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 V_ARG (eBBlock **,ebbs);
264 region *aloop = newRegion ();
266 int dfMin = count ,dfMax =0, i;
268 /* make sure regionStack is empty */
269 while (!STACK_EMPTY (regionStack))
270 STACK_POP (regionStack);
272 /* add the entryBlock */
273 addSet (&aloop->regBlocks, ep->to);
274 loopInsert (&aloop->regBlocks, ep->from);
276 while (!STACK_EMPTY (regionStack))
278 block = STACK_POP (regionStack);
279 /* if block != entry */
281 applyToSet (block->predList, insertIntoLoop, &aloop->regBlocks);
284 aloop->entry = ep->to;
285 /* set max & min dfNum for loopRegion */
286 for ( block = setFirstItem(aloop->regBlocks); block;
287 block = setNextItem(aloop->regBlocks)) {
288 if (block->dfnum > dfMax) dfMax = block->dfnum;
289 if (block->dfnum < dfMin) dfMin = block->dfnum;
292 /* all blocks that have dfnumbers between dfMin & dfMax are also
294 for (i = 0 ; i < count ; i++) {
295 if (ebbs[i]->dfnum > dfMin &&
296 ebbs[i]->dfnum < dfMax &&
297 !isinSet(aloop->regBlocks,ebbs[i])) {
298 if (!ebbs[i]->partOfLoop) ebbs[i]->partOfLoop = aloop;
302 /* now add it to the set */
303 addSetHead (allRegion, aloop);
307 /*-----------------------------------------------------------------*/
308 /* dominatedBy - will return 1 if item is dominated by block */
309 /*-----------------------------------------------------------------*/
310 DEFSETFUNC (dominatedBy)
313 V_ARG (eBBlock *, block);
315 return bitVectBitValue (ebp->domVect, block->bbnum);
318 /*-----------------------------------------------------------------*/
319 /* addDefInExprs - adds an expression into the inexpressions */
320 /*-----------------------------------------------------------------*/
321 DEFSETFUNC (addDefInExprs)
324 V_ARG (cseDef *, cdp);
325 V_ARG (eBBlock **, ebbs);
328 addSetHead (&ebp->inExprs, cdp);
329 cseBBlock (ebp, 0, ebbs, count);
333 /*-----------------------------------------------------------------*/
334 /* assignmentsToSym - for a set of blocks determine # time assigned */
335 /*-----------------------------------------------------------------*/
337 assignmentsToSym (set * sset, operand * sym)
341 set *blocks = setFromSet (sset);
343 for (ebp = setFirstItem (blocks); ebp;
344 ebp = setNextItem (blocks))
347 /* get all the definitions for this symbol
349 bitVect *defs = bitVectIntersect (ebp->ldefs, OP_DEFS (sym));
350 assigns += bitVectnBitsOn (defs);
351 setToNull ((void **) &defs);
359 /*-----------------------------------------------------------------*/
360 /* isOperandInvariant - determines if an operand is an invariant */
361 /*-----------------------------------------------------------------*/
363 isOperandInvariant (operand * op, region * theLoop, set * lInvars)
366 /* operand is an invariant if it is a */
368 /* b. that have defintions reaching loop entry */
369 /* c. that are already defined as invariant */
370 /* d. has no assignments in the loop */
373 if (IS_OP_LITERAL (op))
375 else if (IS_SYMOP (op) &&
376 OP_SYMBOL (op)->addrtaken)
378 else if (ifDefSymIs (theLoop->entry->inExprs, op))
380 else if (ifDefSymIs (lInvars, op))
382 else if (IS_SYMOP (op) &&
383 !IS_OP_GLOBAL (op) &&
384 !IS_OP_VOLATILE (op) &&
385 assignmentsToSym (theLoop->regBlocks, op) == 0)
394 /*-----------------------------------------------------------------*/
395 /* pointerAssigned - will return 1 if pointer set found */
396 /*-----------------------------------------------------------------*/
397 DEFSETFUNC (pointerAssigned)
400 V_ARG (operand *, op);
402 return ebp->hasFcall || bitVectBitValue (ebp->ptrsSet, op->key);
