src/Backend/satelemencoder.cc

   1 #include "satencoder.h"
   2 #include "structs.h"
   3 #include "common.h"
   4 #include "ops.h"
   5 #include "element.h"
   6 #include "set.h"
   7 #include "predicate.h"
   8
   9
  10 void SATEncoder::shouldMemoize(Element *elem, uint64_t val, bool & memo) {
  11         uint numParents = elem->parents.getSize();
  12         uint posPolarity = 0;
  13         uint negPolarity = 0;
  14         memo = false;
  15         if (elem->type == ELEMFUNCRETURN) {
  16                 memo = true;
  17         }
  18         for(uint i = 0; i < numParents; i++) {
  19                 ASTNode * node = elem->parents.get(i);
  20                 if (node->type == PREDICATEOP) {
  21                         BooleanPredicate * pred = (BooleanPredicate *) node;
  22                         Polarity polarity = pred->polarity;
  23                         FunctionEncodingType encType = pred->encoding.type;
  24                         bool generateNegation = encType == ENUMERATEIMPLICATIONSNEGATE;
  25                         if (pred->predicate->type == TABLEPRED) {
  26                                 //Could be smarter, but just do default thing for now
  27
  28                                 UndefinedBehavior undefStatus = ((PredicateTable *)pred->predicate)->undefinedbehavior;
  29
  30                                 Polarity tpolarity=polarity;
  31                                 if (generateNegation)
  32                                         tpolarity = negatePolarity(tpolarity);
  33                                 if (undefStatus ==SATC_FLAGFORCEUNDEFINED)
  34                                         tpolarity = P_BOTHTRUEFALSE;
  35                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_TRUE)
  36                                         memo = true;
  37                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_FALSE)
  38                                         memo = true;
  39                         } else if (pred->predicate->type == OPERATORPRED) {
  40                                         if (pred->encoding.type == ENUMERATEIMPLICATIONS || pred->encoding.type == ENUMERATEIMPLICATIONSNEGATE) {
  41                                                 Polarity tpolarity = polarity;
  42                                                 if (generateNegation)
  43                                                         tpolarity = negatePolarity(tpolarity);
  44                                                 PredicateOperator *predicate = (PredicateOperator *)pred->predicate;
  45                                                 uint numDomains = predicate->domains.getSize();
  46                                                 bool isConstant = true;
  47                                                 for (uint i = 0; i < numDomains; i++) {
  48                                                         Element *e = pred->inputs.get(i);
  49                                                         if (elem != e && e->type != ELEMCONST) {
  50                                                                 isConstant = false;
  51                                                         }
  52                                                 }
  53                                                 if (predicate->getOp() == SATC_EQUALS) {
  54                                                         if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_TRUE)
  55                                                                 posPolarity++;
  56                                                         if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_FALSE)
  57                                                                 negPolarity++;
  58                                                 } else {
  59                                                         if (isConstant) {
  60                                                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_TRUE)
  61                                                                         posPolarity++;
  62                                                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_FALSE)
  63                                                                         negPolarity++;
  64                                                         } else {
  65                                                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_TRUE)
  66                                                                         memo = true;
  67                                                                 if (tpolarity == P_BOTHTRUEFALSE || tpolarity == P_FALSE)
  68                                                                         memo = true;
  69                                                         }
  70                                                 }
  71                                         }
  72                                 } else {
  73                                 ASSERT(0);
  74                         }
