1 /*-------------------------------------------------------------------------
3 SDCCloop.c - source file for loop detection & optimizations
5 Written By - Sandeep Dutta . sandeep.dutta@usa.net (1998)
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 In other words, you are welcome to use, share and improve this program.
22 You are forbidden to forbid anyone else to use, share and improve
23 what you give them. Help stamp out software-hoarding!
24 -------------------------------------------------------------------------*/
29 DEFSETFUNC (isDefAlive);
31 STACK_DCL (regionStack, eBBlock *, MAX_NEST_LEVEL * 10);
33 /*-----------------------------------------------------------------*/
34 /* newInduction - creates a new induction variable */
35 /*-----------------------------------------------------------------*/
37 newInduction (operand * sym, unsigned int op,
38 long constVal, iCode * ic, operand * asym)
42 ip = Safe_calloc (1, sizeof (induction));
53 /*-----------------------------------------------------------------*/
54 /* newRegion - allocate & returns a loop structure */
55 /*-----------------------------------------------------------------*/
61 lp = Safe_calloc (1, sizeof (region));
67 /*-----------------------------------------------------------------*/
68 /* pinduction - prints induction */
69 /*-----------------------------------------------------------------*/
70 DEFSETFUNC (pinduction)
75 fprintf (stdout, "\t");
76 printOperand (ip->sym, stdout);
77 icTab = getTableEntry (ip->ic->op);
78 icTab->iCodePrint (stdout, ip->ic, icTab->printName);
79 fprintf (stdout, " %04d\n", (int) ip->cval);
83 /*-----------------------------------------------------------------*/
84 /* pregion - prints loop information */
85 /*-----------------------------------------------------------------*/
90 printf ("================\n");
91 printf (" loop with entry -- > ");
92 printEntryLabel (lp->entry, ap);
94 printf (" loop body --> ");
95 applyToSet (lp->regBlocks, printEntryLabel);
97 printf (" loop exits --> ");
98 applyToSet (lp->exits, printEntryLabel);
103 /*-----------------------------------------------------------------*/
104 /* backEdges - returns a list of back edges */
105 /*-----------------------------------------------------------------*/
106 DEFSETFUNC (backEdges)
109 V_ARG (set **, bEdges);
111 /* if this is a back edge ; to determine this we check */
112 /* to see if the 'to' is in the dominator list of the */
113 /* 'from' if yes then this is a back edge */
114 if (bitVectBitValue (ep->from->domVect, ep->to->bbnum))
116 addSetHead (bEdges, ep);
123 /*-----------------------------------------------------------------*/
124 /* intersectLoopSucc - returns intersection of loop Successors */
125 /*-----------------------------------------------------------------*/
127 intersectLoopSucc (set * lexits, eBBlock ** ebbs)
129 bitVect *succVect = NULL;
130 eBBlock *exit = setFirstItem (lexits);
135 succVect = bitVectCopy (exit->succVect);
137 for (exit = setNextItem (lexits); exit;
138 exit = setNextItem (lexits))
140 succVect = bitVectIntersect (succVect,
148 /*-----------------------------------------------------------------*/
149 /* loopInsert will insert a block into the loop set */
150 /*-----------------------------------------------------------------*/
152 loopInsert (set ** regionSet, eBBlock * block)
154 if (!isinSet (*regionSet, block))
156 addSetHead (regionSet, block);
157 STACK_PUSH (regionStack, block);
161 /*-----------------------------------------------------------------*/
