debugger/expr.c

   1 /*
   2  * File expr.c - expression handling for Wine internal debugger.
   3  *
   4  * Copyright (C) 1997, Eric Youngdale.
   5  *
   6  */
   7
   8 #include "config.h"
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <assert.h>
  13 #include "winbase.h"
  14 #include "wine/winbase16.h"
  15 #include "task.h"
  16 #include "debugger.h"
  17 #include "expr.h"
  18
  19 #include <stdarg.h>
  20
  21 struct expr
  22 {
  23   unsigned int  perm;
  24   unsigned int  type:31;
  25   union
  26   {
  27     struct
  28     {
  29       int value;
  30     } constant;
  31
  32     struct
  33     {
  34       const char * str;
  35     } string;
  36
  37     struct
  38     {
  39       unsigned int value;
  40     } u_const;
  41
  42     struct
  43     {
  44       const char * name;
  45     } symbol;
  46
  47     struct
  48     {
  49       enum debug_regs reg;
  50       int             result;
  51     } rgister;
  52
  53     struct
  54     {
  55       int unop_type;
  56       struct expr * exp1;
  57       int             result;
  58     } unop;
  59
  60     struct
  61     {
  62       int binop_type;
  63       int result;
  64       struct expr * exp1;
  65       struct expr * exp2;
  66     } binop;
  67
  68     struct
  69     {
  70       struct datatype * cast;
  71       struct expr     * expr;
  72     } cast;
  73
  74     struct
  75     {
  76       struct expr * exp1;
  77       const char * element_name;
  78       int result;
  79     } structure;
  80
  81     struct
  82     {
  83       struct expr * base;
  84       struct expr * index;
  85     } array;
  86
  87     struct
  88     {
  89       const char  * funcname;
  90       int           nargs;
  91       int           result;
  92       struct expr * arg[5];
  93     } call;
  94
  95   } un;
  96 };
  97
  98 #define EXPR_TYPE_CONST         0
  99 #define EXPR_TYPE_US_CONST      1
 100 #define EXPR_TYPE_SYMBOL        2
 101 #define EXPR_TYPE_REGISTER      3
 102 #define EXPR_TYPE_BINOP         4
 103 #define EXPR_TYPE_UNOP          5
 104 #define EXPR_TYPE_STRUCT        6
 105 #define EXPR_TYPE_PSTRUCT       7
 106 #define EXPR_TYPE_ARRAY         8
 107 #define EXPR_TYPE_CALL          9
 108 #define EXPR_TYPE_STRING        10
 109 #define EXPR_TYPE_CAST          11
 110
 111 static char expr_list[4096];
 112 static int next_expr_free = 0;
 113
 114 /*
 115  * This is how we turn an expression address into the actual value.
 116  * This works well in the 32 bit domain - not sure at all about the
 117  * 16 bit world.
