Switch the fixed-length disassembler to be table-driven.

Refactor the TableGen'erated fixed length disassemblmer to use a
table-driven state machine rather than a massive set of nested
switch() statements.

As a result, the ARM Disassembler (ARMDisassembler.cpp) builds much more
quickly and generates a smaller end result. For a Release+Asserts build on
a 16GB 3.4GHz i7 iMac w/ SSD:

Time to compile at -O2 (averaged w/ hot caches):
  Previous: 35.5s
  New:       8.9s

TEXT size:
  Previous: 447,251
  New:      297,661

Builds in 25% of the time previously required and generates code 66% of
the size.

Execution time of the disassembler is only slightly slower (7% disassembling
10 million ARM instructions, 19.6s vs 21.0s). The new implementation has
not yet been tuned, however, so the performance should almost certainly
be recoverable should it become a concern.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161888 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 1230 insertions, 702 deletions

diff --git a/include/llvm/MC/MCFixedLenDisassembler.h b/include/llvm/MC/MCFixedLenDisassembler.h
new file mode 100644
index 0000000000..22b3c32abd
--- /dev/null
+++ b/include/llvm/MC/MCFixedLenDisassembler.h
@@ -0,0 +1,32 @@
+//===-- llvm/MC/MCFixedLenDisassembler.h - Decoder driver -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Fixed length disassembler decoder state machine driver.
+//===----------------------------------------------------------------------===//
+#ifndef MCFIXEDLENDISASSEMBLER_H
+#define MCFIXEDLENDISASSEMBLER_H
+
+namespace llvm {
+
+namespace MCD {
+// Disassembler state machine opcodes.
+enum DecoderOps {
+  OPC_ExtractField = 1, // OPC_ExtractField(uint8_t Start, uint8_t Len)
+  OPC_FilterValue,      // OPC_FilterValue(uleb128 Val, uint16_t NumToSkip)
+  OPC_CheckField,       // OPC_CheckField(uint8_t Start, uint8_t Len,
+                        //                uleb128 Val, uint16_t NumToSkip)
+  OPC_CheckPredicate,   // OPC_CheckPredicate(uleb128 PIdx, uint16_t NumToSkip)
+  OPC_Decode,           // OPC_Decode(uleb128 Opcode, uleb128 DIdx)
+  OPC_SoftFail,         // OPC_SoftFail(uleb128 PMask, uleb128 NMask)
+  OPC_Fail              // OPC_Fail()
+};
+
+} // namespace MCDecode
+} // namespace llvm
+
+#endif
diff --git a/include/llvm/Support/LEB128.h b/include/llvm/Support/LEB128.h
index 00c7eeaebc..410edd4dc7 100644
--- a/include/llvm/Support/LEB128.h
+++ b/include/llvm/Support/LEB128.h
@@ -19,7 +19,7 @@
 
 namespace llvm {
 
-/// Utility function to encode a SLEB128 value.
+/// Utility function to encode a SLEB128 value to an output stream.
 static inline void encodeSLEB128(int64_t Value, raw_ostream &OS) {
   bool More;
   do {
@@ -34,7 +34,7 @@ static inline void encodeSLEB128(int64_t Value, raw_ostream &OS) {
   } while (More);
 }
 
-/// Utility function to encode a ULEB128 value.
+/// Utility function to encode a ULEB128 value to an output stream.
 static inline void encodeULEB128(uint64_t Value, raw_ostream &OS,
                                  unsigned Padding = 0) {
   do {
@@ -53,6 +53,43 @@ static inline void encodeULEB128(uint64_t Value, raw_ostream &OS,
   }
 }
 
