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   1 /*-------------------------------------------------------------------------
   2
   3   pcoderegs.c - post code generation register optimizations
   4
   5    Written By -  Scott Dattalo scott@dattalo.com
   6    Ported To PIC16 By -  m.dubuc@rogers.com
   7
   8    This program is free software; you can redistribute it and/or modify it
   9    under the terms of the GNU General Public License as published by the
  10    Free Software Foundation; either version 2, or (at your option) any
  11    later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21
  22 -------------------------------------------------------------------------*/
  23
  24 /*
  25   pcoderegs.c
  26
  27   The purpose of the code in this file is to optimize the register usage.
  28
  29 */
  30 #include <stdio.h>
  31
  32 #include "common.h"   // Include everything in the SDCC src directory
  33 #include "newalloc.h"
  34 #include "ralloc.h"
  35 #include "device.h"
  36 #include "pcode.h"
  37 #include "pcoderegs.h"
  38 #include "pcodeflow.h"
  39
  40 extern void pic16_pCodeInsertAfter(pCode *pc1, pCode *pc2);
  41 extern pCode * pic16_findPrevInstruction(pCode *pci);
  42 extern pBranch * pic16_pBranchAppend(pBranch *h, pBranch *n);
  43 void pic16_unlinkpCode(pCode *pc);
  44 extern int pic16_pCodeSearchCondition(pCode *pc, unsigned int cond);
  45
  46 static int total_registers_saved=0;
  47 static int register_optimization=1;
  48
  49 /*-----------------------------------------------------------------*
  50  * void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
  51  *-----------------------------------------------------------------*/
  52 /*
  53 void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
  54 {
  55
  56   if(!reg || ! pcfl || !isPCFL(pcflow))
  57     return;
  58
  59   if(!pcfl->registers)
  60     pcfl->registers =  newSet();
  61
  62 }
  63 */
  64
  65
  66 /*-----------------------------------------------------------------*
  67  *
  68  *-----------------------------------------------------------------*/
  69 #if 0
  70 static void dbg_regusage(set *fregs)
  71 {
  72   regs *reg;
  73   pCode *pcfl;
  74   pCode *pc;
  75
  76
  77   for (reg = setFirstItem(fregs) ; reg ;
  78        reg = setNextItem(fregs)) {
  79
  80     if(elementsInSet(reg->reglives.usedpCodes)) {
  81
  82       fprintf (stderr, "%s  addr=0x%03x rIdx=0x%03x",
  83                reg->name,
  84                reg->address,
  85                reg->rIdx);
  86
  87       pcfl = setFirstItem(reg->reglives.usedpFlows);
  88       if(pcfl)
  89         fprintf(stderr, "\n   used in seq");
  90
  91       while(pcfl) {
  92         fprintf(stderr," 0x%03x",pcfl->seq);
  93         pcfl = setNextItem(reg->reglives.usedpFlows);
  94       }
  95
  96       pcfl = setFirstItem(reg->reglives.assignedpFlows);
  97       if(pcfl)
  98         fprintf(stderr, "\n   assigned in seq");
  99
 100       while(pcfl) {
 101         fprintf(stderr," 0x%03x",pcfl->seq);
 102         pcfl = setNextItem(reg->reglives.assignedpFlows);
 103       }
 104
 105       pc = setFirstItem(reg->reglives.usedpCodes);
 106       if(pc)
 107         fprintf(stderr, "\n   used in instructions ");
 108
 109       while(pc) {
 110         pcfl = PCODE(PCI(pc)->pcflow);
 111         if(pcfl)
 112           fprintf(stderr," 0x%03x:",pcfl->seq);
 113         fprintf(stderr,"0x%03x",pc->seq);
 114
 115         pc = setNextItem(reg->reglives.usedpCodes);
 116       }
 117
 118       fprintf(stderr, "\n");
 119     }
 120   }
 121 }
 122 #endif
 123
 124 /*-----------------------------------------------------------------*
 125  *
 126  *-----------------------------------------------------------------*/
 127 #if 0