 118  */
 119 #define VAL(_exp)       DEBUG_GetExprValue(&_exp, NULL)
 120
 121 static
 122 struct expr *
 123 DEBUG_GetFreeExpr()
 124 {
 125   struct expr * rtn;
 126
 127   rtn =  (struct expr *) &expr_list[next_expr_free];
 128
 129   next_expr_free += sizeof(struct expr);
 130   assert(next_expr_free < sizeof(expr_list));
 131
 132   return rtn;
 133 }
 134
 135 void
 136 DEBUG_FreeExprMem()
 137 {
 138   next_expr_free = 0;
 139 }
 140
 141 struct expr *
 142 DEBUG_TypeCastExpr(struct datatype * dt, struct expr * exp)
 143 {
 144   struct expr * ex;
 145
 146   ex = DEBUG_GetFreeExpr();
 147
 148   ex->type        = EXPR_TYPE_CAST;
 149   ex->un.cast.cast = dt;
 150   ex->un.cast.expr = exp;
 151   return ex;
 152 }
 153
 154 struct expr *
 155 DEBUG_RegisterExpr(enum debug_regs regno)
 156 {
 157   struct expr * ex;
 158
 159   ex = DEBUG_GetFreeExpr();
 160
 161   ex->type        = EXPR_TYPE_REGISTER;
 162   ex->un.rgister.reg = regno;
 163   return ex;
 164 }
 165
 166 struct expr *
 167 DEBUG_SymbolExpr(const char * name)
 168 {
 169   struct expr * ex;
 170
 171   ex = DEBUG_GetFreeExpr();
 172
 173   ex->type        = EXPR_TYPE_SYMBOL;
 174   ex->un.symbol.name = name;
 175   return ex;
 176 }
 177
 178 struct expr *
 179 DEBUG_ConstExpr(int value)
 180 {
 181   struct expr * ex;
 182
 183   ex = DEBUG_GetFreeExpr();
 184
 185   ex->type        = EXPR_TYPE_CONST;
 186   ex->un.constant.value = value;
 187   return ex;
 188 }
 189
 190 struct expr *
 191 DEBUG_StringExpr(const char * str)
 192 {
 193   struct expr * ex;
 194   char * pnt;
 195   ex = DEBUG_GetFreeExpr();
 196
 197   ex->type        = EXPR_TYPE_STRING;
 198   ex->un.string.str = str+1;
 199   pnt = strrchr(ex->un.string.str, '"');
 200   if( pnt != NULL )
 201     {
 202       *pnt =  '\0';
 203     }
 204   return ex;
 205 }
 206
 207 struct expr *
 208 DEBUG_USConstExpr(unsigned int value)
 209 {
 210   struct expr * ex;
 211
 212   ex = DEBUG_GetFreeExpr();
 213
 214   ex->type           = EXPR_TYPE_CONST;
 215   ex->un.u_const.value = value;
 216   return ex;
 217 }
 218
 219 struct expr *
 220 DEBUG_BinopExpr(int operator_type, struct expr * exp1, struct expr * exp2)
 221 {
 222   struct expr * ex;
 223
 224   ex = DEBUG_GetFreeExpr();
 225
 226   ex->type           = EXPR_TYPE_BINOP;
 227   ex->un.binop.binop_type = operator_type;
 228   ex->un.binop.exp1     = exp1;
 229   ex->un.binop.exp2     = exp2;
 230   return ex;
 231 }
 232
 233 struct expr *
 234 DEBUG_UnopExpr(int operator_type, struct expr * exp1)
 235 {
 236   struct expr * ex;
 237
 238   ex = DEBUG_GetFreeExpr();
 239
 240   ex->type           = EXPR_TYPE_UNOP;
 241   ex->un.unop.unop_type = operator_type;
 242   ex->un.unop.exp1      = exp1;
 243   return ex;
 244 }
 245
 246 struct expr *
 247 DEBUG_StructExpr(struct expr * exp, const char * element)
 248 {
 249   struct expr * ex;
 250
 251   ex = DEBUG_GetFreeExpr();
 252
 253   ex->type           = EXPR_TYPE_STRUCT;
 254   ex->un.structure.exp1 = exp;
 255   ex->un.structure.element_name = element;
 256   return ex;
 257 }
 258
 259 struct expr *
 260 DEBUG_StructPExpr(struct expr * exp, const char * element)
 261 {
 262   struct expr * ex;
 263
 264   ex = DEBUG_GetFreeExpr();
 265
 266   ex->type           = EXPR_TYPE_PSTRUCT;
 267   ex->un.structure.exp1 = exp;
 268   ex->un.structure.element_name = element;
 269   return ex;