  75                 } else if (node->type == ELEMFUNCRETURN) {
  76                         //we are input to function, so memoize negative case
  77                         memo = true;
  78                 } else {
  79                         ASSERT(0);
  80                 }
  81         }
  82         if (posPolarity > 1)
  83                 memo = true;
  84         if (negPolarity > 1)
  85                 memo = true;
  86 }
  87
  88
  89 Edge SATEncoder::getElementValueConstraint(Element *elem, Polarity p, uint64_t value) {
  90         switch (elem->getElementEncoding()->type) {
  91         case ONEHOT:
  92                 return getElementValueOneHotConstraint(elem, p, value);
  93         case UNARY:
  94                 return getElementValueUnaryConstraint(elem, p, value);
  95         case BINARYINDEX:
  96                 return getElementValueBinaryIndexConstraint(elem, p, value);
  97         case BINARYVAL:
  98                 return getElementValueBinaryValueConstraint(elem, p, value);
  99                 break;
 100         default:
 101                 ASSERT(0);
 102                 break;
 103         }
 104         return E_BOGUS;
 105 }
 106
 107 bool impliesPolarity(Polarity curr, Polarity goal) {
 108         return (((int) curr) & ((int)goal)) == ((int) goal);
 109 }
 110
 111 Edge SATEncoder::getElementValueBinaryIndexConstraint(Element *elem, Polarity p, uint64_t value) {
 112         ASTNodeType type = elem->type;
 113         ASSERT(type == ELEMSET || type == ELEMFUNCRETURN || type == ELEMCONST);
 114         ElementEncoding *elemEnc = elem->getElementEncoding();
 115
 116         //Check if we need to generate proxy variables
 117         if (elemEnc->encoding == EENC_UNKNOWN && elemEnc->numVars > 1) {
 118                 bool memo = false;
 119                 shouldMemoize(elem, value, memo);
 120                 if (memo) {
 121                         elemEnc->encoding = EENC_BOTH;
 122                         elemEnc->polarityArray = (Polarity *) ourcalloc(1, sizeof(Polarity) * elemEnc->encArraySize);
 123                         elemEnc->edgeArray = (Edge *) ourcalloc(1, sizeof(Edge) * elemEnc->encArraySize);
 124                 } else {
 125                         elemEnc->encoding = EENC_NONE;
 126                 }
 127         }
 128
 129         for (uint i = 0; i < elemEnc->encArraySize; i++) {
 130                 if (elemEnc->isinUseElement(i) && elemEnc->encodingArray[i] == value) {
 131                         if (elemEnc->numVars == 0)
 132                                 return E_True;
 133
 134                         if (elemEnc->encoding != EENC_NONE && elemEnc->numVars > 1) {
 135                                 if (impliesPolarity(elemEnc->polarityArray[i], p)) {
 136                                         return elemEnc->edgeArray[i];
 137                                 } else {
 138                                         if (edgeIsNull(elemEnc->edgeArray[i])) {
 139                                                 elemEnc->edgeArray[i] = constraintNewVar(cnf);
 140                                         }
 141                                         if (elemEnc->polarityArray[i] == P_UNDEFINED && p == P_BOTHTRUEFALSE) {
 142                                                 generateProxy(cnf, generateBinaryConstraint(cnf, elemEnc->numVars, elemEnc->variables, i), elemEnc->edgeArray[i], P_BOTHTRUEFALSE);
 143                                                 elemEnc->polarityArray[i] = p;
 144                                         } else if (!impliesPolarity(elemEnc->polarityArray[i], P_TRUE)  && impliesPolarity(p, P_TRUE)) {
 145                                                 generateProxy(cnf, generateBinaryConstraint(cnf, elemEnc->numVars, elemEnc->variables, i), elemEnc->edgeArray[i], P_TRUE);
 146                                                 elemEnc->polarityArray[i] = (Polarity) (((int) elemEnc->polarityArray[i])| ((int)P_TRUE));
 147                                         }       else if (!impliesPolarity(elemEnc->polarityArray[i], P_FALSE)  && impliesPolarity(p, P_FALSE)) {
 148                                                 generateProxy(cnf, generateBinaryConstraint(cnf, elemEnc->numVars, elemEnc->variables, i), elemEnc->edgeArray[i], P_FALSE);
 149                                                 elemEnc->polarityArray[i] = (Polarity) (((int) elemEnc->polarityArray[i])| ((int)P_FALSE));
 150                                         }
 151                                         return elemEnc->edgeArray[i];
 152                                 }
 153                         }
 154                         return generateBinaryConstraint(cnf, elemEnc->numVars, elemEnc->variables, i);
 155                 }
 156         }
 157         return E_False;
 158 }
 159
 160 Edge SATEncoder::getElementValueOneHotConstraint(Element *elem, Polarity p, uint64_t value) {
 161         ASTNodeType type = elem->type;
 162         ASSERT(type == ELEMSET || type == ELEMFUNCRETURN || type == ELEMCONST);
 163         ElementEncoding *elemEnc = elem->getElementEncoding();
