1 /*-------------------------------------------------------------------------
3 pcoderegs.c - post code generation register optimizations
5 Written By - Scott Dattalo scott@dattalo.com
7 This program is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 2, or (at your option) any
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21 -------------------------------------------------------------------------*/
26 The purpose of the code in this file is to optimize the register usage.
31 #include "common.h" // Include everything in the SDCC src directory
36 #include "pcoderegs.h"
37 #include "pcodeflow.h"
39 extern void pCodeInsertAfter(pCode *pc1, pCode *pc2);
40 extern void dbg_dumpregusage(void);
41 extern pCode * findPrevInstruction(pCode *pci);
42 extern pBranch * pBranchAppend(pBranch *h, pBranch *n);
43 void unlinkpCode(pCode *pc);
45 int total_registers_saved=0;
47 /*-----------------------------------------------------------------*
48 * void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
49 *-----------------------------------------------------------------*/
51 void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
54 if(!reg || ! pcfl || !isPCFL(pcflow))
58 pcfl->registers = newSet();
64 /*-----------------------------------------------------------------*
66 *-----------------------------------------------------------------*/
67 void dbg_regusage(set *fregs)
74 for (reg = setFirstItem(fregs) ; reg ;
75 reg = setNextItem(fregs)) {
77 if(elementsInSet(reg->reglives.usedpCodes)) {
79 fprintf (stderr, "%s addr=0x%03x rIdx=0x%03x",
84 pcfl = setFirstItem(reg->reglives.usedpFlows);
86 fprintf(stderr, "\n used in seq");
89 fprintf(stderr," 0x%03x",pcfl->seq);
90 pcfl = setNextItem(reg->reglives.usedpFlows);
93 pcfl = setFirstItem(reg->reglives.assignedpFlows);
95 fprintf(stderr, "\n assigned in seq");
98 fprintf(stderr," 0x%03x",pcfl->seq);
99 pcfl = setNextItem(reg->reglives.assignedpFlows);
102 pc = setFirstItem(reg->reglives.usedpCodes);
104 fprintf(stderr, "\n used in instructions ");
107 pcfl = PCODE(PCI(pc)->pcflow);
109 fprintf(stderr," 0x%03x:",pcfl->seq);
110 fprintf(stderr,"0x%03x",pc->seq);
112 pc = setNextItem(reg->reglives.usedpCodes);
115 fprintf(stderr, "\n");
120 /*-----------------------------------------------------------------*
122 *-----------------------------------------------------------------*/
123 void dbg_dumpregusage(void)
126 fprintf(stderr,"*** Register Usage ***\n");
127 fprintf(stderr,"InternalRegs:\n");
128 dbg_regusage(dynInternalRegs);
129 fprintf(stderr,"AllocRegs:\n");
130 dbg_regusage(dynAllocRegs);
131 fprintf(stderr,"StackRegs:\n");
132 dbg_regusage(dynStackRegs);
133 fprintf(stderr,"DirectRegs:\n");
134 dbg_regusage(dynDirectRegs);
135 fprintf(stderr,"DirectBitRegs:\n");
136 dbg_regusage(dynDirectBitRegs);
137 fprintf(stderr,"ProcessorRegs:\n");
138 dbg_regusage(dynProcessorRegs);
143 /*-----------------------------------------------------------------*
144 * void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
145 *-----------------------------------------------------------------*/
146 void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
158 pc = findNextInstruction(pcfl->pc.next);
160 while(isPCinFlow(pc,PCODE(pcfl))) {
163 reg = getRegFromInstruction(pc);