162 /* insertIntoLoop - insert item into loop */
163 /*-----------------------------------------------------------------*/
164 DEFSETFUNC (insertIntoLoop)
167 V_ARG (set **, regionSet);
169 loopInsert (regionSet, ebp);
173 /*-----------------------------------------------------------------*/
174 /* isNotInBlocks - will return 1 if not is blocks */
175 /*-----------------------------------------------------------------*/
176 DEFSETFUNC (isNotInBlocks)
179 V_ARG (set *, blocks);
181 if (!isinSet (blocks, ebp))
187 /*-----------------------------------------------------------------*/
188 /* hasIncomingDefs - has definitions coming into the loop. i.e. */
189 /* check to see if the preheaders outDefs has any definitions */
190 /*-----------------------------------------------------------------*/
192 hasIncomingDefs (region * lreg, operand * op)
194 eBBlock *preHdr = lreg->entry->preHeader;
196 if (preHdr && bitVectBitsInCommon (preHdr->outDefs, OP_DEFS (op)))
201 /*-----------------------------------------------------------------*/
202 /* findLoopEndSeq - will return the sequence number of the last */
203 /* iCode with the maximum dfNumber in the region */
204 /*-----------------------------------------------------------------*/
206 findLoopEndSeq (region * lreg)
211 for (block = lblock = setFirstItem (lreg->regBlocks); block;
212 block = setNextItem (lreg->regBlocks))
214 if (block != lblock && block->lSeq > lblock->lSeq)
221 /*-----------------------------------------------------------------*/
222 /* addToExitsMarkDepth - will add the the exitSet all blocks that */
223 /* have exits, will also update the depth field in the blocks */
224 /*-----------------------------------------------------------------*/
225 DEFSETFUNC (addToExitsMarkDepth)
228 V_ARG (set *, loopBlocks);
229 V_ARG (set **, exits);
231 V_ARG (region *, lr);
233 /* mark the loop depth of this block */
237 /* put the loop region info in the block */
238 /* NOTE: here we will update only the inner most loop
239 that it is a part of */
240 if (!ebp->partOfLoop)
241 ebp->partOfLoop = lr;
243 /* if any of the successors go out of the loop then */
244 /* we add this one to the exits */
245 if (applyToSet (ebp->succList, isNotInBlocks, loopBlocks))
247 addSetHead (exits, ebp);
254 /*-----------------------------------------------------------------*/
255 /* createLoop - will create a set of region */
256 /*-----------------------------------------------------------------*/
257 DEFSETFUNC (createLoop)
260 V_ARG (set **, allRegion);
261 region *aloop = newRegion ();
264 /* make sure regionStack is empty */
265 while (!STACK_EMPTY (regionStack))
266 STACK_POP (regionStack);
268 /* add the entryBlock */
269 addSet (&aloop->regBlocks, ep->to);
270 loopInsert (&aloop->regBlocks, ep->from);
272 while (!STACK_EMPTY (regionStack))
274 block = STACK_POP (regionStack);
275 /* if block != entry */
277 applyToSet (block->predList, insertIntoLoop, &aloop->regBlocks);
280 aloop->entry = ep->to;
282 /* now add it to the set */
283 addSetHead (allRegion, aloop);
287 /*-----------------------------------------------------------------*/
288 /* dominatedBy - will return 1 if item is dominated by block */
289 /*-----------------------------------------------------------------*/
290 DEFSETFUNC (dominatedBy)
293 V_ARG (eBBlock *, block);
295 return bitVectBitValue (ebp->domVect, block->bbnum);
298 /*-----------------------------------------------------------------*/
