lib/Target/PowerPC/PPC.td

   1 //===-- PPC.td - Describe the PowerPC Target Machine -------*- tablegen -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This is the top level entry point for the PowerPC target.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 // Get the target-independent interfaces which we are implementing.
  15 //
  16 include "llvm/Target/Target.td"
  17
  18 //===----------------------------------------------------------------------===//
  19 // PowerPC Subtarget features.
  20 //
  21
  22 //===----------------------------------------------------------------------===//
  23 // CPU Directives                                                             //
  24 //===----------------------------------------------------------------------===//
  25
  26 def Directive440 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_440", "">;
  27 def Directive601 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_601", "">;
  28 def Directive602 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_602", "">;
  29 def Directive603 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_603", "">;
  30 def Directive604 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_603", "">;
  31 def Directive620 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_603", "">;
  32 def Directive7400: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_7400", "">;
  33 def Directive750 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_750", "">;
  34 def Directive970 : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_970", "">;
  35 def Directive32  : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_32", "">;
  36 def Directive64  : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_64", "">;
  37 def DirectiveA2  : SubtargetFeature<"", "DarwinDirective", "PPC::DIR_A2", "">;
  38 def DirectiveE500mc : SubtargetFeature<"", "DarwinDirective",
  39                                        "PPC::DIR_E500mc", "">;
  40 def DirectiveE5500  : SubtargetFeature<"", "DarwinDirective",
  41                                        "PPC::DIR_E5500", "">;
  42 def DirectivePwr3: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR3", "">;
  43 def DirectivePwr4: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR4", "">;
  44 def DirectivePwr5: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR5", "">;
  45 def DirectivePwr5x: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR5X", "">;
  46 def DirectivePwr6: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR6", "">;
  47 def DirectivePwr6x: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR6X", "">;
  48 def DirectivePwr7: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR7", "">;
  49 def DirectivePwr8: SubtargetFeature<"", "DarwinDirective", "PPC::DIR_PWR8", "">;
  50
  51 def Feature64Bit     : SubtargetFeature<"64bit","Has64BitSupport", "true",
  52                                         "Enable 64-bit instructions">;
  53 def Feature64BitRegs : SubtargetFeature<"64bitregs","Use64BitRegs", "true",
  54                               "Enable 64-bit registers usage for ppc32 [beta]">;
  55 def FeatureCRBits    : SubtargetFeature<"crbits", "UseCRBits", "true",
  56                               "Use condition-register bits individually">;
  57 def FeatureAltivec   : SubtargetFeature<"altivec","HasAltivec", "true",
  58                                         "Enable Altivec instructions">;
  59 def FeatureSPE       : SubtargetFeature<"spe","HasSPE", "true",
  60                                         "Enable SPE instructions">;
  61 def FeatureMFOCRF    : SubtargetFeature<"mfocrf","HasMFOCRF", "true",
  62                                         "Enable the MFOCRF instruction">;
  63 def FeatureFSqrt     : SubtargetFeature<"fsqrt","HasFSQRT", "true",
  64                                         "Enable the fsqrt instruction">;
  65 def FeatureFCPSGN    : SubtargetFeature<"fcpsgn", "HasFCPSGN", "true",
  66                                         "Enable the fcpsgn instruction">;
  67 def FeatureFRE       : SubtargetFeature<"fre", "HasFRE", "true",
  68                                         "Enable the fre instruction">;
  69 def FeatureFRES      : SubtargetFeature<"fres", "HasFRES", "true",
  70                                         "Enable the fres instruction">;
  71 def FeatureFRSQRTE   : SubtargetFeature<"frsqrte", "HasFRSQRTE", "true",
  72                                         "Enable the frsqrte instruction">;
  73 def FeatureFRSQRTES  : SubtargetFeature<"frsqrtes", "HasFRSQRTES", "true",
  74                                         "Enable the frsqrtes instruction">;
  75 def FeatureRecipPrec : SubtargetFeature<"recipprec", "HasRecipPrec", "true",
  76                               "Assume higher precision reciprocal estimates">;
  77 def FeatureSTFIWX    : SubtargetFeature<"stfiwx","HasSTFIWX", "true",
  78                                         "Enable the stfiwx instruction">;