167 fprintf(stderr, "flow seq %d, inst seq %d %s ",PCODE(pcfl)->seq,pc->seq,reg->name);
168 fprintf(stderr, "addr = 0x%03x, type = %d rIdx=0x%03x\n",
169 reg->address,reg->type,reg->rIdx);
172 addSetIfnotP(& (PCFL(pcfl)->registers), reg);
174 if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
175 addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
177 if(PCC_REGISTER & PCI(pc)->outCond)
178 addSetIfnotP(& (reg->reglives.assignedpFlows), pcfl);
180 addSetIfnotP(& (reg->reglives.usedpCodes), pc);
185 pc = findNextInstruction(pc->next);
191 /*-----------------------------------------------------------------*
192 * void pCodeRegMapLiveRanges(pBlock *pb)
193 *-----------------------------------------------------------------*/
194 void pCodeRegMapLiveRanges(pBlock *pb)
198 for( pcflow = findNextpCode(pb->pcHead, PC_FLOW);
200 pcflow = findNextpCode(pcflow->next, PC_FLOW) ) {
202 if(!isPCFL(pcflow)) {
203 fprintf(stderr, "pCodeRegMapLiveRanges - pcflow is not a flow object ");
206 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
210 for( pcflow = findNextpCode(pb->pcHead, PC_FLOW);
212 pcflow = findNextpCode(pcflow->next, PC_FLOW) ) {
214 regs *r = setFirstItem(PCFL(pcflow)->registers);
215 fprintf(stderr,"flow seq %d\n", pcflow->seq);
218 fprintf(stderr, " %s\n",r->name);
219 r = setNextItem(PCFL(pcflow)->registers);
226 // dbg_dumpregusage();
231 /*-----------------------------------------------------------------*
233 *-----------------------------------------------------------------*/
234 static void Remove1pcode(pCode *pc, regs *reg)
241 deleteSetItem (&(reg->reglives.usedpCodes),pc);
243 fprintf(stderr,"removing instruction:\n");
244 pc->print(stderr,pc);
247 pcn = findNextInstruction(pc->next);
250 PCI(pcn)->label = pBranchAppend(PCI(pcn)->label,PCI(pc)->label);
255 pcn = findNextInstruction(pc->next);
258 if(PCI(pcn)->cline) {
259 //fprintf(stderr, "source line has been optimized completely out\n");
260 //pc->print(stderr,pc);
262 PCI(pcn)->cline = PCI(pc)->cline;
271 /*-----------------------------------------------------------------*
272 * void RemoveRegsFromSet(set *regset)
274 *-----------------------------------------------------------------*/
275 void RemoveRegsFromSet(set *regset)
282 regset = regset->next;
284 used = elementsInSet(reg->reglives.usedpCodes);
288 //fprintf(stderr," reg %s isfree=%d, wasused=%d\n",reg->name,reg->isFree,reg->wasUsed);
290 //fprintf(stderr," getting rid of reg %s\n",reg->name);
297 pc = setFirstItem(reg->reglives.usedpCodes);
299 if(reg->type == REG_SFR) {
300 //fprintf(stderr, "not removing SFR reg %s even though used only once\n",reg->name);
307 pCode *pcn = findNextInstruction(pc->next);
309 if(pcn && PCI(pcn)->label) {
310 //fprintf(stderr,"can't delete instruction with label...\n");
311 //pc->print(stderr,pc);
314 /* Move the label to the next instruction */
316 PCI(pcn)->label = PCI(pc)->label;
321 regs *r = getRegFromInstruction(pc);
322 fprintf(stderr, "WARNING, a skip instruction is being optimized out\n");
323 pc->print(stderr,pc);
324 fprintf(stderr,"reg %s, type =%d\n",r->name, r->type);
326 //fprintf(stderr," removing reg %s because it is used only once\n",reg->name);
327 Remove1pcode(pc, reg);
330 deleteSetItem (&(reg->reglives.usedpCodes),pc);
334 total_registers_saved++; // debugging stats.