 164         for (uint i = 0; i < elemEnc->encArraySize; i++) {
 165                 if (elemEnc->isinUseElement(i) && elemEnc->encodingArray[i] == value) {
 166                         return (elemEnc->numVars == 0) ? E_True : elemEnc->variables[i];
 167                 }
 168         }
 169         return E_False;
 170 }
 171
 172 Edge SATEncoder::getElementValueUnaryConstraint(Element *elem, Polarity p, uint64_t value) {
 173         ASTNodeType type = elem->type;
 174         ASSERT(type == ELEMSET || type == ELEMFUNCRETURN || type == ELEMCONST);
 175         ElementEncoding *elemEnc = elem->getElementEncoding();
 176         for (uint i = 0; i < elemEnc->encArraySize; i++) {
 177                 if (elemEnc->isinUseElement(i) && elemEnc->encodingArray[i] == value) {
 178                         if (elemEnc->numVars == 0)
 179                                 return E_True;
 180                         if (i == 0)
 181                                 return constraintNegate(elemEnc->variables[0]);
 182                         else if ((i + 1) == elemEnc->encArraySize)
 183                                 return elemEnc->variables[i - 1];
 184                         else
 185                                 return constraintAND2(cnf, elemEnc->variables[i - 1], constraintNegate(elemEnc->variables[i]));
 186                 }
 187         }
 188         return E_False;
 189 }
 190
 191 Edge SATEncoder::getElementValueBinaryValueConstraint(Element *element, Polarity p, uint64_t value) {
 192         ASTNodeType type = element->type;
 193         ASSERT(type == ELEMSET || type == ELEMFUNCRETURN);
 194         ElementEncoding *elemEnc = element->getElementEncoding();
 195         if (elemEnc->low <= elemEnc->high) {
 196                 if (value < elemEnc->low || value > elemEnc->high)
 197                         return E_False;
 198         } else {
 199                 //Range wraps around 0
 200                 if (value < elemEnc->low && value > elemEnc->high)
 201                         return E_False;
 202         }
 203
 204         uint64_t valueminusoffset = value - elemEnc->offset;
 205         return generateBinaryConstraint(cnf, elemEnc->numVars, elemEnc->variables, valueminusoffset);
 206 }
 207
 208 void allocElementConstraintVariables(ElementEncoding *This, uint numVars) {
 209         This->numVars = numVars;
 210         This->variables = (Edge *)ourmalloc(sizeof(Edge) * numVars);
 211 }
 212
 213 void SATEncoder::generateBinaryValueEncodingVars(ElementEncoding *encoding) {
 214         ASSERT(encoding->type == BINARYVAL);
 215         allocElementConstraintVariables(encoding, encoding->numBits);
 216         getArrayNewVarsSATEncoder(encoding->numVars, encoding->variables);
 217 }
 218
 219 void SATEncoder::generateBinaryIndexEncodingVars(ElementEncoding *encoding) {
 220         ASSERT(encoding->type == BINARYINDEX);
 221         allocElementConstraintVariables(encoding, NUMBITS(encoding->encArraySize - 1));
 222         getArrayNewVarsSATEncoder(encoding->numVars, encoding->variables);
 223 }
 224
 225 void SATEncoder::generateOneHotEncodingVars(ElementEncoding *encoding) {
 226         allocElementConstraintVariables(encoding, encoding->encArraySize);
 227         getArrayNewVarsSATEncoder(encoding->numVars, encoding->variables);
 228         for (uint i = 0; i < encoding->numVars; i++) {
 229                 for (uint j = i + 1; j < encoding->numVars; j++) {
 230                         addConstraintCNF(cnf, constraintNegate(constraintAND2(cnf, encoding->variables[i], encoding->variables[j])));
 231                 }
 232         }
 233         addConstraintCNF(cnf, constraintOR(cnf, encoding->numVars, encoding->variables));
 234 }
 235
 236 void SATEncoder::generateUnaryEncodingVars(ElementEncoding *encoding) {
 237         allocElementConstraintVariables(encoding, encoding->encArraySize - 1);
 238         getArrayNewVarsSATEncoder(encoding->numVars, encoding->variables);
 239         //Add unary constraint
 240         for (uint i = 1; i < encoding->numVars; i++) {
 241                 addConstraintCNF(cnf, constraintOR2(cnf, encoding->variables[i - 1], constraintNegate(encoding->variables[i])));
 242         }
 243 }
 244
 245 void SATEncoder::generateElementEncoding(Element *element) {
 246         ElementEncoding *encoding = element->getElementEncoding();
 247         ASSERT(encoding->type != ELEM_UNASSIGNED);
 248         if (encoding->variables != NULL)
 249                 return;
 250         switch (encoding->type) {
 251         case ONEHOT:
 252                 generateOneHotEncodingVars(encoding);
 253                 return;
 254         case BINARYINDEX:
 255                 generateBinaryIndexEncodingVars(encoding);
 256                 return;
 257         case UNARY:
 258                 generateUnaryEncodingVars(encoding);
 259                 return;
 260         case BINARYVAL:
 261                 generateBinaryValueEncodingVars(encoding);
 262                 return;
 263         default:
 264                 ASSERT(0);
 265         }
 266 }
 267