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llvm-6502/lib/Target/PowerPC/PPCInstrInfo.cpp
Bill Wendling 5f32469bd4 Merging r181423: 
------------------------------------------------------------------------
r181423 | hfinkel | 2013-05-08 05:16:14 -0700 (Wed, 08 May 2013) | 5 lines

PPCInstrInfo::optimizeCompareInstr should not optimize FP compares

The floating-point record forms on PPC don't set the condition register bits
based on a comparison with zero (like the integer record forms do), but rather
based on the exception status bits.
------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@181507 91177308-0d34-0410-b5e6-96231b3b80d8
2013-05-09 07:33:50 +00:00

1536 lines
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//===-- PPCInstrInfo.cpp - PowerPC Instruction Information ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the PowerPC implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "PPCInstrInfo.h"
#include "MCTargetDesc/PPCPredicates.h"
#include "PPC.h"
#include "PPCHazardRecognizers.h"
#include "PPCInstrBuilder.h"
#include "PPCMachineFunctionInfo.h"
#include "PPCTargetMachine.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#define GET_INSTRMAP_INFO
#define GET_INSTRINFO_CTOR
#include "PPCGenInstrInfo.inc"
using namespace llvm;
static cl::
opt<bool> DisableCTRLoopAnal("disable-ppc-ctrloop-analysis", cl::Hidden,
cl::desc("Disable analysis for CTR loops"));
static cl::opt<bool> DisableCmpOpt("disable-ppc-cmp-opt",
cl::desc("Disable compare instruction optimization"), cl::Hidden);
PPCInstrInfo::PPCInstrInfo(PPCTargetMachine &tm)
: PPCGenInstrInfo(PPC::ADJCALLSTACKDOWN, PPC::ADJCALLSTACKUP),
TM(tm), RI(*TM.getSubtargetImpl(), *this) {}
/// CreateTargetHazardRecognizer - Return the hazard recognizer to use for
/// this target when scheduling the DAG.
ScheduleHazardRecognizer *PPCInstrInfo::CreateTargetHazardRecognizer(
const TargetMachine *TM,
const ScheduleDAG *DAG) const {
unsigned Directive = TM->getSubtarget<PPCSubtarget>().getDarwinDirective();
if (Directive == PPC::DIR_440 || Directive == PPC::DIR_A2 ||
Directive == PPC::DIR_E500mc || Directive == PPC::DIR_E5500) {
const InstrItineraryData *II = TM->getInstrItineraryData();
return new PPCScoreboardHazardRecognizer(II, DAG);
}
return TargetInstrInfo::CreateTargetHazardRecognizer(TM, DAG);
}
/// CreateTargetPostRAHazardRecognizer - Return the postRA hazard recognizer
/// to use for this target when scheduling the DAG.
ScheduleHazardRecognizer *PPCInstrInfo::CreateTargetPostRAHazardRecognizer(
const InstrItineraryData *II,
const ScheduleDAG *DAG) const {
unsigned Directive = TM.getSubtarget<PPCSubtarget>().getDarwinDirective();
// Most subtargets use a PPC970 recognizer.
if (Directive != PPC::DIR_440 && Directive != PPC::DIR_A2 &&
Directive != PPC::DIR_E500mc && Directive != PPC::DIR_E5500) {
const TargetInstrInfo *TII = TM.getInstrInfo();
assert(TII && "No InstrInfo?");
return new PPCHazardRecognizer970(*TII);
}
return new PPCScoreboardHazardRecognizer(II, DAG);
}
// Detect 32 -> 64-bit extensions where we may reuse the low sub-register.
bool PPCInstrInfo::isCoalescableExtInstr(const MachineInstr &MI,
unsigned &SrcReg, unsigned &DstReg,
unsigned &SubIdx) const {
switch (MI.getOpcode()) {
default: return false;
case PPC::EXTSW:
case PPC::EXTSW_32_64:
SrcReg = MI.getOperand(1).getReg();
DstReg = MI.getOperand(0).getReg();
SubIdx = PPC::sub_32;
return true;
}
}
unsigned PPCInstrInfo::isLoadFromStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
// Note: This list must be kept consistent with LoadRegFromStackSlot.
switch (MI->getOpcode()) {
default: break;
case PPC::LD:
case PPC::LWZ:
case PPC::LFS:
case PPC::LFD:
case PPC::RESTORE_CR:
case PPC::LVX:
case PPC::RESTORE_VRSAVE:
// Check for the operands added by addFrameReference (the immediate is the
// offset which defaults to 0).
if (MI->getOperand(1).isImm() && !MI->getOperand(1).getImm() &&
MI->getOperand(2).isFI()) {
FrameIndex = MI->getOperand(2).getIndex();
return MI->getOperand(0).getReg();
}
break;
}
return 0;
}
unsigned PPCInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
// Note: This list must be kept consistent with StoreRegToStackSlot.
switch (MI->getOpcode()) {
default: break;
case PPC::STD:
case PPC::STW:
case PPC::STFS:
case PPC::STFD:
case PPC::SPILL_CR:
case PPC::STVX:
case PPC::SPILL_VRSAVE:
// Check for the operands added by addFrameReference (the immediate is the
// offset which defaults to 0).
if (MI->getOperand(1).isImm() && !MI->getOperand(1).getImm() &&
MI->getOperand(2).isFI()) {
FrameIndex = MI->getOperand(2).getIndex();
return MI->getOperand(0).getReg();
}
break;
}
return 0;
}
// commuteInstruction - We can commute rlwimi instructions, but only if the
// rotate amt is zero. We also have to munge the immediates a bit.
MachineInstr *
PPCInstrInfo::commuteInstruction(MachineInstr *MI, bool NewMI) const {
MachineFunction &MF = *MI->getParent()->getParent();
// Normal instructions can be commuted the obvious way.
if (MI->getOpcode() != PPC::RLWIMI &&
MI->getOpcode() != PPC::RLWIMIo)
return TargetInstrInfo::commuteInstruction(MI, NewMI);
// Cannot commute if it has a non-zero rotate count.
if (MI->getOperand(3).getImm() != 0)
return 0;
// If we have a zero rotate count, we have:
// M = mask(MB,ME)
// Op0 = (Op1 & ~M) | (Op2 & M)
// Change this to:
// M = mask((ME+1)&31, (MB-1)&31)
// Op0 = (Op2 & ~M) | (Op1 & M)
// Swap op1/op2
unsigned Reg0 = MI->getOperand(0).getReg();
unsigned Reg1 = MI->getOperand(1).getReg();
unsigned Reg2 = MI->getOperand(2).getReg();
bool Reg1IsKill = MI->getOperand(1).isKill();
bool Reg2IsKill = MI->getOperand(2).isKill();
bool ChangeReg0 = false;
// If machine instrs are no longer in two-address forms, update
// destination register as well.
if (Reg0 == Reg1) {
// Must be two address instruction!
assert(MI->getDesc().getOperandConstraint(0, MCOI::TIED_TO) &&
"Expecting a two-address instruction!");
Reg2IsKill = false;
ChangeReg0 = true;
}
// Masks.
unsigned MB = MI->getOperand(4).getImm();
unsigned ME = MI->getOperand(5).getImm();
if (NewMI) {
// Create a new instruction.
unsigned Reg0 = ChangeReg0 ? Reg2 : MI->getOperand(0).getReg();
bool Reg0IsDead = MI->getOperand(0).isDead();
return BuildMI(MF, MI->getDebugLoc(), MI->getDesc())
.addReg(Reg0, RegState::Define | getDeadRegState(Reg0IsDead))
.addReg(Reg2, getKillRegState(Reg2IsKill))
.addReg(Reg1, getKillRegState(Reg1IsKill))
.addImm((ME+1) & 31)
.addImm((MB-1) & 31);
}
if (ChangeReg0)
MI->getOperand(0).setReg(Reg2);
MI->getOperand(2).setReg(Reg1);
MI->getOperand(1).setReg(Reg2);
MI->getOperand(2).setIsKill(Reg1IsKill);
MI->getOperand(1).setIsKill(Reg2IsKill);
// Swap the mask around.