+/// Utility function to encode a ULEB128 value to a buffer. Returns
+/// the length in bytes of the encoded value.
+static inline unsigned encodeULEB128(uint64_t Value, uint8_t *p,
+                                     unsigned Padding = 0) {
+  uint8_t *orig_p = p;
+  do {
+    uint8_t Byte = Value & 0x7f;
+    Value >>= 7;
+    if (Value != 0 || Padding != 0)
+      Byte |= 0x80; // Mark this byte that that more bytes will follow.
+    *p++ = Byte;
+  } while (Value != 0);
+
+  // Pad with 0x80 and emit a null byte at the end.
+  if (Padding != 0) {
+    for (; Padding != 1; --Padding)
+      *p++ = '\x80';
+    *p++ = '\x00';
+  }
+  return (unsigned)(p - orig_p);
+}
+
+
+/// Utility function to decode a ULEB128 value.
+static inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = 0) {
+  const uint8_t *orig_p = p;
+  uint64_t Value = 0;
+  unsigned Shift = 0;
+  do {
+    Value += (*p & 0x7f) << Shift;
+    Shift += 7;
+  } while (*p++ >= 128);
+  if (n)
+    *n = (unsigned)(p - orig_p);
+  return Value;
+}
+
 }  // namespace llvm
 
 #endif  // LLVM_SYSTEM_LEB128_H
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index e47bf66e3a..01d6e67932 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -18,10 +18,12 @@
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDisassembler.h"
+#include "llvm/MC/MCFixedLenDisassembler.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MemoryObject.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/LEB128.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
 #include <vector>
@@ -427,7 +429,8 @@ DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                   (bytes[0] <<  0);
 
   // Calling the auto-generated decoder function.
-  DecodeStatus result = decodeARMInstruction32(MI, insn, Address, this, STI);
+  DecodeStatus result = decodeInstruction(DecoderTableARM32, MI, insn,
+                                          Address, this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     return result;
@@ -436,14 +439,15 @@ DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   // VFP and NEON instructions, similarly, are shared between ARM
   // and Thumb modes.
   MI.clear();
-  result = decodeVFPInstruction32(MI, insn, Address, this, STI);
+  result = decodeInstruction(DecoderTableVFP32, MI, insn, Address, this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     return result;
   }
 
   MI.clear();
-  result = decodeNEONDataInstruction32(MI, insn, Address, this, STI);
+  result = decodeInstruction(DecoderTableNEONData32, MI, insn, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     // Add a fake predicate operand, because we share these instruction
@@ -454,7 +458,8 @@ DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeNEONLoadStoreInstruction32(MI, insn, Address, this, STI);
+  result = decodeInstruction(DecoderTableNEONLoadStore32, MI, insn, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     // Add a fake predicate operand, because we share these instruction
@@ -465,7 +470,8 @@ DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeNEONDupInstruction32(MI, insn, Address, this, STI);
+  result = decodeInstruction(DecoderTableNEONDup32, MI, insn, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     // Add a fake predicate operand, because we share these instruction
@@ -765,7 +771,8 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   uint16_t insn16 = (bytes[1] << 8) | bytes[0];
-  DecodeStatus result = decodeThumbInstruction16(MI, insn16, Address, this, STI);
+  DecodeStatus result = decodeInstruction(DecoderTableThumb16, MI, insn16,
+                                          Address, this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 2;
     Check(result, AddThumbPredicate(MI));
@@ -773,7 +780,8 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeThumbSBitInstruction16(MI, insn16, Address, this, STI);
+  result = decodeInstruction(DecoderTableThumbSBit16, MI, insn16,
+                             Address, this, STI);
   if (result) {
     Size = 2;
     bool InITBlock = ITBlock.instrInITBlock();
@@ -783,7 +791,8 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeThumb2Instruction16(MI, insn16, Address, this, STI);
+  result = decodeInstruction(DecoderTableThumb216, MI, insn16,
+                             Address, this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 2;
 
@@ -818,7 +827,8 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                     (bytes[1] << 24) |
                     (bytes[0] << 16);
   MI.clear();
-  result = decodeThumbInstruction32(MI, insn32, Address, this, STI);
+  result = decodeInstruction(DecoderTableThumb32, MI, insn32, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     bool InITBlock = ITBlock.instrInITBlock();
@@ -828,7 +838,8 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeThumb2Instruction32(MI, insn32, Address, this, STI);
+  result = decodeInstruction(DecoderTableThumb232, MI, insn32, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     Check(result, AddThumbPredicate(MI));
@@ -836,7 +847,7 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeVFPInstruction32(MI, insn32, Address, this, STI);
+  result = decodeInstruction(DecoderTableVFP32, MI, insn32, Address, this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     UpdateThumbVFPPredicate(MI);
@@ -844,19 +855,21 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   }
 
