X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLocalStackSlotAllocation.cpp;h=80a6da0f93b2c63586ac2c72d4decf1611c5420c;hb=b59d46efa521801a3d42fc5f53fedf3e81b070ce;hp=352ef942591fc2da9811c71b140407dc1b1201b4;hpb=0b8c9a80f20772c3793201ab5b251d3520b9cea3;p=oota-llvm.git diff --git a/lib/CodeGen/LocalStackSlotAllocation.cpp b/lib/CodeGen/LocalStackSlotAllocation.cpp index 352ef942591..80a6da0f93b 100644 --- a/lib/CodeGen/LocalStackSlotAllocation.cpp +++ b/lib/CodeGen/LocalStackSlotAllocation.cpp @@ -46,13 +46,16 @@ namespace { 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 { @@ -194,22 +197,15 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { } static inline bool -lookupCandidateBaseReg(const SmallVector, 8> &Regs, - std::pair &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) { @@ -233,16 +229,15 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { // choose the first one). SmallVector FrameReferenceInsns; - // A base register definition is a register + offset pair. - SmallVector, 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; - // Debug value instructions can't be out of range, so they don't need - // any updates. - if (MI->isDebugValue()) + // Debug value, stackmap and patchpoint instructions can't be out of + // range, so they don't need any updates. + if (MI->isDebugValue() || + MI->getOpcode() == TargetOpcode::STACKMAP || + MI->getOpcode() == TargetOpcode::PATCHPOINT) continue; // For now, allocate the base register(s) within the basic block @@ -258,8 +253,12 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { // 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; } } @@ -271,86 +270,106 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) { 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 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(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; }