MI->getOperand(4).setImm((ME+1) & 31);
MI->getOperand(5).setImm((MB-1) & 31);
return MI;
}
void PPCInstrInfo::insertNoop(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
DebugLoc DL;
BuildMI(MBB, MI, DL, get(PPC::NOP));
}
// Branch analysis.
// Note: If the condition register is set to CTR or CTR8 then this is a
// BDNZ (imm == 1) or BDZ (imm == 0) branch.
bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const {
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
// If the block has no terminators, it just falls into the block after it.
MachineBasicBlock::iterator I = MBB.end();
if (I == MBB.begin())
return false;
--I;
while (I->isDebugValue()) {
if (I == MBB.begin())
return false;
--I;
}
if (!isUnpredicatedTerminator(I))
return false;
// Get the last instruction in the block.
MachineInstr *LastInst = I;
// If there is only one terminator instruction, process it.
if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
if (LastInst->getOpcode() == PPC::B) {
if (!LastInst->getOperand(0).isMBB())
return true;
TBB = LastInst->getOperand(0).getMBB();
return false;
} else if (LastInst->getOpcode() == PPC::BCC) {
if (!LastInst->getOperand(2).isMBB())
return true;
// Block ends with fall-through condbranch.
TBB = LastInst->getOperand(2).getMBB();
Cond.push_back(LastInst->getOperand(0));
Cond.push_back(LastInst->getOperand(1));
return false;
} else if (LastInst->getOpcode() == PPC::BDNZ8 ||
LastInst->getOpcode() == PPC::BDNZ) {
if (!LastInst->getOperand(0).isMBB())
return true;
if (DisableCTRLoopAnal)
return true;
TBB = LastInst->getOperand(0).getMBB();
Cond.push_back(MachineOperand::CreateImm(1));
Cond.push_back(MachineOperand::CreateReg(isPPC64 ? PPC::CTR8 : PPC::CTR,
true));
return false;
} else if (LastInst->getOpcode() == PPC::BDZ8 ||
LastInst->getOpcode() == PPC::BDZ) {
if (!LastInst->getOperand(0).isMBB())
return true;
if (DisableCTRLoopAnal)
return true;
TBB = LastInst->getOperand(0).getMBB();
Cond.push_back(MachineOperand::CreateImm(0));
Cond.push_back(MachineOperand::CreateReg(isPPC64 ? PPC::CTR8 : PPC::CTR,
true));
return false;
}
// Otherwise, don't know what this is.
return true;
}
// Get the instruction before it if it's a terminator.
MachineInstr *SecondLastInst = I;
// If there are three terminators, we don't know what sort of block this is.
if (SecondLastInst && I != MBB.begin() &&
isUnpredicatedTerminator(--I))
return true;
// If the block ends with PPC::B and PPC:BCC, handle it.
if (SecondLastInst->getOpcode() == PPC::BCC &&
LastInst->getOpcode() == PPC::B) {
if (!SecondLastInst->getOperand(2).isMBB() ||
!LastInst->getOperand(0).isMBB())
return true;
TBB = SecondLastInst->getOperand(2).getMBB();
Cond.push_back(SecondLastInst->getOperand(0));
Cond.push_back(SecondLastInst->getOperand(1));
FBB = LastInst->getOperand(0).getMBB();
return false;
} else if ((SecondLastInst->getOpcode() == PPC::BDNZ8 ||
SecondLastInst->getOpcode() == PPC::BDNZ) &&
LastInst->getOpcode() == PPC::B) {
if (!SecondLastInst->getOperand(0).isMBB() ||
!LastInst->getOperand(0).isMBB())
return true;
if (DisableCTRLoopAnal)
return true;
TBB = SecondLastInst->getOperand(0).getMBB();
Cond.push_back(MachineOperand::CreateImm(1));
Cond.push_back(MachineOperand::CreateReg(isPPC64 ? PPC::CTR8 : PPC::CTR,
true));
FBB = LastInst->getOperand(0).getMBB();
return false;
} else if ((SecondLastInst->getOpcode() == PPC::BDZ8 ||
SecondLastInst->getOpcode() == PPC::BDZ) &&
LastInst->getOpcode() == PPC::B) {
if (!SecondLastInst->getOperand(0).isMBB() ||
!LastInst->getOperand(0).isMBB())
return true;
if (DisableCTRLoopAnal)
return true;
TBB = SecondLastInst->getOperand(0).getMBB();
Cond.push_back(MachineOperand::CreateImm(0));
Cond.push_back(MachineOperand::CreateReg(isPPC64 ? PPC::CTR8 : PPC::CTR,
true));
FBB = LastInst->getOperand(0).getMBB();
return false;
}
// If the block ends with two PPC:Bs, handle it. The second one is not
// executed, so remove it.
if (SecondLastInst->getOpcode() == PPC::B &&
LastInst->getOpcode() == PPC::B) {
if (!SecondLastInst->getOperand(0).isMBB())
return true;
TBB = SecondLastInst->getOperand(0).getMBB();
I = LastInst;
if (AllowModify)
I->eraseFromParent();
return false;
}
// Otherwise, can't handle this.
return true;
}
unsigned PPCInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator I = MBB.end();
if (I == MBB.begin()) return 0;
--I;
while (I->isDebugValue()) {
if (I == MBB.begin())
return 0;
--I;
}
if (I->getOpcode() != PPC::B && I->getOpcode() != PPC::BCC &&
I->getOpcode() != PPC::BDNZ8 && I->getOpcode() != PPC::BDNZ &&
I->getOpcode() != PPC::BDZ8 && I->getOpcode() != PPC::BDZ)
return 0;
// Remove the branch.
I->eraseFromParent();
I = MBB.end();
if (I == MBB.begin()) return 1;
--I;
if (I->getOpcode() != PPC::BCC &&
I->getOpcode() != PPC::BDNZ8 && I->getOpcode() != PPC::BDNZ &&
I->getOpcode() != PPC::BDZ8 && I->getOpcode() != PPC::BDZ)
return 1;
// Remove the branch.