 270 }
 271
 272 struct expr *
 273 DEBUG_CallExpr(const char * funcname, int nargs, ...)
 274 {
 275   struct expr * ex;
 276   va_list ap;
 277   int i;
 278
 279   ex = DEBUG_GetFreeExpr();
 280
 281   ex->type           = EXPR_TYPE_CALL;
 282   ex->un.call.funcname = funcname;
 283   ex->un.call.nargs = nargs;
 284
 285   va_start(ap, nargs);
 286   for(i=0; i < nargs; i++)
 287     {
 288       ex->un.call.arg[i] = va_arg(ap, struct expr *);
 289     }
 290   va_end(ap);
 291   return ex;
 292 }
 293
 294 DBG_ADDR
 295 DEBUG_EvalExpr(struct expr * exp)
 296 {
 297   DBG_ADDR      rtn;
 298   int           i;
 299   DBG_ADDR      exp1;
 300   DBG_ADDR      exp2;
 301   unsigned int  cexp[5];
 302   int           (*fptr)();
 303   int               scale1;
 304   int               scale2;
 305   int               scale3;
 306   struct datatype * type1;
 307   struct datatype * type2;
 308
 309   rtn.type = NULL;
 310   rtn.off = NULL;
 311   rtn.seg = NULL;
 312
 313   switch(exp->type)
 314     {
 315     case EXPR_TYPE_CAST:
 316       rtn = DEBUG_EvalExpr(exp->un.cast.expr);
 317       rtn.type = exp->un.cast.cast;
 318       break;
 319     case EXPR_TYPE_STRING:
 320       rtn.type = DEBUG_TypeString;
 321       rtn.off = (unsigned int) &exp->un.string.str;
 322       rtn.seg = 0;
 323       break;
 324     case EXPR_TYPE_CONST:
 325       rtn.type = DEBUG_TypeIntConst;
 326       rtn.off = (unsigned int) &exp->un.constant.value;
 327       rtn.seg = 0;
 328       break;
 329     case EXPR_TYPE_US_CONST:
 330       rtn.type = DEBUG_TypeUSInt;
 331       rtn.off = (unsigned int) &exp->un.u_const.value;
 332       rtn.seg = 0;
 333       break;
 334     case EXPR_TYPE_SYMBOL:
 335       if( !DEBUG_GetSymbolValue(exp->un.symbol.name, -1, &rtn, FALSE ) )
 336         {
 337           rtn.type = NULL;
 338           rtn.off = 0;
 339           rtn.seg = 0;
 340         };
 341       break;
 342     case EXPR_TYPE_PSTRUCT:
 343       exp1 =  DEBUG_EvalExpr(exp->un.structure.exp1);
 344       if( exp1.type == NULL )
 345         {
 346           break;
 347         }
 348       rtn.off = DEBUG_TypeDerefPointer(&exp1, &type1);
 349       if( type1 == NULL )
 350         {
 351           break;
 352         }
 353       rtn.type = type1;
 354       DEBUG_FindStructElement(&rtn, exp->un.structure.element_name,
 355                               &exp->un.structure.result);
 356       break;
 357     case EXPR_TYPE_STRUCT:
 358       exp1 =  DEBUG_EvalExpr(exp->un.structure.exp1);
 359       if( exp1.type == NULL )
 360         {
 361           break;
 362         }
 363       rtn = exp1;
 364       DEBUG_FindStructElement(&rtn, exp->un.structure.element_name,
 365                               &exp->un.structure.result);
 366       break;
 367     case EXPR_TYPE_CALL:
 368       /*
 369        * First, evaluate all of the arguments.  If any of them are not
 370        * evaluable, then bail.
 371        */
 372       for(i=0; i < exp->un.call.nargs; i++)
 373         {
 374           exp1  = DEBUG_EvalExpr(exp->un.call.arg[i]);
 375           if( exp1.type == NULL )
 376             {
 377               return rtn;
 378             }
 379           cexp[i] = DEBUG_GetExprValue(&exp1, NULL);
 380         }
 381
 382       /*
 383        * Now look up the address of the function itself.