299 /* addDefInExprs - adds an expression into the inexpressions */
300 /*-----------------------------------------------------------------*/
301 DEFSETFUNC (addDefInExprs)
304 V_ARG (cseDef *, cdp);
305 V_ARG (eBBlock **, ebbs);
308 addSetHead (&ebp->inExprs, cdp);
309 cseBBlock (ebp, 0, ebbs, count);
313 /*-----------------------------------------------------------------*/
314 /* assignmentsToSym - for a set of blocks determine # time assigned */
315 /*-----------------------------------------------------------------*/
317 assignmentsToSym (set * sset, operand * sym)
321 set *blocks = setFromSet (sset);
323 for (ebp = setFirstItem (blocks); ebp;
324 ebp = setNextItem (blocks))
327 /* get all the definitions for this symbol
329 bitVect *defs = bitVectIntersect (ebp->ldefs, OP_DEFS (sym));
330 assigns += bitVectnBitsOn (defs);
331 setToNull ((void **) &defs);
339 /*-----------------------------------------------------------------*/
340 /* isOperandInvariant - determines if an operand is an invariant */
341 /*-----------------------------------------------------------------*/
343 isOperandInvariant (operand * op, region * theLoop, set * lInvars)
346 /* operand is an invariant if it is a */
348 /* b. that have defintions reaching loop entry */
349 /* c. that are already defined as invariant */
350 /* d. has no assignments in the loop */
353 if (IS_OP_LITERAL (op))
355 else if (IS_SYMOP (op) &&
356 OP_SYMBOL (op)->addrtaken)
358 else if (ifDefSymIs (theLoop->entry->inExprs, op))
360 else if (ifDefSymIs (lInvars, op))
362 else if (IS_SYMOP (op) &&
363 !IS_OP_GLOBAL (op) &&
364 !IS_OP_VOLATILE (op) &&
365 assignmentsToSym (theLoop->regBlocks, op) == 0)
374 /*-----------------------------------------------------------------*/
375 /* pointerAssigned - will return 1 if pointer set found */
376 /*-----------------------------------------------------------------*/
377 DEFSETFUNC (pointerAssigned)
380 V_ARG (operand *, op);
382 return ebp->hasFcall || bitVectBitValue (ebp->ptrsSet, op->key);
385 /*-----------------------------------------------------------------*/
386 /* hasNonPtrUse - returns true if operand has non pointer usage */
387 /*-----------------------------------------------------------------*/
388 DEFSETFUNC (hasNonPtrUse)
391 V_ARG (operand *, op);
392 iCode *ic = usedInRemaining (op, ebp->sch);
394 if (ic && !POINTER_SET (ic) && !POINTER_GET (ic))
401 /*-----------------------------------------------------------------*/
402 /* loopInvariants - takes loop invariants out of region */
403 /*-----------------------------------------------------------------*/
405 loopInvariants (region * theLoop, eBBlock ** ebbs, int count)
412 /* if the preHeader does not exist then do nothing */
413 /* or no exits then do nothing ( have to think about this situation */
414 if (theLoop->entry->preHeader == NULL ||
415 theLoop->exits == NULL)
418 /* we will do the elimination for those blocks */
419 /* in the loop that dominates all exits from the loop */
420 for (lBlock = setFirstItem (theLoop->regBlocks); lBlock;
421 lBlock = setNextItem (theLoop->regBlocks))
428 /* mark the dominates all exits flag */
429 domsAllExits = (applyToSet (theLoop->exits, dominatedBy, lBlock) ==
430 elementsInSet (theLoop->exits));
433 /* now we go thru the instructions of this block and */
434 /* collect those instructions with invariant operands */
435 for (ic = lBlock->sch; ic; ic = ic->next)
441 if (SKIP_IC (ic) || POINTER_SET (ic) || ic->op == IFX)
444 /* if result is volatile then skip */
445 if (IC_RESULT (ic) &&