I->eraseFromParent();
return 2;
}
unsigned
PPCInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond,
DebugLoc DL) const {
// Shouldn't be a fall through.
assert(TBB && "InsertBranch must not be told to insert a fallthrough");
assert((Cond.size() == 2 || Cond.size() == 0) &&
"PPC branch conditions have two components!");
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
// One-way branch.
if (FBB == 0) {
if (Cond.empty()) // Unconditional branch
BuildMI(&MBB, DL, get(PPC::B)).addMBB(TBB);
else if (Cond[1].getReg() == PPC::CTR || Cond[1].getReg() == PPC::CTR8)
BuildMI(&MBB, DL, get(Cond[0].getImm() ?
(isPPC64 ? PPC::BDNZ8 : PPC::BDNZ) :
(isPPC64 ? PPC::BDZ8 : PPC::BDZ))).addMBB(TBB);
else // Conditional branch
BuildMI(&MBB, DL, get(PPC::BCC))
.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
return 1;
}
// Two-way Conditional Branch.
if (Cond[1].getReg() == PPC::CTR || Cond[1].getReg() == PPC::CTR8)
BuildMI(&MBB, DL, get(Cond[0].getImm() ?
(isPPC64 ? PPC::BDNZ8 : PPC::BDNZ) :
(isPPC64 ? PPC::BDZ8 : PPC::BDZ))).addMBB(TBB);
else
BuildMI(&MBB, DL, get(PPC::BCC))
.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
BuildMI(&MBB, DL, get(PPC::B)).addMBB(FBB);
return 2;
}
// Select analysis.
bool PPCInstrInfo::canInsertSelect(const MachineBasicBlock &MBB,
const SmallVectorImpl<MachineOperand> &Cond,
unsigned TrueReg, unsigned FalseReg,
int &CondCycles, int &TrueCycles, int &FalseCycles) const {
if (!TM.getSubtargetImpl()->hasISEL())
return false;
if (Cond.size() != 2)
return false;
// If this is really a bdnz-like condition, then it cannot be turned into a
// select.
if (Cond[1].getReg() == PPC::CTR || Cond[1].getReg() == PPC::CTR8)
return false;
// Check register classes.
const MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
const TargetRegisterClass *RC =
RI.getCommonSubClass(MRI.getRegClass(TrueReg), MRI.getRegClass(FalseReg));
if (!RC)
return false;
// isel is for regular integer GPRs only.
if (!PPC::GPRCRegClass.hasSubClassEq(RC) &&
!PPC::G8RCRegClass.hasSubClassEq(RC))
return false;
// FIXME: These numbers are for the A2, how well they work for other cores is
// an open question. On the A2, the isel instruction has a 2-cycle latency
// but single-cycle throughput. These numbers are used in combination with
// the MispredictPenalty setting from the active SchedMachineModel.
CondCycles = 1;
TrueCycles = 1;
FalseCycles = 1;
return true;
}
void PPCInstrInfo::insertSelect(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI, DebugLoc dl,
unsigned DestReg,
const SmallVectorImpl<MachineOperand> &Cond,
unsigned TrueReg, unsigned FalseReg) const {
assert(Cond.size() == 2 &&
"PPC branch conditions have two components!");
assert(TM.getSubtargetImpl()->hasISEL() &&
"Cannot insert select on target without ISEL support");
// Get the register classes.
MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
const TargetRegisterClass *RC =
RI.getCommonSubClass(MRI.getRegClass(TrueReg), MRI.getRegClass(FalseReg));
assert(RC && "TrueReg and FalseReg must have overlapping register classes");
assert((PPC::GPRCRegClass.hasSubClassEq(RC) ||
PPC::G8RCRegClass.hasSubClassEq(RC)) &&
"isel is for regular integer GPRs only");
unsigned OpCode =
PPC::GPRCRegClass.hasSubClassEq(RC) ? PPC::ISEL : PPC::ISEL8;
unsigned SelectPred = Cond[0].getImm();
unsigned SubIdx;
bool SwapOps;
switch (SelectPred) {
default: llvm_unreachable("invalid predicate for isel");
case PPC::PRED_EQ: SubIdx = PPC::sub_eq; SwapOps = false; break;
case PPC::PRED_NE: SubIdx = PPC::sub_eq; SwapOps = true; break;
case PPC::PRED_LT: SubIdx = PPC::sub_lt; SwapOps = false; break;
case PPC::PRED_GE: SubIdx = PPC::sub_lt; SwapOps = true; break;
case PPC::PRED_GT: SubIdx = PPC::sub_gt; SwapOps = false; break;
case PPC::PRED_LE: SubIdx = PPC::sub_gt; SwapOps = true; break;
case PPC::PRED_UN: SubIdx = PPC::sub_un; SwapOps = false; break;
case PPC::PRED_NU: SubIdx = PPC::sub_un; SwapOps = true; break;
}
unsigned FirstReg = SwapOps ? FalseReg : TrueReg,
SecondReg = SwapOps ? TrueReg : FalseReg;
// The first input register of isel cannot be r0. If it is a member
// of a register class that can be r0, then copy it first (the
// register allocator should eliminate the copy).
if (MRI.getRegClass(FirstReg)->contains(PPC::R0) ||
MRI.getRegClass(FirstReg)->contains(PPC::X0)) {
const TargetRegisterClass *FirstRC =
MRI.getRegClass(FirstReg)->contains(PPC::X0) ?
&PPC::G8RC_NOX0RegClass : &PPC::GPRC_NOR0RegClass;
unsigned OldFirstReg = FirstReg;
FirstReg = MRI.createVirtualRegister(FirstRC);
BuildMI(MBB, MI, dl, get(TargetOpcode::COPY), FirstReg)
.addReg(OldFirstReg);
}
BuildMI(MBB, MI, dl, get(OpCode), DestReg)
.addReg(FirstReg).addReg(SecondReg)
.addReg(Cond[1].getReg(), 0, SubIdx);
}
void PPCInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
bool KillSrc) const {
unsigned Opc;
if (PPC::GPRCRegClass.contains(DestReg, SrcReg))
Opc = PPC::OR;
else if (PPC::G8RCRegClass.contains(DestReg, SrcReg))
Opc = PPC::OR8;
else if (PPC::F4RCRegClass.contains(DestReg, SrcReg))
Opc = PPC::FMR;
else if (PPC::CRRCRegClass.contains(DestReg, SrcReg))
Opc = PPC::MCRF;
else if (PPC::VRRCRegClass.contains(DestReg, SrcReg))
Opc = PPC::VOR;
else if (PPC::CRBITRCRegClass.contains(DestReg, SrcReg))
Opc = PPC::CROR;
else
llvm_unreachable("Impossible reg-to-reg copy");
const MCInstrDesc &MCID = get(Opc);
if (MCID.getNumOperands() == 3)
BuildMI(MBB, I, DL, MCID, DestReg)
.addReg(SrcReg).addReg(SrcReg, getKillRegState(KillSrc));
else
BuildMI(MBB, I, DL, MCID, DestReg).addReg(SrcReg, getKillRegState(KillSrc));
}
// This function returns true if a CR spill is necessary and false otherwise.
bool
PPCInstrInfo::StoreRegToStackSlot(MachineFunction &MF,
unsigned SrcReg, bool isKill,
int FrameIdx,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs,
bool &NonRI, bool &SpillsVRS) const{
// Note: If additional store instructions are added here,
// update isStoreToStackSlot.