 128 static void dbg_dumpregusage(void)
 129 {
 130
 131   fprintf(stderr,"***  Register Usage  ***\n");
 132   fprintf(stderr,"InternalRegs:\n");
 133   dbg_regusage(pic16_dynInternalRegs);
 134   fprintf(stderr,"AllocRegs:\n");
 135   dbg_regusage(pic16_dynAllocRegs);
 136   fprintf(stderr,"StackRegs:\n");
 137   dbg_regusage(pic16_dynStackRegs);
 138   fprintf(stderr,"DirectRegs:\n");
 139   dbg_regusage(pic16_dynDirectRegs);
 140   fprintf(stderr,"DirectBitRegs:\n");
 141   dbg_regusage(pic16_dynDirectBitRegs);
 142   fprintf(stderr,"ProcessorRegs:\n");
 143   dbg_regusage(pic16_dynProcessorRegs);
 144
 145 }
 146 #endif
 147
 148 /*-----------------------------------------------------------------*
 149  * void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
 150  *-----------------------------------------------------------------*/
 151 static void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
 152 {
 153
 154   pCode *pc=NULL;
 155   pCode *pcprev=NULL;
 156
 157   regs *reg;
 158
 159   if(!pcfl)
 160     return;
 161
 162
 163   pc = pic16_findNextInstruction(pcfl->pc.next);
 164
 165   while(pic16_isPCinFlow(pc,PCODE(pcfl))) {
 166
 167
 168     reg = pic16_getRegFromInstruction(pc);
 169
 170     if(reg) {
 171
 172 #if 0
 173       fprintf(stderr, "reg= %p\n", reg);
 174       fprintf(stderr, "flow seq %d, inst seq %d  %s  ",PCODE(pcfl)->seq,pc->seq,reg->name);
 175       fprintf(stderr, "addr = 0x%03x, type = %d  rIdx=0x%03x",
 176               reg->address,reg->type,reg->rIdx);
 177       fprintf(stderr, "command = %s\n", PCI(pc)->mnemonic);
 178
 179 #endif
 180
 181       addSetIfnotP(& (PCFL(pcfl)->registers), reg);
 182
 183       if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
 184         addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
 185
 186       if(PCC_REGISTER & PCI(pc)->outCond)
 187         addSetIfnotP(& (reg->reglives.assignedpFlows), pcfl);
 188
 189       addSetIfnotP(& (reg->reglives.usedpCodes), pc);
 190
 191 #if 1
 192         /* check to see if this pCode has 2 memory operands,
 193            and set up the second operand too */
 194         if(PCI(pc)->is2MemOp) {
 195                         reg = pic16_getRegFromInstruction2(pc);
 196
 197 //                      fprintf(stderr, "trying to get second operand from pCode reg= %s\n", reg->name);
 198                         addSetIfnotP(& (PCFL(pcfl)->registers), reg);
 199
 200                         if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
 201                                 addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
 202
 203                         if(PCC_REGISTER & PCI(pc)->outCond)
 204                                 addSetIfnotP(& (reg->reglives.assignedpFlows), pcfl);
 205
 206                         addSetIfnotP(& (reg->reglives.usedpCodes), pc);
 207
 208         }
 209 #endif
 210
 211     }
 212
 213
 214     pcprev = pc;
 215     pc = pic16_findNextInstruction(pc->next);
 216
 217   }
 218
 219 }
 220
 221 /*-----------------------------------------------------------------*
 222  * void pic16_pCodeRegMapLiveRanges(pBlock *pb)
 223  *-----------------------------------------------------------------*/
 224 void pic16_pCodeRegMapLiveRanges(pBlock *pb)
 225 {
 226   pCode *pcflow;
 227
 228   for( pcflow = pic16_findNextpCode(pb->pcHead, PC_FLOW);
 229        pcflow != NULL;
 230        pcflow = pic16_findNextpCode(pcflow->next, PC_FLOW) ) {
 231
 232     if(!isPCFL(pcflow)) {
 233       fprintf(stderr, "pCodeRegMapLiveRanges - pcflow is not a flow object ");
 234       continue;
 235     }
 236     pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
 237   }
 238
 239 #if 0
 240   for( pcflow = pic16_findNextpCode(pb->pcHead, PC_FLOW);
 241        pcflow != NULL;
