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 /* 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, optimize.global_cse, 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);
385 if (bitVectBitValue (ebp->ptrsSet, op->key))
388 /* Unfortunately, one of the other pointer set operations */
389 /* may be using an alias of this operand, and the above */
390 /* test would miss it. To be thorough, some aliasing */
391 /* analysis should be done here. In the meantime, be */
392 /* conservative and assume any other pointer set operation */
394 if (!bitVectIsZero (ebp->ptrsSet))
400 /*-----------------------------------------------------------------*/
401 /* hasNonPtrUse - returns true if operand has non pointer usage */
402 /*-----------------------------------------------------------------*/
403 DEFSETFUNC (hasNonPtrUse)
406 V_ARG (operand *, op);
407 iCode *ic = usedInRemaining (op, ebp->sch);
409 if (ic && !POINTER_SET (ic) && !POINTER_GET (ic))
416 /*-----------------------------------------------------------------*/
417 /* loopInvariants - takes loop invariants out of region */
418 /*-----------------------------------------------------------------*/
420 loopInvariants (region * theLoop, eBBlock ** ebbs, int count)
428 /* if the preHeader does not exist then do nothing */
429 /* or no exits then do nothing ( have to think about this situation */
430 if (theLoop->entry->preHeader == NULL ||
431 theLoop->exits == NULL)
434 /* we will do the elimination for those blocks */
435 /* in the loop that dominates all exits from the loop */
436 for (lBlock = setFirstItem (theLoop->regBlocks); lBlock;
437 lBlock = setNextItem (theLoop->regBlocks))
444 /* mark the dominates all exits flag */
445 domsAllExits = (applyToSet (theLoop->exits, dominatedBy, lBlock) ==
446 elementsInSet (theLoop->exits));
448 /* find out if we have a function call in this block */
449 for (ic = lBlock->sch, fCallsInBlock=0; ic; ic = ic->next) {
455 /* now we go thru the instructions of this block and */
456 /* collect those instructions with invariant operands */
457 for (ic = lBlock->sch; ic; ic = ic->next)
463 /* TODO this is only needed if the call is between
464 here and the definition, but I am too lazy to do that now */
466 /* if there are function calls in this block */
469 /* if this is a pointer get */
470 if (POINTER_GET(ic)) {
474 /* if this is an assignment from a global */
475 if (ic->op=='=' && isOperandGlobal(IC_RIGHT(ic))) {
480 if (SKIP_IC (ic) || POINTER_SET (ic) || ic->op == IFX)
483 /* iTemp assignment from a literal may be invariant, but it
484 will needlessly increase register pressure if the
485 iCode(s) that use this iTemp are not also invariant */
486 if (ic->op=='=' && IS_ITEMP (IC_RESULT (ic))
487 && IS_OP_LITERAL (IC_RIGHT (ic)))
490 /* if result is volatile then skip */
491 if (IC_RESULT (ic) &&
492 (isOperandVolatile (IC_RESULT (ic), TRUE) ||
493 IS_OP_PARM (IC_RESULT (ic))))
496 /* if result depends on a volatile then skip */
497 if ((IC_LEFT(ic) && isOperandVolatile(IC_LEFT(ic), TRUE)) ||
498 (IC_RIGHT(ic) && isOperandVolatile(IC_RIGHT(ic), TRUE)))
504 /* if address of then it is an invariant */
505 if (ic->op == ADDRESS_OF &&
506 IS_SYMOP (IC_LEFT (ic)) &&
507 IS_AGGREGATE (operandType (IC_LEFT (ic))))
510 /* check if left operand is an invariant */
511 if ((lin = isOperandInvariant (IC_LEFT (ic), theLoop, lInvars)))
