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_alloc ( sizeof (induction));
49 updateSpillLocation(ic,1);
53 /*-----------------------------------------------------------------*/
54 /* newRegion - allocate & returns a loop structure */
55 /*-----------------------------------------------------------------*/
61 lp = Safe_alloc ( 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 */
235 if (ebp->depth<depth)
238 /* put the loop region info in the block */
239 /* NOTE: here we will update only the inner most loop
240 that it is a part of */
241 if (!ebp->partOfLoop)
242 ebp->partOfLoop = lr;
244 /* if any of the successors go out of the loop then */
245 /* we add this one to the exits */
246 if (applyToSet (ebp->succList, isNotInBlocks, loopBlocks))
248 addSetHead (exits, ebp);
255 /*-----------------------------------------------------------------*/
256 /* createLoop - will create a set of region */
257 /*-----------------------------------------------------------------*/
258 DEFSETFUNC (createLoop)
261 V_ARG (set **, allRegion);
262 region *aloop = newRegion ();
265 /* make sure regionStack is empty */
266 while (!STACK_EMPTY (regionStack))
267 STACK_POP (regionStack);
269 /* add the entryBlock */
270 addSet (&aloop->regBlocks, ep->to);
271 loopInsert (&aloop->regBlocks, ep->from);
273 while (!STACK_EMPTY (regionStack))
275 block = STACK_POP (regionStack);
276 /* if block != entry */
278 applyToSet (block->predList, insertIntoLoop, &aloop->regBlocks);
281 aloop->entry = ep->to;
283 /* now add it to the set */
284 addSetHead (allRegion, aloop);
288 /*-----------------------------------------------------------------*/
289 /* dominatedBy - will return 1 if item is dominated by block */
290 /*-----------------------------------------------------------------*/
291 DEFSETFUNC (dominatedBy)
294 V_ARG (eBBlock *, block);
296 return bitVectBitValue (ebp->domVect, block->bbnum);
299 /*-----------------------------------------------------------------*/
300 /* addDefInExprs - adds an expression into the inexpressions */
301 /*-----------------------------------------------------------------*/
302 DEFSETFUNC (addDefInExprs)
305 V_ARG (cseDef *, cdp);
306 V_ARG (eBBlock **, ebbs);
309 addSetHead (&ebp->inExprs, cdp);
310 cseBBlock (ebp, 0, ebbs, count);
314 /*-----------------------------------------------------------------*/
315 /* assignmentsToSym - for a set of blocks determine # time assigned */
316 /*-----------------------------------------------------------------*/
318 assignmentsToSym (set * sset, operand * sym)
322 set *blocks = setFromSet (sset);
324 for (ebp = setFirstItem (blocks); ebp;
325 ebp = setNextItem (blocks))
328 /* get all the definitions for this symbol
330 bitVect *defs = bitVectIntersect (ebp->ldefs, OP_DEFS (sym));
331 assigns += bitVectnBitsOn (defs);
332 setToNull ((void **) &defs);
340 /*-----------------------------------------------------------------*/
341 /* isOperandInvariant - determines if an operand is an invariant */
342 /*-----------------------------------------------------------------*/
344 isOperandInvariant (operand * op, region * theLoop, set * lInvars)
347 /* operand is an invariant if it is a */
349 /* b. that have defintions reaching loop entry */
350 /* c. that are already defined as invariant */
351 /* d. has no assignments in the loop */
354 if (IS_OP_LITERAL (op))
356 else if (IS_SYMOP (op) &&
357 OP_SYMBOL (op)->addrtaken)
359 else if (ifDefSymIs (theLoop->entry->inExprs, op))
361 else if (ifDefSymIs (lInvars, op))
363 else if (IS_SYMOP (op) &&
364 !IS_OP_GLOBAL (op) &&
365 !IS_OP_VOLATILE (op) &&
