| |
| case Hexagon::C2_cmpgtu: |
| if (secondRegNewified) |
| return taken ? Hexagon::J4_cmpltu_t_jumpnv_t |
| : Hexagon::J4_cmpltu_t_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgtu_t_jumpnv_t |
| : Hexagon::J4_cmpgtu_t_jumpnv_nt; |
| |
| case Hexagon::C2_cmpgtui: |
| return taken ? Hexagon::J4_cmpgtui_t_jumpnv_t |
| : Hexagon::J4_cmpgtui_t_jumpnv_nt; |
| |
| case Hexagon::C4_cmpneq: |
| return taken ? Hexagon::J4_cmpeq_f_jumpnv_t |
| : Hexagon::J4_cmpeq_f_jumpnv_nt; |
| |
| case Hexagon::C4_cmplte: |
| if (secondRegNewified) |
| return taken ? Hexagon::J4_cmplt_f_jumpnv_t |
| : Hexagon::J4_cmplt_f_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgt_f_jumpnv_t |
| : Hexagon::J4_cmpgt_f_jumpnv_nt; |
| |
| case Hexagon::C4_cmplteu: |
| if (secondRegNewified) |
| return taken ? Hexagon::J4_cmpltu_f_jumpnv_t |
| : Hexagon::J4_cmpltu_f_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgtu_f_jumpnv_t |
| : Hexagon::J4_cmpgtu_f_jumpnv_nt; |
| |
| case Hexagon::C4_cmpltei: |
| if (reg >= 0) |
| return taken ? Hexagon::J4_cmpgti_f_jumpnv_t |
| : Hexagon::J4_cmpgti_f_jumpnv_nt; |
| return taken ? Hexagon::J4_cmpgtn1_f_jumpnv_t |
| : Hexagon::J4_cmpgtn1_f_jumpnv_nt; |
| |
| case Hexagon::C4_cmplteui: |
| return taken ? Hexagon::J4_cmpgtui_f_jumpnv_t |
| : Hexagon::J4_cmpgtui_f_jumpnv_nt; |
| |
| default: |
| llvm_unreachable("Could not find matching New Value Jump instruction."); |
| } |
| // return *some value* to avoid compiler warning |
| return 0; |
| } |
| |
| bool HexagonNewValueJump::isNewValueJumpCandidate( |
| const MachineInstr &MI) const { |
| switch (MI.getOpcode()) { |
| case Hexagon::C2_cmpeq: |
| case Hexagon::C2_cmpeqi: |
| case Hexagon::C2_cmpgt: |
| case Hexagon::C2_cmpgti: |
| case Hexagon::C2_cmpgtu: |
| case Hexagon::C2_cmpgtui: |
| case Hexagon::C4_cmpneq: |
| case Hexagon::C4_cmpneqi: |
| case Hexagon::C4_cmplte: |
| case Hexagon::C4_cmplteu: |
| case Hexagon::C4_cmpltei: |
| case Hexagon::C4_cmplteui: |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| bool HexagonNewValueJump::runOnMachineFunction(MachineFunction &MF) { |
| LLVM_DEBUG(dbgs() << "********** Hexagon New Value Jump **********\n" |
| << "********** Function: " << MF.getName() << "\n"); |
| |
| if (skipFunction(MF.getFunction())) |
| return false; |
| |
| // If we move NewValueJump before register allocation we'll need live variable |
| // analysis here too. |
| |
| QII = static_cast<const HexagonInstrInfo *>(MF.getSubtarget().getInstrInfo()); |
| QRI = static_cast<const HexagonRegisterInfo *>( |
| MF.getSubtarget().getRegisterInfo()); |
| MBPI = &getAnalysis<MachineBranchProbabilityInfo>(); |
| |
| if (DisableNewValueJumps || |
| !MF.getSubtarget<HexagonSubtarget>().useNewValueJumps()) |
| return false; |
| |
| int nvjCount = DbgNVJCount; |
| int nvjGenerated = 0; |
| |
| // Loop through all the bb's of the function |
| for (MachineFunction::iterator MBBb = MF.begin(), MBBe = MF.end(); |
| MBBb != MBBe; ++MBBb) { |
| MachineBasicBlock *MBB = &*MBBb; |
| |
| LLVM_DEBUG(dbgs() << "** dumping bb ** " << MBB->getNumber() << "\n"); |
| LLVM_DEBUG(MBB->dump()); |
| LLVM_DEBUG(dbgs() << "\n" |
| << "********** dumping instr bottom up **********\n"); |
| bool foundJump = false; |
| bool foundCompare = false; |
| bool invertPredicate = false; |
| unsigned predReg = 0; // predicate reg of the jump. |
| unsigned cmpReg1 = 0; |
| int cmpOp2 = 0; |
| MachineBasicBlock::iterator jmpPos; |
| MachineBasicBlock::iterator cmpPos; |
| MachineInstr *cmpInstr = nullptr, *jmpInstr = nullptr; |
| MachineBasicBlock *jmpTarget = nullptr; |
| bool afterRA = false; |
| bool isSecondOpReg = false; |
| bool isSecondOpNewified = false; |
| // Traverse the basic block - bottom up |
