Add a disassembler to the PowerPC backend

The tests for the disassembler were adapted from the encoder tests, and for the
most part, the output from the disassembler matches that encoder-test inputs.
There are some places where more-informative mnemonics could be produced
(notably for the branch instructions), and those cases are noted in the tests
with FIXMEs.

Future work includes:

 - Generating more-informative mnemonics when possible (this may also be done
   in the printer).

 - Remove the dependence on positional "numbered" operand-to-variable mapping
   (for both encoding and decoding).

 - Internally using 64-bit instruction variants in 64-bit mode (if this turns
   out to matter).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197693 91177308-0d34-0410-b5e6-96231b3b80d8

11 files changed, 361 insertions, 3 deletions

diff --git a/lib/Target/PowerPC/CMakeLists.txt b/lib/Target/PowerPC/CMakeLists.txt
index f2cb05a9d2..ea4de63a24 100644
--- a/lib/Target/PowerPC/CMakeLists.txt
+++ b/lib/Target/PowerPC/CMakeLists.txt
@@ -3,6 +3,7 @@ set(LLVM_TARGET_DEFINITIONS PPC.td)
 tablegen(LLVM PPCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM PPCGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM PPCGenCodeEmitter.inc -gen-emitter)
+tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM PPCGenMCCodeEmitter.inc -gen-emitter -mc-emitter)
 tablegen(LLVM PPCGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM PPCGenInstrInfo.inc -gen-instr-info)
@@ -35,6 +36,7 @@ add_llvm_target(PowerPCCodeGen
   )
 