   MI.clear();
-  result = decodeNEONDupInstruction32(MI, insn32, Address, this, STI);
+  result = decodeInstruction(DecoderTableNEONDup32, MI, insn32, Address,
+                             this, STI);
   if (result != MCDisassembler::Fail) {
     Size = 4;
     Check(result, AddThumbPredicate(MI));
     return result;
   }
 
-  if (fieldFromInstruction32(insn32, 24, 8) == 0xF9) {
+  if (fieldFromInstruction(insn32, 24, 8) == 0xF9) {
     MI.clear();
     uint32_t NEONLdStInsn = insn32;
     NEONLdStInsn &= 0xF0FFFFFF;
     NEONLdStInsn |= 0x04000000;
-    result = decodeNEONLoadStoreInstruction32(MI, NEONLdStInsn, Address, this, STI);
+    result = decodeInstruction(DecoderTableNEONLoadStore32, MI, NEONLdStInsn,
+                               Address, this, STI);
     if (result != MCDisassembler::Fail) {
       Size = 4;
       Check(result, AddThumbPredicate(MI));
@@ -864,13 +877,14 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
     }
   }
 
-  if (fieldFromInstruction32(insn32, 24, 4) == 0xF) {
+  if (fieldFromInstruction(insn32, 24, 4) == 0xF) {
     MI.clear();
     uint32_t NEONDataInsn = insn32;
     NEONDataInsn &= 0xF0FFFFFF; // Clear bits 27-24
     NEONDataInsn |= (NEONDataInsn & 0x10000000) >> 4; // Move bit 28 to bit 24
     NEONDataInsn |= 0x12000000; // Set bits 28 and 25
-    result = decodeNEONDataInstruction32(MI, NEONDataInsn, Address, this, STI);
+    result = decodeInstruction(DecoderTableNEONData32, MI, NEONDataInsn,
+                               Address, this, STI);
     if (result != MCDisassembler::Fail) {
       Size = 4;
       Check(result, AddThumbPredicate(MI));
@@ -1117,9 +1131,9 @@ static DecodeStatus DecodeSORegImmOperand(MCInst &Inst, unsigned Val,
                                uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
-  unsigned type = fieldFromInstruction32(Val, 5, 2);
-  unsigned imm = fieldFromInstruction32(Val, 7, 5);
+  unsigned Rm = fieldFromInstruction(Val, 0, 4);
+  unsigned type = fieldFromInstruction(Val, 5, 2);
+  unsigned imm = fieldFromInstruction(Val, 7, 5);
 
   // Register-immediate
   if (!Check(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)))
@@ -1154,9 +1168,9 @@ static DecodeStatus DecodeSORegRegOperand(MCInst &Inst, unsigned Val,
                                uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
-  unsigned type = fieldFromInstruction32(Val, 5, 2);
-  unsigned Rs = fieldFromInstruction32(Val, 8, 4);
+  unsigned Rm = fieldFromInstruction(Val, 0, 4);
+  unsigned type = fieldFromInstruction(Val, 5, 2);
+  unsigned Rs = fieldFromInstruction(Val, 8, 4);
 
   // Register-register
   if (!Check(S, DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)))
@@ -1224,8 +1238,8 @@ static DecodeStatus DecodeSPRRegListOperand(MCInst &Inst, unsigned Val,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Vd = fieldFromInstruction32(Val, 8, 5);
-  unsigned regs = fieldFromInstruction32(Val, 0, 8);
+  unsigned Vd = fieldFromInstruction(Val, 8, 5);
+  unsigned regs = fieldFromInstruction(Val, 0, 8);
 
   if (!Check(S, DecodeSPRRegisterClass(Inst, Vd, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -1241,8 +1255,8 @@ static DecodeStatus DecodeDPRRegListOperand(MCInst &Inst, unsigned Val,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Vd = fieldFromInstruction32(Val, 8, 5);
-  unsigned regs = fieldFromInstruction32(Val, 0, 8);
+  unsigned Vd = fieldFromInstruction(Val, 8, 5);
+  unsigned regs = fieldFromInstruction(Val, 0, 8);
 
   regs = regs >> 1;
 