512 /* if this is a pointer get then make sure
513 that the pointer set does not exist in
515 if (POINTER_GET (ic) &&
516 (applyToSet (theLoop->regBlocks,
517 pointerAssigned, IC_LEFT (ic))))
521 /* do the same for right */
522 rin = isOperandInvariant (IC_RIGHT (ic), theLoop, lInvars);
524 /* if this is a POINTER_GET then special case, make sure all
525 usages within the loop are POINTER_GET any other usage
526 would mean that this is not an invariant , since the pointer
527 could then be passed as a parameter */
528 if (POINTER_GET (ic) &&
529 applyToSet (theLoop->regBlocks, hasNonPtrUse, IC_LEFT (ic)))
533 /* if both the left & right are invariants : then check that */
534 /* this definition exists in the out definition of all the */
535 /* blocks, this will ensure that this is not assigned any */
536 /* other value in the loop , and not used in this block */
537 /* prior to this definition which means only this definition */
538 /* is used in this loop */
539 if (lin && rin && IC_RESULT (ic))
542 set *lSet = setFromSet (theLoop->regBlocks);
544 /* if this block does not dominate all exits */
545 /* make sure this defintion is not used anywhere else */
549 if (isOperandGlobal (IC_RESULT (ic)))
551 /* for successors for all exits */
552 for (sBlock = setFirstItem (theLoop->exits); sBlock;
553 sBlock = setNextItem (theLoop->exits))
556 for (i = 0; i < count; ebbs[i++]->visited = 0);
558 if (applyToSet (sBlock->succList, isDefAlive, ic))
562 /* we have found usage */
567 /* now make sure this is the only definition */
568 for (sBlock = setFirstItem (lSet); sBlock;
569 sBlock = setNextItem (lSet))
571 /* if this is the block make sure the definition */
572 /* reaches the end of the block */
573 if (sBlock == lBlock)
575 if (!ifDiCodeIs (sBlock->outExprs, ic))
578 else if (bitVectBitsInCommon (sBlock->defSet, OP_DEFS (IC_RESULT (ic))))
583 continue; /* another definition present in the block */
585 /* now check if it exists in the in of this block */
586 /* if not then it was killed before this instruction */
587 if (!bitVectBitValue (lBlock->inDefs, ic->key))
590 /* now we know it is a true invariant */
591 /* remove it from the insts chain & put */
592 /* in the invariant set */
594 OP_SYMBOL (IC_RESULT (ic))->isinvariant = 1;
595 SPIL_LOC (IC_RESULT (ic)) = NULL;
596 remiCodeFromeBBlock (lBlock, ic);
598 /* maintain the data flow */
599 /* this means removing from definition from the */
600 /* defset of this block and adding it to the */
601 /* inexpressions of all blocks within the loop */
602 bitVectUnSetBit (lBlock->defSet, ic->key);
603 bitVectUnSetBit (lBlock->ldefs, ic->key);
604 ivar = newCseDef (IC_RESULT (ic), ic);
605 applyToSet (theLoop->regBlocks, addDefInExprs, ivar, ebbs, count);
606 addSet (&lInvars, ivar);
609 } /* for all loop blocks */
611 /* if we have some invariants then */
614 eBBlock *preHdr = theLoop->entry->preHeader;
615 iCode *icFirst = NULL, *icLast = NULL;
618 /* create an iCode chain from it */
619 for (cdp = setFirstItem (lInvars); cdp; cdp = setNextItem (lInvars))
622 /* maintain data flow .. add it to the */
623 /* ldefs defSet & outExprs of the preheader */
624 preHdr->defSet = bitVectSetBit (preHdr->defSet, cdp->diCode->key);
625 preHdr->ldefs = bitVectSetBit (preHdr->ldefs, cdp->diCode->key);
626 cdp->diCode->lineno = preHdr->ech->lineno;