  79 def FeatureLFIWAX    : SubtargetFeature<"lfiwax","HasLFIWAX", "true",
  80                                         "Enable the lfiwax instruction">;
  81 def FeatureFPRND     : SubtargetFeature<"fprnd", "HasFPRND", "true",
  82                                         "Enable the fri[mnpz] instructions">;
  83 def FeatureFPCVT     : SubtargetFeature<"fpcvt", "HasFPCVT", "true",
  84   "Enable fc[ft]* (unsigned and single-precision) and lfiwzx instructions">;
  85 def FeatureISEL      : SubtargetFeature<"isel","HasISEL", "true",
  86                                         "Enable the isel instruction">;
  87 def FeaturePOPCNTD   : SubtargetFeature<"popcntd","HasPOPCNTD", "true",
  88                                         "Enable the popcnt[dw] instructions">;
  89 def FeatureBPERMD    : SubtargetFeature<"bpermd", "HasBPERMD", "true",
  90                                         "Enable the bpermd instruction">;
  91 def FeatureExtDiv    : SubtargetFeature<"extdiv", "HasExtDiv", "true",
  92                                         "Enable extended divide instructions">;
  93 def FeatureLDBRX     : SubtargetFeature<"ldbrx","HasLDBRX", "true",
  94                                         "Enable the ldbrx instruction">;
  95 def FeatureCMPB      : SubtargetFeature<"cmpb", "HasCMPB", "true",
  96                                         "Enable the cmpb instruction">;
  97 def FeatureICBT      : SubtargetFeature<"icbt","HasICBT", "true",
  98                                         "Enable icbt instruction">;
  99 def FeatureBookE     : SubtargetFeature<"booke", "IsBookE", "true",
 100                                         "Enable Book E instructions",
 101                                         [FeatureICBT]>;
 102 def FeatureMSYNC     : SubtargetFeature<"msync", "HasOnlyMSYNC", "true",
 103                               "Has only the msync instruction instead of sync",
 104                               [FeatureBookE]>;
 105 def FeatureE500      : SubtargetFeature<"e500", "IsE500", "true",
 106                                         "Enable E500/E500mc instructions">;
 107 def FeaturePPC4xx    : SubtargetFeature<"ppc4xx", "IsPPC4xx", "true",
 108                                         "Enable PPC 4xx instructions">;
 109 def FeaturePPC6xx    : SubtargetFeature<"ppc6xx", "IsPPC6xx", "true",
 110                                         "Enable PPC 6xx instructions">;
 111 def FeatureQPX       : SubtargetFeature<"qpx","HasQPX", "true",
 112                                         "Enable QPX instructions">;
 113 def FeatureVSX       : SubtargetFeature<"vsx","HasVSX", "true",
 114                                         "Enable VSX instructions",
 115                                         [FeatureAltivec]>;
 116 def FeatureP8Altivec : SubtargetFeature<"power8-altivec", "HasP8Altivec", "true",
 117                                         "Enable POWER8 Altivec instructions",
 118                                         [FeatureAltivec]>;
 119 def FeatureP8Crypto : SubtargetFeature<"crypto", "HasP8Crypto", "true",
 120                                        "Enable POWER8 Crypto instructions",
 121                                        [FeatureP8Altivec]>;
 122 def FeatureP8Vector  : SubtargetFeature<"power8-vector", "HasP8Vector", "true",
 123                                         "Enable POWER8 vector instructions",
 124                                         [FeatureVSX, FeatureP8Altivec]>;
 125 def FeatureDirectMove :
 126   SubtargetFeature<"direct-move", "HasDirectMove", "true",
 127                    "Enable Power8 direct move instructions",
 128                    [FeatureVSX]>;
 129 def FeaturePartwordAtomic : SubtargetFeature<"partword-atomics",
 130                                              "HasPartwordAtomics", "true",
 131                                              "Enable l[bh]arx and st[bh]cx.">;
 132 def FeatureInvariantFunctionDescriptors :
 133   SubtargetFeature<"invariant-function-descriptors",
 134                    "HasInvariantFunctionDescriptors", "true",
 135                    "Assume function descriptors are invariant">;
 136 def FeatureHTM : SubtargetFeature<"htm", "HasHTM", "true",
 137                                   "Enable Hardware Transactional Memory instructions">;
 138 def FeatureMFTB   : SubtargetFeature<"", "FeatureMFTB", "true",
 139                                         "Implement mftb using the mfspr instruction">;
 140 def FeatureFusion : SubtargetFeature<"fusion", "HasFusion", "true",
 141                                      "Target supports add/load integer fusion.">;
 142
 143 def DeprecatedDST    : SubtargetFeature<"", "DeprecatedDST", "true",
 144   "Treat vector data stream cache control instructions as deprecated">;
 145
 146 /*  Since new processors generally contain a superset of features of those that
 147     came before them, the idea is to make implementations of new processors
 148     less error prone and easier to read.