 384        */
 385       if( !DEBUG_GetSymbolValue(exp->un.call.funcname, -1, &rtn, FALSE ) )
 386         {
 387           fprintf(stderr, "Failed to find symbol\n");
 388           break;
 389         }
 390
 391       fptr = (int (*)()) rtn.off;
 392       switch(exp->un.call.nargs)
 393         {
 394         case 0:
 395           exp->un.call.result = (*fptr)();
 396           break;
 397         case 1:
 398           exp->un.call.result = (*fptr)(cexp[0]);
 399           break;
 400         case 2:
 401           exp->un.call.result = (*fptr)(cexp[0], cexp[1]);
 402           break;
 403         case 3:
 404           exp->un.call.result = (*fptr)(cexp[0], cexp[1], cexp[2]);
 405           break;
 406         case 4:
 407           exp->un.call.result = (*fptr)(cexp[0], cexp[1], cexp[2], cexp[3]);
 408           break;
 409         case 5:
 410           exp->un.call.result = (*fptr)(cexp[0], cexp[1], cexp[2], cexp[3], cexp[4]);
 411           break;
 412         }
 413       rtn.type = DEBUG_TypeInt;
 414       rtn.off = (unsigned int) &exp->un.call.result;
 415       break;
 416     case EXPR_TYPE_REGISTER:
 417       rtn.type = DEBUG_TypeIntConst;
 418       exp->un.rgister.result = DEBUG_GetRegister(exp->un.rgister.reg);
 419       rtn.off = (unsigned int) &exp->un.rgister.result;
 420 #ifdef __i386__
 421       if( exp->un.rgister.reg == REG_EIP )
 422           rtn.seg = CS_reg(&DEBUG_context);
 423       else
 424           rtn.seg = DS_reg(&DEBUG_context);
 425 #endif
 426       DBG_FIX_ADDR_SEG( &rtn, 0 );
 427       break;
 428     case EXPR_TYPE_BINOP:
 429       exp1 = DEBUG_EvalExpr(exp->un.binop.exp1);
 430       exp2 = DEBUG_EvalExpr(exp->un.binop.exp2);
 431       if( exp1.type == NULL || exp2.type == NULL )
 432         {
 433           break;
 434         }
 435       if( exp1.type == DEBUG_TypeIntConst && exp2.type == DEBUG_TypeIntConst )
 436         {
 437           rtn.type = exp1.type;
 438         }
 439       else
 440         {
 441           rtn.type = DEBUG_TypeInt;
 442         }
 443       rtn.off = (unsigned int) &exp->un.binop.result;
 444       switch(exp->un.binop.binop_type)
 445         {
 446         case EXP_OP_ADD:
 447           type1 = DEBUG_GetPointerType(exp1.type);
 448           type2 = DEBUG_GetPointerType(exp2.type);
 449           scale1 = 1;
 450           scale2 = 1;
 451           if( type1 != NULL && type2 != NULL )
 452             {
 453               break;
 454             }
 455           else if( type1 != NULL )
 456             {
 457               scale2 = DEBUG_GetObjectSize(type1);
 458               rtn.type = exp1.type;
 459             }
 460           else if( type2 != NULL )
 461             {
 462               scale1 = DEBUG_GetObjectSize(type2);
 463               rtn.type = exp2.type;
 464             }
 465           rtn.seg = 0;
 466           exp->un.binop.result = (VAL(exp1) * scale1  + scale2 * VAL(exp2));
 467           break;
 468         case EXP_OP_SUB:
 469           type1 = DEBUG_GetPointerType(exp1.type);
 470           type2 = DEBUG_GetPointerType(exp2.type);
 471           scale1 = 1;
 472           scale2 = 1;
 473           scale3 = 1;
 474           if( type1 != NULL && type2 != NULL )
 475             {
 476               if( type1 != type2 )
 477                 {
 478                   break;
 479                 }
 480               scale3 = DEBUG_GetObjectSize(type1);
 481             }
