-def PC : MSP430Reg<0, "r0">;
-def SP : MSP430Reg<1, "r1">;
-def SR : MSP430Reg<2, "r2">;
-def CG : MSP430Reg<3, "r3">;
-def FP : MSP430Reg<4, "r4">;
-def R5 : MSP430Reg<5, "r5">;
-def R6 : MSP430Reg<6, "r6">;
-def R7 : MSP430Reg<7, "r7">;
-def R8 : MSP430Reg<8, "r8">;
-def R9 : MSP430Reg<9, "r9">;
-def R10 : MSP430Reg<10, "r10">;
-def R11 : MSP430Reg<11, "r11">;
-def R12 : MSP430Reg<12, "r12">;
-def R13 : MSP430Reg<13, "r13">;
-def R14 : MSP430Reg<14, "r14">;
-def R15 : MSP430Reg<15, "r15">;
+def PCB : MSP430Reg<0, "r0">;
+def SPB : MSP430Reg<1, "r1">;
+def SRB : MSP430Reg<2, "r2">;
+def CGB : MSP430Reg<3, "r3">;
+def FPB : MSP430Reg<4, "r4">;
+def R5B : MSP430Reg<5, "r5">;
+def R6B : MSP430Reg<6, "r6">;
+def R7B : MSP430Reg<7, "r7">;
+def R8B : MSP430Reg<8, "r8">;
+def R9B : MSP430Reg<9, "r9">;
+def R10B : MSP430Reg<10, "r10">;
+def R11B : MSP430Reg<11, "r11">;
+def R12B : MSP430Reg<12, "r12">;
+def R13B : MSP430Reg<13, "r13">;
+def R14B : MSP430Reg<14, "r14">;
+def R15B : MSP430Reg<15, "r15">;
+
+def subreg_8bit : SubRegIndex { let Namespace = "MSP430"; }
+
+let SubRegIndices = [subreg_8bit] in {
+def PCW : MSP430RegWithSubregs<0, "r0", [PCB]>;
+def SPW : MSP430RegWithSubregs<1, "r1", [SPB]>;
+def SRW : MSP430RegWithSubregs<2, "r2", [SRB]>;
+def CGW : MSP430RegWithSubregs<3, "r3", [CGB]>;
+def FPW : MSP430RegWithSubregs<4, "r4", [FPB]>;
+def R5W : MSP430RegWithSubregs<5, "r5", [R5B]>;
+def R6W : MSP430RegWithSubregs<6, "r6", [R6B]>;
+def R7W : MSP430RegWithSubregs<7, "r7", [R7B]>;
+def R8W : MSP430RegWithSubregs<8, "r8", [R8B]>;
+def R9W : MSP430RegWithSubregs<9, "r9", [R9B]>;
+def R10W : MSP430RegWithSubregs<10, "r10", [R10B]>;
+def R11W : MSP430RegWithSubregs<11, "r11", [R11B]>;
+def R12W : MSP430RegWithSubregs<12, "r12", [R12B]>;
+def R13W : MSP430RegWithSubregs<13, "r13", [R13B]>;
+def R14W : MSP430RegWithSubregs<14, "r14", [R14B]>;
+def R15W : MSP430RegWithSubregs<15, "r15", [R15B]>;
+}