627 addSetHead (&preHdr->outExprs, cdp);
631 icFirst = cdp->diCode;
634 icLast->next = cdp->diCode;
635 cdp->diCode->prev = icLast;
636 icLast = cdp->diCode;
639 icLast = cdp->diCode;
643 /* add the instruction chain to the end of the
644 preheader for this loop, preheaders will always
645 have atleast a label */
646 preHdr->ech->next = icFirst;
647 icFirst->prev = preHdr->ech;
648 preHdr->ech = icLast;
655 /*-----------------------------------------------------------------*/
656 /* addressTaken - returns true if the symbol is found in the addrof */
657 /*-----------------------------------------------------------------*/
659 addressTaken (set * sset, operand * sym)
665 for (loop = sset; loop; loop = loop->next)
671 if (isOperandEqual ((operand *) loop2->item, sym))
681 /*-----------------------------------------------------------------*/
682 /* findInduction :- returns 1 & the item if the induction is found */
683 /*-----------------------------------------------------------------*/
684 DEFSETFUNC (findInduction)
686 induction *ip = item;
687 V_ARG (operand *, sym);
688 V_ARG (induction **, ipp);
690 if (isOperandEqual (ip->sym, sym))
699 /*-----------------------------------------------------------------*/
700 /* findDefInRegion - finds the definition within the region */
701 /*-----------------------------------------------------------------*/
703 findDefInRegion (set * regBlocks, operand * defOp, eBBlock ** owner)
707 /* for all blocks in the region */
708 for (lBlock = setFirstItem (regBlocks); lBlock;
709 lBlock = setNextItem (regBlocks))
712 /* if a definition for this exists */
713 if (bitVectBitsInCommon (lBlock->defSet, OP_DEFS (defOp)))
717 /* go thru the instruction chain to find it */
718 for (ic = lBlock->sch; ic; ic = ic->next)
719 if (bitVectBitValue (OP_DEFS (defOp), ic->key))
731 /*-----------------------------------------------------------------*/
732 /* basicInduction - finds the basic induction variables in a loop */
733 /*-----------------------------------------------------------------*/
735 basicInduction (region * loopReg, eBBlock ** ebbs, int count)
740 /* i.e. all assignments of the form a := a +/- const */
741 /* for all blocks within the loop do */
742 for (lBlock = setFirstItem (loopReg->regBlocks); lBlock;
743 lBlock = setNextItem (loopReg->regBlocks))
748 /* for all instructions in the blocks do */
749 for (ic = lBlock->sch; ic; ic = ic->next)
753 unsigned long litValue;
756 eBBlock *owner = NULL;
759 /* look for assignments of the form */
760 /* symbolVar := iTempNN */
764 if (!IS_TRUE_SYMOP (IC_RESULT (ic)) &&
765 !OP_SYMBOL (IC_RESULT (ic))->isreqv)
768 if (isOperandGlobal (IC_RESULT (ic)))
771 if (!IS_ITEMP (IC_RIGHT (ic)))
774 /* if it has multiple assignments within the loop then skip */
775 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
778 /* if the address of this was taken inside the loop then continue */
779 if (addressTaken (loopReg->regBlocks, IC_RESULT (ic)))
782 /* find the definition for the result in the block */
783 if (!(dic = findDefInRegion (setFromSet (loopReg->regBlocks),
784 IC_RIGHT (ic), &owner)))
787 /* if not +/- continue */
788 if (dic->op != '+' && dic->op != '-')
791 /* make sure definition is of the form a +/- c */
792 if (!IS_OP_LITERAL (IC_LEFT (dic)) && !IS_OP_LITERAL (IC_RIGHT (dic)))
795 aSym = (IS_OP_LITERAL (IC_RIGHT (dic)) ?