@@ -1263,8 +1277,8 @@ static DecodeStatus DecodeBitfieldMaskOperand(MCInst &Inst, unsigned Val,
   // the mask of all bits LSB-and-lower, and then xor them to create
   // the mask of that's all ones on [msb, lsb].  Finally we not it to
   // create the final mask.
-  unsigned msb = fieldFromInstruction32(Val, 5, 5);
-  unsigned lsb = fieldFromInstruction32(Val, 0, 5);
+  unsigned msb = fieldFromInstruction(Val, 5, 5);
+  unsigned lsb = fieldFromInstruction(Val, 0, 5);
 
   DecodeStatus S = MCDisassembler::Success;
   if (lsb > msb) Check(S, MCDisassembler::SoftFail);
@@ -1281,12 +1295,12 @@ static DecodeStatus DecodeCopMemInstruction(MCInst &Inst, unsigned Insn,
                                   uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
-  unsigned CRd = fieldFromInstruction32(Insn, 12, 4);
-  unsigned coproc = fieldFromInstruction32(Insn, 8, 4);
-  unsigned imm = fieldFromInstruction32(Insn, 0, 8);
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned U = fieldFromInstruction32(Insn, 23, 1);
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
+  unsigned CRd = fieldFromInstruction(Insn, 12, 4);
+  unsigned coproc = fieldFromInstruction(Insn, 8, 4);
+  unsigned imm = fieldFromInstruction(Insn, 0, 8);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned U = fieldFromInstruction(Insn, 23, 1);
 
   switch (Inst.getOpcode()) {
     case ARM::LDC_OFFSET:
@@ -1426,14 +1440,14 @@ DecodeAddrMode2IdxInstruction(MCInst &Inst, unsigned Insn,
                               uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned imm = fieldFromInstruction32(Insn, 0, 12);
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
-  unsigned reg = fieldFromInstruction32(Insn, 25, 1);
-  unsigned P = fieldFromInstruction32(Insn, 24, 1);
-  unsigned W = fieldFromInstruction32(Insn, 21, 1);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rt = fieldFromInstruction(Insn, 12, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned imm = fieldFromInstruction(Insn, 0, 12);
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
+  unsigned reg = fieldFromInstruction(Insn, 25, 1);
+  unsigned P = fieldFromInstruction(Insn, 24, 1);
+  unsigned W = fieldFromInstruction(Insn, 21, 1);
 
   // On stores, the writeback operand precedes Rt.
   switch (Inst.getOpcode()) {
@@ -1476,7 +1490,7 @@ DecodeAddrMode2IdxInstruction(MCInst &Inst, unsigned Insn,
     return MCDisassembler::Fail;
 
   ARM_AM::AddrOpc Op = ARM_AM::add;
-  if (!fieldFromInstruction32(Insn, 23, 1))
+  if (!fieldFromInstruction(Insn, 23, 1))
     Op = ARM_AM::sub;
 
   bool writeback = (P == 0) || (W == 1);
@@ -1493,7 +1507,7 @@ DecodeAddrMode2IdxInstruction(MCInst &Inst, unsigned Insn,
     if (!Check(S, DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)))
       return MCDisassembler::Fail;
     ARM_AM::ShiftOpc Opc = ARM_AM::lsl;
-    switch( fieldFromInstruction32(Insn, 5, 2)) {
+    switch( fieldFromInstruction(Insn, 5, 2)) {
       case 0:
         Opc = ARM_AM::lsl;
         break;
@@ -1509,7 +1523,7 @@ DecodeAddrMode2IdxInstruction(MCInst &Inst, unsigned Insn,
       default:
         return MCDisassembler::Fail;
     }
-    unsigned amt = fieldFromInstruction32(Insn, 7, 5);
+    unsigned amt = fieldFromInstruction(Insn, 7, 5);
     unsigned imm = ARM_AM::getAM2Opc(Op, amt, Opc, idx_mode);
 
