--- /dev/null
+//=== A15SDOptimizerPass.cpp - Optimize DPR and SPR register accesses on A15==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The Cortex-A15 processor employs a tracking scheme in its register renaming
+// in order to process each instruction's micro-ops speculatively and
+// out-of-order with appropriate forwarding. The ARM architecture allows VFP
+// instructions to read and write 32-bit S-registers. Each S-register
+// corresponds to one half (upper or lower) of an overlaid 64-bit D-register.
+//
+// There are several instruction patterns which can be used to provide this
+// capability which can provide higher performance than other, potentially more
+// direct patterns, specifically around when one micro-op reads a D-register
+// operand that has recently been written as one or more S-register results.
+//
+// This file defines a pre-regalloc pass which looks for SPR producers which
+// are going to be used by a DPR (or QPR) consumers and creates the more
+// optimized access pattern.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "a15-sd-optimizer"
+#include "ARM.h"
+#include "ARMBaseInstrInfo.h"
+#include "ARMSubtarget.h"
+#include "ARMISelLowering.h"
+#include "ARMTargetMachine.h"
+
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+#include <set>
+
+using namespace llvm;
+
+namespace {
+ struct A15SDOptimizer : public MachineFunctionPass {
+ static char ID;
+ A15SDOptimizer() : MachineFunctionPass(ID) {}
+
+ virtual bool runOnMachineFunction(MachineFunction &Fn);
+
+ virtual const char *getPassName() const {
+ return "ARM A15 S->D optimizer";
+ }
+
+ private:
+ const ARMBaseInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
+ MachineRegisterInfo *MRI;
+
+ bool runOnInstruction(MachineInstr *MI);
+
+ //
+ // Instruction builder helpers
+ //
+ unsigned createDupLane(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Reg, unsigned Lane,
+ bool QPR=false);
+
+ unsigned createExtractSubreg(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned DReg, unsigned Lane,
+ const TargetRegisterClass *TRC);
+
+ unsigned createVExt(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Ssub0, unsigned Ssub1);
+
+ unsigned createRegSequence(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Reg1, unsigned Reg2);
+
+ unsigned createInsertSubreg(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL, unsigned DReg, unsigned Lane,
+ unsigned ToInsert);
+
+ unsigned createImplicitDef(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL);
+
+ //
+ // Various property checkers
+ //
+ bool usesRegClass(MachineOperand &MO, const TargetRegisterClass *TRC);
+ bool hasPartialWrite(MachineInstr *MI);
+ SmallVector<unsigned, 8> getReadDPRs(MachineInstr *MI);
+ unsigned getDPRLaneFromSPR(unsigned SReg);
+
+ //
+ // Methods used for getting the definitions of partial registers
+ //
+
+ MachineInstr *elideCopies(MachineInstr *MI);
+ void elideCopiesAndPHIs(MachineInstr *MI,
+ SmallVectorImpl<MachineInstr*> &Outs);
+
+ //
+ // Pattern optimization methods
+ //
+ unsigned optimizeAllLanesPattern(MachineInstr *MI, unsigned Reg);
+ unsigned optimizeSDPattern(MachineInstr *MI);
+ unsigned getPrefSPRLane(unsigned SReg);
+
+ //
+ // Sanitizing method - used to make sure if don't leave dead code around.
+ //
+ void eraseInstrWithNoUses(MachineInstr *MI);
+
+ //
+ // A map used to track the changes done by this pass.
+ //
+ std::map<MachineInstr*, unsigned> Replacements;
+ std::set<MachineInstr *> DeadInstr;
+ };
+ char A15SDOptimizer::ID = 0;
+} // end anonymous namespace
+
+// Returns true if this is a use of a SPR register.
+bool A15SDOptimizer::usesRegClass(MachineOperand &MO,
+ const TargetRegisterClass *TRC) {
+ if (!MO.isReg())
+ return false;
+ unsigned Reg = MO.getReg();
+
+ if (TargetRegisterInfo::isVirtualRegister(Reg))
+ return MRI->getRegClass(Reg)->hasSuperClassEq(TRC);
+ else
+ return TRC->contains(Reg);
+}
+
+unsigned A15SDOptimizer::getDPRLaneFromSPR(unsigned SReg) {
+ unsigned DReg = TRI->getMatchingSuperReg(SReg, ARM::ssub_1,
+ &ARM::DPRRegClass);
+ if (DReg != ARM::NoRegister) return ARM::ssub_1;
+ return ARM::ssub_0;
+}
+
+// Get the subreg type that is most likely to be coalesced
+// for an SPR register that will be used in VDUP32d pseudo.