405 /*-----------------------------------------------------------------*/
406 /* hasNonPtrUse - returns true if operand has non pointer usage */
407 /*-----------------------------------------------------------------*/
408 DEFSETFUNC (hasNonPtrUse)
411 V_ARG (operand *, op);
412 iCode *ic = usedInRemaining (op, ebp->sch);
414 if (ic && !POINTER_SET (ic) && !POINTER_GET (ic))
421 /*-----------------------------------------------------------------*/
422 /* loopInvariants - takes loop invariants out of region */
423 /*-----------------------------------------------------------------*/
425 loopInvariants (region * theLoop, eBBlock ** ebbs, int count)
433 /* if the preHeader does not exist then do nothing */
434 /* or no exits then do nothing ( have to think about this situation */
435 if (theLoop->entry->preHeader == NULL ||
436 theLoop->exits == NULL)
439 /* we will do the elimination for those blocks */
440 /* in the loop that dominates all exits from the loop */
441 for (lBlock = setFirstItem (theLoop->regBlocks); lBlock;
442 lBlock = setNextItem (theLoop->regBlocks))
449 /* mark the dominates all exits flag */
450 domsAllExits = (applyToSet (theLoop->exits, dominatedBy, lBlock) ==
451 elementsInSet (theLoop->exits));
453 /* find out if we have a function call in this block */
454 for (ic = lBlock->sch, fCallsInBlock=0; ic; ic = ic->next) {
460 /* now we go thru the instructions of this block and */
461 /* collect those instructions with invariant operands */
462 for (ic = lBlock->sch; ic; ic = ic->next)
468 /* jwk: TODO this is only needed if the call is between
469 here and the definition, but I am too lazy to do that now */
471 /* if there are function calls in this block */
474 /* if this is a pointer get */
475 if (POINTER_GET(ic)) {
479 /* if this is an assignment from a global */
480 if (ic->op=='=' && isOperandGlobal(IC_RIGHT(ic))) {
485 if (SKIP_IC (ic) || POINTER_SET (ic) || ic->op == IFX)
488 /* if result is volatile then skip */
489 if (IC_RESULT (ic) &&
490 (isOperandVolatile (IC_RESULT (ic), TRUE) ||
491 IS_OP_PARM (IC_RESULT (ic))))
494 /* if result depends on a volatile then skip */
495 if ((IC_LEFT(ic) && isOperandVolatile(IC_LEFT(ic), TRUE)) ||
496 (IC_RIGHT(ic) && isOperandVolatile(IC_RIGHT(ic), TRUE)))
502 /* if address of then it is an invariant */
503 if (ic->op == ADDRESS_OF &&
504 IS_SYMOP (IC_LEFT (ic)) &&
505 IS_AGGREGATE (operandType (IC_LEFT (ic))))
508 /* check if left operand is an invariant */
509 if ((lin = isOperandInvariant (IC_LEFT (ic), theLoop, lInvars)))
510 /* if this is a pointer get then make sure
511 that the pointer set does not exist in
513 if (POINTER_GET (ic) &&
514 (applyToSet (theLoop->regBlocks,
515 pointerAssigned, IC_LEFT (ic))))
519 /* do the same for right */
520 rin = isOperandInvariant (IC_RIGHT (ic), theLoop, lInvars);
522 /* if this is a POINTER_GET then special case, make sure all
523 usages within the loop are POINTER_GET any other usage
524 would mean that this is not an invariant , since the pointer
525 could then be passed as a parameter */
526 if (POINTER_GET (ic) &&
527 applyToSet (theLoop->regBlocks, hasNonPtrUse, IC_LEFT (ic)))
530 /* if both the left & right are invariants : then check that */
531 /* this definition exists in the out definition of all the */
532 /* blocks, this will ensure that this is not assigned any */
533 /* other value in the loop , and not used in this block */
534 /* prior to this definition which means only this definition */
535 /* is used in this loop */