 add_subdirectory(AsmParser)
+add_subdirectory(Disassembler)
 add_subdirectory(InstPrinter)
 add_subdirectory(TargetInfo)
 add_subdirectory(MCTargetDesc)
diff --git a/lib/Target/PowerPC/Disassembler/CMakeLists.txt b/lib/Target/PowerPC/Disassembler/CMakeLists.txt
new file mode 100644
index 0000000000..ca457df88d
--- /dev/null
+++ b/lib/Target/PowerPC/Disassembler/CMakeLists.txt
@@ -0,0 +1,3 @@
+add_llvm_library(LLVMPowerPCDisassembler
+  PPCDisassembler.cpp
+  )
diff --git a/lib/Target/PowerPC/Disassembler/LLVMBuild.txt b/lib/Target/PowerPC/Disassembler/LLVMBuild.txt
new file mode 100644
index 0000000000..7f29040eb6
--- /dev/null
+++ b/lib/Target/PowerPC/Disassembler/LLVMBuild.txt
@@ -0,0 +1,23 @@
+;===-- ./lib/Target/PowerPC/Disassembler/LLVMBuild.txt ---------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Library
+name = PowerPCDisassembler
+parent = PowerPC
+required_libraries = MC Support PowerPCDesc PowerPCInfo
+add_to_library_groups = PowerPC
diff --git a/lib/Target/PowerPC/Disassembler/Makefile b/lib/Target/PowerPC/Disassembler/Makefile
new file mode 100644
index 0000000000..86e3b47522
--- /dev/null
+++ b/lib/Target/PowerPC/Disassembler/Makefile
@@ -0,0 +1,16 @@
+##===-- lib/Target/PowerPC/Disassembler/Makefile -----------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../../..
+LIBRARYNAME = LLVMPowerPCDisassembler
+
+# Hack: we need to include 'main' PPC target directory to grab private headers
+CPP.Flags += -I$(PROJ_OBJ_DIR)/.. -I$(PROJ_SRC_DIR)/..
+
+include $(LEVEL)/Makefile.common
diff --git a/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp b/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp
new file mode 100644
index 0000000000..1dab14b2ca
--- /dev/null
+++ b/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp
@@ -0,0 +1,293 @@
+//===------ PPCDisassembler.cpp - Disassembler for PowerPC ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PPC.h"
+#include "llvm/MC/MCDisassembler.h"
+#include "llvm/MC/MCFixedLenDisassembler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Support/MemoryObject.h"
+#include "llvm/Support/TargetRegistry.h"
+
+using namespace llvm;
+
+typedef MCDisassembler::DecodeStatus DecodeStatus;
+
+namespace {
+class PPCDisassembler : public MCDisassembler {
+public:
+  PPCDisassembler(const MCSubtargetInfo &STI)
+    : MCDisassembler(STI) {}
+  virtual ~PPCDisassembler() {}
+
+  // Override MCDisassembler.
+  virtual DecodeStatus getInstruction(MCInst &instr,
+                                      uint64_t &size,
+                                      const MemoryObject &region,
+                                      uint64_t address,
+                                      raw_ostream &vStream,
+                                      raw_ostream &cStream) const LLVM_OVERRIDE;
+};
+} // end anonymous namespace
+
+static MCDisassembler *createPPCDisassembler(const Target &T,
+                                             const MCSubtargetInfo &STI) {
+  return new PPCDisassembler(STI);
+}
+
+extern "C" void LLVMInitializePowerPCDisassembler() {
+  // Register the disassembler for each target.
+  TargetRegistry::RegisterMCDisassembler(ThePPC32Target,
+                                         createPPCDisassembler);
+  TargetRegistry::RegisterMCDisassembler(ThePPC64Target,
+                                         createPPCDisassembler);
+  TargetRegistry::RegisterMCDisassembler(ThePPC64LETarget,
+                                         createPPCDisassembler);
+}
+
+// FIXME: These can be generated by TableGen from the existing register
+// encoding values!
+
+static const unsigned CRRegs[] = {
+  PPC::CR0, PPC::CR1, PPC::CR2, PPC::CR3,
+  PPC::CR4, PPC::CR5, PPC::CR6, PPC::CR7
+};
+
+static const unsigned CRBITRegs[] = {
+  PPC::CR0LT, PPC::CR0GT, PPC::CR0EQ, PPC::CR0UN,
