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);
44 extern int pCodeSearchCondition(pCode *pc, unsigned int cond);
46 int total_registers_saved=0;
47 int register_optimization=1;
49 /*-----------------------------------------------------------------*
50 * void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
51 *-----------------------------------------------------------------*/
53 void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
56 if(!reg || ! pcfl || !isPCFL(pcflow))
60 pcfl->registers = newSet();
66 /*-----------------------------------------------------------------*
68 *-----------------------------------------------------------------*/
69 void dbg_regusage(set *fregs)
76 for (reg = setFirstItem(fregs) ; reg ;
77 reg = setNextItem(fregs)) {
79 if(elementsInSet(reg->reglives.usedpCodes)) {
81 fprintf (stderr, "%s addr=0x%03x rIdx=0x%03x",
86 pcfl = setFirstItem(reg->reglives.usedpFlows);
88 fprintf(stderr, "\n used in seq");
91 fprintf(stderr," 0x%03x",pcfl->seq);
92 pcfl = setNextItem(reg->reglives.usedpFlows);
95 pcfl = setFirstItem(reg->reglives.assignedpFlows);
97 fprintf(stderr, "\n assigned in seq");
100 fprintf(stderr," 0x%03x",pcfl->seq);
101 pcfl = setNextItem(reg->reglives.assignedpFlows);
104 pc = setFirstItem(reg->reglives.usedpCodes);
106 fprintf(stderr, "\n used in instructions ");
109 pcfl = PCODE(PCI(pc)->pcflow);
111 fprintf(stderr," 0x%03x:",pcfl->seq);
112 fprintf(stderr,"0x%03x",pc->seq);
114 pc = setNextItem(reg->reglives.usedpCodes);
117 fprintf(stderr, "\n");
122 /*-----------------------------------------------------------------*
124 *-----------------------------------------------------------------*/
125 void dbg_dumpregusage(void)
128 fprintf(stderr,"*** Register Usage ***\n");
129 fprintf(stderr,"InternalRegs:\n");
130 dbg_regusage(dynInternalRegs);
131 fprintf(stderr,"AllocRegs:\n");
132 dbg_regusage(dynAllocRegs);
133 fprintf(stderr,"StackRegs:\n");
134 dbg_regusage(dynStackRegs);
135 fprintf(stderr,"DirectRegs:\n");
136 dbg_regusage(dynDirectRegs);
137 fprintf(stderr,"DirectBitRegs:\n");
138 dbg_regusage(dynDirectBitRegs);
139 fprintf(stderr,"ProcessorRegs:\n");
140 dbg_regusage(dynProcessorRegs);
145 /*-----------------------------------------------------------------*
146 * void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
147 *-----------------------------------------------------------------*/
148 void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
160 pc = findNextInstruction(pcfl->pc.next);
162 while(isPCinFlow(pc,PCODE(pcfl))) {
165 reg = getRegFromInstruction(pc);
169 fprintf(stderr, "flow seq %d, inst seq %d %s ",PCODE(pcfl)->seq,pc->seq,reg->name);
170 fprintf(stderr, "addr = 0x%03x, type = %d rIdx=0x%03x\n",
171 reg->address,reg->type,reg->rIdx);
174 addSetIfnotP(& (PCFL(pcfl)->registers), reg);
176 if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
177 addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
179 if(PCC_REGISTER & PCI(pc)->outCond)
180 addSetIfnotP(& (reg->reglives.assignedpFlows), pcfl);
182 addSetIfnotP(& (reg->reglives.usedpCodes), pc);
187 pc = findNextInstruction(pc->next);
193 /*-----------------------------------------------------------------*
194 * void pCodeRegMapLiveRanges(pBlock *pb)
195 *-----------------------------------------------------------------*/
196 void pCodeRegMapLiveRanges(pBlock *pb)
200 for( pcflow = findNextpCode(pb->pcHead, PC_FLOW);
202 pcflow = findNextpCode(pcflow->next, PC_FLOW) ) {
204 if(!isPCFL(pcflow)) {
205 fprintf(stderr, "pCodeRegMapLiveRanges - pcflow is not a flow object ");
208 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
212 for( pcflow = findNextpCode(pb->pcHead, PC_FLOW);
214 pcflow = findNextpCode(pcflow->next, PC_FLOW) ) {
216 regs *r = setFirstItem(PCFL(pcflow)->registers);
217 fprintf(stderr,"flow seq %d\n", pcflow->seq);
220 fprintf(stderr, " %s\n",r->name);
221 r = setNextItem(PCFL(pcflow)->registers);
228 // dbg_dumpregusage();
233 /*-----------------------------------------------------------------*
235 *-----------------------------------------------------------------*/
236 static void Remove1pcode(pCode *pc, regs *reg)
243 deleteSetItem (&(reg->reglives.usedpCodes),pc);
245 fprintf(stderr,"removing instruction:\n");
246 pc->print(stderr,pc);
249 pcn = findNextInstruction(pc->next);
