+ /// Get the weight in units of pressure for this register unit.
+ virtual unsigned getRegUnitWeight(unsigned RegUnit) const = 0;
+
+ /// Get the number of dimensions of register pressure.
+ virtual unsigned getNumRegPressureSets() const = 0;
+
+ /// Get the name of this register unit pressure set.
+ virtual const char *getRegPressureSetName(unsigned Idx) const = 0;
+
+ /// Get the register unit pressure limit for this dimension.
+ /// This limit must be adjusted dynamically for reserved registers.
+ virtual unsigned getRegPressureSetLimit(unsigned Idx) const = 0;
+
+ /// Get the dimensions of register pressure impacted by this register class.
+ /// Returns a -1 terminated array of pressure set IDs.
+ virtual const int *getRegClassPressureSets(
+ const TargetRegisterClass *RC) const = 0;
+
+ /// Get the dimensions of register pressure impacted by this register unit.
+ /// Returns a -1 terminated array of pressure set IDs.
+ virtual const int *getRegUnitPressureSets(unsigned RegUnit) const = 0;
+
+ /// Get a list of 'hint' registers that the register allocator should try
+ /// first when allocating a physical register for the virtual register
+ /// VirtReg. These registers are effectively moved to the front of the
+ /// allocation order.
+ ///
+ /// The Order argument is the allocation order for VirtReg's register class
+ /// as returned from RegisterClassInfo::getOrder(). The hint registers must
+ /// come from Order, and they must not be reserved.
+ ///
+ /// The default implementation of this function can resolve
+ /// target-independent hints provided to MRI::setRegAllocationHint with
+ /// HintType == 0. Targets that override this function should defer to the
+ /// default implementation if they have no reason to change the allocation
+ /// order for VirtReg. There may be target-independent hints.
+ virtual void getRegAllocationHints(unsigned VirtReg,
+ ArrayRef<MCPhysReg> Order,
+ SmallVectorImpl<MCPhysReg> &Hints,
+ const MachineFunction &MF,
+ const VirtRegMap *VRM = 0) const;
+
+ /// avoidWriteAfterWrite - Return true if the register allocator should avoid
+ /// writing a register from RC in two consecutive instructions.
+ /// This can avoid pipeline stalls on certain architectures.
+ /// It does cause increased register pressure, though.
+ virtual bool avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
+ return false;