+  PPC::CR1LT, PPC::CR1GT, PPC::CR1EQ, PPC::CR1UN,
+  PPC::CR2LT, PPC::CR2GT, PPC::CR2EQ, PPC::CR2UN,
+  PPC::CR3LT, PPC::CR3GT, PPC::CR3EQ, PPC::CR3UN,
+  PPC::CR4LT, PPC::CR4GT, PPC::CR4EQ, PPC::CR4UN,
+  PPC::CR5LT, PPC::CR5GT, PPC::CR5EQ, PPC::CR5UN,
+  PPC::CR6LT, PPC::CR6GT, PPC::CR6EQ, PPC::CR6UN,
+  PPC::CR7LT, PPC::CR7GT, PPC::CR7EQ, PPC::CR7UN
+};
+
+static const unsigned FRegs[] = {
+  PPC::F0, PPC::F1, PPC::F2, PPC::F3,
+  PPC::F4, PPC::F5, PPC::F6, PPC::F7,
+  PPC::F8, PPC::F9, PPC::F10, PPC::F11,
+  PPC::F12, PPC::F13, PPC::F14, PPC::F15,
+  PPC::F16, PPC::F17, PPC::F18, PPC::F19,
+  PPC::F20, PPC::F21, PPC::F22, PPC::F23,
+  PPC::F24, PPC::F25, PPC::F26, PPC::F27,
+  PPC::F28, PPC::F29, PPC::F30, PPC::F31
+};
+
+static const unsigned VRegs[] = {
+  PPC::V0, PPC::V1, PPC::V2, PPC::V3,
+  PPC::V4, PPC::V5, PPC::V6, PPC::V7,
+  PPC::V8, PPC::V9, PPC::V10, PPC::V11,
+  PPC::V12, PPC::V13, PPC::V14, PPC::V15,
+  PPC::V16, PPC::V17, PPC::V18, PPC::V19,
+  PPC::V20, PPC::V21, PPC::V22, PPC::V23,
+  PPC::V24, PPC::V25, PPC::V26, PPC::V27,
+  PPC::V28, PPC::V29, PPC::V30, PPC::V31
+};
+
+static const unsigned GPRegs[] = {
+  PPC::R0, PPC::R1, PPC::R2, PPC::R3,
+  PPC::R4, PPC::R5, PPC::R6, PPC::R7,
+  PPC::R8, PPC::R9, PPC::R10, PPC::R11,
+  PPC::R12, PPC::R13, PPC::R14, PPC::R15,
+  PPC::R16, PPC::R17, PPC::R18, PPC::R19,
+  PPC::R20, PPC::R21, PPC::R22, PPC::R23,
+  PPC::R24, PPC::R25, PPC::R26, PPC::R27,
+  PPC::R28, PPC::R29, PPC::R30, PPC::R31
+};
+
+static const unsigned GP0Regs[] = {
+  PPC::ZERO, PPC::R1, PPC::R2, PPC::R3,
+  PPC::R4, PPC::R5, PPC::R6, PPC::R7,
+  PPC::R8, PPC::R9, PPC::R10, PPC::R11,
+  PPC::R12, PPC::R13, PPC::R14, PPC::R15,
+  PPC::R16, PPC::R17, PPC::R18, PPC::R19,
+  PPC::R20, PPC::R21, PPC::R22, PPC::R23,
+  PPC::R24, PPC::R25, PPC::R26, PPC::R27,
+  PPC::R28, PPC::R29, PPC::R30, PPC::R31
+};
+
+static const unsigned G8Regs[] = {
+  PPC::X0, PPC::X1, PPC::X2, PPC::X3,
+  PPC::X4, PPC::X5, PPC::X6, PPC::X7,
+  PPC::X8, PPC::X9, PPC::X10, PPC::X11,
+  PPC::X12, PPC::X13, PPC::X14, PPC::X15,
+  PPC::X16, PPC::X17, PPC::X18, PPC::X19,
+  PPC::X20, PPC::X21, PPC::X22, PPC::X23,
+  PPC::X24, PPC::X25, PPC::X26, PPC::X27,
+  PPC::X28, PPC::X29, PPC::X30, PPC::X31
+};
+
+template <std::size_t N>
+static DecodeStatus decodeRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                        const unsigned (&Regs)[N]) {
+  assert(RegNo < N && "Invalid register number");
+  Inst.addOperand(MCOperand::CreateReg(Regs[RegNo]));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus DecodeCRRCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, CRRegs);
+}
+
+static DecodeStatus DecodeCRBITRCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, CRBITRegs);
+}
+
+static DecodeStatus DecodeF4RCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, FRegs);
+}
+
+static DecodeStatus DecodeF8RCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, FRegs);
+}
+
+static DecodeStatus DecodeVRRCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, VRegs);
+}
+
+static DecodeStatus DecodeGPRCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, GPRegs);
+}
+
+static DecodeStatus DecodeGPRC_NOR0RegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, GP0Regs);
+}
+
+static DecodeStatus DecodeG8RCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                            uint64_t Address,
+                                            const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, G8Regs);
+}
+
+#define DecodePointerLikeRegClass0 DecodeGPRCRegisterClass
+#define DecodePointerLikeRegClass1 DecodeGPRC_NOR0RegisterClass
+
+template<unsigned N>
+static DecodeStatus decodeUImmOperand(MCInst &Inst, uint64_t Imm,
+                                      int64_t Address, const void *Decoder) {
+  assert(isUInt<N>(Imm) && "Invalid immediate");