 242        pcflow = pic16_findNextpCode(pcflow->next, PC_FLOW) ) {
 243
 244     regs *r = setFirstItem(PCFL(pcflow)->registers);
 245     fprintf(stderr,"flow seq %d\n", pcflow->seq);
 246
 247     while (r) {
 248       fprintf(stderr, "  %s\n",r->name);
 249       r = setNextItem(PCFL(pcflow)->registers);
 250
 251     }
 252
 253   }
 254 #endif
 255
 256 //  dbg_dumpregusage();
 257
 258 }
 259
 260
 261 /*-----------------------------------------------------------------*
 262  *
 263  *-----------------------------------------------------------------*/
 264 static void Remove1pcode(pCode *pc, regs *reg)
 265 {
 266   pCode *pcn=NULL;
 267
 268   if(!reg || !pc)
 269     return;
 270
 271   deleteSetItem (&(reg->reglives.usedpCodes),pc);
 272
 273 #if 0
 274   fprintf(stderr,"removing instruction:\n");
 275   pc->print(stderr,pc);
 276 #endif
 277
 278   if(PCI(pc)->label) {
 279     pcn = pic16_findNextInstruction(pc->next);
 280
 281     if(pcn)
 282       PCI(pcn)->label = pic16_pBranchAppend(PCI(pcn)->label,PCI(pc)->label);
 283   }
 284
 285   if(PCI(pc)->cline) {
 286     if(!pcn)
 287       pcn = pic16_findNextInstruction(pc->next);
 288
 289     if(pcn) {
 290       if(PCI(pcn)->cline) {
 291         //fprintf(stderr, "source line has been optimized completely out\n");
 292         //pc->print(stderr,pc);
 293       } else {
 294         PCI(pcn)->cline = PCI(pc)->cline;
 295       }
 296     }
 297   }
 298
 299   pc->destruct(pc);
 300
 301 }
 302
 303 /*-----------------------------------------------------------------*
 304  * void RemoveRegsFromSet(set *regset)
 305  *
 306  *-----------------------------------------------------------------*/
 307 static void  RemoveRegsFromSet(set *regset)
 308 {
 309   regs *reg;
 310   int used;
 311
 312   while(regset) {
 313     reg = regset->item;
 314     regset = regset->next;
 315
 316     used = elementsInSet(reg->reglives.usedpCodes);
 317
 318     if(used <= 1) {
 319
 320 //      fprintf(stderr," reg %s isfree=%d, wasused=%d\n",reg->name,reg->isFree,reg->wasUsed);
 321       if(used == 0) {
 322 //              fprintf(stderr,"%s:%d: getting rid of reg %s\n",__FILE__, __LINE__, reg->name);
 323         reg->isFree = 1;
 324         reg->wasUsed = 0;
 325       } else {
 326         pCode *pc;
 327
 328
 329         pc = setFirstItem(reg->reglives.usedpCodes);
 330
 331         if(reg->type == REG_SFR) {
 332                 fprintf(stderr, "not removing SFR reg %s even though used only once\n",reg->name);
 333           continue;
 334         }
 335
 336
 337         if(isPCI(pc)) {
 338           if(PCI(pc)->label) {
 339             pCode *pcn = pic16_findNextInstruction(pc->next);
 340
 341             if(pcn && PCI(pcn)->label) {
 342               //fprintf(stderr,"can't delete instruction with label...\n");
 343               //pc->print(stderr,pc);
 344               continue;
 345             }
 346             /* Move the label to the next instruction */
 347
 348             PCI(pcn)->label = PCI(pc)->label;
 349
 350           }
 351
 352           if(isPCI_SKIP(pc)) {
 353             regs *r = pic16_getRegFromInstruction(pc);
 354             fprintf(stderr, "WARNING, a skip instruction is being optimized out\n");
 355             pc->print(stderr,pc);
 356             fprintf(stderr,"reg %s, type =%d\n",r->name, r->type);
 357           }
 358 //              fprintf(stderr,"%s:%d: removing reg %s because it is used only once\n",__FILE__, __LINE__, reg->name);
 359           Remove1pcode(pc, reg);
 360           /*
 361             pic16_unlinkpCode(pc);
 362             deleteSetItem (&(reg->reglives.usedpCodes),pc);
 363           */
 364           reg->isFree = 1;
 365           reg->wasUsed = 0;
 366           total_registers_saved++;  // debugging stats.