 482           else if( type1 != NULL )
 483             {
 484               scale2 = DEBUG_GetObjectSize(type1);
 485               rtn.type = exp1.type;
 486             }
 487
 488           else if( type2 != NULL )
 489             {
 490               scale1 = DEBUG_GetObjectSize(type2);
 491               rtn.type = exp2.type;
 492             }
 493           rtn.seg = 0;
 494           exp->un.binop.result = (VAL(exp1) - VAL(exp2)) / scale3;
 495           break;
 496         case EXP_OP_SEG:
 497           rtn.seg = VAL(exp1);
 498           exp->un.binop.result = VAL(exp2);
 499 #ifdef __i386__
 500           if (ISV86(&DEBUG_context)) {
 501             TDB *pTask = (TDB*)GlobalLock16( GetCurrentTask() );
 502             rtn.seg |= (DWORD)(pTask?(pTask->hModule):0)<<16;
 503             GlobalUnlock16( GetCurrentTask() );
 504           }
 505 #endif
 506           break;
 507         case EXP_OP_LOR:
 508           rtn.seg = 0;
 509           exp->un.binop.result = (VAL(exp1) || VAL(exp2));
 510           break;
 511         case EXP_OP_LAND:
 512           rtn.seg = 0;
 513           exp->un.binop.result = (VAL(exp1) && VAL(exp2));
 514           break;
 515         case EXP_OP_OR:
 516           rtn.seg = 0;
 517           exp->un.binop.result = (VAL(exp1) | VAL(exp2));
 518           break;
 519         case EXP_OP_AND:
 520           rtn.seg = 0;
 521           exp->un.binop.result = (VAL(exp1) & VAL(exp2));
 522           break;
 523         case EXP_OP_XOR:
 524           rtn.seg = 0;
 525           exp->un.binop.result = (VAL(exp1) ^ VAL(exp2));
 526           break;
 527         case EXP_OP_EQ:
 528           rtn.seg = 0;
 529           exp->un.binop.result = (VAL(exp1) == VAL(exp2));
 530           break;
 531         case EXP_OP_GT:
 532           rtn.seg = 0;
 533           exp->un.binop.result = (VAL(exp1) > VAL(exp2));
 534           break;
 535         case EXP_OP_LT:
 536           rtn.seg = 0;
 537           exp->un.binop.result = (VAL(exp1) < VAL(exp2));
 538           break;
 539         case EXP_OP_GE:
 540           rtn.seg = 0;
 541           exp->un.binop.result = (VAL(exp1) >= VAL(exp2));
 542           break;
 543         case EXP_OP_LE:
 544           rtn.seg = 0;
 545           exp->un.binop.result = (VAL(exp1) <= VAL(exp2));
 546           break;
 547         case EXP_OP_NE:
 548           rtn.seg = 0;
 549           exp->un.binop.result = (VAL(exp1) != VAL(exp2));
 550           break;
 551         case EXP_OP_SHL:
 552           rtn.seg = 0;
 553           exp->un.binop.result = ((unsigned) VAL(exp1) << VAL(exp2));
 554           break;
 555         case EXP_OP_SHR:
 556           rtn.seg = 0;
 557           exp->un.binop.result = ((unsigned) VAL(exp1) >> VAL(exp2));
 558           break;
 559         case EXP_OP_MUL:
 560           rtn.seg = 0;
 561           exp->un.binop.result = (VAL(exp1) * VAL(exp2));
 562           break;
 563         case EXP_OP_DIV:
 564           if( VAL(exp2) != 0 )
 565             {
 566               rtn.seg = 0;
 567               exp->un.binop.result = (VAL(exp1) / VAL(exp2));
 568             }
 569           else
 570             {
 571               rtn.seg = 0;
 572               rtn.type = NULL;
 573               rtn.off = 0;
 574             }
 575           break;
 576         case EXP_OP_REM:
 577           if( VAL(exp2) != 0 )
 578             {
 579               rtn.seg = 0;