+unsigned A15SDOptimizer::getPrefSPRLane(unsigned SReg) {
+ if (!TRI->isVirtualRegister(SReg))
+ return getDPRLaneFromSPR(SReg);
+
+ MachineInstr *MI = MRI->getVRegDef(SReg);
+ if (!MI) return ARM::ssub_0;
+ MachineOperand *MO = MI->findRegisterDefOperand(SReg);
+
+ assert(MO->isReg() && "Non register operand found!");
+ if (!MO) return ARM::ssub_0;
+
+ if (MI->isCopy() && usesRegClass(MI->getOperand(1),
+ &ARM::SPRRegClass)) {
+ SReg = MI->getOperand(1).getReg();
+ }
+
+ if (TargetRegisterInfo::isVirtualRegister(SReg)) {
+ if (MO->getSubReg() == ARM::ssub_1) return ARM::ssub_1;
+ return ARM::ssub_0;
+ }
+ return getDPRLaneFromSPR(SReg);
+}
+
+// MI is known to be dead. Figure out what instructions
+// are also made dead by this and mark them for removal.
+void A15SDOptimizer::eraseInstrWithNoUses(MachineInstr *MI) {
+ SmallVector<MachineInstr *, 8> Front;
+ DeadInstr.insert(MI);
+
+ DEBUG(dbgs() << "Deleting base instruction " << *MI << "\n");
+ Front.push_back(MI);
+
+ while (Front.size() != 0) {
+ MI = Front.back();
+ Front.pop_back();
+
+ // MI is already known to be dead. We need to see
+ // if other instructions can also be removed.
+ for (unsigned int i = 0; i < MI->getNumOperands(); ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if ((!MO.isReg()) || (!MO.isUse()))
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!TRI->isVirtualRegister(Reg))
+ continue;
+ MachineOperand *Op = MI->findRegisterDefOperand(Reg);
+
+ if (!Op)
+ continue;
+
+ MachineInstr *Def = Op->getParent();
+
+ // We don't need to do anything if we have already marked
+ // this instruction as being dead.
+ if (DeadInstr.find(Def) != DeadInstr.end())
+ continue;
+
+ // Check if all the uses of this instruction are marked as
+ // dead. If so, we can also mark this instruction as being
+ // dead.
+ bool IsDead = true;
+ for (unsigned int j = 0; j < Def->getNumOperands(); ++j) {
+ MachineOperand &MODef = Def->getOperand(j);
+ if ((!MODef.isReg()) || (!MODef.isDef()))
+ continue;
+ unsigned DefReg = MODef.getReg();
+ if (!TRI->isVirtualRegister(DefReg)) {
+ IsDead = false;
+ break;
+ }
+ for (MachineRegisterInfo::use_iterator II = MRI->use_begin(Reg),
+ EE = MRI->use_end();
+ II != EE; ++II) {
+ // We don't care about self references.
+ if (&*II == Def)
+ continue;
+ if (DeadInstr.find(&*II) == DeadInstr.end()) {
+ IsDead = false;
+ break;
+ }
+ }
+ }
+
+ if (!IsDead) continue;
+
+ DEBUG(dbgs() << "Deleting instruction " << *Def << "\n");
+ DeadInstr.insert(Def);
+ }
+ }
+}
+
+// Creates the more optimized patterns and generally does all the code
+// transformations in this pass.
+unsigned A15SDOptimizer::optimizeSDPattern(MachineInstr *MI) {
+ if (MI->isCopy()) {
+ return optimizeAllLanesPattern(MI, MI->getOperand(1).getReg());
+ }
+
+ if (MI->isInsertSubreg()) {
+ unsigned DPRReg = MI->getOperand(1).getReg();
+ unsigned SPRReg = MI->getOperand(2).getReg();
+
+ if (TRI->isVirtualRegister(DPRReg) && TRI->isVirtualRegister(SPRReg)) {
+ MachineInstr *DPRMI = MRI->getVRegDef(MI->getOperand(1).getReg());
+ MachineInstr *SPRMI = MRI->getVRegDef(MI->getOperand(2).getReg());
+
+ if (DPRMI && SPRMI) {
+ // See if the first operand of this insert_subreg is IMPLICIT_DEF
+ MachineInstr *ECDef = elideCopies(DPRMI);
+ if (ECDef != 0 && ECDef->isImplicitDef()) {
+ // Another corner case - if we're inserting something that is purely
+ // a subreg copy of a DPR, just use that DPR.