+  Inst.addOperand(MCOperand::CreateImm(Imm));
+  return MCDisassembler::Success;
+}
+
+template<unsigned N>
+static DecodeStatus decodeSImmOperand(MCInst &Inst, uint64_t Imm,
+                                      int64_t Address, const void *Decoder) {
+  assert(isUInt<N>(Imm) && "Invalid immediate");
+  Inst.addOperand(MCOperand::CreateImm(SignExtend64<N>(Imm)));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus decodeMemRIOperands(MCInst &Inst, uint64_t Imm,
+                                        int64_t Address, const void *Decoder) {
+  // Decode the memri field (imm, reg), which has the low 16-bits as the
+  // displacement and the next 5 bits as the register #.
+
+  uint64_t Base = Imm >> 16;
+  uint64_t Disp = Imm & 0xFFFF;
+
+  assert(Base < 32 && "Invalid base register");
+
+  switch (Inst.getOpcode()) {
+  default: break;
+  case PPC::LBZU:
+  case PPC::LHAU:
+  case PPC::LHZU:
+  case PPC::LWZU:
+  case PPC::LFSU:
+  case PPC::LFDU:
+    // Add the tied output operand.
+    Inst.addOperand(MCOperand::CreateReg(GP0Regs[Base]));
+    break;
+  case PPC::STBU:
+  case PPC::STHU:
+  case PPC::STWU:
+  case PPC::STFSU:
+  case PPC::STFDU:
+    Inst.insert(Inst.begin(), MCOperand::CreateReg(GP0Regs[Base]));
+    break;
+  }
+
+  Inst.addOperand(MCOperand::CreateImm(SignExtend64<16>(Disp)));
+  Inst.addOperand(MCOperand::CreateReg(GP0Regs[Base]));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus decodeMemRIXOperands(MCInst &Inst, uint64_t Imm,
+                                         int64_t Address, const void *Decoder) {
+  // Decode the memrix field (imm, reg), which has the low 14-bits as the
+  // displacement and the next 5 bits as the register #.
+
+  uint64_t Base = Imm >> 14;
+  uint64_t Disp = Imm & 0x3FFF;
+
+  assert(Base < 32 && "Invalid base register");
+
+  if (Inst.getOpcode() == PPC::LDU)
+    // Add the tied output operand.
+    Inst.addOperand(MCOperand::CreateReg(GP0Regs[Base]));
+  else if (Inst.getOpcode() == PPC::STDU)
+    Inst.insert(Inst.begin(), MCOperand::CreateReg(GP0Regs[Base]));
+
+  Inst.addOperand(MCOperand::CreateImm(SignExtend64<16>(Disp << 2)));
+  Inst.addOperand(MCOperand::CreateReg(GP0Regs[Base]));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus decodeCRBitMOperand(MCInst &Inst, uint64_t Imm,
+                                        int64_t Address, const void *Decoder) {
+  // The cr bit encoding is 0x80 >> cr_reg_num.
+
+  unsigned Zeros = countTrailingZeros(Imm);
+  assert(Zeros < 8 && "Invalid CR bit value");
+
+  Inst.addOperand(MCOperand::CreateReg(CRRegs[7 - Zeros]));
+  return MCDisassembler::Success;
+}
+
+#include "PPCGenDisassemblerTables.inc"
+
+DecodeStatus PPCDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
+                                                 const MemoryObject &Region,
+                                                 uint64_t Address,
+                                                 raw_ostream &os,
+                                                 raw_ostream &cs) const {
+  // Get the four bytes of the instruction.
+  uint8_t Bytes[4];
+  Size = 4;
+  if (Region.readBytes(Address, Size, Bytes) == -1) {
+    Size = 0;
+    return MCDisassembler::Fail;
+  }
+
+  // The instruction is big-endian encoded.
+  uint32_t Inst = (Bytes[0] << 24) |
+                  (Bytes[1] << 16) |
+                  (Bytes[2] <<  8) |
+                  (Bytes[3] <<  0);
+
+  return decodeInstruction(DecoderTable32, MI, Inst, Address, this, STI);
+}
+
diff --git a/lib/Target/PowerPC/LLVMBuild.txt b/lib/Target/PowerPC/LLVMBuild.txt
index 3ddef36d07..9d173d64b9 100644
--- a/lib/Target/PowerPC/LLVMBuild.txt
+++ b/lib/Target/PowerPC/LLVMBuild.txt
@@ -16,7 +16,7 @@
 ;===------------------------------------------------------------------------===;
 
