+ assert(MO->getReg() == Head->getReg() && "Different regs on the same list!");
+
+ // Insert MO between Last and Head in the circular Prev chain.
+ MachineOperand *Last = Head->Contents.Reg.Prev;
+ assert(Last && "Inconsistent use list");
+ assert(MO->getReg() == Last->getReg() && "Different regs on the same list!");
+ Head->Contents.Reg.Prev = MO;
+ MO->Contents.Reg.Prev = Last;
+
+ // Def operands always precede uses. This allows def_iterator to stop early.
+ // Insert def operands at the front, and use operands at the back.
+ if (MO->isDef()) {
+ // Insert def at the front.
+ MO->Contents.Reg.Next = Head;
+ HeadRef = MO;
+ } else {
+ // Insert use at the end.
+ MO->Contents.Reg.Next = nullptr;
+ Last->Contents.Reg.Next = MO;
+ }
+}
+
+/// Remove MO from its use-def list.
+void MachineRegisterInfo::removeRegOperandFromUseList(MachineOperand *MO) {
+ assert(MO->isOnRegUseList() && "Operand not on use list");
+ MachineOperand *&HeadRef = getRegUseDefListHead(MO->getReg());
+ MachineOperand *const Head = HeadRef;
+ assert(Head && "List already empty");
+
+ // Unlink this from the doubly linked list of operands.
+ MachineOperand *Next = MO->Contents.Reg.Next;
+ MachineOperand *Prev = MO->Contents.Reg.Prev;
+
+ // Prev links are circular, next link is NULL instead of looping back to Head.
+ if (MO == Head)
+ HeadRef = Next;
+ else
+ Prev->Contents.Reg.Next = Next;
+
+ (Next ? Next : Head)->Contents.Reg.Prev = Prev;
+
+ MO->Contents.Reg.Prev = nullptr;
+ MO->Contents.Reg.Next = nullptr;
+}
+
+/// Move NumOps operands from Src to Dst, updating use-def lists as needed.
+///
+/// The Dst range is assumed to be uninitialized memory. (Or it may contain
+/// operands that won't be destroyed, which is OK because the MO destructor is
+/// trivial anyway).
+///
+/// The Src and Dst ranges may overlap.
+void MachineRegisterInfo::moveOperands(MachineOperand *Dst,
+ MachineOperand *Src,
+ unsigned NumOps) {
+ assert(Src != Dst && NumOps && "Noop moveOperands");
+
+ // Copy backwards if Dst is within the Src range.
+ int Stride = 1;
+ if (Dst >= Src && Dst < Src + NumOps) {
+ Stride = -1;
+ Dst += NumOps - 1;
+ Src += NumOps - 1;
+ }
+
+ // Copy one operand at a time.
+ do {
+ new (Dst) MachineOperand(*Src);
+
+ // Dst takes Src's place in the use-def chain.
+ if (Src->isReg()) {
+ MachineOperand *&Head = getRegUseDefListHead(Src->getReg());
+ MachineOperand *Prev = Src->Contents.Reg.Prev;
+ MachineOperand *Next = Src->Contents.Reg.Next;
+ assert(Head && "List empty, but operand is chained");
+ assert(Prev && "Operand was not on use-def list");
+
+ // Prev links are circular, next link is NULL instead of looping back to
+ // Head.
+ if (Src == Head)
+ Head = Dst;
+ else
+ Prev->Contents.Reg.Next = Dst;
+
+ // Update Prev pointer. This also works when Src was pointing to itself
+ // in a 1-element list. In that case Head == Dst.
+ (Next ? Next : Head)->Contents.Reg.Prev = Dst;
+ }
+
+ Dst += Stride;
+ Src += Stride;
+ } while (--NumOps);