     Inst.addOperand(MCOperand::CreateImm(imm));
@@ -1529,11 +1543,11 @@ static DecodeStatus DecodeSORegMemOperand(MCInst &Inst, unsigned Val,
                                   uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rn = fieldFromInstruction32(Val, 13, 4);
-  unsigned Rm = fieldFromInstruction32(Val,  0, 4);
-  unsigned type = fieldFromInstruction32(Val, 5, 2);
-  unsigned imm = fieldFromInstruction32(Val, 7, 5);
-  unsigned U = fieldFromInstruction32(Val, 12, 1);
+  unsigned Rn = fieldFromInstruction(Val, 13, 4);
+  unsigned Rm = fieldFromInstruction(Val,  0, 4);
+  unsigned type = fieldFromInstruction(Val, 5, 2);
+  unsigned imm = fieldFromInstruction(Val, 7, 5);
+  unsigned U = fieldFromInstruction(Val, 12, 1);
 
   ARM_AM::ShiftOpc ShOp = ARM_AM::lsl;
   switch (type) {
@@ -1570,15 +1584,15 @@ DecodeAddrMode3Instruction(MCInst &Inst, unsigned Insn,
                            uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned type = fieldFromInstruction32(Insn, 22, 1);
-  unsigned imm = fieldFromInstruction32(Insn, 8, 4);
-  unsigned U = ((~fieldFromInstruction32(Insn, 23, 1)) & 1) << 8;
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
-  unsigned W = fieldFromInstruction32(Insn, 21, 1);
-  unsigned P = fieldFromInstruction32(Insn, 24, 1);
+  unsigned Rt = fieldFromInstruction(Insn, 12, 4);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned type = fieldFromInstruction(Insn, 22, 1);
+  unsigned imm = fieldFromInstruction(Insn, 8, 4);
+  unsigned U = ((~fieldFromInstruction(Insn, 23, 1)) & 1) << 8;
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
+  unsigned W = fieldFromInstruction(Insn, 21, 1);
+  unsigned P = fieldFromInstruction(Insn, 24, 1);
   unsigned Rt2 = Rt + 1;
 
   bool writeback = (W == 1) | (P == 0);
@@ -1609,7 +1623,7 @@ DecodeAddrMode3Instruction(MCInst &Inst, unsigned Insn,
         S = MCDisassembler::SoftFail;
       if (Rt2 == 15)
         S = MCDisassembler::SoftFail;
-      if (!type && fieldFromInstruction32(Insn, 8, 4))
+      if (!type && fieldFromInstruction(Insn, 8, 4))
         S = MCDisassembler::SoftFail;
       break;
     case ARM::STRH:
@@ -1761,8 +1775,8 @@ static DecodeStatus DecodeRFEInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned mode = fieldFromInstruction32(Insn, 23, 2);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned mode = fieldFromInstruction(Insn, 23, 2);
 
   switch (mode) {
     case 0:
@@ -1791,9 +1805,9 @@ static DecodeStatus DecodeMemMultipleWritebackInstruction(MCInst &Inst,
                                   uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
-  unsigned reglist = fieldFromInstruction32(Insn, 0, 16);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
+  unsigned reglist = fieldFromInstruction(Insn, 0, 16);
 
   if (pred == 0xF) {
     switch (Inst.getOpcode()) {
@@ -1850,9 +1864,9 @@ static DecodeStatus DecodeMemMultipleWritebackInstruction(MCInst &Inst,
     }
 
     // For stores (which become SRS's, the only operand is the mode.
-    if (fieldFromInstruction32(Insn, 20, 1) == 0) {
+    if (fieldFromInstruction(Insn, 20, 1) == 0) {
       Inst.addOperand(
-          MCOperand::CreateImm(fieldFromInstruction32(Insn, 0, 4)));
+          MCOperand::CreateImm(fieldFromInstruction(Insn, 0, 4)));
       return S;
     }
 
@@ -1873,10 +1887,10 @@ static DecodeStatus DecodeMemMultipleWritebackInstruction(MCInst &Inst,
 
 static DecodeStatus DecodeCPSInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
-  unsigned imod = fieldFromInstruction32(Insn, 18, 2);
-  unsigned M = fieldFromInstruction32(Insn, 17, 1);
-  unsigned iflags = fieldFromInstruction32(Insn, 6, 3);
-  unsigned mode = fieldFromInstruction32(Insn, 0, 5);
+  unsigned imod = fieldFromInstruction(Insn, 18, 2);
+  unsigned M = fieldFromInstruction(Insn, 17, 1);
+  unsigned iflags = fieldFromInstruction(Insn, 6, 3);
+  unsigned mode = fieldFromInstruction(Insn, 0, 5);
 