DebugLoc DL;
if (PPC::GPRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::STW))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
} else if (PPC::G8RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::STD))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
} else if (PPC::F8RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::STFD))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
} else if (PPC::F4RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::STFS))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
} else if (PPC::CRRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::SPILL_CR))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
return true;
} else if (PPC::CRBITRCRegClass.hasSubClassEq(RC)) {
// FIXME: We use CRi here because there is no mtcrf on a bit. Since the
// backend currently only uses CR1EQ as an individual bit, this should
// not cause any bug. If we need other uses of CR bits, the following
// code may be invalid.
unsigned Reg = 0;
if (SrcReg == PPC::CR0LT || SrcReg == PPC::CR0GT ||
SrcReg == PPC::CR0EQ || SrcReg == PPC::CR0UN)
Reg = PPC::CR0;
else if (SrcReg == PPC::CR1LT || SrcReg == PPC::CR1GT ||
SrcReg == PPC::CR1EQ || SrcReg == PPC::CR1UN)
Reg = PPC::CR1;
else if (SrcReg == PPC::CR2LT || SrcReg == PPC::CR2GT ||
SrcReg == PPC::CR2EQ || SrcReg == PPC::CR2UN)
Reg = PPC::CR2;
else if (SrcReg == PPC::CR3LT || SrcReg == PPC::CR3GT ||
SrcReg == PPC::CR3EQ || SrcReg == PPC::CR3UN)
Reg = PPC::CR3;
else if (SrcReg == PPC::CR4LT || SrcReg == PPC::CR4GT ||
SrcReg == PPC::CR4EQ || SrcReg == PPC::CR4UN)
Reg = PPC::CR4;
else if (SrcReg == PPC::CR5LT || SrcReg == PPC::CR5GT ||
SrcReg == PPC::CR5EQ || SrcReg == PPC::CR5UN)
Reg = PPC::CR5;
else if (SrcReg == PPC::CR6LT || SrcReg == PPC::CR6GT ||
SrcReg == PPC::CR6EQ || SrcReg == PPC::CR6UN)
Reg = PPC::CR6;
else if (SrcReg == PPC::CR7LT || SrcReg == PPC::CR7GT ||
SrcReg == PPC::CR7EQ || SrcReg == PPC::CR7UN)
Reg = PPC::CR7;
return StoreRegToStackSlot(MF, Reg, isKill, FrameIdx,
&PPC::CRRCRegClass, NewMIs, NonRI, SpillsVRS);
} else if (PPC::VRRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::STVX))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
NonRI = true;
} else if (PPC::VRSAVERCRegClass.hasSubClassEq(RC)) {
assert(TM.getSubtargetImpl()->isDarwin() &&
"VRSAVE only needs spill/restore on Darwin");
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::SPILL_VRSAVE))
.addReg(SrcReg,
getKillRegState(isKill)),
FrameIdx));
SpillsVRS = true;
} else {
llvm_unreachable("Unknown regclass!");
}
return false;
}
void
PPCInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned SrcReg, bool isKill, int FrameIdx,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
MachineFunction &MF = *MBB.getParent();
SmallVector<MachineInstr*, 4> NewMIs;
PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
FuncInfo->setHasSpills();
bool NonRI = false, SpillsVRS = false;
if (StoreRegToStackSlot(MF, SrcReg, isKill, FrameIdx, RC, NewMIs,
NonRI, SpillsVRS))
FuncInfo->setSpillsCR();
if (SpillsVRS)
FuncInfo->setSpillsVRSAVE();
if (NonRI)
FuncInfo->setHasNonRISpills();
for (unsigned i = 0, e = NewMIs.size(); i != e; ++i)
MBB.insert(MI, NewMIs[i]);
const MachineFrameInfo &MFI = *MF.getFrameInfo();
MachineMemOperand *MMO =
MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIdx),
MachineMemOperand::MOStore,
MFI.getObjectSize(FrameIdx),
MFI.getObjectAlignment(FrameIdx));
NewMIs.back()->addMemOperand(MF, MMO);
}
bool
PPCInstrInfo::LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
unsigned DestReg, int FrameIdx,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs,
bool &NonRI, bool &SpillsVRS) const{
// Note: If additional load instructions are added here,
// update isLoadFromStackSlot.
if (PPC::GPRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LWZ),
DestReg), FrameIdx));
} else if (PPC::G8RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LD), DestReg),
FrameIdx));
} else if (PPC::F8RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LFD), DestReg),
FrameIdx));
} else if (PPC::F4RCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LFS), DestReg),
FrameIdx));
} else if (PPC::CRRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL,
get(PPC::RESTORE_CR), DestReg),
FrameIdx));
return true;
} else if (PPC::CRBITRCRegClass.hasSubClassEq(RC)) {
unsigned Reg = 0;
if (DestReg == PPC::CR0LT || DestReg == PPC::CR0GT ||
DestReg == PPC::CR0EQ || DestReg == PPC::CR0UN)
Reg = PPC::CR0;
else if (DestReg == PPC::CR1LT || DestReg == PPC::CR1GT ||
DestReg == PPC::CR1EQ || DestReg == PPC::CR1UN)
Reg = PPC::CR1;
else if (DestReg == PPC::CR2LT || DestReg == PPC::CR2GT ||
DestReg == PPC::CR2EQ || DestReg == PPC::CR2UN)
Reg = PPC::CR2;
else if (DestReg == PPC::CR3LT || DestReg == PPC::CR3GT ||
DestReg == PPC::CR3EQ || DestReg == PPC::CR3UN)
Reg = PPC::CR3;
else if (DestReg == PPC::CR4LT || DestReg == PPC::CR4GT ||
DestReg == PPC::CR4EQ || DestReg == PPC::CR4UN)
Reg = PPC::CR4;
else if (DestReg == PPC::CR5LT || DestReg == PPC::CR5GT ||
DestReg == PPC::CR5EQ || DestReg == PPC::CR5UN)
Reg = PPC::CR5;
else if (DestReg == PPC::CR6LT || DestReg == PPC::CR6GT ||
DestReg == PPC::CR6EQ || DestReg == PPC::CR6UN)
Reg = PPC::CR6;
else if (DestReg == PPC::CR7LT || DestReg == PPC::CR7GT ||
DestReg == PPC::CR7EQ || DestReg == PPC::CR7UN)
Reg = PPC::CR7;
return LoadRegFromStackSlot(MF, DL, Reg, FrameIdx,
&PPC::CRRCRegClass, NewMIs, NonRI, SpillsVRS);
} else if (PPC::VRRCRegClass.hasSubClassEq(RC)) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LVX), DestReg),
FrameIdx));
NonRI = true;
} else if (PPC::VRSAVERCRegClass.hasSubClassEq(RC)) {
assert(TM.getSubtargetImpl()->isDarwin() &&
"VRSAVE only needs spill/restore on Darwin");
NewMIs.push_back(addFrameReference(BuildMI(MF, DL,
get(PPC::RESTORE_VRSAVE),
DestReg),
FrameIdx));
SpillsVRS = true;
} else {
llvm_unreachable("Unknown regclass!");
}
return false;
}
void
PPCInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, int FrameIdx,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
MachineFunction &MF = *MBB.getParent();
SmallVector<MachineInstr*, 4> NewMIs;
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
FuncInfo->setHasSpills();
bool NonRI = false, SpillsVRS = false;
if (LoadRegFromStackSlot(MF, DL, DestReg, FrameIdx, RC, NewMIs,
NonRI, SpillsVRS))
FuncInfo->setSpillsCR();
if (SpillsVRS)
FuncInfo->setSpillsVRSAVE();
if (NonRI)
FuncInfo->setHasNonRISpills();
for (unsigned i = 0, e = NewMIs.size(); i != e; ++i)
MBB.insert(MI, NewMIs[i]);
const MachineFrameInfo &MFI = *MF.getFrameInfo();
MachineMemOperand *MMO =
MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIdx),
MachineMemOperand::MOLoad,
MFI.getObjectSize(FrameIdx),
MFI.getObjectAlignment(FrameIdx));
NewMIs.back()->addMemOperand(MF, MMO);
}
MachineInstr*
PPCInstrInfo::emitFrameIndexDebugValue(MachineFunction &MF,
int FrameIx, uint64_t Offset,
const MDNode *MDPtr,
DebugLoc DL) const {
MachineInstrBuilder MIB = BuildMI(MF, DL, get(PPC::DBG_VALUE));
addFrameReference(MIB, FrameIx, 0, false).addImm(Offset).addMetadata(MDPtr);
return &*MIB;
}
bool PPCInstrInfo::
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
assert(Cond.size() == 2 && "Invalid PPC branch opcode!");
if (Cond[1].getReg() == PPC::CTR8 || Cond[1].getReg() == PPC::CTR)
Cond[0].setImm(Cond[0].getImm() == 0 ? 1 : 0);
else
// Leave the CR# the same, but invert the condition.
