1 /*-------------------------------------------------------------------------
3 pcoderegs.c - post code generation register optimizations
5 Written By - Scott Dattalo scott@dattalo.com
6 Ported To PIC16 By - m.dubuc@rogers.com
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
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.
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.
22 -------------------------------------------------------------------------*/
27 The purpose of the code in this file is to optimize the register usage.
32 #include "common.h" // Include everything in the SDCC src directory
37 #include "pcoderegs.h"
38 #include "pcodeflow.h"
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);
46 static int total_registers_saved=0;
47 static 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 *-----------------------------------------------------------------*/
70 static void dbg_regusage(set *fregs)
77 for (reg = setFirstItem(fregs) ; reg ;
78 reg = setNextItem(fregs)) {
80 if(elementsInSet(reg->reglives.usedpCodes)) {
82 fprintf (stderr, "%s addr=0x%03x rIdx=0x%03x",
87 pcfl = setFirstItem(reg->reglives.usedpFlows);
89 fprintf(stderr, "\n used in seq");
92 fprintf(stderr," 0x%03x",pcfl->seq);
93 pcfl = setNextItem(reg->reglives.usedpFlows);
96 pcfl = setFirstItem(reg->reglives.assignedpFlows);
98 fprintf(stderr, "\n assigned in seq");
101 fprintf(stderr," 0x%03x",pcfl->seq);
102 pcfl = setNextItem(reg->reglives.assignedpFlows);
105 pc = setFirstItem(reg->reglives.usedpCodes);
107 fprintf(stderr, "\n used in instructions ");
110 pcfl = PCODE(PCI(pc)->pcflow);
112 fprintf(stderr," 0x%03x:",pcfl->seq);
113 fprintf(stderr,"0x%03x",pc->seq);
115 pc = setNextItem(reg->reglives.usedpCodes);
118 fprintf(stderr, "\n");
124 /*-----------------------------------------------------------------*
126 *-----------------------------------------------------------------*/
128 static void dbg_dumpregusage(void)
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);
148 /*-----------------------------------------------------------------*
149 * void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
150 *-----------------------------------------------------------------*/
151 static void pCodeRegMapLiveRangesInFlow(pCodeFlow *pcfl)
163 pc = pic16_findNextInstruction(pcfl->pc.next);
165 while(pic16_isPCinFlow(pc,PCODE(pcfl))) {
168 reg = pic16_getRegFromInstruction(pc);
173 fprintf(stderr, "flow seq %d, inst seq %d %s ",PCODE(pcfl)->seq,pc->seq,reg->name);
174 fprintf(stderr, "addr = 0x%03x, type = %d rIdx=0x%03x",
175 reg->address,reg->type,reg->rIdx);
176 fprintf(stderr, "command = %s\n", PCI(pc)->mnemonic);
180 addSetIfnotP(& (PCFL(pcfl)->registers), reg);
182 if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
183 addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
185 if(PCC_REGISTER & PCI(pc)->outCond)
186 addSetIfnotP(& (reg->reglives.assignedpFlows), pcfl);
188 addSetIfnotP(& (reg->reglives.usedpCodes), pc);
191 /* check to see if this pCode has 2 memory operands,
192 and set up the second operand too */
193 if(PCI(pc)->is2MemOp) {
194 reg = pic16_getRegFromInstruction2(pc);