366 assignmentsToSym (theLoop->regBlocks, op) == 0)
375 /*-----------------------------------------------------------------*/
376 /* pointerAssigned - will return 1 if pointer set found */
377 /*-----------------------------------------------------------------*/
378 DEFSETFUNC (pointerAssigned)
381 V_ARG (operand *, op);
383 return ebp->hasFcall || bitVectBitValue (ebp->ptrsSet, op->key);
386 /*-----------------------------------------------------------------*/
387 /* hasNonPtrUse - returns true if operand has non pointer usage */
388 /*-----------------------------------------------------------------*/
389 DEFSETFUNC (hasNonPtrUse)
392 V_ARG (operand *, op);
393 iCode *ic = usedInRemaining (op, ebp->sch);
395 if (ic && !POINTER_SET (ic) && !POINTER_GET (ic))
402 /*-----------------------------------------------------------------*/
403 /* loopInvariants - takes loop invariants out of region */
404 /*-----------------------------------------------------------------*/
406 loopInvariants (region * theLoop, eBBlock ** ebbs, int count)
414 /* if the preHeader does not exist then do nothing */
415 /* or no exits then do nothing ( have to think about this situation */
416 if (theLoop->entry->preHeader == NULL ||
417 theLoop->exits == NULL)
420 /* we will do the elimination for those blocks */
421 /* in the loop that dominates all exits from the loop */
422 for (lBlock = setFirstItem (theLoop->regBlocks); lBlock;
423 lBlock = setNextItem (theLoop->regBlocks))
430 /* mark the dominates all exits flag */
431 domsAllExits = (applyToSet (theLoop->exits, dominatedBy, lBlock) ==
432 elementsInSet (theLoop->exits));
434 /* find out if we have a function call in this block */
435 for (ic = lBlock->sch, fCallsInBlock=0; ic; ic = ic->next) {
441 /* now we go thru the instructions of this block and */
442 /* collect those instructions with invariant operands */
443 for (ic = lBlock->sch; ic; ic = ic->next)
449 /* if there are function calls in this block and this
450 is a pointer get, the function could have changed it
451 so skip, ISO-C99 according to David A. Long */
452 if (fCallsInBlock && POINTER_GET(ic)) {
456 if (SKIP_IC (ic) || POINTER_SET (ic) || ic->op == IFX)
459 /* if result is volatile then skip */
460 if (IC_RESULT (ic) &&
461 (isOperandVolatile (IC_RESULT (ic), TRUE) ||
462 IS_OP_PARM (IC_RESULT (ic))))
465 /* if result depends on a volatile then skip */
466 if ((IC_LEFT(ic) && isOperandVolatile(IC_LEFT(ic), TRUE)) ||
467 (IC_RIGHT(ic) && isOperandVolatile(IC_RIGHT(ic), TRUE)))
473 /* if address of then it is an invariant */
474 if (ic->op == ADDRESS_OF &&
475 IS_SYMOP (IC_LEFT (ic)) &&
476 IS_AGGREGATE (operandType (IC_LEFT (ic))))
479 /* check if left operand is an invariant */
480 if ((lin = isOperandInvariant (IC_LEFT (ic), theLoop, lInvars)))
481 /* if this is a pointer get then make sure
482 that the pointer set does not exist in
484 if (POINTER_GET (ic) &&
485 (applyToSet (theLoop->regBlocks,
486 pointerAssigned, IC_LEFT (ic))))
490 /* do the same for right */
491 rin = isOperandInvariant (IC_RIGHT (ic), theLoop, lInvars);
493 /* if this is a POINTER_GET then special case, make sure all
494 usages within the loop are POINTER_GET any other usage
495 would mean that this is not an invariant , since the pointer
496 could then be passed as a parameter */
497 if (POINTER_GET (ic) &&
498 applyToSet (theLoop->regBlocks, hasNonPtrUse, IC_LEFT (ic)))
501 /* if both the left & right are invariants : then check that */
502 /* this definition exists in the out definition of all the */
503 /* blocks, this will ensure that this is not assigned any */