Cond[0].setImm(PPC::InvertPredicate((PPC::Predicate)Cond[0].getImm()));
return false;
}
bool PPCInstrInfo::FoldImmediate(MachineInstr *UseMI, MachineInstr *DefMI,
unsigned Reg, MachineRegisterInfo *MRI) const {
// For some instructions, it is legal to fold ZERO into the RA register field.
// A zero immediate should always be loaded with a single li.
unsigned DefOpc = DefMI->getOpcode();
if (DefOpc != PPC::LI && DefOpc != PPC::LI8)
return false;
if (!DefMI->getOperand(1).isImm())
return false;
if (DefMI->getOperand(1).getImm() != 0)
return false;
// Note that we cannot here invert the arguments of an isel in order to fold
// a ZERO into what is presented as the second argument. All we have here
// is the condition bit, and that might come from a CR-logical bit operation.
const MCInstrDesc &UseMCID = UseMI->getDesc();
// Only fold into real machine instructions.
if (UseMCID.isPseudo())
return false;
unsigned UseIdx;
for (UseIdx = 0; UseIdx < UseMI->getNumOperands(); ++UseIdx)
if (UseMI->getOperand(UseIdx).isReg() &&
UseMI->getOperand(UseIdx).getReg() == Reg)
break;
assert(UseIdx < UseMI->getNumOperands() && "Cannot find Reg in UseMI");
assert(UseIdx < UseMCID.getNumOperands() && "No operand description for Reg");
const MCOperandInfo *UseInfo = &UseMCID.OpInfo[UseIdx];
// We can fold the zero if this register requires a GPRC_NOR0/G8RC_NOX0
// register (which might also be specified as a pointer class kind).
if (UseInfo->isLookupPtrRegClass()) {
if (UseInfo->RegClass /* Kind */ != 1)
return false;
} else {
if (UseInfo->RegClass != PPC::GPRC_NOR0RegClassID &&
UseInfo->RegClass != PPC::G8RC_NOX0RegClassID)
return false;
}
// Make sure this is not tied to an output register (or otherwise
// constrained). This is true for ST?UX registers, for example, which
// are tied to their output registers.
if (UseInfo->Constraints != 0)
return false;
unsigned ZeroReg;
if (UseInfo->isLookupPtrRegClass()) {
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
ZeroReg = isPPC64 ? PPC::ZERO8 : PPC::ZERO;
} else {
ZeroReg = UseInfo->RegClass == PPC::G8RC_NOX0RegClassID ?
PPC::ZERO8 : PPC::ZERO;
}
bool DeleteDef = MRI->hasOneNonDBGUse(Reg);
UseMI->getOperand(UseIdx).setReg(ZeroReg);
if (DeleteDef)
DefMI->eraseFromParent();
return true;
}
static bool MBBDefinesCTR(MachineBasicBlock &MBB) {
for (MachineBasicBlock::iterator I = MBB.begin(), IE = MBB.end();
I != IE; ++I)
if (I->definesRegister(PPC::CTR) || I->definesRegister(PPC::CTR8))
return true;
return false;
}
// We should make sure that, if we're going to predicate both sides of a
// condition (a diamond), that both sides don't define the counter register. We
// can predicate counter-decrement-based branches, but while that predicates
// the branching, it does not predicate the counter decrement. If we tried to
// merge the triangle into one predicated block, we'd decrement the counter
// twice.
bool PPCInstrInfo::isProfitableToIfCvt(MachineBasicBlock &TMBB,
unsigned NumT, unsigned ExtraT,
MachineBasicBlock &FMBB,
unsigned NumF, unsigned ExtraF,
const BranchProbability &Probability) const {
return !(MBBDefinesCTR(TMBB) && MBBDefinesCTR(FMBB));
}
bool PPCInstrInfo::isPredicated(const MachineInstr *MI) const {
// The predicated branches are identified by their type, not really by the
// explicit presence of a predicate. Furthermore, some of them can be
// predicated more than once. Because if conversion won't try to predicate
// any instruction which already claims to be predicated (by returning true
// here), always return false. In doing so, we let isPredicable() be the
// final word on whether not the instruction can be (further) predicated.
return false;
}
bool PPCInstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
if (!MI->isTerminator())
return false;
// Conditional branch is a special case.
if (MI->isBranch() && !MI->isBarrier())
return true;
return !isPredicated(MI);
}
bool PPCInstrInfo::PredicateInstruction(
MachineInstr *MI,
const SmallVectorImpl<MachineOperand> &Pred) const {
unsigned OpC = MI->getOpcode();
if (OpC == PPC::BLR) {
if (Pred[1].getReg() == PPC::CTR8 || Pred[1].getReg() == PPC::CTR) {
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
MI->setDesc(get(Pred[0].getImm() ?
(isPPC64 ? PPC::BDNZLR8 : PPC::BDNZLR) :
(isPPC64 ? PPC::BDZLR8 : PPC::BDZLR)));
} else {
MI->setDesc(get(PPC::BCLR));
MachineInstrBuilder(*MI->getParent()->getParent(), MI)
.addImm(Pred[0].getImm())
.addReg(Pred[1].getReg());
}
return true;
} else if (OpC == PPC::B) {
if (Pred[1].getReg() == PPC::CTR8 || Pred[1].getReg() == PPC::CTR) {
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
MI->setDesc(get(Pred[0].getImm() ?