+
+ MachineInstr *EC = elideCopies(SPRMI);
+ // Is it a subreg copy of ssub_0?
+ if (EC && EC->isCopy() &&
+ EC->getOperand(1).getSubReg() == ARM::ssub_0) {
+ DEBUG(dbgs() << "Found a subreg copy: " << *SPRMI);
+
+ // Find the thing we're subreg copying out of - is it of the same
+ // regclass as DPRMI? (i.e. a DPR or QPR).
+ unsigned FullReg = SPRMI->getOperand(1).getReg();
+ const TargetRegisterClass *TRC =
+ MRI->getRegClass(MI->getOperand(1).getReg());
+ if (TRC->hasSuperClassEq(MRI->getRegClass(FullReg))) {
+ DEBUG(dbgs() << "Subreg copy is compatible - returning ");
+ DEBUG(dbgs() << PrintReg(FullReg) << "\n");
+ eraseInstrWithNoUses(MI);
+ return FullReg;
+ }
+ }
+
+ return optimizeAllLanesPattern(MI, MI->getOperand(2).getReg());
+ }
+ }
+ }
+ return optimizeAllLanesPattern(MI, MI->getOperand(0).getReg());
+ }
+
+ if (MI->isRegSequence() && usesRegClass(MI->getOperand(1),
+ &ARM::SPRRegClass)) {
+ // See if all bar one of the operands are IMPLICIT_DEF and insert the
+ // optimizer pattern accordingly.
+ unsigned NumImplicit = 0, NumTotal = 0;
+ unsigned NonImplicitReg = ~0U;
+
+ for (unsigned I = 1; I < MI->getNumExplicitOperands(); ++I) {
+ if (!MI->getOperand(I).isReg())
+ continue;
+ ++NumTotal;
+ unsigned OpReg = MI->getOperand(I).getReg();
+
+ if (!TRI->isVirtualRegister(OpReg))
+ break;
+
+ MachineInstr *Def = MRI->getVRegDef(OpReg);
+ if (!Def)
+ break;
+ if (Def->isImplicitDef())
+ ++NumImplicit;
+ else
+ NonImplicitReg = MI->getOperand(I).getReg();
+ }
+
+ if (NumImplicit == NumTotal - 1)
+ return optimizeAllLanesPattern(MI, NonImplicitReg);
+ else
+ return optimizeAllLanesPattern(MI, MI->getOperand(0).getReg());
+ }
+
+ assert(0 && "Unhandled update pattern!");
+ return 0;
+}
+
+// Return true if this MachineInstr inserts a scalar (SPR) value into
+// a D or Q register.
+bool A15SDOptimizer::hasPartialWrite(MachineInstr *MI) {
+ // The only way we can do a partial register update is through a COPY,
+ // INSERT_SUBREG or REG_SEQUENCE.
+ if (MI->isCopy() && usesRegClass(MI->getOperand(1), &ARM::SPRRegClass))
+ return true;
+
+ if (MI->isInsertSubreg() && usesRegClass(MI->getOperand(2),
+ &ARM::SPRRegClass))
+ return true;
+
+ if (MI->isRegSequence() && usesRegClass(MI->getOperand(1), &ARM::SPRRegClass))
+ return true;
+
+ return false;
+}
+
+// Looks through full copies to get the instruction that defines the input
+// operand for MI.
+MachineInstr *A15SDOptimizer::elideCopies(MachineInstr *MI) {
+ if (!MI->isFullCopy())
+ return MI;
+ if (!TRI->isVirtualRegister(MI->getOperand(1).getReg()))
+ return NULL;
+ MachineInstr *Def = MRI->getVRegDef(MI->getOperand(1).getReg());
+ if (!Def)
+ return NULL;
+ return elideCopies(Def);
+}
+
+// Look through full copies and PHIs to get the set of non-copy MachineInstrs
+// that can produce MI.
+void A15SDOptimizer::elideCopiesAndPHIs(MachineInstr *MI,
+ SmallVectorImpl<MachineInstr*> &Outs) {
+ // Looking through PHIs may create loops so we need to track what
+ // instructions we have visited before.