504 /* other value in the loop , and not used in this block */
505 /* prior to this definition which means only this definition */
506 /* is used in this loop */
507 if (lin && rin && IC_RESULT (ic))
510 set *lSet = setFromSet (theLoop->regBlocks);
512 /* if this block does not dominate all exists */
513 /* make sure this defintion is not used anywhere else */
517 if (isOperandGlobal (IC_RESULT (ic)))
519 /* for successors for all exits */
520 for (sBlock = setFirstItem (theLoop->exits); sBlock;
521 sBlock = setNextItem (theLoop->exits))
524 for (i = 0; i < count; ebbs[i++]->visited = 0);
526 if (applyToSet (sBlock->succList, isDefAlive, ic))
530 /* we have found usage */
535 /* now make sure this is the only definition */
536 for (sBlock = setFirstItem (lSet); sBlock;
537 sBlock = setNextItem (lSet))
539 /* if this is the block make sure the definition */
540 /* reaches the end of the block */
541 if (sBlock == lBlock)
543 if (!ifDiCodeIs (sBlock->outExprs, ic))
546 else if (bitVectBitsInCommon (sBlock->defSet, OP_DEFS (IC_RESULT (ic))))
551 continue; /* another definition present in the block */
553 /* now check if it exists in the in of this block */
554 /* if not then it was killed before this instruction */
555 if (!bitVectBitValue (lBlock->inDefs, ic->key))
558 /* now we know it is a true invariant */
559 /* remove it from the insts chain & put */
560 /* in the invariant set */
561 OP_SYMBOL (IC_RESULT (ic))->isinvariant = 1;
562 remiCodeFromeBBlock (lBlock, ic);
564 /* maintain the data flow */
565 /* this means removing from definition from the */
566 /* defset of this block and adding it to the */
567 /* inexpressions of all blocks within the loop */
568 bitVectUnSetBit (lBlock->defSet, ic->key);
569 bitVectUnSetBit (lBlock->ldefs, ic->key);
570 ivar = newCseDef (IC_RESULT (ic), ic);
571 applyToSet (theLoop->regBlocks, addDefInExprs, ivar, ebbs, count);
572 addSet (&lInvars, ivar);
575 } /* for all loop blocks */
577 /* if we have some invariants then */
580 eBBlock *preHdr = theLoop->entry->preHeader;
581 iCode *icFirst = NULL, *icLast = NULL;
584 /* create an iCode chain from it */
585 for (cdp = setFirstItem (lInvars); cdp; cdp = setNextItem (lInvars))
588 /* maintain data flow .. add it to the */
589 /* ldefs defSet & outExprs of the preheader */
590 preHdr->defSet = bitVectSetBit (preHdr->defSet, cdp->diCode->key);
591 preHdr->ldefs = bitVectSetBit (preHdr->ldefs, cdp->diCode->key);
592 cdp->diCode->lineno = preHdr->ech->lineno;
593 addSetHead (&preHdr->outExprs, cdp);
597 icFirst = cdp->diCode;
600 icLast->next = cdp->diCode;
601 cdp->diCode->prev = icLast;
602 icLast = cdp->diCode;
605 icLast = cdp->diCode;
609 /* add the instruction chain to the end of the
610 preheader for this loop, preheaders will always
611 have atleast a label */
612 preHdr->ech->next = icFirst;
613 icFirst->prev = preHdr->ech;
614 preHdr->ech = icLast;
621 /*-----------------------------------------------------------------*/
622 /* addressTaken - returns true if the symbol is found in the addrof */
623 /*-----------------------------------------------------------------*/
625 addressTaken (set * sset, operand * sym)
631 for (loop = sset; loop; loop = loop->next)
637 if (isOperandEqual ((operand *) loop2->item, sym))
647 /*-----------------------------------------------------------------*/
648 /* findInduction :- returns 1 & the item if the induction is found */
649 /*-----------------------------------------------------------------*/
650 DEFSETFUNC (findInduction)
652 induction *ip = item;
653 V_ARG (operand *, sym);
654 V_ARG (induction **, ipp);