 149     Namely:
 150         list<SubtargetFeature> Power8FeatureList = ...
 151         list<SubtargetFeature> FutureProcessorSpecificFeatureList =
 152             [ features that Power8 does not support ]
 153         list<SubtargetFeature> FutureProcessorFeatureList =
 154             !listconcat(Power8FeatureList, FutureProcessorSpecificFeatureList)
 155
 156     Makes it explicit and obvious what is new in FutureProcesor vs. Power8 as
 157     well as providing a single point of definition if the feature set will be
 158     used elsewhere.
 159 */
 160 def ProcessorFeatures {
 161   list<SubtargetFeature> Power7FeatureList =
 162       [DirectivePwr7, FeatureAltivec, FeatureVSX,
 163        FeatureMFOCRF, FeatureFCPSGN, FeatureFSqrt, FeatureFRE,
 164        FeatureFRES, FeatureFRSQRTE, FeatureFRSQRTES,
 165        FeatureRecipPrec, FeatureSTFIWX, FeatureLFIWAX,
 166        FeatureFPRND, FeatureFPCVT, FeatureISEL,
 167        FeaturePOPCNTD, FeatureCMPB, FeatureLDBRX,
 168        Feature64Bit /*, Feature64BitRegs */,
 169        FeatureBPERMD, FeatureExtDiv,
 170        FeatureMFTB, DeprecatedDST];
 171   list<SubtargetFeature> Power8SpecificFeatures =
 172       [DirectivePwr8, FeatureP8Altivec, FeatureP8Vector, FeatureP8Crypto,
 173        FeatureHTM, FeatureDirectMove, FeatureICBT, FeaturePartwordAtomic,
 174        FeatureFusion];
 175   list<SubtargetFeature> Power8FeatureList =
 176       !listconcat(Power7FeatureList, Power8SpecificFeatures);
 177 }
 178
 179 // Note: Future features to add when support is extended to more
 180 // recent ISA levels:
 181 //
 182 // DFP          p6, p6x, p7        decimal floating-point instructions
 183 // POPCNTB      p5 through p7      popcntb and related instructions
 184
 185 //===----------------------------------------------------------------------===//
 186 // Classes used for relation maps.
 187 //===----------------------------------------------------------------------===//
 188 // RecFormRel - Filter class used to relate non-record-form instructions with
 189 // their record-form variants.
 190 class RecFormRel;
 191
 192 // AltVSXFMARel - Filter class used to relate the primary addend-killing VSX
 193 // FMA instruction forms with their corresponding factor-killing forms.
 194 class AltVSXFMARel {
 195   bit IsVSXFMAAlt = 0;
 196 }
 197
 198 //===----------------------------------------------------------------------===//
 199 // Relation Map Definitions.
 200 //===----------------------------------------------------------------------===//
 201
 202 def getRecordFormOpcode : InstrMapping {
 203   let FilterClass = "RecFormRel";
 204   // Instructions with the same BaseName and Interpretation64Bit values
 205   // form a row.
 206   let RowFields = ["BaseName", "Interpretation64Bit"];
 207   // Instructions with the same RC value form a column.
 208   let ColFields = ["RC"];
 209   // The key column are the non-record-form instructions.
