Apply again changes to support ARM memory asm parsing. I removed
all LDR/STR changes and left them to a future patch. Passing all
checks now.

- Implement asm parsing support for LDRT, LDRBT, STRT, STRBT and
  fix the encoding wherever is possible.
- Add a new encoding bit to describe the index mode used and teach
  printAddrMode2Operand to check by the addressing mode which index
  mode to print.
- Testcases

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128689 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMAddressingModes.h b/lib/Target/ARM/ARMAddressingModes.h
index 19fbf05..0b5fb1d 100644
--- a/lib/Target/ARM/ARMAddressingModes.h
+++ b/lib/Target/ARM/ARMAddressingModes.h
@@ -408,16 +408,18 @@
   //
   // The first operand is always a Reg.  The second operand is a reg if in
   // reg/reg form, otherwise it's reg#0.  The third field encodes the operation
-  // in bit 12, the immediate in bits 0-11, and the shift op in 13-15.
+  // in bit 12, the immediate in bits 0-11, and the shift op in 13-15. The
+  // forth operand 16-17 encodes the index mode.
   //
   // If this addressing mode is a frame index (before prolog/epilog insertion
   // and code rewriting), this operand will have the form:  FI#, reg0, <offs>
   // with no shift amount for the frame offset.
   //
-  static inline unsigned getAM2Opc(AddrOpc Opc, unsigned Imm12, ShiftOpc SO) {
+  static inline unsigned getAM2Opc(AddrOpc Opc, unsigned Imm12, ShiftOpc SO,
+                                   unsigned IdxMode = 0) {
     assert(Imm12 < (1 << 12) && "Imm too large!");
     bool isSub = Opc == sub;
-    return Imm12 | ((int)isSub << 12) | (SO << 13);
+    return Imm12 | ((int)isSub << 12) | (SO << 13) | (IdxMode << 16) ;
   }
   static inline unsigned getAM2Offset(unsigned AM2Opc) {
     return AM2Opc & ((1 << 12)-1);
@@ -426,7 +428,10 @@
     return ((AM2Opc >> 12) & 1) ? sub : add;
   }
   static inline ShiftOpc getAM2ShiftOpc(unsigned AM2Opc) {
-    return (ShiftOpc)(AM2Opc >> 13);
+    return (ShiftOpc)((AM2Opc >> 13) & 7);
+  }
+  static inline unsigned getAM2IdxMode(unsigned AM2Opc) {
+    return (AM2Opc >> 16);
   }