+ /// getSubRegIndex - For a given register pair, return the sub-register index
+ /// if the second register is a sub-register of the first. Return zero
+ /// otherwise.
+ virtual unsigned getSubRegIndex(unsigned RegNo, unsigned SubRegNo) const = 0;
+
+ /// getMatchingSuperReg - Return a super-register of the specified register
+ /// Reg so its sub-register of index SubIdx is Reg.
+ unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx,
+ const TargetRegisterClass *RC) const {
+ for (const unsigned *SRs = getSuperRegisters(Reg); unsigned SR = *SRs;++SRs)
+ if (Reg == getSubReg(SR, SubIdx) && RC->contains(SR))
+ return SR;
+ return 0;
+ }
+
+ /// canCombineSubRegIndices - Given a register class and a list of
+ /// subregister indices, return true if it's possible to combine the
+ /// subregister indices into one that corresponds to a larger
+ /// subregister. Return the new subregister index by reference. Note the
+ /// new index may be zero if the given subregisters can be combined to
+ /// form the whole register.
+ virtual bool canCombineSubRegIndices(const TargetRegisterClass *RC,
+ SmallVectorImpl<unsigned> &SubIndices,
+ unsigned &NewSubIdx) const {
+ return 0;
+ }
+
+ /// getMatchingSuperRegClass - Return a subclass of the specified register
+ /// class A so that each register in it has a sub-register of the
+ /// specified sub-register index which is in the specified register class B.
+ virtual const TargetRegisterClass *
+ getMatchingSuperRegClass(const TargetRegisterClass *A,
+ const TargetRegisterClass *B, unsigned Idx) const {
+ return 0;
+ }
+
+ /// composeSubRegIndices - Return the subregister index you get from composing
+ /// two subregister indices.
+ ///
+ /// If R:a:b is the same register as R:c, then composeSubRegIndices(a, b)
+ /// returns c. Note that composeSubRegIndices does not tell you about illegal
+ /// compositions. If R does not have a subreg a, or R:a does not have a subreg
+ /// b, composeSubRegIndices doesn't tell you.
+ ///
+ /// The ARM register Q0 has two D subregs dsub_0:D0 and dsub_1:D1. It also has
+ /// ssub_0:S0 - ssub_3:S3 subregs.
+ /// If you compose subreg indices dsub_1, ssub_0 you get ssub_2.
+ ///
+ virtual unsigned composeSubRegIndices(unsigned a, unsigned b) const {
+ // This default implementation is correct for most targets.
+ return b;
+ }
+