536 if (lin && rin && IC_RESULT (ic))
539 set *lSet = setFromSet (theLoop->regBlocks);
541 /* if this block does not dominate all exists */
542 /* make sure this defintion is not used anywhere else */
546 if (isOperandGlobal (IC_RESULT (ic)))
548 /* for successors for all exits */
549 for (sBlock = setFirstItem (theLoop->exits); sBlock;
550 sBlock = setNextItem (theLoop->exits))
553 for (i = 0; i < count; ebbs[i++]->visited = 0);
555 if (applyToSet (sBlock->succList, isDefAlive, ic))
559 /* we have found usage */
564 /* now make sure this is the only definition */
565 for (sBlock = setFirstItem (lSet); sBlock;
566 sBlock = setNextItem (lSet))
568 /* if this is the block make sure the definition */
569 /* reaches the end of the block */
570 if (sBlock == lBlock)
572 if (!ifDiCodeIs (sBlock->outExprs, ic))
575 else if (bitVectBitsInCommon (sBlock->defSet, OP_DEFS (IC_RESULT (ic))))
580 continue; /* another definition present in the block */
582 /* now check if it exists in the in of this block */
583 /* if not then it was killed before this instruction */
584 if (!bitVectBitValue (lBlock->inDefs, ic->key))
587 /* now we know it is a true invariant */
588 /* remove it from the insts chain & put */
589 /* in the invariant set */
590 OP_SYMBOL (IC_RESULT (ic))->isinvariant = 1;
591 remiCodeFromeBBlock (lBlock, ic);
593 /* maintain the data flow */
594 /* this means removing from definition from the */
595 /* defset of this block and adding it to the */
596 /* inexpressions of all blocks within the loop */
597 bitVectUnSetBit (lBlock->defSet, ic->key);
598 bitVectUnSetBit (lBlock->ldefs, ic->key);
599 ivar = newCseDef (IC_RESULT (ic), ic);
600 applyToSet (theLoop->regBlocks, addDefInExprs, ivar, ebbs, count);
601 addSet (&lInvars, ivar);
604 } /* for all loop blocks */
606 /* if we have some invariants then */
609 eBBlock *preHdr = theLoop->entry->preHeader;
610 iCode *icFirst = NULL, *icLast = NULL;
613 /* create an iCode chain from it */
614 for (cdp = setFirstItem (lInvars); cdp; cdp = setNextItem (lInvars))
617 /* maintain data flow .. add it to the */
618 /* ldefs defSet & outExprs of the preheader */
619 preHdr->defSet = bitVectSetBit (preHdr->defSet, cdp->diCode->key);
620 preHdr->ldefs = bitVectSetBit (preHdr->ldefs, cdp->diCode->key);
621 cdp->diCode->lineno = preHdr->ech->lineno;
622 addSetHead (&preHdr->outExprs, cdp);
626 icFirst = cdp->diCode;
629 icLast->next = cdp->diCode;
630 cdp->diCode->prev = icLast;
631 icLast = cdp->diCode;
634 icLast = cdp->diCode;
638 /* add the instruction chain to the end of the
639 preheader for this loop, preheaders will always
640 have atleast a label */
641 preHdr->ech->next = icFirst;
642 icFirst->prev = preHdr->ech;
643 preHdr->ech = icLast;
650 /*-----------------------------------------------------------------*/
651 /* addressTaken - returns true if the symbol is found in the addrof */
652 /*-----------------------------------------------------------------*/
654 addressTaken (set * sset, operand * sym)
660 for (loop = sset; loop; loop = loop->next)
666 if (isOperandEqual ((operand *) loop2->item, sym))
676 /*-----------------------------------------------------------------*/
677 /* findInduction :- returns 1 & the item if the induction is found */
678 /*-----------------------------------------------------------------*/
679 DEFSETFUNC (findInduction)
681 induction *ip = item;
682 V_ARG (operand *, sym);
683 V_ARG (induction **, ipp);
685 if (isOperandEqual (ip->sym, sym))
694 /*-----------------------------------------------------------------*/