   DecodeStatus S = MCDisassembler::Success;
 
@@ -1913,10 +1927,10 @@ static DecodeStatus DecodeCPSInstruction(MCInst &Inst, unsigned Insn,
 
 static DecodeStatus DecodeT2CPSInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
-  unsigned imod = fieldFromInstruction32(Insn, 9, 2);
-  unsigned M = fieldFromInstruction32(Insn, 8, 1);
-  unsigned iflags = fieldFromInstruction32(Insn, 5, 3);
-  unsigned mode = fieldFromInstruction32(Insn, 0, 5);
+  unsigned imod = fieldFromInstruction(Insn, 9, 2);
+  unsigned M = fieldFromInstruction(Insn, 8, 1);
+  unsigned iflags = fieldFromInstruction(Insn, 5, 3);
+  unsigned mode = fieldFromInstruction(Insn, 0, 5);
 
   DecodeStatus S = MCDisassembler::Success;
 
@@ -1955,13 +1969,13 @@ static DecodeStatus DecodeT2MOVTWInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 8, 4);
+  unsigned Rd = fieldFromInstruction(Insn, 8, 4);
   unsigned imm = 0;
 
-  imm |= (fieldFromInstruction32(Insn, 0, 8) << 0);
-  imm |= (fieldFromInstruction32(Insn, 12, 3) << 8);
-  imm |= (fieldFromInstruction32(Insn, 16, 4) << 12);
-  imm |= (fieldFromInstruction32(Insn, 26, 1) << 11);
+  imm |= (fieldFromInstruction(Insn, 0, 8) << 0);
+  imm |= (fieldFromInstruction(Insn, 12, 3) << 8);
+  imm |= (fieldFromInstruction(Insn, 16, 4) << 12);
+  imm |= (fieldFromInstruction(Insn, 26, 1) << 11);
 
   if (Inst.getOpcode() == ARM::t2MOVTi16)
     if (!Check(S, DecoderGPRRegisterClass(Inst, Rd, Address, Decoder)))
@@ -1979,12 +1993,12 @@ static DecodeStatus DecodeArmMOVTWInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
   unsigned imm = 0;
 
-  imm |= (fieldFromInstruction32(Insn, 0, 12) << 0);
-  imm |= (fieldFromInstruction32(Insn, 16, 4) << 12);
+  imm |= (fieldFromInstruction(Insn, 0, 12) << 0);
+  imm |= (fieldFromInstruction(Insn, 16, 4) << 12);
 
   if (Inst.getOpcode() == ARM::MOVTi16)
     if (!Check(S, DecoderGPRRegisterClass(Inst, Rd, Address, Decoder)))
@@ -2005,11 +2019,11 @@ static DecodeStatus DecodeSMLAInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rn = fieldFromInstruction32(Insn, 0, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 8, 4);
-  unsigned Ra = fieldFromInstruction32(Insn, 12, 4);
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
+  unsigned Rd = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rn = fieldFromInstruction(Insn, 0, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 8, 4);
+  unsigned Ra = fieldFromInstruction(Insn, 12, 4);
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
 
   if (pred == 0xF)
     return DecodeCPSInstruction(Inst, Insn, Address, Decoder);
@@ -2033,9 +2047,9 @@ static DecodeStatus DecodeAddrModeImm12Operand(MCInst &Inst, unsigned Val,
                            uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned add = fieldFromInstruction32(Val, 12, 1);
-  unsigned imm = fieldFromInstruction32(Val, 0, 12);
-  unsigned Rn = fieldFromInstruction32(Val, 13, 4);
+  unsigned add = fieldFromInstruction(Val, 12, 1);
+  unsigned imm = fieldFromInstruction(Val, 0, 12);
+  unsigned Rn = fieldFromInstruction(Val, 13, 4);
 