| for (MachineBasicBlock::iterator MII = MBB->end(), E = MBB->begin(); |
| MII != E;) { |
| MachineInstr &MI = *--MII; |
| if (MI.isDebugInstr()) { |
| continue; |
| } |
| |
| if ((nvjCount == 0) || (nvjCount > -1 && nvjCount <= nvjGenerated)) |
| break; |
| |
| LLVM_DEBUG(dbgs() << "Instr: "; MI.dump(); dbgs() << "\n"); |
| |
| if (!foundJump && (MI.getOpcode() == Hexagon::J2_jumpt || |
| MI.getOpcode() == Hexagon::J2_jumptpt || |
| MI.getOpcode() == Hexagon::J2_jumpf || |
| MI.getOpcode() == Hexagon::J2_jumpfpt || |
| MI.getOpcode() == Hexagon::J2_jumptnewpt || |
| MI.getOpcode() == Hexagon::J2_jumptnew || |
| MI.getOpcode() == Hexagon::J2_jumpfnewpt || |
| MI.getOpcode() == Hexagon::J2_jumpfnew)) { |
| // This is where you would insert your compare and |
| // instr that feeds compare |
| jmpPos = MII; |
| jmpInstr = &MI; |
| predReg = MI.getOperand(0).getReg(); |
| afterRA = Register::isPhysicalRegister(predReg); |
| |
| // If ifconverter had not messed up with the kill flags of the |
| // operands, the following check on the kill flag would suffice. |
| // if(!jmpInstr->getOperand(0).isKill()) break; |
| |
| // This predicate register is live out of BB |
| // this would only work if we can actually use Live |
| // variable analysis on phy regs - but LLVM does not |
| // provide LV analysis on phys regs. |
| //if(LVs.isLiveOut(predReg, *MBB)) break; |
| |
| // Get all the successors of this block - which will always |
| // be 2. Check if the predicate register is live-in in those |
| // successor. If yes, we can not delete the predicate - |
| // I am doing this only because LLVM does not provide LiveOut |
| // at the BB level. |
| bool predLive = false; |
| for (const MachineBasicBlock *SuccMBB : MBB->successors()) |
| if (SuccMBB->isLiveIn(predReg)) |
| predLive = true; |
| if (predLive) |
| break; |
| |
| if (!MI.getOperand(1).isMBB()) |
| continue; |
| jmpTarget = MI.getOperand(1).getMBB(); |
| foundJump = true; |
| if (MI.getOpcode() == Hexagon::J2_jumpf || |
| MI.getOpcode() == Hexagon::J2_jumpfnewpt || |
| MI.getOpcode() == Hexagon::J2_jumpfnew) { |
| invertPredicate = true; |
| } |
| continue; |
| } |
| |
| // No new value jump if there is a barrier. A barrier has to be in its |
| // own packet. A barrier has zero operands. We conservatively bail out |
| // here if we see any instruction with zero operands. |
| if (foundJump && MI.getNumOperands() == 0) |
| break; |
| |
| if (foundJump && !foundCompare && MI.getOperand(0).isReg() && |
| MI.getOperand(0).getReg() == predReg) { |
| // Not all compares can be new value compare. Arch Spec: 7.6.1.1 |
| if (isNewValueJumpCandidate(MI)) { |
| assert( |
| (MI.getDesc().isCompare()) && |
| "Only compare instruction can be collapsed into New Value Jump"); |
| isSecondOpReg = MI.getOperand(2).isReg(); |
| |
| if (!canCompareBeNewValueJump(QII, QRI, MII, predReg, isSecondOpReg, |
| afterRA, jmpPos, MF)) |
| break; |
| |
| cmpInstr = &MI; |
| cmpPos = MII; |
| foundCompare = true; |
| |
| // We need cmpReg1 and cmpOp2(imm or reg) while building |
| // new value jump instruction. |
| cmpReg1 = MI.getOperand(1).getReg(); |
| |
| if (isSecondOpReg) |
| cmpOp2 = MI.getOperand(2).getReg(); |
| else |
| cmpOp2 = MI.getOperand(2).getImm(); |
| continue; |
| } |
| } |
| |
| if (foundCompare && foundJump) { |
| // If "common" checks fail, bail out on this BB. |
| if (!commonChecksToProhibitNewValueJump(afterRA, MII)) |
| break; |
| |
| bool foundFeeder = false; |
| MachineBasicBlock::iterator feederPos = MII; |
| if (MI.getOperand(0).isReg() && MI.getOperand(0).isDef() && |
| (MI.getOperand(0).getReg() == cmpReg1 || |
| (isSecondOpReg && |
| MI.getOperand(0).getReg() == (unsigned)cmpOp2))) { |
| |
