class FrameRef {
MachineBasicBlock::iterator MI; // Instr referencing the frame
int64_t LocalOffset; // Local offset of the frame idx referenced
+ int FrameIdx; // The frame index
public:
- FrameRef(MachineBasicBlock::iterator I, int64_t Offset) :
- MI(I), LocalOffset(Offset) {}
+ FrameRef(MachineBasicBlock::iterator I, int64_t Offset, int Idx) :
+ MI(I), LocalOffset(Offset), FrameIdx(Idx) {}
bool operator<(const FrameRef &RHS) const {
return LocalOffset < RHS.LocalOffset;
}
- MachineBasicBlock::iterator getMachineInstr() { return MI; }
+ MachineBasicBlock::iterator getMachineInstr() const { return MI; }
+ int64_t getLocalOffset() const { return LocalOffset; }
+ int getFrameIndex() const { return FrameIdx; }
};
class LocalStackSlotPass: public MachineFunctionPass {
}
static inline bool
-lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
- std::pair<unsigned, int64_t> &RegOffset,
+lookupCandidateBaseReg(int64_t BaseOffset,
int64_t FrameSizeAdjust,
int64_t LocalFrameOffset,
const MachineInstr *MI,
const TargetRegisterInfo *TRI) {
- unsigned e = Regs.size();
- for (unsigned i = 0; i < e; ++i) {
- RegOffset = Regs[i];
- // Check if the relative offset from the where the base register references
- // to the target address is in range for the instruction.
- int64_t Offset = FrameSizeAdjust + LocalFrameOffset - RegOffset.second;
- if (TRI->isFrameOffsetLegal(MI, Offset))
- return true;
- }
- return false;
+ // Check if the relative offset from the where the base register references
+ // to the target address is in range for the instruction.
+ int64_t Offset = FrameSizeAdjust + LocalFrameOffset - BaseOffset;
+ return TRI->isFrameOffsetLegal(MI, Offset);
}
bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// choose the first one).
SmallVector<FrameRef, 64> FrameReferenceInsns;
- // A base register definition is a register + offset pair.
- SmallVector<std::pair<unsigned, int64_t>, 8> BaseRegisters;
-
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
MachineInstr *MI = I;
// Don't try this with values not in the local block.
if (!MFI->isObjectPreAllocated(MI->getOperand(i).getIndex()))
break;
+ int Idx = MI->getOperand(i).getIndex();
+ int64_t LocalOffset = LocalOffsets[Idx];
+ if (!TRI->needsFrameBaseReg(MI, LocalOffset))
+ break;
FrameReferenceInsns.
- push_back(FrameRef(MI, LocalOffsets[MI->getOperand(i).getIndex()]));
+ push_back(FrameRef(MI, LocalOffset, Idx));
break;
}
}
MachineBasicBlock *Entry = Fn.begin();
+ unsigned BaseReg = 0;
+ int64_t BaseOffset = 0;
+
// Loop through the frame references and allocate for them as necessary.
for (int ref = 0, e = FrameReferenceInsns.size(); ref < e ; ++ref) {
- MachineBasicBlock::iterator I =
- FrameReferenceInsns[ref].getMachineInstr();
+ FrameRef &FR = FrameReferenceInsns[ref];
+ MachineBasicBlock::iterator I = FR.getMachineInstr();
MachineInstr *MI = I;
- for (unsigned idx = 0, e = MI->getNumOperands(); idx != e; ++idx) {
- // Consider replacing all frame index operands that reference
- // an object allocated in the local block.
- if (MI->getOperand(idx).isFI()) {
- int FrameIdx = MI->getOperand(idx).getIndex();
-
- assert(MFI->isObjectPreAllocated(FrameIdx) &&
- "Only pre-allocated locals expected!");
-
- DEBUG(dbgs() << "Considering: " << *MI);
- if (TRI->needsFrameBaseReg(MI, LocalOffsets[FrameIdx])) {
- unsigned BaseReg = 0;
- int64_t Offset = 0;
- int64_t FrameSizeAdjust =
- StackGrowsDown ? MFI->getLocalFrameSize() : 0;
-
- DEBUG(dbgs() << " Replacing FI in: " << *MI);
-
- // If we have a suitable base register available, use it; otherwise
- // create a new one. Note that any offset encoded in the
- // instruction itself will be taken into account by the target,
- // so we don't have to adjust for it here when reusing a base
- // register.
- std::pair<unsigned, int64_t> RegOffset;
- if (lookupCandidateBaseReg(BaseRegisters, RegOffset,
- FrameSizeAdjust,
- LocalOffsets[FrameIdx],
- MI, TRI)) {
- DEBUG(dbgs() << " Reusing base register " <<
- RegOffset.first << "\n");
- // We found a register to reuse.
- BaseReg = RegOffset.first;
- Offset = FrameSizeAdjust + LocalOffsets[FrameIdx] -
- RegOffset.second;
- } else {
- // No previously defined register was in range, so create a
- // new one.