 210   let KeyCol = ["0"];
 211   // Value columns RC=1
 212   let ValueCols = [["1"]];
 213 }
 214
 215 def getNonRecordFormOpcode : InstrMapping {
 216   let FilterClass = "RecFormRel";
 217   // Instructions with the same BaseName and Interpretation64Bit values
 218   // form a row.
 219   let RowFields = ["BaseName", "Interpretation64Bit"];
 220   // Instructions with the same RC value form a column.
 221   let ColFields = ["RC"];
 222   // The key column are the record-form instructions.
 223   let KeyCol = ["1"];
 224   // Value columns are RC=0
 225   let ValueCols = [["0"]];
 226 }
 227
 228 def getAltVSXFMAOpcode : InstrMapping {
 229   let FilterClass = "AltVSXFMARel";
 230   // Instructions with the same BaseName and Interpretation64Bit values
 231   // form a row.
 232   let RowFields = ["BaseName"];
 233   // Instructions with the same RC value form a column.
 234   let ColFields = ["IsVSXFMAAlt"];
 235   // The key column are the (default) addend-killing instructions.
 236   let KeyCol = ["0"];
 237   // Value columns IsVSXFMAAlt=1
 238   let ValueCols = [["1"]];
 239 }
 240
 241 //===----------------------------------------------------------------------===//
 242 // Register File Description
 243 //===----------------------------------------------------------------------===//
 244
 245 include "PPCRegisterInfo.td"
 246 include "PPCSchedule.td"
 247 include "PPCInstrInfo.td"
 248
 249 //===----------------------------------------------------------------------===//
 250 // PowerPC processors supported.
 251 //
 252
 253 def : Processor<"generic", G3Itineraries, [Directive32, FeatureMFTB]>;
 254 def : ProcessorModel<"440", PPC440Model, [Directive440, FeatureISEL,
 255                                           FeatureFRES, FeatureFRSQRTE,
 256                                           FeatureICBT, FeatureBookE,
 257                                           FeatureMSYNC, FeatureMFTB]>;
 258 def : ProcessorModel<"450", PPC440Model, [Directive440, FeatureISEL,
 259                                           FeatureFRES, FeatureFRSQRTE,
 260                                           FeatureICBT, FeatureBookE,
 261                                           FeatureMSYNC, FeatureMFTB]>;
 262 def : Processor<"601", G3Itineraries, [Directive601]>;
 263 def : Processor<"602", G3Itineraries, [Directive602,
 264                                        FeatureMFTB]>;
 265 def : Processor<"603", G3Itineraries, [Directive603,
 266                                        FeatureFRES, FeatureFRSQRTE,
 267                                        FeatureMFTB]>;
 268 def : Processor<"603e", G3Itineraries, [Directive603,
 269                                         FeatureFRES, FeatureFRSQRTE,
 270                                         FeatureMFTB]>;
 271 def : Processor<"603ev", G3Itineraries, [Directive603,
 272                                          FeatureFRES, FeatureFRSQRTE,
 273                                          FeatureMFTB]>;
 274 def : Processor<"604", G3Itineraries, [Directive604,
 275                                        FeatureFRES, FeatureFRSQRTE,
 276                                        FeatureMFTB]>;
 277 def : Processor<"604e", G3Itineraries, [Directive604,
 278                                         FeatureFRES, FeatureFRSQRTE,
 279                                         FeatureMFTB]>;
 280 def : Processor<"620", G3Itineraries, [Directive620,
 281                                        FeatureFRES, FeatureFRSQRTE,
 282                                        FeatureMFTB]>;
 283 def : Processor<"750", G4Itineraries, [Directive750,