(isPPC64 ? PPC::BDNZ8 : PPC::BDNZ) :
(isPPC64 ? PPC::BDZ8 : PPC::BDZ)));
} else {
MachineBasicBlock *MBB = MI->getOperand(0).getMBB();
MI->RemoveOperand(0);
MI->setDesc(get(PPC::BCC));
MachineInstrBuilder(*MI->getParent()->getParent(), MI)
.addImm(Pred[0].getImm())
.addReg(Pred[1].getReg())
.addMBB(MBB);
}
return true;
} else if (OpC == PPC::BCTR || OpC == PPC::BCTR8 ||
OpC == PPC::BCTRL || OpC == PPC::BCTRL8) {
if (Pred[1].getReg() == PPC::CTR8 || Pred[1].getReg() == PPC::CTR)
llvm_unreachable("Cannot predicate bctr[l] on the ctr register");
bool setLR = OpC == PPC::BCTRL || OpC == PPC::BCTRL8;
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
MI->setDesc(get(isPPC64 ? (setLR ? PPC::BCCTRL8 : PPC::BCCTR8) :
(setLR ? PPC::BCCTRL : PPC::BCCTR)));
MachineInstrBuilder(*MI->getParent()->getParent(), MI)
.addImm(Pred[0].getImm())
.addReg(Pred[1].getReg());
return true;
}
return false;
}
bool PPCInstrInfo::SubsumesPredicate(
const SmallVectorImpl<MachineOperand> &Pred1,
const SmallVectorImpl<MachineOperand> &Pred2) const {
assert(Pred1.size() == 2 && "Invalid PPC first predicate");
assert(Pred2.size() == 2 && "Invalid PPC second predicate");
if (Pred1[1].getReg() == PPC::CTR8 || Pred1[1].getReg() == PPC::CTR)
return false;
if (Pred2[1].getReg() == PPC::CTR8 || Pred2[1].getReg() == PPC::CTR)
return false;
PPC::Predicate P1 = (PPC::Predicate) Pred1[0].getImm();
PPC::Predicate P2 = (PPC::Predicate) Pred2[0].getImm();
if (P1 == P2)
return true;
// Does P1 subsume P2, e.g. GE subsumes GT.
if (P1 == PPC::PRED_LE &&
(P2 == PPC::PRED_LT || P2 == PPC::PRED_EQ))
return true;
if (P1 == PPC::PRED_GE &&
(P2 == PPC::PRED_GT || P2 == PPC::PRED_EQ))
return true;
return false;
}
bool PPCInstrInfo::DefinesPredicate(MachineInstr *MI,
std::vector<MachineOperand> &Pred) const {
// Note: At the present time, the contents of Pred from this function is
// unused by IfConversion. This implementation follows ARM by pushing the
// CR-defining operand. Because the 'DZ' and 'DNZ' count as types of
// predicate, instructions defining CTR or CTR8 are also included as
// predicate-defining instructions.
const TargetRegisterClass *RCs[] =
{ &PPC::CRRCRegClass, &PPC::CRBITRCRegClass,
&PPC::CTRRCRegClass, &PPC::CTRRC8RegClass };
bool Found = false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
for (unsigned c = 0; c < array_lengthof(RCs) && !Found; ++c) {
const TargetRegisterClass *RC = RCs[c];
if (MO.isReg()) {
if (MO.isDef() && RC->contains(MO.getReg())) {
Pred.push_back(MO);
Found = true;
}
} else if (MO.isRegMask()) {
for (TargetRegisterClass::iterator I = RC->begin(),
IE = RC->end(); I != IE; ++I)
if (MO.clobbersPhysReg(*I)) {
Pred.push_back(MO);
Found = true;
}
}
}
}
return Found;
}
bool PPCInstrInfo::isPredicable(MachineInstr *MI) const {
unsigned OpC = MI->getOpcode();
switch (OpC) {
default:
return false;
case PPC::B:
case PPC::BLR:
case PPC::BCTR:
case PPC::BCTR8:
case PPC::BCTRL:
case PPC::BCTRL8:
return true;
}
}
bool PPCInstrInfo::analyzeCompare(const MachineInstr *MI,
unsigned &SrcReg, unsigned &SrcReg2,
int &Mask, int &Value) const {
unsigned Opc = MI->getOpcode();
switch (Opc) {
default: return false;
case PPC::CMPWI:
case PPC::CMPLWI:
case PPC::CMPDI:
case PPC::CMPLDI:
SrcReg = MI->getOperand(1).getReg();
SrcReg2 = 0;
Value = MI->getOperand(2).getImm();
Mask = 0xFFFF;
return true;
case PPC::CMPW:
case PPC::CMPLW:
case PPC::CMPD:
case PPC::CMPLD:
case PPC::FCMPUS:
case PPC::FCMPUD:
SrcReg = MI->getOperand(1).getReg();
SrcReg2 = MI->getOperand(2).getReg();
return true;
}
}
bool PPCInstrInfo::optimizeCompareInstr(MachineInstr *CmpInstr,
unsigned SrcReg, unsigned SrcReg2,
int Mask, int Value,
const MachineRegisterInfo *MRI) const {
if (DisableCmpOpt)
return false;
int OpC = CmpInstr->getOpcode();
unsigned CRReg = CmpInstr->getOperand(0).getReg();
// FP record forms set CR1 based on the execption status bits, not a
// comparison with zero.
if (OpC == PPC::FCMPUS || OpC == PPC::FCMPUD)
return false;
// The record forms set the condition register based on a signed comparison
// with zero (so says the ISA manual). This is not as straightforward as it
// seems, however, because this is always a 64-bit comparison on PPC64, even
// for instructions that are 32-bit in nature (like slw for example).
// So, on PPC32, for unsigned comparisons, we can use the record forms only
// for equality checks (as those don't depend on the sign). On PPC64,
// we are restricted to equality for unsigned 64-bit comparisons and for
// signed 32-bit comparisons the applicability is more restricted.
bool isPPC64 = TM.getSubtargetImpl()->isPPC64();
bool is32BitSignedCompare = OpC == PPC::CMPWI || OpC == PPC::CMPW;
bool is32BitUnsignedCompare = OpC == PPC::CMPLWI || OpC == PPC::CMPLW;
bool is64BitUnsignedCompare = OpC == PPC::CMPLDI || OpC == PPC::CMPLD;
// Get the unique definition of SrcReg.
MachineInstr *MI = MRI->getUniqueVRegDef(SrcReg);
if (!MI) return false;
int MIOpC = MI->getOpcode();
bool equalityOnly = false;
bool noSub = false;
if (isPPC64) {
if (is32BitSignedCompare) {
// We can perform this optimization only if MI is sign-extending.
if (MIOpC == PPC::SRAW || MIOpC == PPC::SRAWo ||
MIOpC == PPC::SRAWI || MIOpC == PPC::SRAWIo ||
MIOpC == PPC::EXTSB || MIOpC == PPC::EXTSBo ||
MIOpC == PPC::EXTSH || MIOpC == PPC::EXTSHo ||
MIOpC == PPC::EXTSW || MIOpC == PPC::EXTSWo) {
noSub = true;
} else
return false;
} else if (is32BitUnsignedCompare) {
// We can perform this optimization, equality only, if MI is
// zero-extending.
if (MIOpC == PPC::CNTLZW || MIOpC == PPC::CNTLZWo ||
MIOpC == PPC::SLW || MIOpC == PPC::SLWo ||
MIOpC == PPC::SRW || MIOpC == PPC::SRWo) {
noSub = true;
equalityOnly = true;
} else
return false;
} else
equalityOnly = is64BitUnsignedCompare;
} else
equalityOnly = is32BitUnsignedCompare;
if (equalityOnly) {
// We need to check the uses of the condition register in order to reject
// non-equality comparisons.
for (MachineRegisterInfo::use_iterator I = MRI->use_begin(CRReg),
IE = MRI->use_end(); I != IE; ++I) {
MachineInstr *UseMI = &*I;
if (UseMI->getOpcode() == PPC::BCC) {
unsigned Pred = UseMI->getOperand(0).getImm();
if (Pred == PPC::PRED_EQ || Pred == PPC::PRED_NE)
continue;
return false;
} else if (UseMI->getOpcode() == PPC::ISEL ||
UseMI->getOpcode() == PPC::ISEL8) {
unsigned SubIdx = UseMI->getOperand(3).getSubReg();
if (SubIdx == PPC::sub_eq)
continue;
return false;
} else
return false;
}
}
// Get ready to iterate backward from CmpInstr.