- int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, idx);
- const MachineFunction *MF = MI->getParent()->getParent();
- const TargetRegisterClass *RC = TRI->getPointerRegClass(*MF);
- BaseReg = Fn.getRegInfo().createVirtualRegister(RC);
-
- DEBUG(dbgs() << " Materializing base register " << BaseReg <<
- " at frame local offset " <<
- LocalOffsets[FrameIdx] + InstrOffset << "\n");
-
- // Tell the target to insert the instruction to initialize
- // the base register.
- // MachineBasicBlock::iterator InsertionPt = Entry->begin();
- TRI->materializeFrameBaseRegister(Entry, BaseReg, FrameIdx,
- InstrOffset);
-
- // The base register already includes any offset specified
- // by the instruction, so account for that so it doesn't get
- // applied twice.
- Offset = -InstrOffset;
-
- int64_t BaseOffset = FrameSizeAdjust + LocalOffsets[FrameIdx] +
- InstrOffset;
- BaseRegisters.push_back(
- std::pair<unsigned, int64_t>(BaseReg, BaseOffset));
- ++NumBaseRegisters;
- UsedBaseReg = true;
- }
- assert(BaseReg != 0 && "Unable to allocate virtual base register!");
-
- // Modify the instruction to use the new base register rather
- // than the frame index operand.
- TRI->resolveFrameIndex(I, BaseReg, Offset);
- DEBUG(dbgs() << "Resolved: " << *MI);
-
- ++NumReplacements;
- }
+ int64_t LocalOffset = FR.getLocalOffset();
+ int FrameIdx = FR.getFrameIndex();
+ assert(MFI->isObjectPreAllocated(FrameIdx) &&
+ "Only pre-allocated locals expected!");
+
+ DEBUG(dbgs() << "Considering: " << *MI);
+
+ unsigned idx = 0;
+ for (unsigned f = MI->getNumOperands(); idx != f; ++idx) {
+ if (!MI->getOperand(idx).isFI())
+ continue;
+
+ if (FrameIdx == I->getOperand(idx).getIndex())
+ break;
+ }
+
+ assert(idx < MI->getNumOperands() && "Cannot find FI operand");
+
+ int64_t Offset = 0;
+ int64_t FrameSizeAdjust = StackGrowsDown ? MFI->getLocalFrameSize() : 0;
+
+ DEBUG(dbgs() << " Replacing FI in: " << *MI);
+
+ // If we have a suitable base register available, use it; otherwise
+ // create a new one. Note that any offset encoded in the
+ // instruction itself will be taken into account by the target,
+ // so we don't have to adjust for it here when reusing a base
+ // register.
+ if (UsedBaseReg && lookupCandidateBaseReg(BaseOffset, FrameSizeAdjust,
+ LocalOffset, MI, TRI)) {
+ DEBUG(dbgs() << " Reusing base register " << BaseReg << "\n");
+ // We found a register to reuse.
+ Offset = FrameSizeAdjust + LocalOffset - BaseOffset;
+ } else {
+ // No previously defined register was in range, so create a // new one.
+
+ int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, idx);
+
+ int64_t PrevBaseOffset = BaseOffset;
+ BaseOffset = FrameSizeAdjust + LocalOffset + InstrOffset;
+
+ // We'd like to avoid creating single-use virtual base registers.
+ // Because the FrameRefs are in sorted order, and we've already
+ // processed all FrameRefs before this one, just check whether or not
+ // the next FrameRef will be able to reuse this new register. If not,
+ // then don't bother creating it.
+ bool CanReuse = false;
+ for (int refn = ref + 1; refn < e; ++refn) {
+ FrameRef &FRN = FrameReferenceInsns[refn];
+ MachineBasicBlock::iterator J = FRN.getMachineInstr();
+ MachineInstr *MIN = J;
+
+ CanReuse = lookupCandidateBaseReg(BaseOffset, FrameSizeAdjust,
+ FRN.getLocalOffset(), MIN, TRI);
+ break;
}
+
+ if (!CanReuse) {
+ BaseOffset = PrevBaseOffset;
+ continue;
+ }
+
+ const MachineFunction *MF = MI->getParent()->getParent();
+ const TargetRegisterClass *RC = TRI->getPointerRegClass(*MF);
+ BaseReg = Fn.getRegInfo().createVirtualRegister(RC);
+
+ DEBUG(dbgs() << " Materializing base register " << BaseReg <<
+ " at frame local offset " << LocalOffset + InstrOffset << "\n");
+
+ // Tell the target to insert the instruction to initialize
+ // the base register.
+ // MachineBasicBlock::iterator InsertionPt = Entry->begin();
+ TRI->materializeFrameBaseRegister(Entry, BaseReg, FrameIdx,
+ InstrOffset);
+
+ // The base register already includes any offset specified
+ // by the instruction, so account for that so it doesn't get
+ // applied twice.
+ Offset = -InstrOffset;
+
+ ++NumBaseRegisters;
+ UsedBaseReg = true;
}
+ assert(BaseReg != 0 && "Unable to allocate virtual base register!");
+
+ // Modify the instruction to use the new base register rather
+ // than the frame index operand.
+ TRI->resolveFrameIndex(I, BaseReg, Offset);
+ DEBUG(dbgs() << "Resolved: " << *MI);
+
+ ++NumReplacements;
}
+
return UsedBaseReg;
}
projects / oota-llvm.git / commitdiff