 580               exp->un.binop.result = (VAL(exp1) % VAL(exp2));
 581             }
 582           else
 583             {
 584               rtn.seg = 0;
 585               rtn.type = NULL;
 586               rtn.off = 0;
 587             }
 588           break;
 589         case EXP_OP_ARR:
 590           DEBUG_ArrayIndex(&exp1, &rtn, VAL(exp2));
 591           break;
 592         default:
 593           break;
 594         }
 595       break;
 596     case EXPR_TYPE_UNOP:
 597       exp1 = DEBUG_EvalExpr(exp->un.unop.exp1);
 598       if( exp1.type == NULL )
 599         {
 600           break;
 601         }
 602       rtn.off = (unsigned int) &exp->un.unop.result;
 603       if( exp1.type == DEBUG_TypeIntConst )
 604         {
 605           rtn.type = exp1.type;
 606         }
 607       else
 608         {
 609           rtn.type = DEBUG_TypeInt;
 610         }
 611       switch(exp->un.unop.unop_type)
 612         {
 613         case EXP_OP_NEG:
 614           rtn.seg = 0;
 615           exp->un.unop.result = -VAL(exp1);
 616           break;
 617         case EXP_OP_NOT:
 618           rtn.seg = 0;
 619           exp->un.unop.result = !VAL(exp1);
 620           break;
 621         case EXP_OP_LNOT:
 622           rtn.seg = 0;
 623           exp->un.unop.result = ~VAL(exp1);
 624           break;
 625         case EXP_OP_DEREF:
 626           rtn.seg = 0;
 627           rtn.off = (unsigned int) DEBUG_TypeDerefPointer(&exp1, &rtn.type);
 628           break;
 629         case EXP_OP_FORCE_DEREF:
 630           rtn.seg = exp1.seg;
 631           rtn.off = *(unsigned int *) exp1.off;
 632           break;
 633         case EXP_OP_ADDR:
 634           rtn.seg = 0;
 635           rtn.type = DEBUG_FindOrMakePointerType(exp1.type);
 636           exp->un.unop.result = exp1.off;
 637           break;
 638         }
 639       break;
 640     default:
 641       fprintf(stderr,"Unexpected expression.\n");
 642       DEBUG_Exit(123);
 643       break;
 644     }
 645
 646   return rtn;
 647 }
 648
 649
 650 int
 651 DEBUG_DisplayExpr(struct expr * exp)
 652 {
 653   int           i;
 654
 655
 656   switch(exp->type)
 657     {
 658     case EXPR_TYPE_CAST:
 659       fprintf(stderr, "((");
 660       DEBUG_PrintTypeCast(exp->un.cast.cast);
 661       fprintf(stderr, ")");
 662       DEBUG_DisplayExpr(exp->un.cast.expr);
 663       fprintf(stderr, ")");
 664       break;
 665     case EXPR_TYPE_REGISTER:
 666       DEBUG_PrintRegister(exp->un.rgister.reg);
 667       break;
 668     case EXPR_TYPE_US_CONST:
 669       fprintf(stderr, "%ud", exp->un.u_const.value);
 670       break;
 671     case EXPR_TYPE_CONST:
 672       fprintf(stderr, "%d", exp->un.u_const.value);
 673       break;
 674     case EXPR_TYPE_STRING:
 675       fprintf(stderr, "\"%s\"", exp->un.string.str);
 676       break;
 677     case EXPR_TYPE_SYMBOL:
 678       fprintf(stderr, "%s" , exp->un.symbol.name);
 679       break;
 680     case EXPR_TYPE_PSTRUCT:
 681       DEBUG_DisplayExpr(exp->un.structure.exp1);
 682       fprintf(stderr, "->%s", exp->un.structure.element_name);
 683       break;
 684     case EXPR_TYPE_STRUCT:
 685       DEBUG_DisplayExpr(exp->un.structure.exp1);
 686       fprintf(stderr, ".%s", exp->un.structure.element_name);
 687       break;
 688     case EXPR_TYPE_CALL:
 689       /*
 690        * First, evaluate all of the arguments.  If any of them are not
 691        * evaluable, then bail.