196 // fprintf(stderr, "trying to get second operand from pCode reg= %s\n", reg->name);
197 addSetIfnotP(& (PCFL(pcfl)->registers), reg);
198 addSetIfnotP(& (reg->reglives.usedpCodes), pc);
207 pc = pic16_findNextInstruction(pc->next);
213 /*-----------------------------------------------------------------*
214 * void pic16_pCodeRegMapLiveRanges(pBlock *pb)
215 *-----------------------------------------------------------------*/
216 void pic16_pCodeRegMapLiveRanges(pBlock *pb)
220 for( pcflow = pic16_findNextpCode(pb->pcHead, PC_FLOW);
222 pcflow = pic16_findNextpCode(pcflow->next, PC_FLOW) ) {
224 if(!isPCFL(pcflow)) {
225 fprintf(stderr, "pCodeRegMapLiveRanges - pcflow is not a flow object ");
228 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
232 for( pcflow = pic16_findNextpCode(pb->pcHead, PC_FLOW);
234 pcflow = pic16_findNextpCode(pcflow->next, PC_FLOW) ) {
236 regs *r = setFirstItem(PCFL(pcflow)->registers);
237 fprintf(stderr,"flow seq %d\n", pcflow->seq);
240 fprintf(stderr, " %s\n",r->name);
241 r = setNextItem(PCFL(pcflow)->registers);
248 // dbg_dumpregusage();
253 /*-----------------------------------------------------------------*
255 *-----------------------------------------------------------------*/
256 static void Remove1pcode(pCode *pc, regs *reg)
263 deleteSetItem (&(reg->reglives.usedpCodes),pc);
266 fprintf(stderr,"removing instruction:\n");
267 pc->print(stderr,pc);
271 pcn = pic16_findNextInstruction(pc->next);
274 PCI(pcn)->label = pic16_pBranchAppend(PCI(pcn)->label,PCI(pc)->label);
279 pcn = pic16_findNextInstruction(pc->next);
282 if(PCI(pcn)->cline) {
283 //fprintf(stderr, "source line has been optimized completely out\n");
284 //pc->print(stderr,pc);
286 PCI(pcn)->cline = PCI(pc)->cline;
295 /*-----------------------------------------------------------------*
296 * void RemoveRegsFromSet(set *regset)
298 *-----------------------------------------------------------------*/
299 static void RemoveRegsFromSet(set *regset)
306 regset = regset->next;
308 used = elementsInSet(reg->reglives.usedpCodes);
312 // fprintf(stderr," reg %s isfree=%d, wasused=%d\n",reg->name,reg->isFree,reg->wasUsed);
314 // fprintf(stderr,"%s:%d: getting rid of reg %s\n",__FILE__, __LINE__, reg->name);
321 pc = setFirstItem(reg->reglives.usedpCodes);
323 if(reg->type == REG_SFR) {
324 //fprintf(stderr, "not removing SFR reg %s even though used only once\n",reg->name);
331 pCode *pcn = pic16_findNextInstruction(pc->next);
333 if(pcn && PCI(pcn)->label) {
334 //fprintf(stderr,"can't delete instruction with label...\n");
335 //pc->print(stderr,pc);
338 /* Move the label to the next instruction */
340 PCI(pcn)->label = PCI(pc)->label;
345 regs *r = pic16_getRegFromInstruction(pc);
346 fprintf(stderr, "WARNING, a skip instruction is being optimized out\n");
347 pc->print(stderr,pc);
348 fprintf(stderr,"reg %s, type =%d\n",r->name, r->type);
350 // fprintf(stderr,"%s:%d: removing reg %s because it is used only once\n",__FILE__, __LINE__, reg->name);
351 Remove1pcode(pc, reg);
353 pic16_unlinkpCode(pc);
354 deleteSetItem (&(reg->reglives.usedpCodes),pc);
358 total_registers_saved++; // debugging stats.
