llvm-6502/lib/Target/ARM/A15SDOptimizer.cpp
Eric Christopher 6035518e3b Have MachineFunction cache a pointer to the subtarget to make lookups
shorter/easier and have the DAG use that to do the same lookup. This
can be used in the future for TargetMachine based caching lookups from
the MachineFunction easily.

Update the MIPS subtarget switching machinery to update this pointer
at the same time it runs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214838 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-05 02:39:49 +00:00

712 lines
25 KiB
C++

//=== 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.
//
//===----------------------------------------------------------------------===//
#include "ARM.h"
#include "ARMBaseInstrInfo.h"
#include "ARMBaseRegisterInfo.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/Debug.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <set>
using namespace llvm;
#define DEBUG_TYPE "a15-sd-optimizer"
namespace {
struct A15SDOptimizer : public MachineFunctionPass {
static char ID;
A15SDOptimizer() : MachineFunctionPass(ID) {}
bool runOnMachineFunction(MachineFunction &Fn) override;
const char *getPassName() const override {
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_instr_iterator
II = MRI->use_instr_begin(Reg), EE = MRI->use_instr_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 && 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());
}
llvm_unreachable("Unhandled update pattern!");
}
// 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 nullptr;
MachineInstr *Def = MRI->getVRegDef(MI->getOperand(1).getReg());
if (!Def)
return nullptr;
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) &&
!usesRegClass(MO, &ARM::DPairRegClass)) // Treat DPair as QPR
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;
// DPair has the same length as QPR and also has two DPRs as subreg.
// Treat DPair as QPR.
if (MRI->getRegClass(Reg)->hasSuperClassEq(&ARM::QPRRegClass) ||
MRI->getRegClass(Reg)->hasSuperClassEq(&ARM::DPairRegClass)) {
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!");
}
// Treat DPair as QPR
bool UsesQPR = usesRegClass(MI->getOperand(0), &ARM::QPRRegClass) ||
usesRegClass(MI->getOperand(0), &ARM::DPairRegClass);
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 (SmallVectorImpl<unsigned>::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 (SmallVectorImpl<MachineInstr *>::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);
// We can optimize this.
unsigned NewReg = optimizeSDPattern(MI);
if (NewReg != 0) {
Modified = true;
for (SmallVectorImpl<MachineOperand *>::const_iterator I = Uses.begin(),
E = Uses.end(); I != E; ++I) {
// Make sure to constrain the register class of the new register to
// match what we're replacing. Otherwise we can optimize a DPR_VFP2
// reference into a plain DPR, and that will end poorly. NewReg is
// always virtual here, so there will always be a matching subclass
// to find.
MRI->constrainRegClass(NewReg, MRI->getRegClass((*I)->getReg()));
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.getSubtarget().getInstrInfo());
TRI = Fn.getSubtarget().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();
}