656 if (isOperandEqual (ip->sym, sym))
665 /*-----------------------------------------------------------------*/
666 /* findDefInRegion - finds the definition within the region */
667 /*-----------------------------------------------------------------*/
669 findDefInRegion (set * regBlocks, operand * defOp, eBBlock ** owner)
673 /* for all blocks in the region */
674 for (lBlock = setFirstItem (regBlocks); lBlock;
675 lBlock = setNextItem (regBlocks))
678 /* if a definition for this exists */
679 if (bitVectBitsInCommon (lBlock->defSet, OP_DEFS (defOp)))
683 /* go thru the instruction chain to find it */
684 for (ic = lBlock->sch; ic; ic = ic->next)
685 if (bitVectBitValue (OP_DEFS (defOp), ic->key))
697 /*-----------------------------------------------------------------*/
698 /* basicInduction - finds the basic induction variables in a loop */
699 /*-----------------------------------------------------------------*/
701 basicInduction (region * loopReg, eBBlock ** ebbs, int count)
706 /* i.e. all assignments of the form a := a +/- const */
707 /* for all blocks within the loop do */
708 for (lBlock = setFirstItem (loopReg->regBlocks); lBlock;
709 lBlock = setNextItem (loopReg->regBlocks))
714 /* for all instructions in the blocks do */
715 for (ic = lBlock->sch; ic; ic = ic->next)
719 unsigned long litValue;
722 eBBlock *owner = NULL;
725 /* look for assignments of the form */
726 /* symbolVar := iTempNN */
730 if (!IS_TRUE_SYMOP (IC_RESULT (ic)) &&
731 !OP_SYMBOL (IC_RESULT (ic))->isreqv)
734 if (isOperandGlobal (IC_RESULT (ic)))
737 if (!IS_ITEMP (IC_RIGHT (ic)))
740 /* if it has multiple assignments within the loop then skip */
741 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
744 /* if the address of this was taken inside the loop then continue */
745 if (addressTaken (loopReg->regBlocks, IC_RESULT (ic)))
748 /* find the definition for the result in the block */
749 if (!(dic = findDefInRegion (setFromSet (loopReg->regBlocks),
750 IC_RIGHT (ic), &owner)))
753 /* if not +/- continue */
754 if (dic->op != '+' && dic->op != '-')
757 /* make sure definition is of the form a +/- c */
758 if (!IS_OP_LITERAL (IC_LEFT (dic)) && !IS_OP_LITERAL (IC_RIGHT (dic)))
761 aSym = (IS_OP_LITERAL (IC_RIGHT (dic)) ?
762 (litValue = (unsigned long) operandLitValue (IC_RIGHT (dic)), IC_LEFT (dic)) :
763 (litValue = (unsigned long) operandLitValue (IC_LEFT (dic)), IC_RIGHT (dic)));
765 if (!isOperandEqual (IC_RESULT (ic), aSym) &&
766 !isOperandEqual (IC_RIGHT (ic), aSym))
769 /* find the definition for this and check */
770 if (!(ddic = findDefInRegion (setFromSet (loopReg->regBlocks),
777 if (!isOperandEqual (IC_RESULT (ddic), aSym) ||
778 !isOperandEqual (IC_RIGHT (ddic), IC_RESULT (ic)))
782 /* if the right hand side has more than one usage then
783 don't make it an induction (will have to think some more) */
784 if (bitVectnBitsOn (OP_USES (IC_RIGHT (ic))) > 1)
787 /* if the definition is volatile then it cannot be
788 an induction object */
789 if (isOperandVolatile (IC_RIGHT (ic), FALSE) ||
790 isOperandVolatile (IC_RESULT (ic), FALSE))
793 /* whew !! that was a lot of work to find the definition */
794 /* create an induction object */
795 indIc = newiCode ('=', NULL, IC_RESULT (ic));
796 indIc->lineno = ic->lineno;
797 IC_RESULT (indIc) = operandFromOperand (IC_RIGHT (ic));
798 IC_RESULT (indIc)->isaddr = 0;
799 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
800 ip = newInduction (IC_RIGHT (ic), dic->op, litValue, indIc, NULL);
802 /* replace the inducted variable by the iTemp */
803 replaceSymBySym (loopReg->regBlocks, IC_RESULT (ic), IC_RIGHT (ic));