 284                                        FeatureFRES, FeatureFRSQRTE,
 285                                        FeatureMFTB]>;
 286 def : Processor<"g3", G3Itineraries, [Directive750,
 287                                       FeatureFRES, FeatureFRSQRTE,
 288                                       FeatureMFTB]>;
 289 def : Processor<"7400", G4Itineraries, [Directive7400, FeatureAltivec,
 290                                         FeatureFRES, FeatureFRSQRTE,
 291                                         FeatureMFTB]>;
 292 def : Processor<"g4", G4Itineraries, [Directive7400, FeatureAltivec,
 293                                       FeatureFRES, FeatureFRSQRTE,
 294                                       FeatureMFTB]>;
 295 def : Processor<"7450", G4PlusItineraries, [Directive7400, FeatureAltivec,
 296                                             FeatureFRES, FeatureFRSQRTE,
 297                                             FeatureMFTB]>;
 298 def : Processor<"g4+", G4PlusItineraries, [Directive7400, FeatureAltivec,
 299                                            FeatureFRES, FeatureFRSQRTE,
 300                                            FeatureMFTB]>;
 301
 302 def : ProcessorModel<"970", G5Model,
 303                   [Directive970, FeatureAltivec,
 304                    FeatureMFOCRF, FeatureFSqrt,
 305                    FeatureFRES, FeatureFRSQRTE, FeatureSTFIWX,
 306                    Feature64Bit /*, Feature64BitRegs */,
 307                    FeatureMFTB]>;
 308 def : ProcessorModel<"g5", G5Model,
 309                   [Directive970, FeatureAltivec,
 310                    FeatureMFOCRF, FeatureFSqrt, FeatureSTFIWX,
 311                    FeatureFRES, FeatureFRSQRTE,
 312                    Feature64Bit /*, Feature64BitRegs */,
 313                    FeatureMFTB, DeprecatedDST]>;
 314 def : ProcessorModel<"e500mc", PPCE500mcModel,
 315                   [DirectiveE500mc,
 316                    FeatureSTFIWX, FeatureICBT, FeatureBookE,
 317                    FeatureISEL, FeatureMFTB]>;
 318 def : ProcessorModel<"e5500", PPCE5500Model,
 319                   [DirectiveE5500, FeatureMFOCRF, Feature64Bit,
 320                    FeatureSTFIWX, FeatureICBT, FeatureBookE,
 321                    FeatureISEL, FeatureMFTB]>;
 322 def : ProcessorModel<"a2", PPCA2Model,
 323                   [DirectiveA2, FeatureICBT, FeatureBookE, FeatureMFOCRF,
 324                    FeatureFCPSGN, FeatureFSqrt, FeatureFRE, FeatureFRES,
 325                    FeatureFRSQRTE, FeatureFRSQRTES, FeatureRecipPrec,
 326                    FeatureSTFIWX, FeatureLFIWAX,
 327                    FeatureFPRND, FeatureFPCVT, FeatureISEL,
 328                    FeaturePOPCNTD, FeatureCMPB, FeatureLDBRX, Feature64Bit
 329                /*, Feature64BitRegs */, FeatureMFTB]>;
 330 def : ProcessorModel<"a2q", PPCA2Model,
 331                   [DirectiveA2, FeatureICBT, FeatureBookE, FeatureMFOCRF,
 332                    FeatureFCPSGN, FeatureFSqrt, FeatureFRE, FeatureFRES,
 333                    FeatureFRSQRTE, FeatureFRSQRTES, FeatureRecipPrec,
 334                    FeatureSTFIWX, FeatureLFIWAX,
 335                    FeatureFPRND, FeatureFPCVT, FeatureISEL,
 336                    FeaturePOPCNTD, FeatureCMPB, FeatureLDBRX, Feature64Bit
 337                /*, Feature64BitRegs */, FeatureQPX, FeatureMFTB]>;
 338 def : ProcessorModel<"pwr3", G5Model,
 339                   [DirectivePwr3, FeatureAltivec,
 340                    FeatureFRES, FeatureFRSQRTE, FeatureMFOCRF,
 341                    FeatureSTFIWX, Feature64Bit]>;
 342 def : ProcessorModel<"pwr4", G5Model,