252 PCI(pcn)->label = pBranchAppend(PCI(pcn)->label,PCI(pc)->label);
257 pcn = findNextInstruction(pc->next);
260 if(PCI(pcn)->cline) {
261 //fprintf(stderr, "source line has been optimized completely out\n");
262 //pc->print(stderr,pc);
264 PCI(pcn)->cline = PCI(pc)->cline;
273 /*-----------------------------------------------------------------*
274 * void RemoveRegsFromSet(set *regset)
276 *-----------------------------------------------------------------*/
277 void RemoveRegsFromSet(set *regset)
284 regset = regset->next;
286 used = elementsInSet(reg->reglives.usedpCodes);
290 //fprintf(stderr," reg %s isfree=%d, wasused=%d\n",reg->name,reg->isFree,reg->wasUsed);
292 //fprintf(stderr," getting rid of reg %s\n",reg->name);
299 pc = setFirstItem(reg->reglives.usedpCodes);
301 if(reg->type == REG_SFR) {
302 //fprintf(stderr, "not removing SFR reg %s even though used only once\n",reg->name);
309 pCode *pcn = findNextInstruction(pc->next);
311 if(pcn && PCI(pcn)->label) {
312 //fprintf(stderr,"can't delete instruction with label...\n");
313 //pc->print(stderr,pc);
316 /* Move the label to the next instruction */
318 PCI(pcn)->label = PCI(pc)->label;
323 regs *r = getRegFromInstruction(pc);
324 fprintf(stderr, "WARNING, a skip instruction is being optimized out\n");
325 pc->print(stderr,pc);
326 fprintf(stderr,"reg %s, type =%d\n",r->name, r->type);
328 //fprintf(stderr," removing reg %s because it is used only once\n",reg->name);
329 Remove1pcode(pc, reg);
332 deleteSetItem (&(reg->reglives.usedpCodes),pc);
336 total_registers_saved++; // debugging stats.
343 /*-----------------------------------------------------------------*
344 * void RemoveUnusedRegisters(void)
346 *-----------------------------------------------------------------*/
347 void RemoveUnusedRegisters(void)
349 /* First, get rid of registers that are used only one time */
351 //RemoveRegsFromSet(dynInternalRegs);
352 RemoveRegsFromSet(dynAllocRegs);
353 RemoveRegsFromSet(dynStackRegs);
355 don't do DirectRegs yet - there's a problem with arrays
356 RemoveRegsFromSet(dynDirectRegs);
358 RemoveRegsFromSet(dynDirectBitRegs);
360 if(total_registers_saved) fprintf(stderr, " *** Saved %d registers ***\n", total_registers_saved);
364 /*-----------------------------------------------------------------*
366 *-----------------------------------------------------------------*/
367 static void Remove2pcodes(pCode *pcflow, pCode *pc1, pCode *pc2, regs *reg, int can_free)
373 Remove1pcode(pc1, reg);
376 Remove1pcode(pc2, reg);
377 deleteSetItem (&(PCFL(pcflow)->registers), reg);
386 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
389 /*-----------------------------------------------------------------*
391 *-----------------------------------------------------------------*/
392 int regUsedinRange(pCode *pc1, pCode *pc2, regs *reg)
398 testreg = getRegFromInstruction(pc1);
399 if(testreg && (testreg->rIdx == reg->rIdx)) {
403 pc1 = findNextInstruction(pc1->next);
405 } while (pc1 && (pc1 != pc2) && (i++ < 100)) ;
408 fprintf(stderr, "warning, regUsedinRange searched through too many pcodes\n");
413 /*-----------------------------------------------------------------*
414 * void pCodeOptime2pCodes(pCode *pc1, pCode *pc2)
416 * ADHOC pattern checking
417 * Now look for specific sequences that are easy to optimize.
418 * Many of these sequences are characteristic of the compiler
419 * (i.e. it'd probably be a waste of time to apply these adhoc
420 * checks to hand written assembly.)
423 *-----------------------------------------------------------------*/
424 int pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free, int optimize_level)
429 int t = total_registers_saved;
431 if(pc2->seq < pc1->seq) {
437 fprintf(stderr,"pCodeOptime2pCodes\n");
438 pc1->print(stderr,pc1);
439 pc2->print(stderr,pc2);
441 if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
455 //fprintf(stderr, " CLRF/MOVFW. instruction after MOVFW is:\n");
456 pct1 = findNextInstruction(pc2->next);
458 if(PCI(pct1)->op == POC_MOVWF) {
459 newpc = newpCode(POC_CLRF, PCI(pct1)->pcop);
460 pct1->destruct(pct1);
462 newpc = newpCode(POC_MOVLW, newpCodeOpLit(0));
465 pCodeInsertAfter(pc2, newpc);
466 PCI(newpc)->pcflow = PCFL(pcfl_used);
467 newpc->seq = pc2->seq;
469 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
470 total_registers_saved++; // debugging stats.