+ std::set<MachineInstr *> Reached;
+ SmallVector<MachineInstr *, 8> Front;
+ Front.push_back(MI);
+ while (Front.size() != 0) {
+ MI = Front.back();
+ Front.pop_back();
+
+ // If we have already explored this MachineInstr, ignore it.
+ if (Reached.find(MI) != Reached.end())
+ continue;
+ Reached.insert(MI);
+ if (MI->isPHI()) {
+ for (unsigned I = 1, E = MI->getNumOperands(); I != E; I += 2) {
+ unsigned Reg = MI->getOperand(I).getReg();
+ if (!TRI->isVirtualRegister(Reg)) {
+ continue;
+ }
+ MachineInstr *NewMI = MRI->getVRegDef(Reg);
+ if (!NewMI)
+ continue;
+ Front.push_back(NewMI);
+ }
+ } else if (MI->isFullCopy()) {
+ if (!TRI->isVirtualRegister(MI->getOperand(1).getReg()))
+ continue;
+ MachineInstr *NewMI = MRI->getVRegDef(MI->getOperand(1).getReg());
+ if (!NewMI)
+ continue;
+ Front.push_back(NewMI);
+ } else {
+ DEBUG(dbgs() << "Found partial copy" << *MI <<"\n");
+ Outs.push_back(MI);
+ }
+ }
+}
+
+// Return the DPR virtual registers that are read by this machine instruction
+// (if any).
+SmallVector<unsigned, 8> A15SDOptimizer::getReadDPRs(MachineInstr *MI) {
+ if (MI->isCopyLike() || MI->isInsertSubreg() || MI->isRegSequence() ||
+ MI->isKill())
+ return SmallVector<unsigned, 8>();
+
+ SmallVector<unsigned, 8> Defs;
+ for (unsigned i = 0; i < MI->getNumOperands(); ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+
+ if (!MO.isReg() || !MO.isUse())
+ continue;
+ if (!usesRegClass(MO, &ARM::DPRRegClass) &&
+ !usesRegClass(MO, &ARM::QPRRegClass))
+ continue;
+
+ Defs.push_back(MO.getReg());
+ }
+ return Defs;
+}
+
+// Creates a DPR register from an SPR one by using a VDUP.
+unsigned
+A15SDOptimizer::createDupLane(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Reg, unsigned Lane, bool QPR) {
+ unsigned Out = MRI->createVirtualRegister(QPR ? &ARM::QPRRegClass :
+ &ARM::DPRRegClass);
+ AddDefaultPred(BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(QPR ? ARM::VDUPLN32q : ARM::VDUPLN32d),
+ Out)
+ .addReg(Reg)
+ .addImm(Lane));
+
+ return Out;
+}
+
+// Creates a SPR register from a DPR by copying the value in lane 0.
+unsigned
+A15SDOptimizer::createExtractSubreg(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned DReg, unsigned Lane,
+ const TargetRegisterClass *TRC) {
+ unsigned Out = MRI->createVirtualRegister(TRC);
+ BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(TargetOpcode::COPY), Out)
+ .addReg(DReg, 0, Lane);
+
+ return Out;
+}
+
+// Takes two SPR registers and creates a DPR by using a REG_SEQUENCE.
+unsigned
+A15SDOptimizer::createRegSequence(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Reg1, unsigned Reg2) {
+ unsigned Out = MRI->createVirtualRegister(&ARM::QPRRegClass);
+ BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(TargetOpcode::REG_SEQUENCE), Out)
+ .addReg(Reg1)
+ .addImm(ARM::dsub_0)
+ .addReg(Reg2)
+ .addImm(ARM::dsub_1);
+ return Out;
+}
+
+// Takes two DPR registers that have previously been VDUPed (Ssub0 and Ssub1)
+// and merges them into one DPR register.
