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add RESTORE_CR and support CR unspills
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145961 91177308-0d34-0410-b5e6-96231b3b80d8
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Hal Finkel committed Dec 6, 2011
1 parent 16588e7 commit d21e930
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Showing 5 changed files with 89 additions and 28 deletions.
59 changes: 36 additions & 23 deletions lib/Target/PowerPC/PPCInstrInfo.cpp
View file
Expand Up @@ -511,7 +511,7 @@ PPCInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
NewMIs.back()->addMemOperand(MF, MMO);
}

void
bool
PPCInstrInfo::LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
unsigned DestReg, int FrameIdx,
const TargetRegisterClass *RC,
Expand Down Expand Up @@ -541,28 +541,36 @@ PPCInstrInfo::LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LFS), DestReg),
FrameIdx));
} else if (PPC::CRRCRegisterClass->hasSubClassEq(RC)) {
// FIXME: We need a scatch reg here. The trouble with using R0 is that
// it's possible for the stack frame to be so big the save location is
// out of range of immediate offsets, necessitating another register.
// We hack this on Darwin by reserving R2. It's probably broken on Linux
// at the moment.
unsigned ScratchReg = TM.getSubtargetImpl()->isDarwinABI() ?
PPC::R2 : PPC::R0;
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LWZ),
ScratchReg), FrameIdx));

// If the reloaded register isn't CR0, shift the bits right so that they are
// in the right CR's slot.
if (DestReg != PPC::CR0) {
unsigned ShiftBits = getPPCRegisterNumbering(DestReg)*4;
// rlwinm r11, r11, 32-ShiftBits, 0, 31.
NewMIs.push_back(BuildMI(MF, DL, get(PPC::RLWINM), ScratchReg)
.addReg(ScratchReg).addImm(32-ShiftBits).addImm(0)
.addImm(31));
if ((!DisablePPC32RS && !TM.getSubtargetImpl()->isPPC64()) ||
(!DisablePPC64RS && TM.getSubtargetImpl()->isPPC64())) {
NewMIs.push_back(addFrameReference(BuildMI(MF, DL,
get(PPC::RESTORE_CR), DestReg)
, FrameIdx));
return true;
} else {
// FIXME: We need a scatch reg here. The trouble with using R0 is that
// it's possible for the stack frame to be so big the save location is
// out of range of immediate offsets, necessitating another register.
// We hack this on Darwin by reserving R2. It's probably broken on Linux
// at the moment.
unsigned ScratchReg = TM.getSubtargetImpl()->isDarwinABI() ?
PPC::R2 : PPC::R0;
NewMIs.push_back(addFrameReference(BuildMI(MF, DL, get(PPC::LWZ),
ScratchReg), FrameIdx));

// If the reloaded register isn't CR0, shift the bits right so that they are
// in the right CR's slot.
if (DestReg != PPC::CR0) {
unsigned ShiftBits = getPPCRegisterNumbering(DestReg)*4;
// rlwinm r11, r11, 32-ShiftBits, 0, 31.
NewMIs.push_back(BuildMI(MF, DL, get(PPC::RLWINM), ScratchReg)
.addReg(ScratchReg).addImm(32-ShiftBits).addImm(0)
.addImm(31));
}

NewMIs.push_back(BuildMI(MF, DL, get(PPC::MTCRF), DestReg)
.addReg(ScratchReg));
}

NewMIs.push_back(BuildMI(MF, DL, get(PPC::MTCRF), DestReg)
.addReg(ScratchReg));
} else if (PPC::CRBITRCRegisterClass->hasSubClassEq(RC)) {

unsigned Reg = 0;
Expand Down Expand Up @@ -607,6 +615,8 @@ PPCInstrInfo::LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
} else {
llvm_unreachable("Unknown regclass!");
}

return false;
}

void
Expand All @@ -619,7 +629,10 @@ PPCInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
SmallVector<MachineInstr*, 4> NewMIs;
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
LoadRegFromStackSlot(MF, DL, DestReg, FrameIdx, RC, NewMIs);
if (LoadRegFromStackSlot(MF, DL, DestReg, FrameIdx, RC, NewMIs)) {
PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
FuncInfo->setSpillsCR();
}
for (unsigned i = 0, e = NewMIs.size(); i != e; ++i)
MBB.insert(MI, NewMIs[i]);

Expand Down
2 changes: 1 addition & 1 deletion lib/Target/PowerPC/PPCInstrInfo.h
View file
Expand Up @@ -72,7 +72,7 @@ class PPCInstrInfo : public PPCGenInstrInfo {
unsigned SrcReg, bool isKill, int FrameIdx,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs) const;
void LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
bool LoadRegFromStackSlot(MachineFunction &MF, DebugLoc DL,
unsigned DestReg, int FrameIdx,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs) const;
Expand Down
5 changes: 5 additions & 0 deletions lib/Target/PowerPC/PPCInstrInfo.td
View file
Expand Up @@ -402,6 +402,11 @@ let usesCustomInserter = 1, // Expanded after instruction selection.
def SPILL_CR : Pseudo<(outs), (ins GPRC:$cond, memri:$F),
"", []>;