796 (litValue = (unsigned long) operandLitValue (IC_RIGHT (dic)), IC_LEFT (dic)) :
797 (litValue = (unsigned long) operandLitValue (IC_LEFT (dic)), IC_RIGHT (dic)));
799 if (!isOperandEqual (IC_RESULT (ic), aSym) &&
800 !isOperandEqual (IC_RIGHT (ic), aSym))
803 /* find the definition for this and check */
804 if (!(ddic = findDefInRegion (setFromSet (loopReg->regBlocks),
811 if (!isOperandEqual (IC_RESULT (ddic), aSym) ||
812 !isOperandEqual (IC_RIGHT (ddic), IC_RESULT (ic)))
816 /* if the right hand side has more than one usage then
817 don't make it an induction (will have to think some more) */
818 if (bitVectnBitsOn (OP_USES (IC_RIGHT (ic))) > 1)
821 /* if the definition is volatile then it cannot be
822 an induction object */
823 if (isOperandVolatile (IC_RIGHT (ic), FALSE) ||
824 isOperandVolatile (IC_RESULT (ic), FALSE))
827 /* whew !! that was a lot of work to find the definition */
828 /* create an induction object */
829 indIc = newiCode ('=', NULL, IC_RESULT (ic));
830 indIc->lineno = ic->lineno;
831 IC_RESULT (indIc) = operandFromOperand (IC_RIGHT (ic));
832 IC_RESULT (indIc)->isaddr = 0;
833 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
834 ip = newInduction (IC_RIGHT (ic), dic->op, litValue, indIc, NULL);
836 /* replace the inducted variable by the iTemp */
837 replaceSymBySym (loopReg->regBlocks, IC_RESULT (ic), IC_RIGHT (ic));
839 /* if it has only one exit then remove it from here
840 and put it in the exit block */
841 nexits = elementsInSet (loopReg->exits);
844 eBBlock *exit = setFirstItem (loopReg->exits);
845 /* if it is the same block then there is no
846 need to move it about */
849 iCode *saveic = ic->prev;
851 remiCodeFromeBBlock (lBlock, ic);
852 /* clear the definition */
853 bitVectUnSetBit (lBlock->defSet, ic->key);
854 /* add it to the exit */
855 addiCodeToeBBlock (exit, ic, NULL);
856 /* set the definition bit */
857 exit->defSet = bitVectSetBit (exit->defSet, ic->key);
862 /* if the number of exits is greater than one then
863 we use another trick ; we will create an intersection
864 of succesors of the exits, then take those that are not
865 part of the loop and have dfNumber greater loop entry
866 and insert a new definition in them */
870 bitVect *loopSuccs = intersectLoopSucc (loopReg->exits, ebbs);
872 /* loopSuccs now contains intersection
873 of all the loops successors */
877 for (i = 0; i < loopSuccs->size; i++)
879 if (bitVectBitValue (loopSuccs, i))
882 eBBlock *eblock = NULL;
885 /* Need to search for bbnum == i since ebbs is */
886 /* sorted by dfnum; a direct index won't do. */
887 for (j=0; j<count; j++)
888 if (ebbs[j]->bbnum == i)
895 /* if the successor does not belong to the loop
896 and will be executed after the loop : then
897 add a definition to the block */
898 if (!isinSet (loopReg->regBlocks, eblock) &&
899 eblock->dfnum > loopReg->entry->dfnum)
901 /* create the definition */
902 iCode *newic = newiCode ('=', NULL,
903 operandFromOperand (IC_RIGHT (ic)));
904 IC_RESULT (newic) = operandFromOperand (IC_RESULT (ic));
905 OP_DEFS(IC_RESULT (newic))=
906 bitVectSetBit (OP_DEFS (IC_RESULT (newic)), newic->key);
907 OP_USES(IC_RIGHT (newic))=
908 bitVectSetBit (OP_USES (IC_RIGHT (newic)), newic->key);
910 if (eblock->sch && eblock->sch->op == LABEL)
911 addiCodeToeBBlock (eblock, newic, eblock->sch->next);
913 addiCodeToeBBlock (eblock, newic, eblock->sch);
914 /* set the definition bit */
915 eblock->defSet = bitVectSetBit (eblock->defSet, ic->key);
922 addSet (&indVars, ip);
925 } /* end of all blocks for basic induction variables */
930 /*-----------------------------------------------------------------*/
931 /* loopInduction - remove induction variables from a loop */
932 /*-----------------------------------------------------------------*/
934 loopInduction (region * loopReg, eBBlock ** ebbs, int count)
937 eBBlock *lBlock, *lastBlock = NULL;
939 set *basicInd = NULL;
941 if (loopReg->entry->preHeader == NULL)
944 /* we first determine the basic Induction variables */
945 basicInd = setFromSet (indVars = basicInduction (loopReg, ebbs, count));
947 /* find other induction variables : by other we mean definitions of */
948 /* the form x := y (* | / ) <constant> .. we will move this one to */
949 /* beginning of the loop and reduce strength i.e. replace with +/- */
950 /* these expensive expressions: OH! and y must be induction too */
951 for (lBlock = setFirstItem (loopReg->regBlocks), lastBlock = lBlock;
953 lBlock = setNextItem (loopReg->regBlocks))
959 /* last block is the one with the highest block
961 if (lastBlock->bbnum < lBlock->bbnum)
964 for (ic = lBlock->sch; ic; ic = ic->next)
967 unsigned long litVal;
970 /* consider only * & / */
971 if (ic->op != '*' && ic->op != '/')
974 /* if the result has more definitions then */
975 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
978 /* check if the operands are what we want */
979 /* i.e. one of them an symbol the other a literal */
980 if (!((IS_SYMOP (IC_LEFT (ic)) && IS_OP_LITERAL (IC_RIGHT (ic))) ||
981 (IS_OP_LITERAL (IC_LEFT (ic)) && IS_SYMOP (IC_RIGHT (ic)))))
984 aSym = (IS_SYMOP (IC_LEFT (ic)) ?