446 (isOperandVolatile (IC_RESULT (ic), TRUE) ||
447 IS_OP_PARM (IC_RESULT (ic))))
453 /* if address of then it is an invariant */
454 if (ic->op == ADDRESS_OF &&
455 IS_SYMOP (IC_LEFT (ic)) &&
456 IS_AGGREGATE (operandType (IC_LEFT (ic))))
459 /* check if left operand is an invariant */
460 if ((lin = isOperandInvariant (IC_LEFT (ic), theLoop, lInvars)))
461 /* if this is a pointer get then make sure
462 that the pointer set does not exist in
464 if (POINTER_GET (ic) &&
465 (applyToSet (theLoop->regBlocks, pointerAssigned, IC_LEFT (ic))))
468 /* do the same for right */
469 rin = isOperandInvariant (IC_RIGHT (ic), theLoop, lInvars);
471 /* if this is a POINTER_GET then special case, make sure all
472 usages within the loop are POINTER_GET any other usage
473 would mean that this is not an invariant , since the pointer
474 could then be passed as a parameter */
475 if (POINTER_GET (ic) &&
476 applyToSet (theLoop->regBlocks, hasNonPtrUse, IC_LEFT (ic)))
479 /* if both the left & right are invariants : then check that */
480 /* this definition exists in the out definition of all the */
481 /* blocks, this will ensure that this is not assigned any */
482 /* other value in the loop , and not used in this block */
483 /* prior to this definition which means only this definition */
484 /* is used in this loop */
485 if (lin && rin && IC_RESULT (ic))
488 set *lSet = setFromSet (theLoop->regBlocks);
490 /* if this block does not dominate all exists */
491 /* make sure this defintion is not used anywhere else */
495 if (isOperandGlobal (IC_RESULT (ic)))
497 /* for successors for all exits */
498 for (sBlock = setFirstItem (theLoop->exits); sBlock;
499 sBlock = setNextItem (theLoop->exits))
502 for (i = 0; i < count; ebbs[i++]->visited = 0);
504 if (applyToSet (sBlock->succList, isDefAlive, ic))
508 /* we have found usage */
513 /* now make sure this is the only definition */
514 for (sBlock = setFirstItem (lSet); sBlock;
515 sBlock = setNextItem (lSet))
517 /* if this is the block make sure the definition */
518 /* reaches the end of the block */
519 if (sBlock == lBlock)
521 if (!ifDiCodeIs (sBlock->outExprs, ic))
524 else if (bitVectBitsInCommon (sBlock->defSet, OP_DEFS (IC_RESULT (ic))))
529 continue; /* another definition present in the block */
531 /* now check if it exists in the in of this block */
532 /* if not then it was killed before this instruction */
533 if (!bitVectBitValue (lBlock->inDefs, ic->key))
536 /* now we know it is a true invariant */
537 /* remove it from the insts chain & put */
538 /* in the invariant set */
539 OP_SYMBOL (IC_RESULT (ic))->isinvariant = 1;
540 remiCodeFromeBBlock (lBlock, ic);
542 /* maintain the data flow */
543 /* this means removing from definition from the */
544 /* defset of this block and adding it to the */
545 /* inexpressions of all blocks within the loop */
546 bitVectUnSetBit (lBlock->defSet, ic->key);
547 bitVectUnSetBit (lBlock->ldefs, ic->key);
548 ivar = newCseDef (IC_RESULT (ic), ic);
549 applyToSet (theLoop->regBlocks, addDefInExprs, ivar, ebbs, count);
550 addSet (&lInvars, ivar);
553 } /* for all loop blocks */
555 /* if we have some invariants then */
558 eBBlock *preHdr = theLoop->entry->preHeader;
559 iCode *icFirst = NULL, *icLast = NULL;
562 /* create an iCode chain from it */
563 for (cdp = setFirstItem (lInvars); cdp; cdp = setNextItem (lInvars))
566 /* maintain data flow .. add it to the */
567 /* ldefs defSet & outExprs of the preheader */
568 preHdr->defSet = bitVectSetBit (preHdr->defSet, cdp->diCode->key);