 [common]
-subdirectories = AsmParser InstPrinter MCTargetDesc TargetInfo
+subdirectories = AsmParser Disassembler InstPrinter MCTargetDesc TargetInfo
 
 [component_0]
 type = TargetGroup
@@ -24,6 +24,7 @@ name = PowerPC
 parent = Target
 has_asmparser = 1
 has_asmprinter = 1
+has_disassembler = 1
 has_jit = 1
 
 [component_1]
diff --git a/lib/Target/PowerPC/Makefile b/lib/Target/PowerPC/Makefile
index 21fdcd9350..c96674809b 100644
--- a/lib/Target/PowerPC/Makefile
+++ b/lib/Target/PowerPC/Makefile
@@ -16,8 +16,9 @@ BUILT_SOURCES = PPCGenRegisterInfo.inc PPCGenAsmMatcher.inc \
                 PPCGenAsmWriter.inc  PPCGenCodeEmitter.inc \
                 PPCGenInstrInfo.inc PPCGenDAGISel.inc \
                 PPCGenSubtargetInfo.inc PPCGenCallingConv.inc \
-                PPCGenMCCodeEmitter.inc PPCGenFastISel.inc
+                PPCGenMCCodeEmitter.inc PPCGenFastISel.inc \
+                PPCGenDisassemblerTables.inc
 
-DIRS = AsmParser InstPrinter TargetInfo MCTargetDesc
+DIRS = AsmParser Disassembler InstPrinter TargetInfo MCTargetDesc
 
 include $(LEVEL)/Makefile.common
diff --git a/lib/Target/PowerPC/PPC.td b/lib/Target/PowerPC/PPC.td
index 044740e4c7..6611498378 100644
--- a/lib/Target/PowerPC/PPC.td
+++ b/lib/Target/PowerPC/PPC.td
@@ -283,6 +283,9 @@ include "PPCCallingConv.td"
 
 def PPCInstrInfo : InstrInfo {
   let isLittleEndianEncoding = 1;
+
+  // FIXME: Unset this when no longer needed!
+  let decodePositionallyEncodedOperands = 1;
 }
 
 def PPCAsmParser : AsmParser {
diff --git a/lib/Target/PowerPC/PPCInstr64Bit.td b/lib/Target/PowerPC/PPCInstr64Bit.td
index bfbcdf25f1..5d54150278 100644
--- a/lib/Target/PowerPC/PPCInstr64Bit.td
+++ b/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -19,11 +19,13 @@ def s16imm64 : Operand<i64> {
   let PrintMethod = "printS16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCS16ImmAsmOperand;
+  let DecoderMethod = "decodeSImmOperand<16>";
 }
 def u16imm64 : Operand<i64> {
   let PrintMethod = "printU16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCU16ImmAsmOperand;
+  let DecoderMethod = "decodeUImmOperand<16>";
 }
 def s17imm64 : Operand<i64> {
   // This operand type is used for addis/lis to allow the assembler parser
@@ -32,6 +34,7 @@ def s17imm64 : Operand<i64> {
   let PrintMethod = "printS16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCS17ImmAsmOperand;
+  let DecoderMethod = "decodeSImmOperand<16>";
 }
 def tocentry : Operand<iPTR> {
   let MIOperandInfo = (ops i64imm:$imm);
diff --git a/lib/Target/PowerPC/PPCInstrFormats.td b/lib/Target/PowerPC/PPCInstrFormats.td
index c5e179fec2..dae40c0cc2 100644
--- a/lib/Target/PowerPC/PPCInstrFormats.td
+++ b/lib/Target/PowerPC/PPCInstrFormats.td
@@ -14,6 +14,8 @@
 class I<bits<6> opcode, dag OOL, dag IOL, string asmstr, InstrItinClass itin>
         : Instruction {
   field bits<32> Inst;
+  field bits<32> SoftFail = 0;
+  let Size = 4;
 
   bit PPC64 = 0;  // Default value, override with isPPC64
 
@@ -67,6 +69,8 @@ class I2<bits<6> opcode1, bits<6> opcode2, dag OOL, dag IOL, string asmstr,
          InstrItinClass itin>
         : Instruction {
   field bits<64> Inst;
+  field bits<64> SoftFail = 0;
+  let Size = 8;
 