985 (lr = 1, litVal = (unsigned long) operandLitValue (IC_RIGHT (ic)), IC_LEFT (ic)) :
986 (litVal = (unsigned long) operandLitValue (IC_LEFT (ic)), IC_RIGHT (ic)));
989 /* check if this is an induction variable */
990 if (!applyToSetFTrue (basicInd, findInduction, aSym, &ip))
993 /* ask port for size not worth if native instruction
994 exist for multiply & divide */
995 if (getSize (operandType (IC_LEFT (ic))) <= (unsigned long) port->support.muldiv ||
996 getSize (operandType (IC_RIGHT (ic))) <= (unsigned long) port->support.muldiv)
999 /* if this is a division then the remainder should be zero
1000 for it to be inducted */
1001 if (ic->op == '/' && (ip->cval % litVal))
1004 /* create the iCode to be placed in the loop header */
1005 /* and create the induction object */
1007 /* create an instruction */
1008 /* this will be put on the loop header */
1009 indIc = newiCode (ic->op,
1010 operandFromOperand (aSym),
1011 operandFromLit (litVal));
1012 indIc->lineno = ic->lineno;
1013 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
1014 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
1016 /* keep track of the inductions */
1017 litVal = (ic->op == '*' ? (litVal * ip->cval) :
1018 (ip->cval / litVal));
1021 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
1023 /* now change this instruction */
1027 IC_LEFT (ic) = operandFromOperand (IC_RESULT (ic));
1028 IC_RIGHT (ic) = operandFromLit (litVal);
1032 IC_RIGHT (ic) = operandFromOperand (IC_RESULT (ic));
1033 IC_LEFT (ic) = operandFromLit (litVal);
1036 /* we need somemore initialisation code */
1037 /* we subtract the litVal from itself if increment */
1040 indIc = newiCode ('-',
1041 operandFromOperand (IC_RESULT (ic)),
1042 operandFromLit (litVal));
1043 indIc->lineno = ic->lineno;
1044 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
1047 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
1052 /* if we have some induction variables then */
1055 eBBlock *preHdr = loopReg->entry->preHeader;
1056 iCode *icFirst = NULL, *icLast = NULL;
1058 bitVect *indVect = NULL;
1060 /* create an iCode chain from it */
1061 for (ip = setFirstItem (indVars);
1063 ip = setNextItem (indVars))
1066 indVect = bitVectSetBit (indVect, ip->ic->key);
1067 ip->ic->lineno = preHdr->ech->lineno;
1072 icLast->next = ip->ic;
1073 ip->ic->prev = icLast;
1081 /* add the instruction chain to the end of the */
1082 /* preheader for this loop */
1083 preHdr->ech->next = icFirst;
1084 icFirst->prev = preHdr->ech;
1085 preHdr->ech = icLast;
1086 icLast->next = NULL;
1088 /* add the induction variable vector to the last
1089 block in the loop */
1090 lastBlock->isLastInLoop = 1;
1091 lastBlock->linds = bitVectUnion(lastBlock->linds,indVect);
1094 setToNull ((void *) &indVars);
1098 /*-----------------------------------------------------------------*/
1099 /* mergeRegions - will merge region with same entry point */
1100 /*-----------------------------------------------------------------*/
1101 DEFSETFUNC (mergeRegions)
1103 region *theLoop = item;
1104 V_ARG (set *, allRegion);
1107 /* if this has already been merged then do nothing */
1108 if (theLoop->merged)
1111 /* go thru all the region and check if any of them have the */
1112 /* entryPoint as the Loop */
1113 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1119 if (lp->entry == theLoop->entry)
1121 theLoop->regBlocks = unionSets (theLoop->regBlocks,
1122 lp->regBlocks, THROW_DEST);
1130 /*-----------------------------------------------------------------*/
