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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119180 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMMCCodeEmitter.cpp b/lib/Target/ARM/ARMMCCodeEmitter.cpp
index b156755..273ca99 100644
--- a/lib/Target/ARM/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMMCCodeEmitter.cpp
@@ -101,6 +101,29 @@
     case ARM_AM::ib: return 3;
     }
   }
+  /// getShiftOp - Return the shift opcode (bit[6:5]) of the immediate value.
+  ///
+  unsigned getShiftOp(ARM_AM::ShiftOpc ShOpc) const {
+    switch (ShOpc) {
+    default: llvm_unreachable("Unknown shift opc!");
+    case ARM_AM::no_shift:
+    case ARM_AM::lsl: return 0;
+    case ARM_AM::lsr: return 1;
+    case ARM_AM::asr: return 2;
+    case ARM_AM::ror:
+    case ARM_AM::rrx: return 3;
+    }
+    return 0;
+  }
+
+  /// getAddrMode2OpValue - Return encoding for addrmode2 operands.
+  uint32_t getAddrMode2OpValue(const MCInst &MI, unsigned OpIdx,
+                               SmallVectorImpl<MCFixup> &Fixups) const;
+
+  /// getAddrMode2OffsetOpValue - Return encoding for am2offset operands.
+  uint32_t getAddrMode2OffsetOpValue(const MCInst &MI, unsigned OpIdx,
+                                     SmallVectorImpl<MCFixup> &Fixups) const;
+
   /// getAddrMode3OffsetOpValue - Return encoding for am3offset operands.
   uint32_t getAddrMode3OffsetOpValue(const MCInst &MI, unsigned OpIdx,
                                      SmallVectorImpl<MCFixup> &Fixups) const;
@@ -380,24 +403,10 @@
   const MCOperand &MO2 = MI.getOperand(OpIdx+2);
   unsigned Rn = getARMRegisterNumbering(MO.getReg());
   unsigned Rm = getARMRegisterNumbering(MO1.getReg());
-  ARM_AM::ShiftOpc ShOp = ARM_AM::getAM2ShiftOpc(MO2.getImm());
   unsigned ShImm = ARM_AM::getAM2Offset(MO2.getImm());
   bool isAdd = ARM_AM::getAM2Op(MO2.getImm()) == ARM_AM::add;
-  unsigned SBits;
-  // LSL - 00
-  // LSR - 01
-  // ASR - 10
-  // ROR - 11
-  switch (ShOp) {
-  default: llvm_unreachable("Unknown shift opc!");
-  case ARM_AM::no_shift:
-    assert(ShImm == 0 && "Non-zero shift amount with no shift type!");
-    // fall through
-  case ARM_AM::lsl: SBits = 0x0; break;
-  case ARM_AM::lsr: SBits = 0x1; break;
-  case ARM_AM::asr: SBits = 0x2; break;
-  case ARM_AM::ror: SBits = 0x3; break;
-  }
+  ARM_AM::ShiftOpc ShOp = ARM_AM::getAM2ShiftOpc(MO2.getImm());
+  unsigned SBits = getShiftOp(ShOp);
 
   // {16-13} = Rn
   // {12}    = isAdd
@@ -416,6 +425,42 @@
 }
 
 uint32_t ARMMCCodeEmitter::
+getAddrMode2OpValue(const MCInst &MI, unsigned OpIdx,
+                    SmallVectorImpl<MCFixup> &Fixups) const {
+  // {17-14}  Rn
+  // {13}     1 == imm12, 0 == Rm
+  // {12}     isAdd
+  // {11-0}   imm12/Rm
+  const MCOperand &MO = MI.getOperand(OpIdx);
+  unsigned Rn = getARMRegisterNumbering(MO.getReg());
+  uint32_t Binary = getAddrMode2OffsetOpValue(MI, OpIdx + 1, Fixups);
+  Binary |= Rn << 14;
+  return Binary;
+}
+
+uint32_t ARMMCCodeEmitter::
+getAddrMode2OffsetOpValue(const MCInst &MI, unsigned OpIdx,
+                          SmallVectorImpl<MCFixup> &Fixups) const {
+  // {13}     1 == imm12, 0 == Rm
+  // {12}     isAdd
+  // {11-0}   imm12/Rm
+  const MCOperand &MO = MI.getOperand(OpIdx);
+  const MCOperand &MO1 = MI.getOperand(OpIdx+1);
+  unsigned Imm = MO1.getImm();
+  bool isAdd = ARM_AM::getAM2Op(Imm) == ARM_AM::add;
+  bool isReg = MO.getReg() != 0;
+  uint32_t Binary = ARM_AM::getAM2Offset(Imm);
+  // if reg +/- reg, Rm will be non-zero. Otherwise, we have reg +/- imm12
+  if (isReg) {
+    ARM_AM::ShiftOpc ShOp = ARM_AM::getAM2ShiftOpc(Imm);
+    Binary <<= 7;                    // Shift amount is bits [11:7]
+    Binary |= getShiftOp(ShOp) << 5; // Shift type is bits [6:5]
+    Binary |= getARMRegisterNumbering(MO.getReg()); // Rm is bits [3:0]
+  }
+  return Binary | (isAdd << 12) | (isReg << 13);
+}
+
+uint32_t ARMMCCodeEmitter::
 getAddrMode3OffsetOpValue(const MCInst &MI, unsigned OpIdx,
                           SmallVectorImpl<MCFixup> &Fixups) const {
   // {9}      1 == imm8, 0 == Rm