   bit PPC64 = 0;  // Default value, override with isPPC64
 
diff --git a/lib/Target/PowerPC/PPCInstrInfo.td b/lib/Target/PowerPC/PPCInstrInfo.td
index cef14f20ae..7caa86e56b 100644
--- a/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/lib/Target/PowerPC/PPCInstrInfo.td
@@ -411,6 +411,7 @@ def PPCS5ImmAsmOperand : AsmOperandClass {
 def s5imm   : Operand<i32> {
   let PrintMethod = "printS5ImmOperand";
   let ParserMatchClass = PPCS5ImmAsmOperand;
+  let DecoderMethod = "decodeSImmOperand<5>";
 }
 def PPCU5ImmAsmOperand : AsmOperandClass {
   let Name = "U5Imm"; let PredicateMethod = "isU5Imm";
@@ -419,6 +420,7 @@ def PPCU5ImmAsmOperand : AsmOperandClass {
 def u5imm   : Operand<i32> {
   let PrintMethod = "printU5ImmOperand";
   let ParserMatchClass = PPCU5ImmAsmOperand;
+  let DecoderMethod = "decodeUImmOperand<5>";
 }
 def PPCU6ImmAsmOperand : AsmOperandClass {
   let Name = "U6Imm"; let PredicateMethod = "isU6Imm";
@@ -427,6 +429,7 @@ def PPCU6ImmAsmOperand : AsmOperandClass {
 def u6imm   : Operand<i32> {
   let PrintMethod = "printU6ImmOperand";
   let ParserMatchClass = PPCU6ImmAsmOperand;
+  let DecoderMethod = "decodeUImmOperand<6>";
 }
 def PPCS16ImmAsmOperand : AsmOperandClass {
   let Name = "S16Imm"; let PredicateMethod = "isS16Imm";
@@ -436,6 +439,7 @@ def s16imm  : Operand<i32> {
   let PrintMethod = "printS16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCS16ImmAsmOperand;
+  let DecoderMethod = "decodeSImmOperand<16>";
 }
 def PPCU16ImmAsmOperand : AsmOperandClass {
   let Name = "U16Imm"; let PredicateMethod = "isU16Imm";
@@ -445,6 +449,7 @@ def u16imm  : Operand<i32> {
   let PrintMethod = "printU16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCU16ImmAsmOperand;
+  let DecoderMethod = "decodeUImmOperand<16>";
 }
 def PPCS17ImmAsmOperand : AsmOperandClass {
   let Name = "S17Imm"; let PredicateMethod = "isS17Imm";
@@ -457,6 +462,7 @@ def s17imm  : Operand<i32> {
   let PrintMethod = "printS16ImmOperand";
   let EncoderMethod = "getImm16Encoding";
   let ParserMatchClass = PPCS17ImmAsmOperand;
+  let DecoderMethod = "decodeSImmOperand<16>";
 }
 def PPCDirectBrAsmOperand : AsmOperandClass {
   let Name = "DirectBr"; let PredicateMethod = "isDirectBr";
@@ -502,6 +508,7 @@ def PPCCRBitMaskOperand : AsmOperandClass {
 def crbitm: Operand<i8> {
   let PrintMethod = "printcrbitm";
   let EncoderMethod = "get_crbitm_encoding";
+  let DecoderMethod = "decodeCRBitMOperand";
   let ParserMatchClass = PPCCRBitMaskOperand;
 }
 // Address operands
@@ -539,6 +546,7 @@ def memri : Operand<iPTR> {
   let PrintMethod = "printMemRegImm";
   let MIOperandInfo = (ops dispRI:$imm, ptr_rc_nor0:$reg);
   let EncoderMethod = "getMemRIEncoding";
+  let DecoderMethod = "decodeMemRIOperands";
 }
 def memrr : Operand<iPTR> {
   let PrintMethod = "printMemRegReg";
@@ -548,6 +556,7 @@ def memrix : Operand<iPTR> {   // memri where the imm is 4-aligned.
   let PrintMethod = "printMemRegImm";
   let MIOperandInfo = (ops dispRIX:$imm, ptr_rc_nor0:$reg);
   let EncoderMethod = "getMemRIXEncoding";
+  let DecoderMethod = "decodeMemRIXOperands";
 }
 
 // A single-register address. This is used with the SjLj