| Register feederReg = MI.getOperand(0).getReg(); |
| |
| // First try to see if we can get the feeder from the first operand |
| // of the compare. If we can not, and if secondOpReg is true |
| // (second operand of the compare is also register), try that one. |
| // TODO: Try to come up with some heuristic to figure out which |
| // feeder would benefit. |
| |
| if (feederReg == cmpReg1) { |
| if (!canBeFeederToNewValueJump(QII, QRI, MII, jmpPos, cmpPos, MF)) { |
| if (!isSecondOpReg) |
| break; |
| else |
| continue; |
| } else |
| foundFeeder = true; |
| } |
| |
| if (!foundFeeder && isSecondOpReg && feederReg == (unsigned)cmpOp2) |
| if (!canBeFeederToNewValueJump(QII, QRI, MII, jmpPos, cmpPos, MF)) |
| break; |
| |
| if (isSecondOpReg) { |
| // In case of CMPLT, or CMPLTU, or EQ with the second register |
| // to newify, swap the operands. |
| unsigned COp = cmpInstr->getOpcode(); |
| if ((COp == Hexagon::C2_cmpeq || COp == Hexagon::C4_cmpneq) && |
| (feederReg == (unsigned)cmpOp2)) { |
| unsigned tmp = cmpReg1; |
| cmpReg1 = cmpOp2; |
| cmpOp2 = tmp; |
| } |
| |
| // Now we have swapped the operands, all we need to check is, |
| // if the second operand (after swap) is the feeder. |
| // And if it is, make a note. |
| if (feederReg == (unsigned)cmpOp2) |
| isSecondOpNewified = true; |
| } |
| |
| // Now that we are moving feeder close the jump, |
| // make sure we are respecting the kill values of |
| // the operands of the feeder. |
| |
| auto TransferKills = [jmpPos,cmpPos] (MachineInstr &MI) { |
| for (MachineOperand &MO : MI.operands()) { |
| if (!MO.isReg() || !MO.isUse()) |
| continue; |
| Register UseR = MO.getReg(); |
| for (auto I = std::next(MI.getIterator()); I != jmpPos; ++I) { |
| if (I == cmpPos) |
| continue; |
| for (MachineOperand &Op : I->operands()) { |
| if (!Op.isReg() || !Op.isUse() || !Op.isKill()) |
| continue; |
| if (Op.getReg() != UseR) |
| continue; |
| // We found that there is kill of a use register |
| // Set up a kill flag on the register |
| Op.setIsKill(false); |
| MO.setIsKill(true); |
| return; |
| } |
| } |
| } |
| }; |
| |
| TransferKills(*feederPos); |
| TransferKills(*cmpPos); |
| bool MO1IsKill = cmpPos->killsRegister(cmpReg1, QRI); |
| bool MO2IsKill = isSecondOpReg && cmpPos->killsRegister(cmpOp2, QRI); |
| |
| MBB->splice(jmpPos, MI.getParent(), MI); |
| MBB->splice(jmpPos, MI.getParent(), cmpInstr); |
| DebugLoc dl = MI.getDebugLoc(); |
| MachineInstr *NewMI; |
| |
| assert((isNewValueJumpCandidate(*cmpInstr)) && |
| "This compare is not a New Value Jump candidate."); |
| unsigned opc = getNewValueJumpOpcode(cmpInstr, cmpOp2, |
| isSecondOpNewified, |
| jmpTarget, MBPI); |
| if (invertPredicate) |
| opc = QII->getInvertedPredicatedOpcode(opc); |
| |
| if (isSecondOpReg) |
| NewMI = BuildMI(*MBB, jmpPos, dl, QII->get(opc)) |
| .addReg(cmpReg1, getKillRegState(MO1IsKill)) |
| .addReg(cmpOp2, getKillRegState(MO2IsKill)) |
| .addMBB(jmpTarget); |
| |
| else |
| NewMI = BuildMI(*MBB, jmpPos, dl, QII->get(opc)) |
| .addReg(cmpReg1, getKillRegState(MO1IsKill)) |
| .addImm(cmpOp2) |
| .addMBB(jmpTarget); |
| |
| assert(NewMI && "New Value Jump Instruction Not created!"); |
| (void)NewMI; |
| if (cmpInstr->getOperand(0).isReg() && |
| cmpInstr->getOperand(0).isKill()) |
| cmpInstr->getOperand(0).setIsKill(false); |
| if (cmpInstr->getOperand(1).isReg() && |
| cmpInstr->getOperand(1).isKill()) |
| cmpInstr->getOperand(1).setIsKill(false); |
| cmpInstr->eraseFromParent(); |
| jmpInstr->eraseFromParent(); |
| ++nvjGenerated; |
| ++NumNVJGenerated; |
| break; |
| } |
| } |
| } |
| } |
| |
| return true; |
| } |
| |
| FunctionPass *llvm::createHexagonNewValueJump() { |
| return new HexagonNewValueJump(); |
| } |