+unsigned
+A15SDOptimizer::createVExt(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL,
+ unsigned Ssub0, unsigned Ssub1) {
+ unsigned Out = MRI->createVirtualRegister(&ARM::DPRRegClass);
+ AddDefaultPred(BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(ARM::VEXTd32), Out)
+ .addReg(Ssub0)
+ .addReg(Ssub1)
+ .addImm(1));
+ return Out;
+}
+
+unsigned
+A15SDOptimizer::createInsertSubreg(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL, unsigned DReg, unsigned Lane,
+ unsigned ToInsert) {
+ unsigned Out = MRI->createVirtualRegister(&ARM::DPR_VFP2RegClass);
+ BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(TargetOpcode::INSERT_SUBREG), Out)
+ .addReg(DReg)
+ .addReg(ToInsert)
+ .addImm(Lane);
+
+ return Out;
+}
+
+unsigned
+A15SDOptimizer::createImplicitDef(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator InsertBefore,
+ DebugLoc DL) {
+ unsigned Out = MRI->createVirtualRegister(&ARM::DPRRegClass);
+ BuildMI(MBB,
+ InsertBefore,
+ DL,
+ TII->get(TargetOpcode::IMPLICIT_DEF), Out);
+ return Out;
+}
+
+// This function inserts instructions in order to optimize interactions between
+// SPR registers and DPR/QPR registers. It does so by performing VDUPs on all
+// lanes, and the using VEXT instructions to recompose the result.
+unsigned
+A15SDOptimizer::optimizeAllLanesPattern(MachineInstr *MI, unsigned Reg) {
+ MachineBasicBlock::iterator InsertPt(MI);
+ DebugLoc DL = MI->getDebugLoc();
+ MachineBasicBlock &MBB = *MI->getParent();
+ InsertPt++;
+ unsigned Out;
+
+ if (MRI->getRegClass(Reg)->hasSuperClassEq(&ARM::QPRRegClass)) {
+ unsigned DSub0 = createExtractSubreg(MBB, InsertPt, DL, Reg,
+ ARM::dsub_0, &ARM::DPRRegClass);
+ unsigned DSub1 = createExtractSubreg(MBB, InsertPt, DL, Reg,
+ ARM::dsub_1, &ARM::DPRRegClass);
+
+ unsigned Out1 = createDupLane(MBB, InsertPt, DL, DSub0, 0);
+ unsigned Out2 = createDupLane(MBB, InsertPt, DL, DSub0, 1);
+ Out = createVExt(MBB, InsertPt, DL, Out1, Out2);
+
+ unsigned Out3 = createDupLane(MBB, InsertPt, DL, DSub1, 0);
+ unsigned Out4 = createDupLane(MBB, InsertPt, DL, DSub1, 1);
+ Out2 = createVExt(MBB, InsertPt, DL, Out3, Out4);
+
+ Out = createRegSequence(MBB, InsertPt, DL, Out, Out2);
+
+ } else if (MRI->getRegClass(Reg)->hasSuperClassEq(&ARM::DPRRegClass)) {
+ unsigned Out1 = createDupLane(MBB, InsertPt, DL, Reg, 0);
+ unsigned Out2 = createDupLane(MBB, InsertPt, DL, Reg, 1);
+ Out = createVExt(MBB, InsertPt, DL, Out1, Out2);
+
+ } else {
+ assert(MRI->getRegClass(Reg)->hasSuperClassEq(&ARM::SPRRegClass) &&
+ "Found unexpected regclass!");
+
+ unsigned PrefLane = getPrefSPRLane(Reg);
+ unsigned Lane;
+ switch (PrefLane) {
+ case ARM::ssub_0: Lane = 0; break;
+ case ARM::ssub_1: Lane = 1; break;
+ default: llvm_unreachable("Unknown preferred lane!");
+ }
+
+ bool UsesQPR = usesRegClass(MI->getOperand(0), &ARM::QPRRegClass);
+
+ Out = createImplicitDef(MBB, InsertPt, DL);
+ Out = createInsertSubreg(MBB, InsertPt, DL, Out, PrefLane, Reg);
+ Out = createDupLane(MBB, InsertPt, DL, Out, Lane, UsesQPR);
+ eraseInstrWithNoUses(MI);
+ }
+ return Out;
+}
+
+bool A15SDOptimizer::runOnInstruction(MachineInstr *MI) {
+ // We look for instructions that write S registers that are then read as
+ // D/Q registers. These can only be caused by COPY, INSERT_SUBREG and
+ // REG_SEQUENCE pseudos that insert an SPR value into a DPR register or
+ // merge two SPR values to form a DPR register. In order avoid false
+ // positives we make sure that there is an SPR producer so we look past
+ // COPY and PHI nodes to find it.