472 } else if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_IORFW) ){
473 //fprintf(stderr, " CLRF/IORFW.\n");
475 pct2 = findNextInstruction(pc2->next);
477 if(pCodeSearchCondition(pct2, PCC_Z) > 0) {
478 pct2 = newpCode(POC_IORLW, newpCodeOpLit(0));
479 pct2->seq = pc2->seq;
480 PCI(pct2)->pcflow = PCFL(pcfl_used);
481 pCodeInsertAfter(pc1,pct2);
483 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
484 total_registers_saved++; // debugging stats.
486 } else if(PCI(pc1)->op == POC_MOVWF) {
488 pct2 = findNextInstruction(pc2->next);
490 if(PCI(pc2)->op == POC_MOVFW) {
492 fprintf(stderr, " MOVWF/MOVFW. instruction after MOVFW is:\n");
493 pct2->print(stderr,pct2);
496 if(PCI(pct2)->op == POC_MOVWF) {
511 reg2 = getRegFromInstruction(pct2);
512 //if(reg2 && !regUsedinRange(pc1,pc2,reg2) && (reg2->type != REG_SFR)) {
513 if(reg2 && !regUsedinRange(pc1,pc2,reg2)) {
515 if(pCodeSearchCondition(pct2, PCC_Z) < 1) {
516 pCode *pct3 = findNextInstruction(pct2->next);
517 pct2->seq = pc1->seq;
519 pCodeInsertAfter(findPrevInstruction(pc1->prev),pct2);
521 #define usesW(x) ((x) && (isPCI(x)) && ( (PCI(x)->inCond & PCC_W) != 0))
524 ; // Remove2pcodes(pcfl_used, pc1, NULL, reg, can_free);
526 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
528 total_registers_saved++; // debugging stats.
531 //fprintf(stderr,"didn't optimize because Z bit is used\n");
535 fprintf(stderr, " couldn't optimize\n");
537 fprintf(stderr, " %s is used in range\n",reg2->name);
539 fprintf(stderr, " reg2 is NULL\n");
544 pct1 = findPrevInstruction(pc1->prev);
545 if(pct1 && (PCI(pct1)->pcflow == PCI(pc1)->pcflow)) {
547 if ( (PCI(pct1)->op == POC_MOVFW) &&
548 (PCI(pc2)->op == POC_MOVFW)) {
550 reg1 = getRegFromInstruction(pct1);
551 if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
553 fprintf(stderr, " MOVF/MOVFW. \n");
554 fprintf(stderr, " ...optimizing\n");
572 Or, if we're not deleting the register then the "To" is:
581 pct2 = newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
582 pCodeInsertAfter(pc2, pct2);
583 PCI(pct2)->pcflow = PCFL(pcfl_used);
584 pct2->seq = pc2->seq;
587 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
589 /* If we're not freeing the register then that means (probably)
590 * the register is needed somewhere else.*/
592 pCodeInsertAfter(pct2, pc1);
594 Remove2pcodes(pcfl_used, pc2, NULL, reg, can_free);
597 Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
598 total_registers_saved++; // debugging stats.
601 } else if ( (PCI(pct1)->op == POC_MOVWF) &&
602 (PCI(pc2)->op == POC_MOVFW)) {
603 //fprintf(stderr,"movwf MOVWF/MOVFW\n");
604 if(optimize_level > 1 && can_free) {
605 pct2 = newpCode(POC_MOVFW, PCI(pc1)->pcop);
606 pCodeInsertAfter(pc2, pct2);
607 Remove2pcodes(pcfl_used, pc1, pc2, reg, 1);
608 total_registers_saved++; // debugging stats.
617 return (total_registers_saved != t);
620 /*-----------------------------------------------------------------*
621 * void pCodeRegOptimeRegUsage(pBlock *pb)
622 *-----------------------------------------------------------------*/
623 void OptimizeRegUsage(set *fregs, int optimize_multi_uses, int optimize_level)
627 pCode *pc1=NULL, *pc2=NULL;
631 pCode *pcfl_used, *pcfl_assigned;
633 /* Step through the set by directly accessing the 'next' pointer.