341 /*-----------------------------------------------------------------*
342 * void RemoveUnusedRegisters(void)
344 *-----------------------------------------------------------------*/
345 void RemoveUnusedRegisters(void)
347 /* First, get rid of registers that are used only one time */
350 RemoveRegsFromSet(dynInternalRegs);
351 RemoveRegsFromSet(dynAllocRegs);
352 RemoveRegsFromSet(dynStackRegs);
354 don't do DirectRegs yet - there's a problem with arrays
355 RemoveRegsFromSet(dynDirectRegs);
357 RemoveRegsFromSet(dynDirectBitRegs);
359 if(total_registers_saved) fprintf(stderr, " *** Saved %d registers ***\n", total_registers_saved);
363 /*-----------------------------------------------------------------*
365 *-----------------------------------------------------------------*/
366 static void Remove2pcodes(pCode *pcflow, pCode *pc1, pCode *pc2, regs *reg, int can_free)
372 Remove1pcode(pc1, reg);
375 Remove1pcode(pc2, reg);
376 deleteSetItem (&(PCFL(pcflow)->registers), reg);
385 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
388 /*-----------------------------------------------------------------*
390 *-----------------------------------------------------------------*/
391 int regUsedinRange(pCode *pc1, pCode *pc2, regs *reg)
397 testreg = getRegFromInstruction(pc1);
398 if(testreg && (testreg->rIdx == reg->rIdx)) {
402 pc1 = findNextInstruction(pc1->next);
404 } while (pc1 && (pc1 != pc2) && (i++ < 100)) ;
407 fprintf(stderr, "warning, regUsedinRange searched through too many pcodes\n");
412 /*-----------------------------------------------------------------*
413 * void pCodeOptime2pCodes(pCode *pc1, pCode *pc2)
415 * ADHOC pattern checking
416 * Now look for specific sequences that are easy to optimize.
417 * Many of these sequences are characteristic of the compiler
418 * (i.e. it'd probably be a waste of time to apply these adhoc
419 * checks to hand written assembly.)
422 *-----------------------------------------------------------------*/
423 void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free)
428 if(pc2->seq < pc1->seq) {
435 if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
449 //fprintf(stderr, " CLRF/MOVFW. instruction after MOVFW is:\n");
450 pct1 = findNextInstruction(pc2->next);
451 //t->print(stderr,t);
453 if(PCI(pct1)->op == POC_MOVWF) {
454 newpc = newpCode(POC_CLRF, PCI(pct1)->pcop);
455 pct1->destruct(pct1);
457 newpc = newpCode(POC_MOVLW, newpCodeOpLit(0));
460 pCodeInsertAfter(pc2, newpc);
461 PCI(newpc)->pcflow = PCFL(pcfl_used);
462 newpc->seq = pc2->seq;
464 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
465 total_registers_saved++; // debugging stats.
467 } else if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_IORFW) ){
468 //fprintf(stderr, " CLRF/IORFW.\n");
470 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
471 total_registers_saved++; // debugging stats.
473 } else if(PCI(pc1)->op == POC_MOVWF) {
475 pct2 = findNextInstruction(pc2->next);
477 if(PCI(pc2)->op == POC_MOVFW) {
478 //fprintf(stderr, " MOVWF/MOVFW. instruction after MOVFW is:\n");
479 //pct2->print(stderr,pct2);
481 if(PCI(pct2)->op == POC_MOVWF) {
482 reg2 = getRegFromInstruction(pct2);
483 if(reg2 && !regUsedinRange(pc1,pc2,reg2)) {
484 pct2->seq = pc1->seq;
486 pCodeInsertAfter(pc1,pct2);
487 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
488 total_registers_saved++; // debugging stats.
492 fprintf(stderr, " couldn't optimize\n");
494 fprintf(stderr, " %s is used in range\n",reg2->name);
496 fprintf(stderr, " reg2 is NULL\n");
501 pct1 = findPrevInstruction(pc1->prev);
503 (PCI(pct1)->pcflow == PCI(pc1)->pcflow) &&
504 (PCI(pct1)->op == POC_MOVFW)) {
506 reg1 = getRegFromInstruction(pct1);
507 if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
508 //fprintf(stderr, " MOVF/MOVFW. \n");
516 pct2 = newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
517 pCodeInsertAfter(pc2, pct2);
518 PCI(pct2)->pcflow = PCFL(pcfl_used);
519 pct2->seq = pc2->seq;
521 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
522 Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
523 total_registers_saved++; // debugging stats.
533 /*-----------------------------------------------------------------*
534 * void pCodeRegOptimeRegUsage(pBlock *pb)
535 *-----------------------------------------------------------------*/
536 void OptimizeRegUsage(set *fregs)
543 pCode *pcfl_used, *pcfl_assigned;
545 /* Step through the set by directly accessing the 'next' pointer.