569 preHdr->ldefs = bitVectSetBit (preHdr->ldefs, cdp->diCode->key);
570 cdp->diCode->lineno = preHdr->ech->lineno;
571 addSetHead (&preHdr->outExprs, cdp);
575 icFirst = cdp->diCode;
578 icLast->next = cdp->diCode;
579 cdp->diCode->prev = icLast;
580 icLast = cdp->diCode;
583 icLast = cdp->diCode;
587 /* add the instruction chain to the end of the
588 preheader for this loop, preheaders will always
589 have atleast a label */
590 preHdr->ech->next = icFirst;
591 icFirst->prev = preHdr->ech;
592 preHdr->ech = icLast;
599 /*-----------------------------------------------------------------*/
600 /* addressTaken - returns true if the symbol is found in the addrof */
601 /*-----------------------------------------------------------------*/
603 addressTaken (set * sset, operand * sym)
609 for (loop = sset; loop; loop = loop->next)
615 if (isOperandEqual ((operand *) loop2->item, sym))
625 /*-----------------------------------------------------------------*/
626 /* findInduction :- returns 1 & the item if the induction is found */
627 /*-----------------------------------------------------------------*/
628 DEFSETFUNC (findInduction)
630 induction *ip = item;
631 V_ARG (operand *, sym);
632 V_ARG (induction **, ipp);
634 if (isOperandEqual (ip->sym, sym))
643 /*-----------------------------------------------------------------*/
644 /* findDefInRegion - finds the definition within the region */
645 /*-----------------------------------------------------------------*/
647 findDefInRegion (set * regBlocks, operand * defOp, eBBlock ** owner)
651 /* for all blocks in the region */
652 for (lBlock = setFirstItem (regBlocks); lBlock;
653 lBlock = setNextItem (regBlocks))
656 /* if a definition for this exists */
657 if (bitVectBitsInCommon (lBlock->defSet, OP_DEFS (defOp)))
661 /* go thru the instruction chain to find it */
662 for (ic = lBlock->sch; ic; ic = ic->next)
663 if (bitVectBitValue (OP_DEFS (defOp), ic->key))
675 /*-----------------------------------------------------------------*/
676 /* basicInduction - finds the basic induction variables in a loop */
677 /*-----------------------------------------------------------------*/
679 basicInduction (region * loopReg, eBBlock ** ebbs, int count)
684 /* i.e. all assignments of the form a := a +/- const */
685 /* for all blocks within the loop do */
686 for (lBlock = setFirstItem (loopReg->regBlocks); lBlock;
687 lBlock = setNextItem (loopReg->regBlocks))
692 /* for all instructions in the blocks do */
693 for (ic = lBlock->sch; ic; ic = ic->next)
697 unsigned long litValue;
700 eBBlock *owner = NULL;
703 /* look for assignments of the form */
704 /* symbolVar := iTempNN */
708 if (!IS_TRUE_SYMOP (IC_RESULT (ic)) &&
709 !OP_SYMBOL (IC_RESULT (ic))->isreqv)
712 if (isOperandGlobal (IC_RESULT (ic)))
715 if (!IS_ITEMP (IC_RIGHT (ic)))
718 /* if it has multiple assignments within the loop then skip */
719 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
722 /* if the address of this was taken inside the loop then continue */
723 if (addressTaken (loopReg->regBlocks, IC_RESULT (ic)))
726 /* find the definition for the result in the block */
727 if (!(dic = findDefInRegion (setFromSet (loopReg->regBlocks),
728 IC_RIGHT (ic), &owner)))
731 /* if not +/- continue */
732 if (dic->op != '+' && dic->op != '-')
735 /* make sure definition is of the form a +/- c */
736 if (!IS_OP_LITERAL (IC_LEFT (dic)) && !IS_OP_LITERAL (IC_RIGHT (dic)))
739 aSym = (IS_OP_LITERAL (IC_RIGHT (dic)) ?