365 /*-----------------------------------------------------------------*
366 * void pic16_RemoveUnusedRegisters(void)
368 *-----------------------------------------------------------------*/
369 void pic16_RemoveUnusedRegisters(void)
371 /* First, get rid of registers that are used only one time */
373 //RemoveRegsFromSet(pic16_dynInternalRegs);
374 RemoveRegsFromSet(pic16_dynAllocRegs);
375 RemoveRegsFromSet(pic16_dynStackRegs);
377 don't do DirectRegs yet - there's a problem with arrays
378 RemoveRegsFromSet(pic16_dynDirectRegs);
380 RemoveRegsFromSet(pic16_dynDirectBitRegs);
382 if(total_registers_saved) fprintf(stderr, " *** Saved %d registers ***\n", total_registers_saved);
386 /*-----------------------------------------------------------------*
388 *-----------------------------------------------------------------*/
389 static void Remove2pcodes(pCode *pcflow, pCode *pc1, pCode *pc2, regs *reg, int can_free)
395 Remove1pcode(pc1, reg);
398 Remove1pcode(pc2, reg);
399 deleteSetItem (&(PCFL(pcflow)->registers), reg);
408 pCodeRegMapLiveRangesInFlow(PCFL(pcflow));
411 /*-----------------------------------------------------------------*
413 *-----------------------------------------------------------------*/
414 static int regUsedinRange(pCode *pc1, pCode *pc2, regs *reg)
420 testreg = pic16_getRegFromInstruction(pc1);
421 if(testreg && (testreg->rIdx == reg->rIdx)) {
425 pc1 = pic16_findNextInstruction(pc1->next);
427 } while (pc1 && (pc1 != pc2) && (i++ < 100)) ;
430 fprintf(stderr, "warning, regUsedinRange searched through too many pcodes\n");
435 /*-----------------------------------------------------------------*
436 * void pCodeOptime2pCodes(pCode *pc1, pCode *pc2)
438 * ADHOC pattern checking
439 * Now look for specific sequences that are easy to optimize.
440 * Many of these sequences are characteristic of the compiler
441 * (i.e. it'd probably be a waste of time to apply these adhoc
442 * checks to hand written assembly.)
445 *-----------------------------------------------------------------*/
446 static int pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free, int optimize_level)
451 int t = total_registers_saved;
453 if(pc2->seq < pc1->seq) {
459 fprintf(stderr,"pCodeOptime2pCodes\n");
460 pc1->print(stderr,pc1);
461 pc2->print(stderr,pc2);
463 if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
477 //fprintf(stderr, " CLRF/MOVFW. instruction after MOVFW is:\n");
478 pct1 = pic16_findNextInstruction(pc2->next);
480 if(PCI(pct1)->op == POC_MOVWF) {
481 newpc = pic16_newpCode(POC_CLRF, PCI(pct1)->pcop);
482 pct1->destruct(pct1);
484 newpc = pic16_newpCode(POC_MOVLW, pic16_newpCodeOpLit(0));
487 pic16_pCodeInsertAfter(pc2, newpc);
488 PCI(newpc)->pcflow = PCFL(pcfl_used);
489 newpc->seq = pc2->seq;
491 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
492 total_registers_saved++; // debugging stats.
494 } else if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_IORFW) ){
495 //fprintf(stderr, " CLRF/IORFW.\n");
497 pct2 = pic16_findNextInstruction(pc2->next);
499 if(pic16_pCodeSearchCondition(pct2, PCC_Z) > 0) {
500 pct2 = pic16_newpCode(POC_IORLW, pic16_newpCodeOpLit(0));
501 pct2->seq = pc2->seq;
502 PCI(pct2)->pcflow = PCFL(pcfl_used);
503 pic16_pCodeInsertAfter(pc1,pct2);
505 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
506 total_registers_saved++; // debugging stats.
508 } else if(PCI(pc1)->op == POC_MOVWF) {
510 pct2 = pic16_findNextInstruction(pc2->next);
512 if(PCI(pc2)->op == POC_MOVFW) {
514 fprintf(stderr, " MOVWF/MOVFW. instruction after MOVFW is:\n");
515 pct2->print(stderr,pct2);
518 if(PCI(pct2)->op == POC_MOVWF) {
533 reg2 = pic16_getRegFromInstruction(pct2);
534 //if(reg2 && !regUsedinRange(pc1,pc2,reg2) && (reg2->type != REG_SFR)) {
535 if(reg2 && !regUsedinRange(pc1,pc2,reg2)) {
537 if(pic16_pCodeSearchCondition(pct2, PCC_Z) < 1) {
538 pCode *pct3 = pic16_findNextInstruction(pct2->next);
539 pct2->seq = pc1->seq;
540 pic16_unlinkpCode(pct2);
541 pic16_pCodeInsertAfter(pic16_findPrevInstruction(pc1->prev),pct2);
543 #define usesW(x) ((x) && (isPCI(x)) && ( (PCI(x)->inCond & PCC_W) != 0))
546 ; // Remove2pcodes(pcfl_used, pc1, NULL, reg, can_free);
548 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
550 total_registers_saved++; // debugging stats.