1131 /* ifMerged - return 1 if the merge flag is 1 */
1132 /*-----------------------------------------------------------------*/
1133 DEFSETFUNC (ifMerged)
1140 /*-----------------------------------------------------------------*/
1141 /* mergeInnerLoops - will merge into body when entry is present */
1142 /*-----------------------------------------------------------------*/
1143 DEFSETFUNC (mergeInnerLoops)
1145 region *theLoop = item;
1146 V_ARG (set *, allRegion);
1147 V_ARG (int *, maxDepth);
1150 /* check if the entry point is present in the body of any */
1151 /* loop then put the body of this loop into the outer loop */
1152 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1158 if (isinSet (lp->regBlocks, theLoop->entry))
1160 lp->containsLoops += theLoop->containsLoops + 1;
1161 if (lp->containsLoops > (*maxDepth))
1162 *maxDepth = lp->containsLoops;
1164 lp->regBlocks = unionSets (lp->regBlocks,
1165 theLoop->regBlocks, THROW_DEST);
1173 /*-----------------------------------------------------------------*/
1174 /* createLoopRegions - will detect and create a set of natural loops */
1175 /*-----------------------------------------------------------------*/
1177 createLoopRegions (eBBlock ** ebbs, int count)
1179 set *allRegion = NULL; /* set of all loops */
1180 hTab *orderedLoops = NULL;
1185 /* get all the back edges in the graph */
1186 if (!applyToSet (graphEdges, backEdges, &bEdges))
1187 return 0; /* found no loops */
1189 /* for each of these back edges get the blocks that */
1190 /* constitute the loops */
1191 applyToSet (bEdges, createLoop, &allRegion);
1193 /* now we will create regions from these loops */
1194 /* loops with the same entry points are considered to be the */
1195 /* same loop & they are merged. If the entry point of a loop */
1196 /* is found in the body of another loop then , all the blocks */
1197 /* in that loop are added to the loops containing the header */
1198 applyToSet (allRegion, mergeRegions, allRegion);
1200 /* delete those already merged */
1201 deleteItemIf (&allRegion, ifMerged);
1203 applyToSet (allRegion, mergeInnerLoops, allRegion, &maxDepth);
1206 /* now create all the exits .. also */
1207 /* create an ordered set of loops */
1208 /* i.e. we process loops in the inner to outer order */
1209 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1211 applyToSet (lp->regBlocks, addToExitsMarkDepth,
1212 lp->regBlocks, &lp->exits,
1213 (maxDepth - lp->containsLoops), lp);
1215 hTabAddItem (&orderedLoops, lp->containsLoops, lp);
1218 return orderedLoops;
1221 /*-----------------------------------------------------------------*/
1222 /* loopOptimizations - identify region & remove invariants & ind */
1223 /*-----------------------------------------------------------------*/
1225 loopOptimizations (hTab * orderedLoops, eBBlock ** ebbs, int count)
1231 /* if no loop optimizations requested */
1232 if (!optimize.loopInvariant &&
1233 !optimize.loopInduction)
1236 /* now we process the loops inner to outer order */
1237 /* this is essential to maintain data flow information */
1238 /* the other choice is an ugly iteration for the depth */
1239 /* of the loops would hate that */
1240 for (lp = hTabFirstItem (orderedLoops, &k); lp;
1241 lp = hTabNextItem (orderedLoops, &k))
1244 if (optimize.loopInvariant)
1245 change += loopInvariants (lp, ebbs, count);
1247 if (optimize.loopInduction)
1248 change += loopInduction (lp, ebbs, count);