805 /* if it has only one exit then remove it from here
806 and put it in the exit block */
807 nexits = elementsInSet (loopReg->exits);
810 eBBlock *exit = setFirstItem (loopReg->exits);
812 /* if it is the same block then there is no
813 need to move it about */
816 iCode *saveic = ic->prev;
818 remiCodeFromeBBlock (lBlock, ic);
819 /* clear the definition */
820 bitVectUnSetBit (lBlock->defSet, ic->key);
821 /* add it to the exit */
822 addiCodeToeBBlock (exit, ic, NULL);
823 /* set the definition bit */
824 exit->defSet = bitVectSetBit (exit->defSet, ic->key);
829 /* if the number of exits is greater than one then
830 we use another trick ; we will create an intersection
831 of succesors of the exits, then take those that are not
832 part of the loop and have dfNumber greater loop entry
833 and insert a new definition in them */
837 bitVect *loopSuccs = intersectLoopSucc (loopReg->exits, ebbs);
839 /* loopSuccs now contains intersection
840 of all the loops successors */
844 for (i = 0; i < loopSuccs->size; i++)
846 if (bitVectBitValue (loopSuccs, i))
849 eBBlock *eblock = ebbs[i];
851 /* if the successor does not belong to the loop
852 and will be executed after the loop : then
853 add a definition to the block */
854 if (!isinSet (loopReg->regBlocks, eblock) &&
855 eblock->dfnum > loopReg->entry->dfnum)
857 /* create the definition */
858 iCode *newic = newiCode ('=', NULL,
859 operandFromOperand (IC_RIGHT (ic)));
860 IC_RESULT (newic) = operandFromOperand (IC_RESULT (ic));
861 OP_DEFS (IC_RESULT (newic)) =
862 bitVectSetBit (OP_DEFS (IC_RESULT (newic)), newic->key);
863 OP_USES (IC_RIGHT (newic)) =
864 bitVectSetBit (OP_USES (IC_RIGHT (newic)), newic->key);
866 if (eblock->sch && eblock->sch->op == LABEL)
867 addiCodeToeBBlock (eblock, newic, eblock->sch->next);
869 addiCodeToeBBlock (eblock, newic, eblock->sch);
870 /* set the definition bit */
871 eblock->defSet = bitVectSetBit (eblock->defSet, ic->key);
878 addSet (&indVars, ip);
881 } /* end of all blocks for basic induction variables */
886 /*-----------------------------------------------------------------*/
887 /* loopInduction - remove induction variables from a loop */
888 /*-----------------------------------------------------------------*/
890 loopInduction (region * loopReg, eBBlock ** ebbs, int count)
893 eBBlock *lBlock, *lastBlock = NULL;
895 set *basicInd = NULL;
897 if (loopReg->entry->preHeader == NULL)
900 /* we first determine the basic Induction variables */
901 basicInd = setFromSet (indVars = basicInduction (loopReg, ebbs, count));
903 /* find other induction variables : by other we mean definitions of */
904 /* the form x := y (* | / ) <constant> .. we will move this one to */
905 /* beginning of the loop and reduce strength i.e. replace with +/- */
906 /* these expensive expressions: OH! and y must be induction too */
907 for (lBlock = setFirstItem (loopReg->regBlocks), lastBlock = lBlock;
909 lBlock = setNextItem (loopReg->regBlocks))
915 /* last block is the one with the highest block
917 if (lastBlock->bbnum < lBlock->bbnum)
920 for (ic = lBlock->sch; ic; ic = ic->next)
923 unsigned long litVal;
926 /* consider only * & / */
927 if (ic->op != '*' && ic->op != '/')
930 /* if the result has more definitions then */
931 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
934 /* check if the operands are what we want */
935 /* i.e. one of them an symbol the other a literal */
936 if (!((IS_SYMOP (IC_LEFT (ic)) && IS_OP_LITERAL (IC_RIGHT (ic))) ||
937 (IS_OP_LITERAL (IC_LEFT (ic)) && IS_SYMOP (IC_RIGHT (ic)))))
940 aSym = (IS_SYMOP (IC_LEFT (ic)) ?
