+ void setPhysRegUnused(unsigned Reg) {
+ UsedPhysRegs.reset(Reg);
+ UsedPhysRegMask.reset(Reg);
+ }
+
+
+ //===--------------------------------------------------------------------===//
+ // Reserved Register Info
+ //===--------------------------------------------------------------------===//
+ //
+ // The set of reserved registers must be invariant during register
+ // allocation. For example, the target cannot suddenly decide it needs a
+ // frame pointer when the register allocator has already used the frame
+ // pointer register for something else.
+ //
+ // These methods can be used by target hooks like hasFP() to avoid changing
+ // the reserved register set during register allocation.
+
+ /// freezeReservedRegs - Called by the register allocator to freeze the set
+ /// of reserved registers before allocation begins.
+ void freezeReservedRegs(const MachineFunction&);
+
+ /// reservedRegsFrozen - Returns true after freezeReservedRegs() was called
+ /// to ensure the set of reserved registers stays constant.
+ bool reservedRegsFrozen() const {
+ return !ReservedRegs.empty();
+ }
+
+ /// canReserveReg - Returns true if PhysReg can be used as a reserved
+ /// register. Any register can be reserved before freezeReservedRegs() is
+ /// called.
+ bool canReserveReg(unsigned PhysReg) const {
+ return !reservedRegsFrozen() || ReservedRegs.test(PhysReg);
+ }
+