740 (litValue = operandLitValue (IC_RIGHT (dic)), IC_LEFT (dic)) :
741 (litValue = operandLitValue (IC_LEFT (dic)), IC_RIGHT (dic)));
743 if (!isOperandEqual (IC_RESULT (ic), aSym) &&
744 !isOperandEqual (IC_RIGHT (ic), aSym))
747 /* find the definition for this and check */
748 if (!(ddic = findDefInRegion (setFromSet (loopReg->regBlocks),
755 if (!isOperandEqual (IC_RESULT (ddic), aSym) ||
756 !isOperandEqual (IC_RIGHT (ddic), IC_RESULT (ic)))
760 /* if the right hand side has more than one usage then
761 don't make it an induction (will have to think some more) */
762 if (bitVectnBitsOn (OP_USES (IC_RIGHT (ic))) > 1)
765 /* if the definition is volatile then it cannot be
766 an induction object */
767 if (isOperandVolatile (IC_RIGHT (ic), FALSE) ||
768 isOperandVolatile (IC_RESULT (ic), FALSE))
771 /* whew !! that was a lot of work to find the definition */
772 /* create an induction object */
773 indIc = newiCode ('=', NULL, IC_RESULT (ic));
774 indIc->lineno = ic->lineno;
775 IC_RESULT (indIc) = operandFromOperand (IC_RIGHT (ic));
776 IC_RESULT (indIc)->isaddr = 0;
777 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
778 ip = newInduction (IC_RIGHT (ic), dic->op, litValue, indIc, NULL);
780 /* replace the inducted variable by the iTemp */
781 replaceSymBySym (loopReg->regBlocks, IC_RESULT (ic), IC_RIGHT (ic));
783 /* if it has only one exit then remove it from here
784 and put it in the exit block */
785 nexits = elementsInSet (loopReg->exits);
788 eBBlock *exit = setFirstItem (loopReg->exits);
790 /* if it is the same block then there is no
791 need to move it about */
794 iCode *saveic = ic->prev;
796 remiCodeFromeBBlock (lBlock, ic);
797 /* clear the definition */
798 bitVectUnSetBit (lBlock->defSet, ic->key);
799 /* add it to the exit */
800 addiCodeToeBBlock (exit, ic, NULL);
801 /* set the definition bit */
802 exit->defSet = bitVectSetBit (exit->defSet, ic->key);
807 /* if the number of exits is greater than one then
808 we use another trick ; we will create an intersection
809 of succesors of the exits, then take those that are not
810 part of the loop and have dfNumber greater loop entry
811 and insert a new definition in them */
815 bitVect *loopSuccs = intersectLoopSucc (loopReg->exits, ebbs);
817 /* loopSuccs now contains intersection
818 of all the loops successors */
822 for (i = 0; i < loopSuccs->size; i++)
824 if (bitVectBitValue (loopSuccs, i))
827 eBBlock *eblock = ebbs[i];
829 /* if the successor does not belong to the loop
830 and will be executed after the loop : then
831 add a definition to the block */
832 if (!isinSet (loopReg->regBlocks, eblock) &&
833 eblock->dfnum > loopReg->entry->dfnum)
835 /* create the definition */
836 iCode *newic = newiCode ('=', NULL,
837 operandFromOperand (IC_RIGHT (ic)));
838 IC_RESULT (newic) = operandFromOperand (IC_RESULT (ic));
839 OP_DEFS (IC_RESULT (newic)) =
840 bitVectSetBit (OP_DEFS (IC_RESULT (newic)), newic->key);
841 OP_USES (IC_RIGHT (newic)) =
842 bitVectSetBit (OP_USES (IC_RIGHT (newic)), newic->key);
844 if (eblock->sch && eblock->sch->op == LABEL)
845 addiCodeToeBBlock (eblock, newic, eblock->sch->next);
847 addiCodeToeBBlock (eblock, newic, eblock->sch);
848 /* set the definition bit */
849 eblock->defSet = bitVectSetBit (eblock->defSet, ic->key);
856 addSet (&indVars, ip);
859 } /* end of all blocks for basic induction variables */
864 /*-----------------------------------------------------------------*/
865 /* loopInduction - remove induction variables from a loop */
866 /*-----------------------------------------------------------------*/
868 loopInduction (region * loopReg, eBBlock ** ebbs, int count)
871 eBBlock *lBlock, *lastBlock = NULL;
873 set *basicInd = NULL;
875 if (loopReg->entry->preHeader == NULL)
878 /* we first determine the basic Induction variables */
879 basicInd = setFromSet (indVars = basicInduction (loopReg, ebbs, count));
881 /* find other induction variables : by other we mean definitions of */
882 /* the form x := y (* | / ) <constant> .. we will move this one to */
883 /* beginning of the loop and reduce strength i.e. replace with +/- */
884 /* these expensive expressions: OH! and y must be induction too */
885 for (lBlock = setFirstItem (loopReg->regBlocks), lastBlock = lBlock;
887 lBlock = setNextItem (loopReg->regBlocks))
893 /* last block is the one with the highest block
895 if (lastBlock->bbnum < lBlock->bbnum)
898 for (ic = lBlock->sch; ic; ic = ic->next)
901 unsigned long litVal;
904 /* consider only * & / */
905 if (ic->op != '*' && ic->op != '/')
908 /* if the result has more definitions then */
909 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
912 /* check if the operands are what we want */
913 /* i.e. one of them an symbol the other a literal */
914 if (!((IS_SYMOP (IC_LEFT (ic)) && IS_OP_LITERAL (IC_RIGHT (ic))) ||
915 (IS_OP_LITERAL (IC_LEFT (ic)) && IS_SYMOP (IC_RIGHT (ic)))))
918 aSym = (IS_SYMOP (IC_LEFT (ic)) ?