695 /* findDefInRegion - finds the definition within the region */
696 /*-----------------------------------------------------------------*/
698 findDefInRegion (set * regBlocks, operand * defOp, eBBlock ** owner)
702 /* for all blocks in the region */
703 for (lBlock = setFirstItem (regBlocks); lBlock;
704 lBlock = setNextItem (regBlocks))
707 /* if a definition for this exists */
708 if (bitVectBitsInCommon (lBlock->defSet, OP_DEFS (defOp)))
712 /* go thru the instruction chain to find it */
713 for (ic = lBlock->sch; ic; ic = ic->next)
714 if (bitVectBitValue (OP_DEFS (defOp), ic->key))
726 /*-----------------------------------------------------------------*/
727 /* basicInduction - finds the basic induction variables in a loop */
728 /*-----------------------------------------------------------------*/
730 basicInduction (region * loopReg, eBBlock ** ebbs, int count)
735 /* i.e. all assignments of the form a := a +/- const */
736 /* for all blocks within the loop do */
737 for (lBlock = setFirstItem (loopReg->regBlocks); lBlock;
738 lBlock = setNextItem (loopReg->regBlocks))
743 /* for all instructions in the blocks do */
744 for (ic = lBlock->sch; ic; ic = ic->next)
748 unsigned long litValue;
751 eBBlock *owner = NULL;
754 /* look for assignments of the form */
755 /* symbolVar := iTempNN */
759 if (!IS_TRUE_SYMOP (IC_RESULT (ic)) &&
760 !OP_SYMBOL (IC_RESULT (ic))->isreqv)
763 if (isOperandGlobal (IC_RESULT (ic)))
766 if (!IS_ITEMP (IC_RIGHT (ic)))
769 /* if it has multiple assignments within the loop then skip */
770 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
773 /* if the address of this was taken inside the loop then continue */
774 if (addressTaken (loopReg->regBlocks, IC_RESULT (ic)))
777 /* find the definition for the result in the block */
778 if (!(dic = findDefInRegion (setFromSet (loopReg->regBlocks),
779 IC_RIGHT (ic), &owner)))
782 /* if not +/- continue */
783 if (dic->op != '+' && dic->op != '-')
786 /* make sure definition is of the form a +/- c */
787 if (!IS_OP_LITERAL (IC_LEFT (dic)) && !IS_OP_LITERAL (IC_RIGHT (dic)))
790 aSym = (IS_OP_LITERAL (IC_RIGHT (dic)) ?
791 (litValue = (unsigned long) operandLitValue (IC_RIGHT (dic)), IC_LEFT (dic)) :
792 (litValue = (unsigned long) operandLitValue (IC_LEFT (dic)), IC_RIGHT (dic)));
794 if (!isOperandEqual (IC_RESULT (ic), aSym) &&
795 !isOperandEqual (IC_RIGHT (ic), aSym))
798 /* find the definition for this and check */
799 if (!(ddic = findDefInRegion (setFromSet (loopReg->regBlocks),
806 if (!isOperandEqual (IC_RESULT (ddic), aSym) ||
807 !isOperandEqual (IC_RIGHT (ddic), IC_RESULT (ic)))
811 /* if the right hand side has more than one usage then
812 don't make it an induction (will have to think some more) */
813 if (bitVectnBitsOn (OP_USES (IC_RIGHT (ic))) > 1)
816 /* if the definition is volatile then it cannot be
817 an induction object */
818 if (isOperandVolatile (IC_RIGHT (ic), FALSE) ||
819 isOperandVolatile (IC_RESULT (ic), FALSE))
822 /* whew !! that was a lot of work to find the definition */
823 /* create an induction object */
824 indIc = newiCode ('=', NULL, IC_RESULT (ic));
825 indIc->lineno = ic->lineno;
826 IC_RESULT (indIc) = operandFromOperand (IC_RIGHT (ic));
827 IC_RESULT (indIc)->isaddr = 0;
828 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
829 ip = newInduction (IC_RIGHT (ic), dic->op, litValue, indIc, NULL);
831 /* replace the inducted variable by the iTemp */
832 replaceSymBySym (loopReg->regBlocks, IC_RESULT (ic), IC_RIGHT (ic));
834 /* if it has only one exit then remove it from here