 692        */
 693       fprintf(stderr, "%s(",exp->un.call.funcname);
 694       for(i=0; i < exp->un.call.nargs; i++)
 695         {
 696           DEBUG_DisplayExpr(exp->un.call.arg[i]);
 697           if( i != exp->un.call.nargs - 1 )
 698             {
 699               fprintf(stderr, ", ");
 700             }
 701         }
 702       fprintf(stderr, ")");
 703       break;
 704     case EXPR_TYPE_BINOP:
 705       fprintf(stderr, "( ");
 706       DEBUG_DisplayExpr(exp->un.binop.exp1);
 707       switch(exp->un.binop.binop_type)
 708         {
 709         case EXP_OP_ADD:
 710           fprintf(stderr, " + ");
 711           break;
 712         case EXP_OP_SUB:
 713           fprintf(stderr, " - ");
 714           break;
 715         case EXP_OP_SEG:
 716           fprintf(stderr, ":");
 717           break;
 718         case EXP_OP_LOR:
 719           fprintf(stderr, " || ");
 720           break;
 721         case EXP_OP_LAND:
 722           fprintf(stderr, " && ");
 723           break;
 724         case EXP_OP_OR:
 725           fprintf(stderr, " | ");
 726           break;
 727         case EXP_OP_AND:
 728           fprintf(stderr, " & ");
 729           break;
 730         case EXP_OP_XOR:
 731           fprintf(stderr, " ^ ");
 732           break;
 733         case EXP_OP_EQ:
 734           fprintf(stderr, " == ");
 735           break;
 736         case EXP_OP_GT:
 737           fprintf(stderr, " > ");
 738           break;
 739         case EXP_OP_LT:
 740           fprintf(stderr, " < ");
 741           break;
 742         case EXP_OP_GE:
 743           fprintf(stderr, " >= ");
 744           break;
 745         case EXP_OP_LE:
 746           fprintf(stderr, " <= ");
 747           break;
 748         case EXP_OP_NE:
 749           fprintf(stderr, " != ");
 750           break;
 751         case EXP_OP_SHL:
 752           fprintf(stderr, " << ");
 753           break;
 754         case EXP_OP_SHR:
 755           fprintf(stderr, " >> ");
 756           break;
 757         case EXP_OP_MUL:
 758           fprintf(stderr, " * ");
 759           break;
 760         case EXP_OP_DIV:
 761           fprintf(stderr, " / ");
 762           break;
 763         case EXP_OP_REM:
 764           fprintf(stderr, " %% ");
 765           break;
 766         case EXP_OP_ARR:
 767           fprintf(stderr, "[");
 768           break;
 769         default:
 770           break;
 771         }
 772       DEBUG_DisplayExpr(exp->un.binop.exp2);
 773       if( exp->un.binop.binop_type == EXP_OP_ARR )
 774         {
 775           fprintf(stderr, "]");
 776         }
 777       fprintf(stderr, " )");
 778       break;
 779     case EXPR_TYPE_UNOP:
 780       switch(exp->un.unop.unop_type)
 781         {
 782         case EXP_OP_NEG:
 783           fprintf(stderr, "-");
 784           break;
 785         case EXP_OP_NOT:
 786           fprintf(stderr, "!");
 787           break;
 788         case EXP_OP_LNOT:
 789           fprintf(stderr, "~");
 790           break;
 791         case EXP_OP_DEREF:
 792           fprintf(stderr, "*");
 793           break;
 794         case EXP_OP_ADDR:
 795           fprintf(stderr, "&");
 796           break;
 797         }
 798       DEBUG_DisplayExpr(exp->un.unop.exp1);
 799       break;
 800     default:
 801       fprintf(stderr,"Unexpected expression.\n");
 802       DEBUG_Exit(123);
 803       break;
 804     }
 805
 806   return TRUE;
 807 }
 808
 809 struct expr *
 810 DEBUG_CloneExpr(struct expr * exp)
 811 {
 812   int           i;
 813   struct expr * rtn;
 814
 815   rtn = (struct expr *) DBG_alloc(sizeof(struct expr));
 816
 817   /*
 818    * First copy the contents of the expression itself.