941 (lr = 1, litVal = (unsigned long) operandLitValue (IC_RIGHT (ic)), IC_LEFT (ic)) :
942 (litVal = (unsigned long) operandLitValue (IC_LEFT (ic)), IC_RIGHT (ic)));
945 /* check if this is an induction variable */
946 if (!applyToSetFTrue (basicInd, findInduction, aSym, &ip))
949 /* ask port for size not worth if native instruction
950 exist for multiply & divide */
951 if (getSize (operandType (IC_LEFT (ic))) <= (unsigned long) port->support.muldiv ||
952 getSize (operandType (IC_RIGHT (ic))) <= (unsigned long) port->support.muldiv)
955 /* if this is a division then the remainder should be zero
956 for it to be inducted */
957 if (ic->op == '/' && (ip->cval % litVal))
960 /* create the iCode to be placed in the loop header */
961 /* and create the induction object */
963 /* create an instruction */
964 /* this will be put on the loop header */
965 indIc = newiCode (ic->op,
966 operandFromOperand (aSym),
967 operandFromLit (litVal));
968 indIc->lineno = ic->lineno;
969 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
970 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
972 /* keep track of the inductions */
973 litVal = (ic->op == '*' ? (litVal * ip->cval) :
974 (ip->cval / litVal));
977 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
979 /* now change this instruction */
983 IC_LEFT (ic) = operandFromOperand (IC_RESULT (ic));
984 IC_RIGHT (ic) = operandFromLit (litVal);
988 IC_RIGHT (ic) = operandFromOperand (IC_RESULT (ic));
989 IC_LEFT (ic) = operandFromLit (litVal);
992 /* we need somemore initialisation code */
993 /* we subtract the litVal from itself if increment */
996 indIc = newiCode ('-',
997 operandFromOperand (IC_RESULT (ic)),
998 operandFromLit (litVal));
999 indIc->lineno = ic->lineno;
1000 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
1003 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
1008 /* if we have some induction variables then */
1011 eBBlock *preHdr = loopReg->entry->preHeader;
1012 iCode *icFirst = NULL, *icLast = NULL;
1014 bitVect *indVect = NULL;
1016 /* create an iCode chain from it */
1017 for (ip = setFirstItem (indVars);
1019 ip = setNextItem (indVars))
1022 indVect = bitVectSetBit (indVect, ip->ic->key);
1023 ip->ic->lineno = preHdr->ech->lineno;
1028 icLast->next = ip->ic;
1029 ip->ic->prev = icLast;
1037 /* add the instruction chain to the end of the */
1038 /* preheader for this loop */
1039 preHdr->ech->next = icFirst;
1040 icFirst->prev = preHdr->ech;
1041 preHdr->ech = icLast;
1042 icLast->next = NULL;
1044 /* add the induction variable vector to the last
1045 block in the loop */
1046 lastBlock->isLastInLoop = 1;
1047 lastBlock->linds = indVect;
1050 setToNull ((void **) &indVars);
1054 /*-----------------------------------------------------------------*/
1055 /* mergeRegions - will merge region with same entry point */
1056 /*-----------------------------------------------------------------*/
1057 DEFSETFUNC (mergeRegions)
1059 region *theLoop = item;
1060 V_ARG (set *, allRegion);
1063 /* if this has already been merged then do nothing */
1064 if (theLoop->merged)
1067 /* go thru all the region and check if any of them have the */
1068 /* entryPoint as the Loop */
1069 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1075 if (lp->entry == theLoop->entry)
1077 theLoop->regBlocks = unionSets (theLoop->regBlocks,
1078 lp->regBlocks, THROW_BOTH);
1086 /*-----------------------------------------------------------------*/