553 //fprintf(stderr,"didn't optimize because Z bit is used\n");
557 fprintf(stderr, " couldn't optimize\n");
559 fprintf(stderr, " %s is used in range\n",reg2->name);
561 fprintf(stderr, " reg2 is NULL\n");
566 pct1 = pic16_findPrevInstruction(pc1->prev);
567 if(pct1 && (PCI(pct1)->pcflow == PCI(pc1)->pcflow)) {
569 if ( (PCI(pct1)->op == POC_MOVFW) &&
570 (PCI(pc2)->op == POC_MOVFW)) {
572 reg1 = pic16_getRegFromInstruction(pct1);
573 if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
575 fprintf(stderr, " MOVF/MOVFW. \n");
576 fprintf(stderr, " ...optimizing\n");
594 Or, if we're not deleting the register then the "To" is:
603 pct2 = pic16_newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
604 pic16_pCodeInsertAfter(pc2, pct2);
605 PCI(pct2)->pcflow = PCFL(pcfl_used);
606 pct2->seq = pc2->seq;
609 Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
611 /* If we're not freeing the register then that means (probably)
612 * the register is needed somewhere else.*/
613 pic16_unlinkpCode(pc1);
614 pic16_pCodeInsertAfter(pct2, pc1);
616 Remove2pcodes(pcfl_used, pc2, NULL, reg, can_free);
619 Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
620 total_registers_saved++; // debugging stats.
623 } else if ( (PCI(pct1)->op == POC_MOVWF) &&
624 (PCI(pc2)->op == POC_MOVFW)) {
625 //fprintf(stderr,"movwf MOVWF/MOVFW\n");
626 if(optimize_level > 1 && can_free) {
627 pct2 = pic16_newpCode(POC_MOVFW, PCI(pc1)->pcop);
628 pic16_pCodeInsertAfter(pc2, pct2);
629 Remove2pcodes(pcfl_used, pc1, pc2, reg, 1);
630 total_registers_saved++; // debugging stats.
639 return (total_registers_saved != t);
642 /*-----------------------------------------------------------------*
643 * void pCodeRegOptimeRegUsage(pBlock *pb)
644 *-----------------------------------------------------------------*/
645 static void OptimizeRegUsage(set *fregs, int optimize_multi_uses, int optimize_level)
649 pCode *pc1=NULL, *pc2=NULL;
653 pCode *pcfl_used, *pcfl_assigned;
655 /* Step through the set by directly accessing the 'next' pointer.
656 * We could also step through by using the set API, but the
657 * the (debug) calls to print instructions affect the state
658 * of the set pointers */
663 if(reg->type == REG_SFR) {
664 //fprintf(stderr,"skipping SFR: %s\n",reg->name);
668 pcfl_used = setFirstItem(reg->reglives.usedpFlows);
669 pcfl_assigned = setFirstItem(reg->reglives.assignedpFlows);
671 used = elementsInSet(reg->reglives.usedpCodes);
672 // fprintf(stderr, "%s:%d register %s used %d times in pCode\n", __FILE__, __LINE__, reg->name, used);
676 * In this section, all registers that are used in only in two
677 * instructions are examined. If possible, they're optimized out.
681 fprintf (stderr, "OptimizeRegUsage: %s addr=0x%03x rIdx=0x%03x type=%d used=%d\n",
684 reg->rIdx, reg->type, used);
686 pc1 = setFirstItem(reg->reglives.usedpCodes);
687 pc2 = setNextItem(reg->reglives.usedpCodes);
689 if(pcfl_used && pcfl_assigned) {
692 expected case - the register has been assigned a value and is
696 //fprintf(stderr," used only twice\n");
697 if(pcfl_used->seq == pcfl_assigned->seq) {
699 //fprintf(stderr, " and used in same flow\n");
701 pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1,optimize_level);
704 // fprintf(stderr, " and used in different flows\n");
708 } else if(pcfl_used) {
711 register has been used twice without ever being assigned */
712 //fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
715 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
716 Remove2pcodes(pcfl_assigned, pc1, pc2, reg, 1);
717 total_registers_saved++; // debugging stats.