 367         }
 368       }
 369     }
 370
 371   }
 372 }
 373 /*-----------------------------------------------------------------*
 374  * void pic16_RemoveUnusedRegisters(void)
 375  *
 376  *-----------------------------------------------------------------*/
 377 void pic16_RemoveUnusedRegisters(void)
 378 {
 379   /* First, get rid of registers that are used only one time */
 380
 381   //RemoveRegsFromSet(pic16_dynInternalRegs);
 382   RemoveRegsFromSet(pic16_dynAllocRegs);
 383   RemoveRegsFromSet(pic16_dynStackRegs);
 384   /*
 385     don't do DirectRegs yet - there's a problem with arrays
 386   RemoveRegsFromSet(pic16_dynDirectRegs);
 387   */
 388   RemoveRegsFromSet(pic16_dynDirectBitRegs);
 389
 390   if(total_registers_saved && pic16_pcode_verbose)
 391         fprintf(stderr, " *** Saved %d registers ***\n", total_registers_saved);
 392 }
 393
 394
 395 /*-----------------------------------------------------------------*
 396  *
 397  *-----------------------------------------------------------------*/
 398 static void Remove2pcodes(pCode *pcflow, pCode *pc1, pCode *pc2, regs *reg, int can_free)
 399 {
 400   if(!reg)
 401     return;
 402
 403   if(pc1)
 404     Remove1pcode(pc1, reg);
 405
 406   if(pc2) {
 407     Remove1pcode(pc2, reg);
 408     deleteSetItem (&(PCFL(pcflow)->registers), reg);
 409
 410     if(can_free) {
 411       reg->isFree = 1;
 412       reg->wasUsed = 0;
 413     }
 414
 415   }
 416
 417   pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
 418 }
 419
 420 /*-----------------------------------------------------------------*
 421  *
 422  *-----------------------------------------------------------------*/
 423 static int regUsedinRange(pCode *pc1, pCode *pc2, regs *reg)
 424 {
 425   int i=0;
 426   regs *testreg;
 427
 428   do {
 429     testreg = pic16_getRegFromInstruction(pc1);
 430     if(testreg && (testreg->rIdx == reg->rIdx)) {
 431       return 1;
 432     }
 433
 434     pc1 = pic16_findNextInstruction(pc1->next);
 435
 436   } while (pc1 && (pc1 != pc2) && (i++ < 100)) ;
 437
 438   if(i >= 100)
 439     fprintf(stderr, "warning, regUsedinRange searched through too many pcodes\n");
 440
 441   return 0;
 442 }
 443
 444 /*-----------------------------------------------------------------*
 445  * void pCodeOptime2pCodes(pCode *pc1, pCode *pc2)
 446  *
 447  * ADHOC pattern checking
 448  * Now look for specific sequences that are easy to optimize.
 449  * Many of these sequences are characteristic of the compiler
 450  * (i.e. it'd probably be a waste of time to apply these adhoc
 451  * checks to hand written assembly.)
 452  *
 453  *
 454  *-----------------------------------------------------------------*/
 455 static int pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free, int optimize_level)
 456 {
 457   pCode *pct1, *pct2;
 458   regs  *reg1, *reg2;
 459
 460   int t = total_registers_saved;
 461
 462   if(pc2->seq < pc1->seq) {
 463     pct1 = pc2;
 464     pc2 = pc1;
 465     pc1 = pct1;
 466   }
 467 /*
 468   fprintf(stderr,"pCodeOptime2pCodes\n");
 469   pc1->print(stderr,pc1);
 470   pc2->print(stderr,pc2);
 471 */
 472   if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
 473
 474     /*
 475       clrf  reg
 476       stuff...
 477       movf  reg,w
 478
 479       can be replaced with
 480
 481       stuff...
 482       movlw 0
 483     */
 484
 485     pCode *newpc;
 486     //fprintf(stderr, "   CLRF/MOVFW. instruction after MOVFW is:\n");
 487     pct1 = pic16_findNextInstruction(pc2->next);
 488
 489     if(PCI(pct1)->op == POC_MOVWF) {
 490       newpc = pic16_newpCode(POC_CLRF, PCI(pct1)->pcop);
 491       pct1->destruct(pct1);
 492     } else {
 493       newpc = pic16_newpCode(POC_MOVLW, pic16_newpCodeOpLit(0));
 494     }
 495
 496     pic16_pCodeInsertAfter(pc2, newpc);
 497     PCI(newpc)->pcflow = PCFL(pcfl_used);
 498     newpc->seq = pc2->seq;
 499
 500     Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
 501     total_registers_saved++;  // debugging stats.