835 and put it in the exit block */
836 nexits = elementsInSet (loopReg->exits);
839 eBBlock *exit = setFirstItem (loopReg->exits);
841 /* if it is the same block then there is no
842 need to move it about */
845 iCode *saveic = ic->prev;
847 remiCodeFromeBBlock (lBlock, ic);
848 /* clear the definition */
849 bitVectUnSetBit (lBlock->defSet, ic->key);
850 /* add it to the exit */
851 addiCodeToeBBlock (exit, ic, NULL);
852 /* set the definition bit */
853 exit->defSet = bitVectSetBit (exit->defSet, ic->key);
858 /* if the number of exits is greater than one then
859 we use another trick ; we will create an intersection
860 of succesors of the exits, then take those that are not
861 part of the loop and have dfNumber greater loop entry
862 and insert a new definition in them */
866 bitVect *loopSuccs = intersectLoopSucc (loopReg->exits, ebbs);
868 /* loopSuccs now contains intersection
869 of all the loops successors */
873 for (i = 0; i < loopSuccs->size; i++)
875 if (bitVectBitValue (loopSuccs, i))
878 eBBlock *eblock = ebbs[i];
880 /* if the successor does not belong to the loop
881 and will be executed after the loop : then
882 add a definition to the block */
883 if (!isinSet (loopReg->regBlocks, eblock) &&
884 eblock->dfnum > loopReg->entry->dfnum)
886 /* create the definition */
887 iCode *newic = newiCode ('=', NULL,
888 operandFromOperand (IC_RIGHT (ic)));
889 IC_RESULT (newic) = operandFromOperand (IC_RESULT (ic));
890 OP_DEFS (IC_RESULT (newic)) =
891 bitVectSetBit (OP_DEFS (IC_RESULT (newic)), newic->key);
892 OP_USES (IC_RIGHT (newic)) =
893 bitVectSetBit (OP_USES (IC_RIGHT (newic)), newic->key);
895 if (eblock->sch && eblock->sch->op == LABEL)
896 addiCodeToeBBlock (eblock, newic, eblock->sch->next);
898 addiCodeToeBBlock (eblock, newic, eblock->sch);
899 /* set the definition bit */
900 eblock->defSet = bitVectSetBit (eblock->defSet, ic->key);
907 addSet (&indVars, ip);
910 } /* end of all blocks for basic induction variables */
915 /*-----------------------------------------------------------------*/
916 /* loopInduction - remove induction variables from a loop */
917 /*-----------------------------------------------------------------*/
919 loopInduction (region * loopReg, eBBlock ** ebbs, int count)
922 eBBlock *lBlock, *lastBlock = NULL;
924 set *basicInd = NULL;
926 if (loopReg->entry->preHeader == NULL)
929 /* we first determine the basic Induction variables */
930 basicInd = setFromSet (indVars = basicInduction (loopReg, ebbs, count));
932 /* find other induction variables : by other we mean definitions of */
933 /* the form x := y (* | / ) <constant> .. we will move this one to */
934 /* beginning of the loop and reduce strength i.e. replace with +/- */
935 /* these expensive expressions: OH! and y must be induction too */
936 for (lBlock = setFirstItem (loopReg->regBlocks), lastBlock = lBlock;
938 lBlock = setNextItem (loopReg->regBlocks))
944 /* last block is the one with the highest block
946 if (lastBlock->bbnum < lBlock->bbnum)
949 for (ic = lBlock->sch; ic; ic = ic->next)
952 unsigned long litVal;
955 /* consider only * & / */
956 if (ic->op != '*' && ic->op != '/')
959 /* if the result has more definitions then */
960 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
963 /* check if the operands are what we want */
964 /* i.e. one of them an symbol the other a literal */
965 if (!((IS_SYMOP (IC_LEFT (ic)) && IS_OP_LITERAL (IC_RIGHT (ic))) ||
966 (IS_OP_LITERAL (IC_LEFT (ic)) && IS_SYMOP (IC_RIGHT (ic)))))
969 aSym = (IS_SYMOP (IC_LEFT (ic)) ?