634 * We could also step through by using the set API, but the
635 * the (debug) calls to print instructions affect the state
636 * of the set pointers */
641 if(reg->type == REG_SFR) {
642 //fprintf(stderr,"skipping SFR: %s\n",reg->name);
646 pcfl_used = setFirstItem(reg->reglives.usedpFlows);
647 pcfl_assigned = setFirstItem(reg->reglives.assignedpFlows);
649 used = elementsInSet(reg->reglives.usedpCodes);
653 * In this section, all registers that are used in only in two
654 * instructions are examined. If possible, they're optimized out.
658 fprintf (stderr, "OptimizeRegUsage: %s addr=0x%03x rIdx=0x%03x type=%d used=%d\n",
661 reg->rIdx, reg->type, used);
663 pc1 = setFirstItem(reg->reglives.usedpCodes);
664 pc2 = setNextItem(reg->reglives.usedpCodes);
666 if(pcfl_used && pcfl_assigned) {
669 expected case - the register has been assigned a value and is
673 //fprintf(stderr," used only twice\n");
674 if(pcfl_used->seq == pcfl_assigned->seq) {
676 //fprintf(stderr, " and used in same flow\n");
678 pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1,optimize_level);
681 // fprintf(stderr, " and used in different flows\n");
685 } else if(pcfl_used) {
688 register has been used twice without ever being assigned */
689 //fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
692 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
693 Remove2pcodes(pcfl_assigned, pc1, pc2, reg, 1);
694 total_registers_saved++; // debugging stats.
698 /* register has been used either once, or more than twice */
700 if(used && !pcfl_used && pcfl_assigned) {
703 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
705 pc = setFirstItem(reg->reglives.usedpCodes);
708 pcfl_assigned = PCODE(PCI(pc)->pcflow);
709 Remove1pcode(pc, reg);
711 deleteSetItem (&(PCFL(pcfl_assigned)->registers), reg);
713 deleteSetItem (&(reg->reglives.usedpCodes),pc);
716 pc = setNextItem(reg->reglives.usedpCodes);
723 total_registers_saved++; // debugging stats.
724 } else if( (used > 2) && optimize_multi_uses) {
730 pCodeFlow *pcfl1=NULL, *pcfl2=NULL;
732 /* examine the number of times this register is used */
735 rset1 = reg->reglives.usedpCodes;
736 while(rset1 && searching) {
741 if(pc1 && isPCI(pc1) && ( (pcfl1 = PCI(pc1)->pcflow) != NULL) ) {
743 //while(rset2 && searching) {
747 if(pc2 && isPCI(pc2) && ( (pcfl2 = PCI(pc2)->pcflow) != NULL) ) {
750 if(pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 0,optimize_level))
755 //rset2 = rset2->next;
767 /*-----------------------------------------------------------------*
768 * void pCodeRegOptimeRegUsage(pBlock *pb)
769 *-----------------------------------------------------------------*/
770 void pCodeRegOptimizeRegUsage(int level)
775 int t = total_registers_saved;
777 if(!register_optimization)
783 saved = total_registers_saved;
785 /* Identify registers used in one flow sequence */
786 OptimizeRegUsage(dynAllocRegs,level, (OPT_PASSES-passes));
787 OptimizeRegUsage(dynStackRegs,level, (OPT_PASSES-passes));
788 OptimizeRegUsage(dynDirectRegs,0, (OPT_PASSES-passes));
790 if(total_registers_saved != saved)
791 fprintf(stderr, " *** pass %d, Saved %d registers, total saved %d ***\n",
792 (1+OPT_PASSES-passes),total_registers_saved-saved,total_registers_saved);
796 } while( passes && ((total_registers_saved != saved) || (passes==OPT_PASSES-1)) );
798 if(total_registers_saved == t)
799 fprintf(stderr, "No registers saved on this pass\n");
803 fprintf(stderr,"dynamically allocated regs:\n");
804 dbg_regusage(dynAllocRegs);
805 fprintf(stderr,"stack regs:\n");
806 dbg_regusage(dynStackRegs);
807 fprintf(stderr,"direct regs:\n");
808 dbg_regusage(dynDirectRegs);
813 /*-----------------------------------------------------------------*
814 * void RegsUnMapLiveRanges(set *regset)
816 *-----------------------------------------------------------------*/
817 void RegsSetUnMapLiveRanges(set *regset)
823 regset = regset->next;
826 deleteSet(®->reglives.usedpCodes);
827 deleteSet(®->reglives.usedpFlows);
828 deleteSet(®->reglives.assignedpFlows);
834 void RegsUnMapLiveRanges(void)
837 RegsSetUnMapLiveRanges(dynAllocRegs);
838 RegsSetUnMapLiveRanges(dynStackRegs);
839 RegsSetUnMapLiveRanges(dynDirectRegs);
840 RegsSetUnMapLiveRanges(dynProcessorRegs);
841 RegsSetUnMapLiveRanges(dynDirectBitRegs);
842 RegsSetUnMapLiveRanges(dynInternalRegs);