 343                   [DirectivePwr4, FeatureAltivec, FeatureMFOCRF,
 344                    FeatureFSqrt, FeatureFRES, FeatureFRSQRTE,
 345                    FeatureSTFIWX, Feature64Bit, FeatureMFTB]>;
 346 def : ProcessorModel<"pwr5", G5Model,
 347                   [DirectivePwr5, FeatureAltivec, FeatureMFOCRF,
 348                    FeatureFSqrt, FeatureFRE, FeatureFRES,
 349                    FeatureFRSQRTE, FeatureFRSQRTES,
 350                    FeatureSTFIWX, Feature64Bit,
 351                    FeatureMFTB, DeprecatedDST]>;
 352 def : ProcessorModel<"pwr5x", G5Model,
 353                   [DirectivePwr5x, FeatureAltivec, FeatureMFOCRF,
 354                    FeatureFSqrt, FeatureFRE, FeatureFRES,
 355                    FeatureFRSQRTE, FeatureFRSQRTES,
 356                    FeatureSTFIWX, FeatureFPRND, Feature64Bit,
 357                    FeatureMFTB, DeprecatedDST]>;
 358 def : ProcessorModel<"pwr6", G5Model,
 359                   [DirectivePwr6, FeatureAltivec,
 360                    FeatureMFOCRF, FeatureFCPSGN, FeatureFSqrt, FeatureFRE,
 361                    FeatureFRES, FeatureFRSQRTE, FeatureFRSQRTES,
 362                    FeatureRecipPrec, FeatureSTFIWX, FeatureLFIWAX, FeatureCMPB,
 363                    FeatureFPRND, Feature64Bit /*, Feature64BitRegs */,
 364                    FeatureMFTB, DeprecatedDST]>;
 365 def : ProcessorModel<"pwr6x", G5Model,
 366                   [DirectivePwr5x, FeatureAltivec, FeatureMFOCRF,
 367                    FeatureFCPSGN, FeatureFSqrt, FeatureFRE, FeatureFRES,
 368                    FeatureFRSQRTE, FeatureFRSQRTES, FeatureRecipPrec,
 369                    FeatureSTFIWX, FeatureLFIWAX, FeatureCMPB,
 370                    FeatureFPRND, Feature64Bit,
 371                    FeatureMFTB, DeprecatedDST]>;
 372 def : ProcessorModel<"pwr7", P7Model, ProcessorFeatures.Power7FeatureList>;
 373 def : ProcessorModel<"pwr8", P8Model, ProcessorFeatures.Power8FeatureList>;
 374 def : Processor<"ppc", G3Itineraries, [Directive32, FeatureMFTB]>;
 375 def : ProcessorModel<"ppc64", G5Model,
 376                   [Directive64, FeatureAltivec,
 377                    FeatureMFOCRF, FeatureFSqrt, FeatureFRES,
 378                    FeatureFRSQRTE, FeatureSTFIWX,
 379                    Feature64Bit /*, Feature64BitRegs */,
 380                    FeatureMFTB]>;
 381 def : ProcessorModel<"ppc64le", P8Model, ProcessorFeatures.Power8FeatureList>;
 382
 383 //===----------------------------------------------------------------------===//
 384 // Calling Conventions
 385 //===----------------------------------------------------------------------===//
 386
 387 include "PPCCallingConv.td"
 388
 389 def PPCInstrInfo : InstrInfo {
 390   let isLittleEndianEncoding = 1;
 391
 392   // FIXME: Unset this when no longer needed!
 393   let decodePositionallyEncodedOperands = 1;
 394
 395   let noNamedPositionallyEncodedOperands = 1;
 396 }
 397
 398 def PPCAsmParser : AsmParser {
 399   let ShouldEmitMatchRegisterName = 0;
 400 }
 401
 402 def PPCAsmParserVariant : AsmParserVariant {
 403   int Variant = 0;
 404
 405   // We do not use hard coded registers in asm strings.  However, some
 406   // InstAlias definitions use immediate literals.  Set RegisterPrefix
 407   // so that those are not misinterpreted as registers.
 408   string RegisterPrefix = "%";
 409   string BreakCharacters = ".";
 410 }
 411
 412 def PPC : Target {
 413   // Information about the instructions.
 414   let InstructionSet = PPCInstrInfo;
 415
 416   let AssemblyParsers = [PPCAsmParser];
 417   let AssemblyParserVariants = [PPCAsmParserVariant];
 418 }