 502
 503   } else if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_IORFW) ){
 504     //fprintf(stderr, "   CLRF/IORFW.\n");
 505
 506     pct2 = pic16_findNextInstruction(pc2->next);
 507
 508     if(pic16_pCodeSearchCondition(pct2, PCC_Z) > 0) {
 509       pct2 = pic16_newpCode(POC_IORLW, pic16_newpCodeOpLit(0));
 510       pct2->seq = pc2->seq;
 511       PCI(pct2)->pcflow = PCFL(pcfl_used);
 512       pic16_pCodeInsertAfter(pc1,pct2);
 513     }
 514     Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
 515     total_registers_saved++;  // debugging stats.
 516
 517   }  else if(PCI(pc1)->op == POC_MOVWF) {
 518
 519     pct2 = pic16_findNextInstruction(pc2->next);
 520
 521     if(PCI(pc2)->op == POC_MOVFW) {
 522       /*
 523         fprintf(stderr, "   MOVWF/MOVFW. instruction after MOVFW is:\n");
 524         pct2->print(stderr,pct2);
 525       */
 526
 527       if(PCI(pct2)->op == POC_MOVWF) {
 528         /*
 529           Change:
 530
 531             movwf   reg
 532
 533             stuff...
 534
 535             movf    reg,w
 536             movwf   reg2
 537
 538           To:
 539
 540
 541         */
 542         reg2 = pic16_getRegFromInstruction(pct2);
 543         //if(reg2 && !regUsedinRange(pc1,pc2,reg2) && (reg2->type != REG_SFR)) {
 544         if(reg2 && !regUsedinRange(pc1,pc2,reg2)) {
 545
 546           if(pic16_pCodeSearchCondition(pct2, PCC_Z) < 1) {
 547             pCode *pct3 = pic16_findNextInstruction(pct2->next);
 548             pct2->seq = pc1->seq;
 549             pic16_unlinkpCode(pct2);
 550             pic16_pCodeInsertAfter(pic16_findPrevInstruction(pc1->prev),pct2);
 551
 552 #define usesW(x)       ((x) && (isPCI(x)) && ( (PCI(x)->inCond & PCC_W) != 0))
 553
 554             if(usesW(pct3))
 555               ; // Remove2pcodes(pcfl_used, pc1, NULL, reg, can_free);
 556             else
 557               Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
 558
 559             total_registers_saved++;  // debugging stats.
 560             return 1;
 561             } else {
 562               //fprintf(stderr,"didn't optimize because Z bit is used\n");
 563             }
 564         }
 565 /*
 566         fprintf(stderr, " couldn't optimize\n");
 567         if(reg2)
 568           fprintf(stderr, " %s is used in range\n",reg2->name);
 569         else
 570           fprintf(stderr, " reg2 is NULL\n");
 571 */
 572       }
 573     }
 574
 575     pct1 = pic16_findPrevInstruction(pc1->prev);
 576     if(pct1 && (PCI(pct1)->pcflow == PCI(pc1)->pcflow)) {
 577
 578       if ( (PCI(pct1)->op == POC_MOVFW) &&
 579            (PCI(pc2)->op == POC_MOVFW)) {
 580
 581         reg1 = pic16_getRegFromInstruction(pct1);
 582         if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
 583           /*
 584             fprintf(stderr, "   MOVF/MOVFW. \n");
 585             fprintf(stderr, "     ...optimizing\n");
 586           */
 587
 588           /*
 589             Change:
 590
 591             movf   reg1,w
 592             movwf  reg
 593
 594             stuff...
 595             movf   reg,w
 596
 597             To:
 598
 599             stuff...
 600
 601             movf   reg1,w
 602
 603             Or, if we're not deleting the register then the "To" is:
 604
 605             stuff...
 606
 607             movf   reg1,w
 608             movwf  reg
 609
 610
 611           */
 612           pct2 = pic16_newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
 613           pic16_pCodeInsertAfter(pc2, pct2);
 614           PCI(pct2)->pcflow = PCFL(pcfl_used);
 615           pct2->seq = pc2->seq;
 616
 617           if(can_free) {
 618             Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
 619           } else {
 620             /* If we're not freeing the register then that means (probably)
 621              * the register is needed somewhere else.*/
 622             pic16_unlinkpCode(pc1);
 623             pic16_pCodeInsertAfter(pct2, pc1);
 624
 625             Remove2pcodes(pcfl_used, pc2, NULL, reg, can_free);
 626           }
 627
 628           Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
 629           total_registers_saved++;  // debugging stats.