919 (lr = 1, litVal = operandLitValue (IC_RIGHT (ic)), IC_LEFT (ic)) :
920 (litVal = operandLitValue (IC_LEFT (ic)), IC_RIGHT (ic)));
923 /* check if this is an induction variable */
924 if (!applyToSetFTrue (basicInd, findInduction, aSym, &ip))
927 /* ask port for size not worth if native instruction
928 exist for multiply & divide */
929 if (getSize (operandType (IC_LEFT (ic))) <= port->muldiv.native_below ||
930 getSize (operandType (IC_RIGHT (ic))) <= port->muldiv.native_below)
933 /* if this is a division then the remainder should be zero
934 for it to be inducted */
935 if (ic->op == '/' && (ip->cval % litVal))
938 /* create the iCode to be placed in the loop header */
939 /* and create the induction object */
941 /* create an instruction */
942 /* this will be put on the loop header */
943 indIc = newiCode (ic->op,
944 operandFromOperand (aSym),
945 operandFromLit (litVal));
946 indIc->lineno = ic->lineno;
947 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
948 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
950 /* keep track of the inductions */
951 litVal = (ic->op == '*' ? (litVal * ip->cval) :
952 (ip->cval / litVal));
955 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
957 /* now change this instruction */
961 IC_LEFT (ic) = operandFromOperand (IC_RESULT (ic));
962 IC_RIGHT (ic) = operandFromLit (litVal);
966 IC_RIGHT (ic) = operandFromOperand (IC_RESULT (ic));
967 IC_LEFT (ic) = operandFromLit (litVal);
970 /* we need somemore initialisation code */
971 /* we subtract the litVal from itself if increment */
974 indIc = newiCode ('-',
975 operandFromOperand (IC_RESULT (ic)),
976 operandFromLit (litVal));
977 indIc->lineno = ic->lineno;
978 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
981 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
986 /* if we have some induction variables then */
989 eBBlock *preHdr = loopReg->entry->preHeader;
990 iCode *icFirst = NULL, *icLast = NULL;
992 bitVect *indVect = NULL;
994 /* create an iCode chain from it */
995 for (ip = setFirstItem (indVars);
997 ip = setNextItem (indVars))
1000 indVect = bitVectSetBit (indVect, ip->ic->key);
1001 ip->ic->lineno = preHdr->ech->lineno;
1006 icLast->next = ip->ic;
1007 ip->ic->prev = icLast;
1015 /* add the instruction chain to the end of the */
1016 /* preheader for this loop */
1017 preHdr->ech->next = icFirst;
1018 icFirst->prev = preHdr->ech;
1019 preHdr->ech = icLast;
1020 icLast->next = NULL;
1022 /* add the induction variable vector to the last
1023 block in the loop */
1024 lastBlock->isLastInLoop = 1;
1025 lastBlock->linds = indVect;
1028 setToNull ((void **) &indVars);
1032 /*-----------------------------------------------------------------*/
1033 /* mergeRegions - will merge region with same entry point */
1034 /*-----------------------------------------------------------------*/
1035 DEFSETFUNC (mergeRegions)
1037 region *theLoop = item;
1038 V_ARG (set *, allRegion);
1041 /* if this has already been merged then do nothing */
1042 if (theLoop->merged)
1045 /* go thru all the region and check if any of them have the */
1046 /* entryPoint as the Loop */
1047 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1053 if (lp->entry == theLoop->entry)
1055 theLoop->regBlocks = unionSets (theLoop->regBlocks,
1056 lp->regBlocks, THROW_BOTH);
1064 /*-----------------------------------------------------------------*/