721 /* register has been used either once, or more than twice */
723 if(used && !pcfl_used && pcfl_assigned) {
726 //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
728 pc = setFirstItem(reg->reglives.usedpCodes);
731 pcfl_assigned = PCODE(PCI(pc)->pcflow);
732 Remove1pcode(pc, reg);
734 deleteSetItem (&(PCFL(pcfl_assigned)->registers), reg);
736 deleteSetItem (&(reg->reglives.usedpCodes),pc);
739 pc = setNextItem(reg->reglives.usedpCodes);
746 total_registers_saved++; // debugging stats.
747 } else if( (used > 2) && optimize_multi_uses) {
753 pCodeFlow *pcfl1=NULL, *pcfl2=NULL;
755 /* examine the number of times this register is used */
758 rset1 = reg->reglives.usedpCodes;
759 while(rset1 && searching) {
764 if(pc1 && isPCI(pc1) && ( (pcfl1 = PCI(pc1)->pcflow) != NULL) ) {
766 //while(rset2 && searching) {
770 if(pc2 && isPCI(pc2) && ( (pcfl2 = PCI(pc2)->pcflow) != NULL) ) {
773 if(pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 0,optimize_level))
778 //rset2 = rset2->next;
790 /*-----------------------------------------------------------------*
791 * void pic16_pCodeRegOptimeRegUsage(pBlock *pb)
792 *-----------------------------------------------------------------*/
793 void pic16_pCodeRegOptimizeRegUsage(int level)
798 int t = total_registers_saved;
800 if(!register_optimization)
806 saved = total_registers_saved;
808 /* Identify registers used in one flow sequence */
809 OptimizeRegUsage(pic16_dynAllocRegs,level, (OPT_PASSES-passes));
810 OptimizeRegUsage(pic16_dynStackRegs,level, (OPT_PASSES-passes));
811 OptimizeRegUsage(pic16_dynDirectRegs,0, (OPT_PASSES-passes));
813 if(total_registers_saved != saved)
814 fprintf(stderr, " *** pass %d, Saved %d registers, total saved %d ***\n",
815 (1+OPT_PASSES-passes),total_registers_saved-saved,total_registers_saved);
819 } while( passes && ((total_registers_saved != saved) || (passes==OPT_PASSES-1)) );
821 if(total_registers_saved == t)
822 fprintf(stderr, "No registers saved on this pass\n");
826 fprintf(stderr,"dynamically allocated regs:\n");
827 dbg_regusage(pic16_dynAllocRegs);
828 fprintf(stderr,"stack regs:\n");
829 dbg_regusage(pic16_dynStackRegs);
830 fprintf(stderr,"direct regs:\n");
831 dbg_regusage(pic16_dynDirectRegs);
836 /*-----------------------------------------------------------------*
837 * void RegsUnMapLiveRanges(set *regset)
839 *-----------------------------------------------------------------*/
840 static void RegsSetUnMapLiveRanges(set *regset)
846 regset = regset->next;
849 deleteSet(®->reglives.usedpCodes);
850 deleteSet(®->reglives.usedpFlows);
851 deleteSet(®->reglives.assignedpFlows);
857 void pic16_RegsUnMapLiveRanges(void)
860 RegsSetUnMapLiveRanges(pic16_dynAllocRegs);
861 RegsSetUnMapLiveRanges(pic16_dynStackRegs);
862 RegsSetUnMapLiveRanges(pic16_dynDirectRegs);
863 RegsSetUnMapLiveRanges(pic16_dynProcessorRegs);
864 RegsSetUnMapLiveRanges(pic16_dynDirectBitRegs);
865 RegsSetUnMapLiveRanges(pic16_dynInternalRegs);