 630
 631         }
 632       } else if ( (PCI(pct1)->op == POC_MOVWF) &&
 633            (PCI(pc2)->op == POC_MOVFW)) {
 634         //fprintf(stderr,"movwf MOVWF/MOVFW\n");
 635         if(optimize_level > 1 && can_free) {
 636           pct2 = pic16_newpCode(POC_MOVFW, PCI(pc1)->pcop);
 637           pic16_pCodeInsertAfter(pc2, pct2);
 638           Remove2pcodes(pcfl_used, pc1, pc2, reg, 1);
 639           total_registers_saved++;  // debugging stats.
 640         }
 641       }
 642
 643
 644     }
 645
 646   }
 647
 648   return (total_registers_saved != t);
 649 }
 650
 651 /*-----------------------------------------------------------------*
 652  * void pCodeRegOptimeRegUsage(pBlock *pb)
 653  *-----------------------------------------------------------------*/
 654 static void OptimizeRegUsage(set *fregs, int optimize_multi_uses, int optimize_level)
 655 {
 656   regs *reg;
 657   int used;
 658   pCode *pc1=NULL, *pc2=NULL;
 659
 660
 661   while(fregs) {
 662     pCode *pcfl_used, *pcfl_assigned;
 663
 664     /* Step through the set by directly accessing the 'next' pointer.
 665      * We could also step through by using the set API, but the
 666      * the (debug) calls to print instructions affect the state
 667      * of the set pointers */
 668
 669     reg = fregs->item;
 670     fregs = fregs->next;
 671
 672         if(reg->type == REG_SFR) {
 673 //              fprintf(stderr,"skipping SFR: %s\n",reg->name);
 674                 continue;
 675         }
 676
 677     pcfl_used = setFirstItem(reg->reglives.usedpFlows);
 678     pcfl_assigned = setFirstItem(reg->reglives.assignedpFlows);
 679
 680     used = elementsInSet(reg->reglives.usedpCodes);
 681 //      fprintf(stderr, "%s:%d register %s used %d times in pCode\n", __FILE__, __LINE__, reg->name, used);
 682     if(used == 2) {
 683
 684       /*
 685        * In this section, all registers that are used in only in two
 686        * instructions are examined. If possible, they're optimized out.
 687        */
 688
 689 #if 0
 690       fprintf (stderr, "OptimizeRegUsage: %s  addr=0x%03x rIdx=0x%03x type=%d used=%d\n",
 691                reg->name,
 692                reg->address,
 693                reg->rIdx, reg->type, used);
 694 #endif
 695
 696       pc1 = setFirstItem(reg->reglives.usedpCodes);
 697       pc2 = setNextItem(reg->reglives.usedpCodes);
 698
 699       if(pcfl_used && pcfl_assigned) {
 700
 701         /*
 702            expected case - the register has been assigned a value and is
 703            subsequently used
 704         */
 705
 706         //fprintf(stderr," used only twice\n");
 707         if(pcfl_used->seq == pcfl_assigned->seq) {
 708
 709           //fprintf(stderr, "  and used in same flow\n");
 710
 711           pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1,optimize_level);
 712
 713         } else {
 714           // fprintf(stderr, "  and used in different flows\n");
 715
 716         }
 717
 718       } else if(pcfl_used) {
 719
 720         /*
 721           register has been used twice without ever being assigned */
 722         //fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
 723
 724       } else {
 725 //              fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
 726         Remove2pcodes(pcfl_assigned, pc1, pc2, reg, 1);
 727         total_registers_saved++;  // debugging stats.
 728       }
 729     } else {
 730
 731       /* register has been used either once, or more than twice */
 732
 733       if(used && !pcfl_used && pcfl_assigned) {
 734         pCode *pc;
 735
 736 //              fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
 737
 738         pc = setFirstItem(reg->reglives.usedpCodes);
 739         while(pc) {
 740
 741           pcfl_assigned = PCODE(PCI(pc)->pcflow);
 742           Remove1pcode(pc, reg);
 743
 744           deleteSetItem (&(PCFL(pcfl_assigned)->registers), reg);
 745           /*
 746           deleteSetItem (&(reg->reglives.usedpCodes),pc);
 747           pc->destruct(pc);
 748           */
 749           pc = setNextItem(reg->reglives.usedpCodes);
 750         }
 751
 752
 753         reg->isFree = 1;
 754         reg->wasUsed = 0;
 755
 756         total_registers_saved++;  // debugging stats.
