+
+/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
+/// slot into the specified machine instruction for the specified operand(s).
+/// If this is possible, a new instruction is returned with the specified
+/// operand folded, otherwise NULL is returned. The client is responsible for
+/// removing the old instruction and adding the new one in the instruction
+/// stream.
+MachineInstr*
+TargetInstrInfo::foldMemoryOperand(MachineFunction &MF,
+ MachineInstr* MI,
+ const SmallVectorImpl<unsigned> &Ops,
+ int FrameIndex) const {
+ unsigned Flags = 0;
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i)
+ if (MI->getOperand(Ops[i]).isDef())
+ Flags |= MachineMemOperand::MOStore;
+ else
+ Flags |= MachineMemOperand::MOLoad;
+
+ // Ask the target to do the actual folding.
+ MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FrameIndex);
+ if (!NewMI) return 0;
+
+ assert((!(Flags & MachineMemOperand::MOStore) ||
+ NewMI->getDesc().mayStore()) &&
+ "Folded a def to a non-store!");
+ assert((!(Flags & MachineMemOperand::MOLoad) ||
+ NewMI->getDesc().mayLoad()) &&
+ "Folded a use to a non-load!");
+ const MachineFrameInfo &MFI = *MF.getFrameInfo();
+ assert(MFI.getObjectOffset(FrameIndex) != -1);
+ MachineMemOperand *MMO =
+ MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FrameIndex),
+ Flags, /*Offset=*/0,
+ MFI.getObjectSize(FrameIndex),
+ MFI.getObjectAlignment(FrameIndex));
+ NewMI->addMemOperand(MF, MMO);
+
+ return NewMI;
+}
+
+/// foldMemoryOperand - Same as the previous version except it allows folding
+/// of any load and store from / to any address, not just from a specific
+/// stack slot.
+MachineInstr*
+TargetInstrInfo::foldMemoryOperand(MachineFunction &MF,
+ MachineInstr* MI,
+ const SmallVectorImpl<unsigned> &Ops,
+ MachineInstr* LoadMI) const {
+ assert(LoadMI->getDesc().canFoldAsLoad() && "LoadMI isn't foldable!");
+#ifndef NDEBUG
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i)
+ assert(MI->getOperand(Ops[i]).isUse() && "Folding load into def!");
+#endif
+
+ // Ask the target to do the actual folding.
+ MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, LoadMI);
+ if (!NewMI) return 0;
+
+ // Copy the memoperands from the load to the folded instruction.
+ NewMI->setMemRefs(LoadMI->memoperands_begin(),
+ LoadMI->memoperands_end());
+
+ return NewMI;
+}
+
+bool
+TargetInstrInfo::isReallyTriviallyReMaterializableGeneric(const MachineInstr *
+ MI,
+ AliasAnalysis *
+ AA) const {
+ const MachineFunction &MF = *MI->getParent()->getParent();
+ const MachineRegisterInfo &MRI = MF.getRegInfo();
+ const TargetMachine &TM = MF.getTarget();
+ const TargetInstrInfo &TII = *TM.getInstrInfo();
+ const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
+
+ // A load from a fixed stack slot can be rematerialized. This may be
+ // redundant with subsequent checks, but it's target-independent,
+ // simple, and a common case.
+ int FrameIdx = 0;
+ if (TII.isLoadFromStackSlot(MI, FrameIdx) &&
+ MF.getFrameInfo()->isImmutableObjectIndex(FrameIdx))
+ return true;
+
+ const TargetInstrDesc &TID = MI->getDesc();
+
+ // Avoid instructions obviously unsafe for remat.
+ if (TID.hasUnmodeledSideEffects() || TID.isNotDuplicable() ||
+ TID.mayStore())
+ return false;
+
+ // Avoid instructions which load from potentially varying memory.
+ if (TID.mayLoad() && !MI->isInvariantLoad(AA))
+ return false;
+
+ // If any of the registers accessed are non-constant, conservatively assume
+ // the instruction is not rematerializable.
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg()) continue;
+ unsigned Reg = MO.getReg();
+ if (Reg == 0)
+ continue;
+
+ // Check for a well-behaved physical register.
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ if (MO.isUse()) {
+ // If the physreg has no defs anywhere, it's just an ambient register
+ // and we can freely move its uses. Alternatively, if it's allocatable,
+ // it could get allocated to something with a def during allocation.
+ if (!MRI.def_empty(Reg))
+ return false;
+ BitVector AllocatableRegs = TRI.getAllocatableSet(MF, 0);
+ if (AllocatableRegs.test(Reg))
+ return false;
+ // Check for a def among the register's aliases too.
+ for (const unsigned *Alias = TRI.getAliasSet(Reg); *Alias; ++Alias) {
+ unsigned AliasReg = *Alias;
+ if (!MRI.def_empty(AliasReg))
+ return false;
+ if (AllocatableRegs.test(AliasReg))
+ return false;
+ }
+ } else {
+ // A physreg def. We can't remat it.
+ return false;
+ }
+ continue;
+ }
+
+ // Only allow one virtual-register def, and that in the first operand.
+ if (MO.isDef() != (i == 0))
+ return false;
+
+ // For the def, it should be the only def of that register.
+ if (MO.isDef() && (llvm::next(MRI.def_begin(Reg)) != MRI.def_end() ||
+ MRI.isLiveIn(Reg)))
+ return false;
+
+ // Don't allow any virtual-register uses. Rematting an instruction with
+ // virtual register uses would length the live ranges of the uses, which
+ // is not necessarily a good idea, certainly not "trivial".
+ if (MO.isUse())
+ return false;
+ }
+
+ // Everything checked out.
+ return true;
+}