   if (!Check(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2053,9 +2067,9 @@ static DecodeStatus DecodeAddrMode5Operand(MCInst &Inst, unsigned Val,
                                    uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rn = fieldFromInstruction32(Val, 9, 4);
-  unsigned U = fieldFromInstruction32(Val, 8, 1);
-  unsigned imm = fieldFromInstruction32(Val, 0, 8);
+  unsigned Rn = fieldFromInstruction(Val, 9, 4);
+  unsigned U = fieldFromInstruction(Val, 8, 1);
+  unsigned imm = fieldFromInstruction(Val, 0, 8);
 
   if (!Check(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2077,11 +2091,11 @@ static DecodeStatus
 DecodeT2BInstruction(MCInst &Inst, unsigned Insn,
                      uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
-  unsigned imm = (fieldFromInstruction32(Insn, 0, 11) << 0) |
-                 (fieldFromInstruction32(Insn, 11, 1) << 18) |
-                 (fieldFromInstruction32(Insn, 13, 1) << 17) |
-                 (fieldFromInstruction32(Insn, 16, 6) << 11) |
-                 (fieldFromInstruction32(Insn, 26, 1) << 19);
+  unsigned imm = (fieldFromInstruction(Insn, 0, 11) << 0) |
+                 (fieldFromInstruction(Insn, 11, 1) << 18) |
+                 (fieldFromInstruction(Insn, 13, 1) << 17) |
+                 (fieldFromInstruction(Insn, 16, 6) << 11) |
+                 (fieldFromInstruction(Insn, 26, 1) << 19);
   if (!tryAddingSymbolicOperand(Address, Address + SignExtend32<20>(imm<<1) + 4,
                                 true, 4, Inst, Decoder))
     Inst.addOperand(MCOperand::CreateImm(SignExtend32<20>(imm << 1)));
@@ -2093,12 +2107,12 @@ DecodeBranchImmInstruction(MCInst &Inst, unsigned Insn,
                            uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
-  unsigned imm = fieldFromInstruction32(Insn, 0, 24) << 2;
+  unsigned pred = fieldFromInstruction(Insn, 28, 4);
+  unsigned imm = fieldFromInstruction(Insn, 0, 24) << 2;
 
   if (pred == 0xF) {
     Inst.setOpcode(ARM::BLXi);
-    imm |= fieldFromInstruction32(Insn, 24, 1) << 1;
+    imm |= fieldFromInstruction(Insn, 24, 1) << 1;
     if (!tryAddingSymbolicOperand(Address, Address + SignExtend32<26>(imm) + 8,
                                   true, 4, Inst, Decoder))
     Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(imm)));
@@ -2119,8 +2133,8 @@ static DecodeStatus DecodeAddrMode6Operand(MCInst &Inst, unsigned Val,
                                    uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
-  unsigned align = fieldFromInstruction32(Val, 4, 2);
+  unsigned Rm = fieldFromInstruction(Val, 0, 4);
+  unsigned align = fieldFromInstruction(Val, 4, 2);
 
   if (!Check(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2136,12 +2150,12 @@ static DecodeStatus DecodeVLDInstruction(MCInst &Inst, unsigned Insn,
                                    uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned wb = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  Rn |= fieldFromInstruction32(Insn, 4, 2) << 4;
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned wb = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  Rn |= fieldFromInstruction(Insn, 4, 2) << 4;
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
 
   // First output register
   switch (Inst.getOpcode()) {
@@ -2410,12 +2424,12 @@ static DecodeStatus DecodeVSTInstruction(MCInst &Inst, unsigned Insn,
                                  uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned wb = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  Rn |= fieldFromInstruction32(Insn, 4, 2) << 4;
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned wb = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  Rn |= fieldFromInstruction(Insn, 4, 2) << 4;
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
 
   // Writeback Operand
   switch (Inst.getOpcode()) {
@@ -2681,12 +2695,12 @@ static DecodeStatus DecodeVLD1DupInstruction(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned align = fieldFromInstruction32(Insn, 4, 1);
-  unsigned size = fieldFromInstruction32(Insn, 6, 2);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned align = fieldFromInstruction(Insn, 4, 1);
+  unsigned size = fieldFromInstruction(Insn, 6, 2);
 
   align *= (1 << size);
 