970 (lr = 1, litVal = (unsigned long) operandLitValue (IC_RIGHT (ic)), IC_LEFT (ic)) :
971 (litVal = (unsigned long) operandLitValue (IC_LEFT (ic)), IC_RIGHT (ic)));
974 /* check if this is an induction variable */
975 if (!applyToSetFTrue (basicInd, findInduction, aSym, &ip))
978 /* ask port for size not worth if native instruction
979 exist for multiply & divide */
980 if (getSize (operandType (IC_LEFT (ic))) <= (unsigned long) port->support.muldiv ||
981 getSize (operandType (IC_RIGHT (ic))) <= (unsigned long) port->support.muldiv)
984 /* if this is a division then the remainder should be zero
985 for it to be inducted */
986 if (ic->op == '/' && (ip->cval % litVal))
989 /* create the iCode to be placed in the loop header */
990 /* and create the induction object */
992 /* create an instruction */
993 /* this will be put on the loop header */
994 indIc = newiCode (ic->op,
995 operandFromOperand (aSym),
996 operandFromLit (litVal));
997 indIc->lineno = ic->lineno;
998 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
999 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
1001 /* keep track of the inductions */
1002 litVal = (ic->op == '*' ? (litVal * ip->cval) :
1003 (ip->cval / litVal));
1006 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
1008 /* now change this instruction */
1012 IC_LEFT (ic) = operandFromOperand (IC_RESULT (ic));
1013 IC_RIGHT (ic) = operandFromLit (litVal);
1017 IC_RIGHT (ic) = operandFromOperand (IC_RESULT (ic));
1018 IC_LEFT (ic) = operandFromLit (litVal);
1021 /* we need somemore initialisation code */
1022 /* we subtract the litVal from itself if increment */
1025 indIc = newiCode ('-',
1026 operandFromOperand (IC_RESULT (ic)),
1027 operandFromLit (litVal));
1028 indIc->lineno = ic->lineno;
1029 IC_RESULT (indIc) = operandFromOperand (IC_RESULT (ic));
1032 newInduction (IC_RESULT (ic), ip->op, litVal, indIc, NULL));
1037 /* if we have some induction variables then */
1040 eBBlock *preHdr = loopReg->entry->preHeader;
1041 iCode *icFirst = NULL, *icLast = NULL;
1043 bitVect *indVect = NULL;
1045 /* create an iCode chain from it */
1046 for (ip = setFirstItem (indVars);
1048 ip = setNextItem (indVars))
1051 indVect = bitVectSetBit (indVect, ip->ic->key);
1052 ip->ic->lineno = preHdr->ech->lineno;
1057 icLast->next = ip->ic;
1058 ip->ic->prev = icLast;
1066 /* add the instruction chain to the end of the */
1067 /* preheader for this loop */
1068 preHdr->ech->next = icFirst;
1069 icFirst->prev = preHdr->ech;
1070 preHdr->ech = icLast;
1071 icLast->next = NULL;
1073 /* add the induction variable vector to the last
1074 block in the loop */
1075 lastBlock->isLastInLoop = 1;
1076 lastBlock->linds = bitVectUnion(lastBlock->linds,indVect);
1079 setToNull ((void **) &indVars);
1083 /*-----------------------------------------------------------------*/
1084 /* mergeRegions - will merge region with same entry point */
1085 /*-----------------------------------------------------------------*/
1086 DEFSETFUNC (mergeRegions)
1088 region *theLoop = item;
1089 V_ARG (set *, allRegion);
1092 /* if this has already been merged then do nothing */
1093 if (theLoop->merged)
1096 /* go thru all the region and check if any of them have the */
1097 /* entryPoint as the Loop */
1098 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1104 if (lp->entry == theLoop->entry)
1106 theLoop->regBlocks = unionSets (theLoop->regBlocks,
1107 lp->regBlocks, THROW_BOTH);
1115 /*-----------------------------------------------------------------*/
