bool supportsGVN()

in hphp/runtime/vm/jit/gvn.cpp [171:350]

• 173 lines of code
• 166 McCabe index (conditional complexity)

bool supportsGVN(const IRInstruction* inst) {
  switch (inst->op()) {
  case AssertType:
  case AbsDbl:
  case AddInt:
  case SubInt:
  case MulInt:
  case AndInt:
  case AddDbl:
  case SubDbl:
  case MulDbl:
  case DivDbl:
  case DivInt:
  case Mod:
  case Sqrt:
  case OrInt:
  case XorInt:
  case Shl:
  case Shr:
  case Floor:
  case Ceil:
  case AddIntO:
  case SubIntO:
  case MulIntO:
  case XorBool:
  case ConvDblToBool:
  case ConvIntToBool:
  case ConvBoolToDbl:
  case ConvIntToDbl:
  case ConvBoolToInt:
  case ConvDblToInt:
  case ConvFuncPrologueFlagsToARFlags:
  case DblAsBits:
  case GtInt:
  case GteInt:
  case LtInt:
  case LteInt:
  case EqInt:
  case NeqInt:
  case CmpInt:
  case GtDbl:
  case GteDbl:
  case LtDbl:
  case LteDbl:
  case EqDbl:
  case NeqDbl:
  case CmpDbl:
  case GtStr:
  case GteStr:
  case LtStr:
  case LteStr:
  case EqStr:
  case NeqStr:
  case SameStr:
  case NSameStr:
  case CmpStr:
  case GtBool:
  case GteBool:
  case LtBool:
  case LteBool:
  case EqBool:
  case NeqBool:
  case CmpBool:
  case SameObj:
  case NSameObj:
  case SameArrLike:
  case NSameArrLike:
  case GtRes:
  case GteRes:
  case LtRes:
  case LteRes:
  case EqRes:
  case NeqRes:
  case CmpRes:
  case EqCls:
  case EqLazyCls:
  case EqFunc:
  case EqStrPtr:
  case InstanceOf:
  case InstanceOfIface:
  case InstanceOfIfaceVtable:
  case ExtendsClass:
  case InstanceOfBitmask:
  case NInstanceOfBitmask:
  case InterfaceSupportsArrLike:
  case InterfaceSupportsStr:
  case InterfaceSupportsInt:
  case InterfaceSupportsDbl:
  case HasToString:
  case IsType:
  case IsNType:
  case IsLegacyArrLike:
  case IsWaitHandle:
  case IsCol:
  case LdRDSAddr:
  case LdFrameThis:
  case LdFrameCls:
  case LdClsCtor:
  case DefConst:
  case LdCls:
  case LdClsCached:
  case LdClsInitData:
  case LdClsFromClsMeth:
  case LdSmashableFunc:
  case LdFuncFromClsMeth:
  case LdFuncInOutBits:
  case LdFuncVecLen:
  case LdClsMethod:
  case LdIfaceMethod:
  case LdPropAddr:
  case LdClsPropAddrOrNull:
  case LdClsPropAddrOrRaise:
  case LdObjClass:
  case LdClsName:
  case LdLazyCls:
  case LdLazyClsName:
  case Mov:
  case LdContActRec:
  case LdAFWHActRec:
  case LdVecElemAddr:
  case OrdStr:
  case ChrInt:
  case CheckRange:
  case CountVec:
  case CountDict:
  case CountKeyset:
  case BespokeGet:
  case BespokeGetThrow:
  case BespokeIterEnd:
  case LdMonotypeDictTombstones:
  case LdMonotypeDictKey:
  case LdMonotypeDictVal:
  case LdMonotypeVecElem:
  case Select:
  case StrictlyIntegerConv:
  case LookupSPropSlot:
  case ConvPtrToLval:
  case RaiseErrorOnInvalidIsAsExpressionType:
  case LdUnitPerRequestFilepath:
  case DirFromFilepath:
  case AKExistsDict:
  case AKExistsKeyset:
  case DictGet:
  case DictGetK:
  case DictGetQuiet:
  case DictIdx:
  case DictIsset:
  case KeysetGet:
  case KeysetGetK:
  case KeysetGetQuiet:
  case KeysetIdx:
  case KeysetIsset:
  case CheckDictOffset:
  case CheckKeysetOffset:
  case CheckDictKeys:
  case CheckArrayCOW:
  case CheckMissingKeyInArrLike:
  case LdFuncRequiredCoeffects:
  case FuncHasAttr:
  case ClassHasAttr:
  case LdTVFromRDS:
  case StructDictSlot:
  case StructDictElemAddr:
    return true;

  case EqArrLike:
  case NeqArrLike:
    // Keyset equality comparisons never re-enter or throw
    return inst->src(0)->type() <= TKeyset && inst->src(1)->type() <= TKeyset;


  case IsTypeStruct:
    // Resources can change type without generating a new SSATmp,
    // so its not safe to GVN
    return !opcodeMayRaise(IsTypeStruct) && !inst->src(1)->type().maybe(TRes);

  default:
    return false;
  }
}