546 * We could also step through by using the set API, but the
547 * the (debug) calls to print instructions affect the state
548 * of the set pointers */
553 if(reg->type == REG_SFR) {
554 //fprintf(stderr,"skipping SFR: %s\n",reg->name);
558 pcfl_used = setFirstItem(reg->reglives.usedpFlows);
559 pcfl_assigned = setFirstItem(reg->reglives.assignedpFlows);
561 used = elementsInSet(reg->reglives.usedpCodes);
565 * In this section, all registers that are used in only in two
566 * instructions are examined. If possible, they're optimized out.
571 fprintf (stderr, "OptimizeRegUsage: %s addr=0x%03x rIdx=0x%03x type=%d used=%d\n",
574 reg->rIdx, reg->type, used);
576 pc1 = setFirstItem(reg->reglives.usedpCodes);
577 pc2 = setNextItem(reg->reglives.usedpCodes);
579 if(pcfl_used && pcfl_assigned) {
582 expected case - the register has been assigned a value and is
586 //fprintf(stderr," used only twice\n");
587 if(pcfl_used->seq == pcfl_assigned->seq) {
589 //fprintf(stderr, " and used in same flow\n");
591 pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1);
594 // fprintf(stderr, " and used in different flows\n");
598 } else if(pcfl_used) {
601 register has been used twice without ever being assigned */
602 //fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
605 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
606 Remove2pcodes(pcfl_assigned, pc1, pc2, reg, 1);
607 total_registers_saved++; // debugging stats.
611 /* register has been used either once, or more than twice */
613 if(used && !pcfl_used && pcfl_assigned) {
616 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
618 pc = setFirstItem(reg->reglives.usedpCodes);
621 pcfl_assigned = PCODE(PCI(pc)->pcflow);
622 Remove1pcode(pc, reg);
624 deleteSetItem (&(PCFL(pcfl_assigned)->registers), reg);
626 deleteSetItem (&(reg->reglives.usedpCodes),pc);
629 pc = setNextItem(reg->reglives.usedpCodes);
636 total_registers_saved++; // debugging stats.
637 } else if(used > 2) {
639 /* examine the number of times this register is used */
647 /*-----------------------------------------------------------------*
648 * void pCodeRegOptimeRegUsage(pBlock *pb)
649 *-----------------------------------------------------------------*/
650 void pCodeRegOptimizeRegUsage(void)
655 int t = total_registers_saved;
658 saved = total_registers_saved;
660 /* Identify registers used in one flow sequence */
661 OptimizeRegUsage(dynAllocRegs);
662 OptimizeRegUsage(dynStackRegs);
663 OptimizeRegUsage(dynDirectRegs);
665 if(total_registers_saved != saved)
666 fprintf(stderr, " *** Saved %d registers, total saved %d ***\n", total_registers_saved-saved,total_registers_saved);
669 } while( passes-- && (total_registers_saved != saved));
671 if(total_registers_saved == t)
672 fprintf(stderr, "No registers saved on this pass\n");
676 fprintf(stderr,"dynamically allocated regs:\n");
677 dbg_regusage(dynAllocRegs);
678 fprintf(stderr,"stack regs:\n");
679 dbg_regusage(dynStackRegs);
680 fprintf(stderr,"direct regs:\n");
681 dbg_regusage(dynDirectRegs);
686 /*-----------------------------------------------------------------*
687 * void RegsUnMapLiveRanges(set *regset)
689 *-----------------------------------------------------------------*/
690 void RegsSetUnMapLiveRanges(set *regset)
696 regset = regset->next;
699 deleteSet(®->reglives.usedpCodes);
700 deleteSet(®->reglives.usedpFlows);
701 deleteSet(®->reglives.assignedpFlows);
707 void RegsUnMapLiveRanges(void)
710 RegsSetUnMapLiveRanges(dynAllocRegs);
711 RegsSetUnMapLiveRanges(dynStackRegs);
712 RegsSetUnMapLiveRanges(dynDirectRegs);
713 RegsSetUnMapLiveRanges(dynProcessorRegs);
714 RegsSetUnMapLiveRanges(dynDirectBitRegs);
715 RegsSetUnMapLiveRanges(dynInternalRegs);