ARM LDR_PRE/LDR_POST/STR_PRE/STR_POST (and the *B counterparts) binary encoding.

llvm-svn: 119180
diff --git a/llvm/lib/Target/ARM/ARMInstrFormats.td b/llvm/lib/Target/ARM/ARMInstrFormats.td
index 774c441..39ae973 100644
--- a/llvm/lib/Target/ARM/ARMInstrFormats.td
+++ b/llvm/lib/Target/ARM/ARMInstrFormats.td
@@ -438,11 +438,13 @@
                 string asm, string cstr, list<dag> pattern>
   : I<oops, iops, AddrMode2, Size4Bytes, im, f, itin,
       opc, asm, cstr, pattern> {
+  bits<4> Rt;
   let Inst{27-26} = 0b01;
   let Inst{24}    = isPre; // P bit
   let Inst{22}    = isByte; // B bit
   let Inst{21}    = isPre; // W bit
   let Inst{20}    = isLd; // L bit
+  let Inst{15-12} = Rt;
 }
 
 class AXI2ldw<dag oops, dag iops, Format f, InstrItinClass itin,