1065 /* ifMerged - return 1 if the merge flag is 1 */
1066 /*-----------------------------------------------------------------*/
1067 DEFSETFUNC (ifMerged)
1074 /*-----------------------------------------------------------------*/
1075 /* mergeInnerLoops - will merge into body when entry is present */
1076 /*-----------------------------------------------------------------*/
1077 DEFSETFUNC (mergeInnerLoops)
1079 region *theLoop = item;
1080 V_ARG (set *, allRegion);
1081 V_ARG (int *, maxDepth);
1084 /* check if the entry point is present in the body of any */
1085 /* loop then put the body of this loop into the outer loop */
1086 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1092 if (isinSet (lp->regBlocks, theLoop->entry))
1094 lp->containsLoops += theLoop->containsLoops + 1;
1095 if (lp->containsLoops > (*maxDepth))
1096 *maxDepth = lp->containsLoops;
1098 lp->regBlocks = unionSets (lp->regBlocks,
1099 theLoop->regBlocks, THROW_DEST);
1107 /*-----------------------------------------------------------------*/
1108 /* createLoopRegions - will detect and create a set of natural loops */
1109 /*-----------------------------------------------------------------*/
1111 createLoopRegions (eBBlock ** ebbs, int count)
1113 set *allRegion = NULL; /* set of all loops */
1114 hTab *orderedLoops = NULL;
1119 /* get all the back edges in the graph */
1120 if (!applyToSet (graphEdges, backEdges, &bEdges))
1121 return 0; /* found no loops */
1123 /* for each of these back edges get the blocks that */
1124 /* constitute the loops */
1125 applyToSet (bEdges, createLoop, &allRegion);
1127 /* now we will create regions from these loops */
1128 /* loops with the same entry points are considered to be the */
1129 /* same loop & they are merged. If the entry point of a loop */
1130 /* is found in the body of another loop then , all the blocks */
1131 /* in that loop are added to the loops containing the header */
1132 applyToSet (allRegion, mergeRegions, allRegion);
1134 /* delete those already merged */
1135 deleteItemIf (&allRegion, ifMerged);
1137 applyToSet (allRegion, mergeInnerLoops, allRegion, &maxDepth);
1139 /* now create all the exits .. also */
1140 /* create an ordered set of loops */
1141 /* i.e. we process loops in the inner to outer order */
1142 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1144 applyToSet (lp->regBlocks, addToExitsMarkDepth,
1145 lp->regBlocks, &lp->exits,
1146 (maxDepth - lp->containsLoops), lp);
1148 hTabAddItem (&orderedLoops, lp->containsLoops, lp);
1151 return orderedLoops;
1154 /*-----------------------------------------------------------------*/
1155 /* loopOptimizations - identify region & remove invariants & ind */
1156 /*-----------------------------------------------------------------*/
1158 loopOptimizations (hTab * orderedLoops, eBBlock ** ebbs, int count)
1165 /* if no loop optimizations requested */
1166 if (!optimize.loopInvariant &&
1167 !optimize.loopInduction)
1170 /* now we process the loops inner to outer order */
1171 /* this is essential to maintain data flow information */
1172 /* the other choice is an ugly iteration for the depth */
1173 /* of the loops would hate that */
1174 for (lp = hTabFirstItem (orderedLoops, &k); lp;
1175 lp = hTabNextItem (orderedLoops, &k))
1178 if (optimize.loopInvariant)
1179 change += loopInvariants (lp, ebbs, count);
1181 if (optimize.loopInduction)
1182 change += loopInduction (lp, ebbs, count);