1087 /* ifMerged - return 1 if the merge flag is 1 */
1088 /*-----------------------------------------------------------------*/
1089 DEFSETFUNC (ifMerged)
1096 /*-----------------------------------------------------------------*/
1097 /* mergeInnerLoops - will merge into body when entry is present */
1098 /*-----------------------------------------------------------------*/
1099 DEFSETFUNC (mergeInnerLoops)
1101 region *theLoop = item;
1102 V_ARG (set *, allRegion);
1103 V_ARG (int *, maxDepth);
1106 /* check if the entry point is present in the body of any */
1107 /* loop then put the body of this loop into the outer loop */
1108 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1114 if (isinSet (lp->regBlocks, theLoop->entry))
1116 lp->containsLoops += theLoop->containsLoops + 1;
1117 if (lp->containsLoops > (*maxDepth))
1118 *maxDepth = lp->containsLoops;
1120 lp->regBlocks = unionSets (lp->regBlocks,
1121 theLoop->regBlocks, THROW_DEST);
1129 /*-----------------------------------------------------------------*/
1130 /* createLoopRegions - will detect and create a set of natural loops */
1131 /*-----------------------------------------------------------------*/
1133 createLoopRegions (eBBlock ** ebbs, int count)
1135 set *allRegion = NULL; /* set of all loops */
1136 hTab *orderedLoops = NULL;
1141 /* get all the back edges in the graph */
1142 if (!applyToSet (graphEdges, backEdges, &bEdges))
1143 return 0; /* found no loops */
1145 /* for each of these back edges get the blocks that */
1146 /* constitute the loops */
1147 applyToSet (bEdges, createLoop, &allRegion);
1149 /* now we will create regions from these loops */
1150 /* loops with the same entry points are considered to be the */
1151 /* same loop & they are merged. If the entry point of a loop */
1152 /* is found in the body of another loop then , all the blocks */
1153 /* in that loop are added to the loops containing the header */
1154 applyToSet (allRegion, mergeRegions, allRegion);
1156 /* delete those already merged */
1157 deleteItemIf (&allRegion, ifMerged);
1159 applyToSet (allRegion, mergeInnerLoops, allRegion, &maxDepth);
1161 /* now create all the exits .. also */
1162 /* create an ordered set of loops */
1163 /* i.e. we process loops in the inner to outer order */
1164 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1166 applyToSet (lp->regBlocks, addToExitsMarkDepth,
1167 lp->regBlocks, &lp->exits,
1168 (maxDepth - lp->containsLoops), lp);
1170 hTabAddItem (&orderedLoops, lp->containsLoops, lp);
1173 return orderedLoops;
1176 /*-----------------------------------------------------------------*/
1177 /* loopOptimizations - identify region & remove invariants & ind */
1178 /*-----------------------------------------------------------------*/
1180 loopOptimizations (hTab * orderedLoops, eBBlock ** ebbs, int count)
1186 /* if no loop optimizations requested */
1187 if (!optimize.loopInvariant &&
1188 !optimize.loopInduction)
1191 /* now we process the loops inner to outer order */
1192 /* this is essential to maintain data flow information */
1193 /* the other choice is an ugly iteration for the depth */
1194 /* of the loops would hate that */
1195 for (lp = hTabFirstItem (orderedLoops, &k); lp;
1196 lp = hTabNextItem (orderedLoops, &k))
1199 if (optimize.loopInvariant)
1200 change += loopInvariants (lp, ebbs, count);
1202 if (optimize.loopInduction)
1203 change += loopInduction (lp, ebbs, count);