MachineBasicBlock::iterator I = CmpInstr, E = MI,
B = CmpInstr->getParent()->begin();
// Scan forward to find the first use of the compare.
for (MachineBasicBlock::iterator EL = CmpInstr->getParent()->end();
I != EL; ++I) {
bool FoundUse = false;
for (MachineRegisterInfo::use_iterator J = MRI->use_begin(CRReg),
JE = MRI->use_end(); J != JE; ++J)
if (&*J == &*I) {
FoundUse = true;
break;
}
if (FoundUse)
break;
}
// Early exit if we're at the beginning of the BB.
if (I == B) return false;
// There are two possible candidates which can be changed to set CR[01].
// One is MI, the other is a SUB instruction.
// For CMPrr(r1,r2), we are looking for SUB(r1,r2) or SUB(r2,r1).
MachineInstr *Sub = NULL;
if (SrcReg2 != 0)
// MI is not a candidate for CMPrr.
MI = NULL;
// FIXME: Conservatively refuse to convert an instruction which isn't in the
// same BB as the comparison. This is to allow the check below to avoid calls
// (and other explicit clobbers); instead we should really check for these
// more explicitly (in at least a few predecessors).
else if (MI->getParent() != CmpInstr->getParent() || Value != 0) {
// PPC does not have a record-form SUBri.
return false;
}
// Search for Sub.
const TargetRegisterInfo *TRI = &getRegisterInfo();
--I;
for (; I != E && !noSub; --I) {
const MachineInstr &Instr = *I;
unsigned IOpC = Instr.getOpcode();
if (&*I != CmpInstr && (
Instr.modifiesRegister(PPC::CR0, TRI) ||
Instr.readsRegister(PPC::CR0, TRI)))
// This instruction modifies or uses the record condition register after
// the one we want to change. While we could do this transformation, it
// would likely not be profitable. This transformation removes one
// instruction, and so even forcing RA to generate one move probably
// makes it unprofitable.
return false;
// Check whether CmpInstr can be made redundant by the current instruction.
if ((OpC == PPC::CMPW || OpC == PPC::CMPLW ||
OpC == PPC::CMPD || OpC == PPC::CMPLD) &&
(IOpC == PPC::SUBF || IOpC == PPC::SUBF8) &&
((Instr.getOperand(1).getReg() == SrcReg &&
Instr.getOperand(2).getReg() == SrcReg2) ||
(Instr.getOperand(1).getReg() == SrcReg2 &&
Instr.getOperand(2).getReg() == SrcReg))) {
Sub = &*I;
break;
}
if (I == B)
// The 'and' is below the comparison instruction.
return false;
}
// Return false if no candidates exist.
if (!MI && !Sub)
return false;
// The single candidate is called MI.
if (!MI) MI = Sub;
int NewOpC = -1;
MIOpC = MI->getOpcode();
if (MIOpC == PPC::ANDIo || MIOpC == PPC::ANDIo8)
NewOpC = MIOpC;
else {
NewOpC = PPC::getRecordFormOpcode(MIOpC);
if (NewOpC == -1 && PPC::getNonRecordFormOpcode(MIOpC) != -1)
NewOpC = MIOpC;
}
// FIXME: On the non-embedded POWER architectures, only some of the record
// forms are fast, and we should use only the fast ones.
// The defining instruction has a record form (or is already a record
// form). It is possible, however, that we'll need to reverse the condition
// code of the users.
if (NewOpC == -1)
return false;
SmallVector<std::pair<MachineOperand*, PPC::Predicate>, 4> PredsToUpdate;
SmallVector<std::pair<MachineOperand*, unsigned>, 4> SubRegsToUpdate;
// If we have SUB(r1, r2) and CMP(r2, r1), the condition code based on CMP
// needs to be updated to be based on SUB. Push the condition code
// operands to OperandsToUpdate. If it is safe to remove CmpInstr, the
// condition code of these operands will be modified.
bool ShouldSwap = false;
if (Sub) {
ShouldSwap = SrcReg2 != 0 && Sub->getOperand(1).getReg() == SrcReg2 &&
Sub->getOperand(2).getReg() == SrcReg;
// The operands to subf are the opposite of sub, so only in the fixed-point
// case, invert the order.
ShouldSwap = !ShouldSwap;
}
if (ShouldSwap)
for (MachineRegisterInfo::use_iterator I = MRI->use_begin(CRReg),
IE = MRI->use_end(); I != IE; ++I) {
MachineInstr *UseMI = &*I;
if (UseMI->getOpcode() == PPC::BCC) {
PPC::Predicate Pred = (PPC::Predicate) UseMI->getOperand(0).getImm();
assert((!equalityOnly ||
Pred == PPC::PRED_EQ || Pred == PPC::PRED_NE) &&
"Invalid predicate for equality-only optimization");
PredsToUpdate.push_back(std::make_pair(&((*I).getOperand(0)),
PPC::getSwappedPredicate(Pred)));
} else if (UseMI->getOpcode() == PPC::ISEL ||
UseMI->getOpcode() == PPC::ISEL8) {
unsigned NewSubReg = UseMI->getOperand(3).getSubReg();
assert((!equalityOnly || NewSubReg == PPC::sub_eq) &&
"Invalid CR bit for equality-only optimization");
if (NewSubReg == PPC::sub_lt)
NewSubReg = PPC::sub_gt;
else if (NewSubReg == PPC::sub_gt)
NewSubReg = PPC::sub_lt;
SubRegsToUpdate.push_back(std::make_pair(&((*I).getOperand(3)),
NewSubReg));
} else // We need to abort on a user we don't understand.
return false;
}
// Create a new virtual register to hold the value of the CR set by the
// record-form instruction. If the instruction was not previously in
// record form, then set the kill flag on the CR.