// RESTORE_CR - Indicate that we're restoring the CR register (previously
// spilled), so we'll need to scavenge a register for it.
def RESTORE_CR : Pseudo<(outs GPRC:$cond), (ins memri:$F),
"", []>;

let isTerminator = 1, isBarrier = 1, PPC970_Unit = 7 in {
let isReturn = 1, Uses = [LR, RM] in
def BLR : XLForm_2_br<19, 16, 0, (outs), (ins pred:$p),
Expand Down
49 changes: 45 additions & 4 deletions lib/Target/PowerPC/PPCRegisterInfo.cpp
View file
Expand Up @@ -459,7 +459,7 @@ void PPCRegisterInfo::lowerCRSpilling(MachineBasicBlock::iterator II,
unsigned FrameIndex, int SPAdj,
RegScavenger *RS) const {
// Get the instruction.
MachineInstr &MI = *II; // ; SPILL_CR <SrcReg>, <offset>, <FI>
MachineInstr &MI = *II; // ; SPILL_CR <SrcReg>, <offset>
// Get the instruction's basic block.
MachineBasicBlock &MBB = *MI.getParent();
DebugLoc dl = MI.getDebugLoc();
Expand Down Expand Up @@ -494,6 +494,44 @@ void PPCRegisterInfo::lowerCRSpilling(MachineBasicBlock::iterator II,
MBB.erase(II);
}

void PPCRegisterInfo::lowerCRRestore(MachineBasicBlock::iterator II,
unsigned FrameIndex, int SPAdj,
RegScavenger *RS) const {
// Get the instruction.
MachineInstr &MI = *II; // ; <DestReg> = RESTORE_CR <offset>
// Get the instruction's basic block.
MachineBasicBlock &MBB = *MI.getParent();
DebugLoc dl = MI.getDebugLoc();

const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
const TargetRegisterClass *RC = Subtarget.isPPC64() ? G8RC : GPRC;
unsigned Reg = findScratchRegister(II, RS, RC, SPAdj);
unsigned DestReg = MI.getOperand(0).getReg();
assert(MI.definesRegister(DestReg) &&
"RESTORE_CR does not define its destination");
bool LP64 = Subtarget.isPPC64();

addFrameReference(BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::LWZ8 : PPC::LWZ),
Reg), FrameIndex);

// If the reloaded register isn't CR0, shift the bits right so that they are
// in the right CR's slot.
if (DestReg != PPC::CR0) {
unsigned ShiftBits = getPPCRegisterNumbering(DestReg)*4;
// rlwinm r11, r11, 32-ShiftBits, 0, 31.
BuildMI(MBB, II, dl, TII.get(PPC::RLWINM), Reg)
.addReg(Reg).addImm(32-ShiftBits).addImm(0)
.addImm(31);
}

BuildMI(MBB, II, dl, TII.get(PPC::MTCRF), DestReg)
.addReg(Reg);

// Discard the pseudo instruction.
MBB.erase(II);
}

void
PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, RegScavenger *RS) const {
Expand Down Expand Up @@ -539,12 +577,16 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
return;
}

// Special case for pseudo-op SPILL_CR.
if (requiresRegisterScavenging(MF))
// Special case for pseudo-ops SPILL_CR and RESTORE_CR.
if (requiresRegisterScavenging(MF)) {
if (OpC == PPC::SPILL_CR) {
lowerCRSpilling(II, FrameIndex, SPAdj, RS);
return;
} else if (OpC == PPC::RESTORE_CR) {
lowerCRRestore(II, FrameIndex, SPAdj, RS);
return;
}
}

// Replace the FrameIndex with base register with GPR1 (SP) or GPR31 (FP).
MI.getOperand(FIOperandNo).ChangeToRegister(TFI->hasFP(MF) ?
Expand Down Expand Up @@ -594,7 +636,6 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,

// The offset doesn't fit into a single register, scavenge one to build the
// offset in.
// FIXME: figure out what SPAdj is doing here.

unsigned SReg;
if (requiresRegisterScavenging(MF))
Expand Down
2 changes: 2 additions & 0 deletions lib/Target/PowerPC/PPCRegisterInfo.h
View file
Expand Up @@ -57,6 +57,8 @@ class PPCRegisterInfo : public PPCGenRegisterInfo {
int SPAdj, RegScavenger *RS) const;
void lowerCRSpilling(MachineBasicBlock::iterator II, unsigned FrameIndex,
int SPAdj, RegScavenger *RS) const;
void lowerCRRestore(MachineBasicBlock::iterator II, unsigned FrameIndex,
int SPAdj, RegScavenger *RS) const;
void eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, RegScavenger *RS = NULL) const;

Expand Down

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