+ //
+ // The best code pattern for when an SPR producer is going to be used by a
+ // DPR or QPR consumer depends on whether the other lanes of the
+ // corresponding DPR/QPR are currently defined.
+ //
+ // We can handle these efficiently, depending on the type of
+ // pseudo-instruction that is producing the pattern
+ //
+ // * COPY: * VDUP all lanes and merge the results together
+ // using VEXTs.
+ //
+ // * INSERT_SUBREG: * If the SPR value was originally in another DPR/QPR
+ // lane, and the other lane(s) of the DPR/QPR register
+ // that we are inserting in are undefined, use the
+ // original DPR/QPR value.
+ // * Otherwise, fall back on the same stategy as COPY.
+ //
+ // * REG_SEQUENCE: * If all except one of the input operands are
+ // IMPLICIT_DEFs, insert the VDUP pattern for just the
+ // defined input operand
+ // * Otherwise, fall back on the same stategy as COPY.
+ //
+
+ // First, get all the reads of D-registers done by this instruction.
+ SmallVector<unsigned, 8> Defs = getReadDPRs(MI);
+ bool Modified = false;
+
+ for (SmallVector<unsigned, 8>::iterator I = Defs.begin(), E = Defs.end();
+ I != E; ++I) {
+ // Follow the def-use chain for this DPR through COPYs, and also through
+ // PHIs (which are essentially multi-way COPYs). It is because of PHIs that
+ // we can end up with multiple defs of this DPR.
+
+ SmallVector<MachineInstr *, 8> DefSrcs;
+ if (!TRI->isVirtualRegister(*I))
+ continue;
+ MachineInstr *Def = MRI->getVRegDef(*I);
+ if (!Def)
+ continue;
+
+ elideCopiesAndPHIs(Def, DefSrcs);
+
+ for (SmallVector<MachineInstr*, 8>::iterator II = DefSrcs.begin(),
+ EE = DefSrcs.end(); II != EE; ++II) {
+ MachineInstr *MI = *II;
+
+ // If we've already analyzed and replaced this operand, don't do
+ // anything.
+ if (Replacements.find(MI) != Replacements.end())
+ continue;
+
+ // Now, work out if the instruction causes a SPR->DPR dependency.
+ if (!hasPartialWrite(MI))
+ continue;
+
+ // Collect all the uses of this MI's DPR def for updating later.
+ SmallVector<MachineOperand*, 8> Uses;
+ unsigned DPRDefReg = MI->getOperand(0).getReg();
+ for (MachineRegisterInfo::use_iterator I = MRI->use_begin(DPRDefReg),
+ E = MRI->use_end(); I != E; ++I)
+ Uses.push_back(&I.getOperand());
+
+ // We can optimize this.
+ unsigned NewReg = optimizeSDPattern(MI);
+
+ if (NewReg != 0) {
+ Modified = true;
+ for (SmallVector<MachineOperand*, 8>::const_iterator I = Uses.begin(),
+ E = Uses.end(); I != E; ++I) {
+ DEBUG(dbgs() << "Replacing operand "
+ << **I << " with "
+ << PrintReg(NewReg) << "\n");
+ (*I)->substVirtReg(NewReg, 0, *TRI);
+ }
+ }
+ Replacements[MI] = NewReg;
+ }
+ }
+ return Modified;
+}
+
+bool A15SDOptimizer::runOnMachineFunction(MachineFunction &Fn) {
+ TII = static_cast<const ARMBaseInstrInfo*>(Fn.getTarget().getInstrInfo());
+ TRI = Fn.getTarget().getRegisterInfo();
+ MRI = &Fn.getRegInfo();
+ bool Modified = false;
+
+ DEBUG(dbgs() << "Running on function " << Fn.getName()<< "\n");
+
+ DeadInstr.clear();
+ Replacements.clear();
+
+ for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
+ ++MFI) {
+
+ for (MachineBasicBlock::iterator MI = MFI->begin(), ME = MFI->end();
+ MI != ME;) {
+ Modified |= runOnInstruction(MI++);
+ }
+
+ }
+
+ for (std::set<MachineInstr *>::iterator I = DeadInstr.begin(),
+ E = DeadInstr.end();
+ I != E; ++I) {
+ (*I)->eraseFromParent();
+ }
+
+ return Modified;
+}
+
+FunctionPass *llvm::createA15SDOptimizerPass() {
+ return new A15SDOptimizer();
+}
projects / oota-llvm.git / commitdiff