CmpInstr->eraseFromParent();
MachineBasicBlock::iterator MII = MI;
BuildMI(*MI->getParent(), llvm::next(MII), MI->getDebugLoc(),
get(TargetOpcode::COPY), CRReg)
.addReg(PPC::CR0, MIOpC != NewOpC ? RegState::Kill : 0);
if (MIOpC != NewOpC) {
// We need to be careful here: we're replacing one instruction with
// another, and we need to make sure that we get all of the right
// implicit uses and defs. On the other hand, the caller may be holding
// an iterator to this instruction, and so we can't delete it (this is
// specifically the case if this is the instruction directly after the
// compare).
const MCInstrDesc &NewDesc = get(NewOpC);
MI->setDesc(NewDesc);
if (NewDesc.ImplicitDefs)
for (const uint16_t *ImpDefs = NewDesc.getImplicitDefs();
*ImpDefs; ++ImpDefs)
if (!MI->definesRegister(*ImpDefs))
MI->addOperand(*MI->getParent()->getParent(),
MachineOperand::CreateReg(*ImpDefs, true, true));
if (NewDesc.ImplicitUses)
for (const uint16_t *ImpUses = NewDesc.getImplicitUses();
*ImpUses; ++ImpUses)
if (!MI->readsRegister(*ImpUses))
MI->addOperand(*MI->getParent()->getParent(),
MachineOperand::CreateReg(*ImpUses, false, true));
}
// Modify the condition code of operands in OperandsToUpdate.
// Since we have SUB(r1, r2) and CMP(r2, r1), the condition code needs to
// be changed from r2 > r1 to r1 < r2, from r2 < r1 to r1 > r2, etc.
for (unsigned i = 0, e = PredsToUpdate.size(); i < e; i++)
PredsToUpdate[i].first->setImm(PredsToUpdate[i].second);
for (unsigned i = 0, e = SubRegsToUpdate.size(); i < e; i++)
SubRegsToUpdate[i].first->setSubReg(SubRegsToUpdate[i].second);
return true;
}
/// GetInstSize - Return the number of bytes of code the specified
/// instruction may be. This returns the maximum number of bytes.
///
unsigned PPCInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
switch (MI->getOpcode()) {
case PPC::INLINEASM: { // Inline Asm: Variable size.
const MachineFunction *MF = MI->getParent()->getParent();
const char *AsmStr = MI->getOperand(0).getSymbolName();
return getInlineAsmLength(AsmStr, *MF->getTarget().getMCAsmInfo());
}
case PPC::PROLOG_LABEL:
case PPC::EH_LABEL:
case PPC::GC_LABEL:
case PPC::DBG_VALUE:
return 0;
case PPC::BL8_NOP:
case PPC::BLA8_NOP:
return 8;
default:
return 4; // PowerPC instructions are all 4 bytes
}
}
#undef DEBUG_TYPE
#define DEBUG_TYPE "ppc-early-ret"
STATISTIC(NumBCLR, "Number of early conditional returns");
STATISTIC(NumBLR, "Number of early returns");
namespace llvm {
void initializePPCEarlyReturnPass(PassRegistry&);
}
namespace {
// PPCEarlyReturn pass - For simple functions without epilogue code, move
// returns up, and create conditional returns, to avoid unnecessary
// branch-to-blr sequences.
struct PPCEarlyReturn : public MachineFunctionPass {
static char ID;
PPCEarlyReturn() : MachineFunctionPass(ID) {
initializePPCEarlyReturnPass(*PassRegistry::getPassRegistry());
}
const PPCTargetMachine *TM;
const PPCInstrInfo *TII;
protected:
bool processBlock(MachineBasicBlock &ReturnMBB) {
bool Changed = false;
MachineBasicBlock::iterator I = ReturnMBB.begin();
I = ReturnMBB.SkipPHIsAndLabels(I);
// The block must be essentially empty except for the blr.
if (I == ReturnMBB.end() || I->getOpcode() != PPC::BLR ||
I != ReturnMBB.getLastNonDebugInstr())
return Changed;
SmallVector<MachineBasicBlock*, 8> PredToRemove;
for (MachineBasicBlock::pred_iterator PI = ReturnMBB.pred_begin(),
PIE = ReturnMBB.pred_end(); PI != PIE; ++PI) {
bool OtherReference = false, BlockChanged = false;
for (MachineBasicBlock::iterator J = (*PI)->getLastNonDebugInstr();;) {
if (J->getOpcode() == PPC::B) {
if (J->getOperand(0).getMBB() == &ReturnMBB) {
// This is an unconditional branch to the return. Replace the
// branch with a blr.
BuildMI(**PI, J, J->getDebugLoc(), TII->get(PPC::BLR));
MachineBasicBlock::iterator K = J--;
K->eraseFromParent();
BlockChanged = true;
++NumBLR;
continue;
}
} else if (J->getOpcode() == PPC::BCC) {
if (J->getOperand(2).getMBB() == &ReturnMBB) {
// This is a conditional branch to the return. Replace the branch
// with a bclr.
BuildMI(**PI, J, J->getDebugLoc(), TII->get(PPC::BCLR))
.addImm(J->getOperand(0).getImm())
.addReg(J->getOperand(1).getReg());
MachineBasicBlock::iterator K = J--;
K->eraseFromParent();
BlockChanged = true;
++NumBCLR;
continue;
}
} else if (J->isBranch()) {
if (J->isIndirectBranch()) {
if (ReturnMBB.hasAddressTaken())
OtherReference = true;
} else
for (unsigned i = 0; i < J->getNumOperands(); ++i)
if (J->getOperand(i).isMBB() &&
J->getOperand(i).getMBB() == &ReturnMBB)
OtherReference = true;
} else if (!J->isTerminator() && !J->isDebugValue())
break;
if (J == (*PI)->begin())
break;
--J;
}
if ((*PI)->canFallThrough() && (*PI)->isLayoutSuccessor(&ReturnMBB))
OtherReference = true;
// Predecessors are stored in a vector and can't be removed here.
if (!OtherReference && BlockChanged) {
PredToRemove.push_back(*PI);
}
if (BlockChanged)
Changed = true;
}
for (unsigned i = 0, ie = PredToRemove.size(); i != ie; ++i)
PredToRemove[i]->removeSuccessor(&ReturnMBB);
if (Changed && !ReturnMBB.hasAddressTaken()) {
// We now might be able to merge this blr-only block into its
// by-layout predecessor.
if (ReturnMBB.pred_size() == 1 &&
(*ReturnMBB.pred_begin())->isLayoutSuccessor(&ReturnMBB)) {
// Move the blr into the preceding block.
MachineBasicBlock &PrevMBB = **ReturnMBB.pred_begin();
PrevMBB.splice(PrevMBB.end(), &ReturnMBB, I);
PrevMBB.removeSuccessor(&ReturnMBB);
}
if (ReturnMBB.pred_empty())
ReturnMBB.eraseFromParent();
}
return Changed;
}
public:
virtual bool runOnMachineFunction(MachineFunction &MF) {
TM = static_cast<const PPCTargetMachine *>(&MF.getTarget());
TII = TM->getInstrInfo();
bool Changed = false;
// If the function does not have at least two blocks, then there is
// nothing to do.
if (MF.size() < 2)
return Changed;
for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
MachineBasicBlock &B = *I++;
if (processBlock(B))
Changed = true;
}
return Changed;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
MachineFunctionPass::getAnalysisUsage(AU);
}
};
}
INITIALIZE_PASS(PPCEarlyReturn, DEBUG_TYPE,
"PowerPC Early-Return Creation", false, false)
char PPCEarlyReturn::ID = 0;
FunctionPass*
llvm::createPPCEarlyReturnPass() { return new PPCEarlyReturn(); }
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