1116 /* ifMerged - return 1 if the merge flag is 1 */
1117 /*-----------------------------------------------------------------*/
1118 DEFSETFUNC (ifMerged)
1125 /*-----------------------------------------------------------------*/
1126 /* mergeInnerLoops - will merge into body when entry is present */
1127 /*-----------------------------------------------------------------*/
1128 DEFSETFUNC (mergeInnerLoops)
1130 region *theLoop = item;
1131 V_ARG (set *, allRegion);
1132 V_ARG (int *, maxDepth);
1135 /* check if the entry point is present in the body of any */
1136 /* loop then put the body of this loop into the outer loop */
1137 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1143 if (isinSet (lp->regBlocks, theLoop->entry))
1145 lp->containsLoops += theLoop->containsLoops + 1;
1146 if (lp->containsLoops > (*maxDepth))
1147 *maxDepth = lp->containsLoops;
1149 lp->regBlocks = unionSets (lp->regBlocks,
1150 theLoop->regBlocks, THROW_DEST);
1158 /*-----------------------------------------------------------------*/
1159 /* createLoopRegions - will detect and create a set of natural loops */
1160 /*-----------------------------------------------------------------*/
1162 createLoopRegions (eBBlock ** ebbs, int count)
1164 set *allRegion = NULL; /* set of all loops */
1165 hTab *orderedLoops = NULL;
1170 /* get all the back edges in the graph */
1171 if (!applyToSet (graphEdges, backEdges, &bEdges))
1172 return 0; /* found no loops */
1174 /* for each of these back edges get the blocks that */
1175 /* constitute the loops */
1176 applyToSet (bEdges, createLoop, &allRegion, ebbs,count);
1178 /* now we will create regions from these loops */
1179 /* loops with the same entry points are considered to be the */
1180 /* same loop & they are merged. If the entry point of a loop */
1181 /* is found in the body of another loop then , all the blocks */
1182 /* in that loop are added to the loops containing the header */
1183 applyToSet (allRegion, mergeRegions, allRegion);
1185 /* delete those already merged */
1186 deleteItemIf (&allRegion, ifMerged);
1188 applyToSet (allRegion, mergeInnerLoops, allRegion, &maxDepth);
1190 /* now create all the exits .. also */
1191 /* create an ordered set of loops */
1192 /* i.e. we process loops in the inner to outer order */
1193 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1195 applyToSet (lp->regBlocks, addToExitsMarkDepth,
1196 lp->regBlocks, &lp->exits,
1197 (maxDepth - lp->containsLoops), lp);
1199 hTabAddItem (&orderedLoops, lp->containsLoops, lp);
1202 return orderedLoops;
1205 /*-----------------------------------------------------------------*/
1206 /* loopOptimizations - identify region & remove invariants & ind */
1207 /*-----------------------------------------------------------------*/
1209 loopOptimizations (hTab * orderedLoops, eBBlock ** ebbs, int count)
1215 /* if no loop optimizations requested */
1216 if (!optimize.loopInvariant &&
1217 !optimize.loopInduction)
1220 /* now we process the loops inner to outer order */
1221 /* this is essential to maintain data flow information */
1222 /* the other choice is an ugly iteration for the depth */
1223 /* of the loops would hate that */
1224 for (lp = hTabFirstItem (orderedLoops, &k); lp;
1225 lp = hTabNextItem (orderedLoops, &k))
1228 if (optimize.loopInvariant)
1229 change += loopInvariants (lp, ebbs, count);
1231 if (optimize.loopInduction)
1232 change += loopInduction (lp, ebbs, count);