 819    */
 820   *rtn = *exp;
 821
 822
 823   switch(exp->type)
 824     {
 825     case EXPR_TYPE_CAST:
 826       rtn->un.cast.expr = DEBUG_CloneExpr(exp->un.cast.expr);
 827       break;
 828     case EXPR_TYPE_REGISTER:
 829     case EXPR_TYPE_US_CONST:
 830     case EXPR_TYPE_CONST:
 831       break;
 832     case EXPR_TYPE_STRING:
 833       rtn->un.string.str = DBG_strdup(exp->un.string.str);
 834       break;
 835     case EXPR_TYPE_SYMBOL:
 836       rtn->un.symbol.name = DBG_strdup(exp->un.symbol.name);
 837       break;
 838     case EXPR_TYPE_PSTRUCT:
 839     case EXPR_TYPE_STRUCT:
 840       rtn->un.structure.exp1 = DEBUG_CloneExpr(exp->un.structure.exp1);
 841       rtn->un.structure.element_name = DBG_strdup(exp->un.structure.element_name);
 842       break;
 843     case EXPR_TYPE_CALL:
 844       /*
 845        * First, evaluate all of the arguments.  If any of them are not
 846        * evaluable, then bail.
 847        */
 848       for(i=0; i < exp->un.call.nargs; i++)
 849         {
 850           rtn->un.call.arg[i]  = DEBUG_CloneExpr(exp->un.call.arg[i]);
 851         }
 852       rtn->un.call.funcname = DBG_strdup(exp->un.call.funcname);
 853       break;
 854     case EXPR_TYPE_BINOP:
 855       rtn->un.binop.exp1 = DEBUG_CloneExpr(exp->un.binop.exp1);
 856       rtn->un.binop.exp2 = DEBUG_CloneExpr(exp->un.binop.exp2);
 857       break;
 858     case EXPR_TYPE_UNOP:
 859       rtn->un.unop.exp1 = DEBUG_CloneExpr(exp->un.unop.exp1);
 860       break;
 861     default:
 862       fprintf(stderr,"Unexpected expression.\n");
 863       DEBUG_Exit(123);
 864       break;
 865     }
 866
 867   return rtn;
 868 }
 869
 870
 871 /*
 872  * Recursively go through an expression tree and free all memory associated
 873  * with it.
 874  */
 875 int
 876 DEBUG_FreeExpr(struct expr * exp)
 877 {
 878   int i;
 879
 880   switch(exp->type)
 881     {
 882     case EXPR_TYPE_CAST:
 883       DEBUG_FreeExpr(exp->un.cast.expr);
 884       break;
 885     case EXPR_TYPE_REGISTER:
 886     case EXPR_TYPE_US_CONST:
 887     case EXPR_TYPE_CONST:
 888       break;
 889     case EXPR_TYPE_STRING:
 890       DBG_free((char *) exp->un.string.str);
 891       break;
 892     case EXPR_TYPE_SYMBOL:
 893       DBG_free((char *) exp->un.symbol.name);
 894       break;
 895     case EXPR_TYPE_PSTRUCT:
 896     case EXPR_TYPE_STRUCT:
 897       DEBUG_FreeExpr(exp->un.structure.exp1);
 898       DBG_free((char *) exp->un.structure.element_name);
 899       break;
 900     case EXPR_TYPE_CALL:
 901       /*
 902        * First, evaluate all of the arguments.  If any of them are not
 903        * evaluable, then bail.
 904        */
 905       for(i=0; i < exp->un.call.nargs; i++)
 906         {
 907           DEBUG_FreeExpr(exp->un.call.arg[i]);
 908         }
 909       DBG_free((char *) exp->un.call.funcname);
 910       break;
 911     case EXPR_TYPE_BINOP:
 912       DEBUG_FreeExpr(exp->un.binop.exp1);
 913       DEBUG_FreeExpr(exp->un.binop.exp2);
 914       break;
 915     case EXPR_TYPE_UNOP:
 916       DEBUG_FreeExpr(exp->un.unop.exp1);
 917       break;
 918     default:
 919       fprintf(stderr,"Unexpected expression.\n");
 920       DEBUG_Exit(123);
 921       break;
 922     }
 923
 924   DBG_free(exp);
 925   return TRUE;
 926 }