@@ -2726,12 +2740,12 @@ static DecodeStatus DecodeVLD2DupInstruction(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned align = fieldFromInstruction32(Insn, 4, 1);
-  unsigned size = 1 << fieldFromInstruction32(Insn, 6, 2);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned align = fieldFromInstruction(Insn, 4, 1);
+  unsigned size = 1 << fieldFromInstruction(Insn, 6, 2);
   align *= 2*size;
 
   switch (Inst.getOpcode()) {
@@ -2774,11 +2788,11 @@ static DecodeStatus DecodeVLD3DupInstruction(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned inc = fieldFromInstruction(Insn, 5, 1) + 1;
 
   if (!Check(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2809,13 +2823,13 @@ static DecodeStatus DecodeVLD4DupInstruction(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  unsigned size = fieldFromInstruction32(Insn, 6, 2);
-  unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
-  unsigned align = fieldFromInstruction32(Insn, 4, 1);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  unsigned size = fieldFromInstruction(Insn, 6, 2);
+  unsigned inc = fieldFromInstruction(Insn, 5, 1) + 1;
+  unsigned align = fieldFromInstruction(Insn, 4, 1);
 
   if (size == 0x3) {
     size = 4;
@@ -2862,14 +2876,14 @@ DecodeNEONModImmInstruction(MCInst &Inst, unsigned Insn,
                             uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned imm = fieldFromInstruction32(Insn, 0, 4);
-  imm |= fieldFromInstruction32(Insn, 16, 3) << 4;
-  imm |= fieldFromInstruction32(Insn, 24, 1) << 7;
-  imm |= fieldFromInstruction32(Insn, 8, 4) << 8;
-  imm |= fieldFromInstruction32(Insn, 5, 1) << 12;
-  unsigned Q = fieldFromInstruction32(Insn, 6, 1);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned imm = fieldFromInstruction(Insn, 0, 4);
+  imm |= fieldFromInstruction(Insn, 16, 3) << 4;
+  imm |= fieldFromInstruction(Insn, 24, 1) << 7;
+  imm |= fieldFromInstruction(Insn, 8, 4) << 8;
+  imm |= fieldFromInstruction(Insn, 5, 1) << 12;
+  unsigned Q = fieldFromInstruction(Insn, 6, 1);
 
   if (Q) {
     if (!Check(S, DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)))
@@ -2907,11 +2921,11 @@ static DecodeStatus DecodeVSHLMaxInstruction(MCInst &Inst, unsigned Insn,
                                         uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  Rm |= fieldFromInstruction32(Insn, 5, 1) << 4;
-  unsigned size = fieldFromInstruction32(Insn, 18, 2);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  Rm |= fieldFromInstruction(Insn, 5, 1) << 4;
+  unsigned size = fieldFromInstruction(Insn, 18, 2);
 
   if (!Check(S, DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2950,13 +2964,13 @@ static DecodeStatus DecodeTBLInstruction(MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
 
-  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
-  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
-  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
-  Rn |= fieldFromInstruction32(Insn, 7, 1) << 4;
-  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
-  Rm |= fieldFromInstruction32(Insn, 5, 1) << 4;
-  unsigned op = fieldFromInstruction32(Insn, 6, 1);
+  unsigned Rd = fieldFromInstruction(Insn, 12, 4);
+  Rd |= fieldFromInstruction(Insn, 22, 1) << 4;
+  unsigned Rn = fieldFromInstruction(Insn, 16, 4);
+  Rn |= fieldFromInstruction(Insn, 7, 1) << 4;
+  unsigned Rm = fieldFromInstruction(Insn, 0, 4);
+  Rm |= fieldFromInstruction(Insn, 5, 1) << 4;
+  unsigned op = fieldFromInstruction(Insn, 6, 1);
 
   if (!Check(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)))
     return MCDisassembler::Fail;
@@ -2986,8 +3000,8 @@ static DecodeStatus DecodeThumbAddSpecialReg(MCInst &Inst, uint16_t Insn,
                                      uint64_t Address, const void *Decoder) {