 757       } else if( (used > 2) && optimize_multi_uses) {
 758
 759         set *rset1=NULL;
 760         set *rset2=NULL;
 761         int searching=1;
 762
 763         pCodeFlow *pcfl1=NULL, *pcfl2=NULL;
 764
 765         /* examine the number of times this register is used */
 766
 767
 768         rset1 = reg->reglives.usedpCodes;
 769         while(rset1 && searching) {
 770
 771           pc1 = rset1->item;
 772           rset2 = rset1->next;
 773
 774           if(pc1 && isPCI(pc1) &&  ( (pcfl1 = PCI(pc1)->pcflow) != NULL) ) {
 775
 776             //while(rset2 && searching) {
 777             if(rset2) {
 778
 779               pc2 = rset2->item;
 780               if(pc2 && isPCI(pc2)  &&  ( (pcfl2 = PCI(pc2)->pcflow) != NULL) )  {
 781                 if(pcfl2 == pcfl1) {
 782
 783                   if(pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 0,optimize_level))
 784                     searching = 0;
 785                 }
 786               }
 787
 788               //rset2 = rset2->next;
 789
 790             }
 791           }
 792           rset1 = rset1->next;
 793         }
 794       }
 795     }
 796
 797   }
 798
 799 }
 800 /*-----------------------------------------------------------------*
 801  * void pic16_pCodeRegOptimeRegUsage(pBlock *pb)
 802  *-----------------------------------------------------------------*/
 803 void pic16_pCodeRegOptimizeRegUsage(int level)
 804 {
 805
 806   int passes;
 807   int saved = 0;
 808   int t = total_registers_saved;
 809
 810   if(!register_optimization)
 811     return;
 812 #define OPT_PASSES 4
 813   passes = OPT_PASSES;
 814
 815   do {
 816     saved = total_registers_saved;
 817
 818     /* Identify registers used in one flow sequence */
 819     OptimizeRegUsage(pic16_dynAllocRegs,level, (OPT_PASSES-passes));
 820     OptimizeRegUsage(pic16_dynStackRegs,level, (OPT_PASSES-passes));
 821     OptimizeRegUsage(pic16_dynDirectRegs,0, (OPT_PASSES-passes));
 822
 823     if((total_registers_saved != saved)
 824         && (pic16_pcode_verbose))
 825       fprintf(stderr, " *** pass %d, Saved %d registers, total saved %d ***\n",
 826               (1+OPT_PASSES-passes),total_registers_saved-saved,total_registers_saved);
 827
 828     passes--;
 829
 830   } while( passes && ((total_registers_saved != saved) || (passes==OPT_PASSES-1)) );
 831
 832   if(total_registers_saved == t)
 833
 834   if(pic16_debug_verbose)
 835     fprintf(stderr, "No registers saved on this pass\n");
 836
 837
 838 /*
 839   fprintf(stderr,"dynamically allocated regs:\n");
 840   dbg_regusage(pic16_dynAllocRegs);
 841   fprintf(stderr,"stack regs:\n");
 842   dbg_regusage(pic16_dynStackRegs);
 843   fprintf(stderr,"direct regs:\n");
 844   dbg_regusage(pic16_dynDirectRegs);
 845 */
 846 }
 847
 848
 849 /*-----------------------------------------------------------------*
 850  * void RegsUnMapLiveRanges(set *regset)
 851  *
 852  *-----------------------------------------------------------------*/
 853 static void  RegsSetUnMapLiveRanges(set *regset)
 854 {
 855   regs *reg;
 856
 857   while(regset) {
 858     reg = regset->item;
 859     regset = regset->next;
 860
 861
 862     deleteSet(&reg->reglives.usedpCodes);
 863     deleteSet(&reg->reglives.usedpFlows);
 864     deleteSet(&reg->reglives.assignedpFlows);
 865
 866   }
 867
 868 }
 869
 870 void  pic16_RegsUnMapLiveRanges(void)
 871 {
 872
 873   RegsSetUnMapLiveRanges(pic16_dynAllocRegs);
 874   RegsSetUnMapLiveRanges(pic16_dynStackRegs);
 875   RegsSetUnMapLiveRanges(pic16_dynDirectRegs);
 876   RegsSetUnMapLiveRanges(pic16_dynProcessorRegs);
 877   RegsSetUnMapLiveRanges(pic16_dynDirectBitRegs);
 878   RegsSetUnMapLiveRanges(pic16_dynInternalRegs);
 879
 880 }