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);
382 return ebp->hasFcall || bitVectBitValue (ebp->ptrsSet, op->key);
385 /*-----------------------------------------------------------------*/
386 /* hasNonPtrUse - returns true if operand has non pointer usage */
387 /*-----------------------------------------------------------------*/
388 DEFSETFUNC (hasNonPtrUse)
391 V_ARG (operand *, op);
392 iCode *ic = usedInRemaining (op, ebp->sch);
394 if (ic && !POINTER_SET (ic) && !POINTER_GET (ic))
401 /*-----------------------------------------------------------------*/
402 /* loopInvariants - takes loop invariants out of region */
403 /*-----------------------------------------------------------------*/
405 loopInvariants (region * theLoop, eBBlock ** ebbs, int count)
413 /* if the preHeader does not exist then do nothing */
414 /* or no exits then do nothing ( have to think about this situation */
415 if (theLoop->entry->preHeader == NULL ||
416 theLoop->exits == NULL)
419 /* we will do the elimination for those blocks */
420 /* in the loop that dominates all exits from the loop */
421 for (lBlock = setFirstItem (theLoop->regBlocks); lBlock;
422 lBlock = setNextItem (theLoop->regBlocks))
429 /* mark the dominates all exits flag */
430 domsAllExits = (applyToSet (theLoop->exits, dominatedBy, lBlock) ==
431 elementsInSet (theLoop->exits));
433 /* find out if we have a function call in this block */
434 for (ic = lBlock->sch, fCallsInBlock=0; ic; ic = ic->next) {
440 /* now we go thru the instructions of this block and */
441 /* collect those instructions with invariant operands */
442 for (ic = lBlock->sch; ic; ic = ic->next)
448 /* TODO this is only needed if the call is between
449 here and the definition, but I am too lazy to do that now */
451 /* if there are function calls in this block */
454 /* if this is a pointer get */
455 if (POINTER_GET(ic)) {
459 /* if this is an assignment from a global */
460 if (ic->op=='=' && isOperandGlobal(IC_RIGHT(ic))) {
465 if (SKIP_IC (ic) || POINTER_SET (ic) || ic->op == IFX)
468 /* iTemp assignment from a literal may be invariant, but it
469 will needlessly increase register pressure if the
470 iCode(s) that use this iTemp are not also invariant */
471 if (ic->op=='=' && IS_ITEMP (IC_RESULT (ic))
472 && IS_OP_LITERAL (IC_RIGHT (ic)))
475 /* if result is volatile then skip */
476 if (IC_RESULT (ic) &&
477 (isOperandVolatile (IC_RESULT (ic), TRUE) ||
478 IS_OP_PARM (IC_RESULT (ic))))
481 /* if result depends on a volatile then skip */
482 if ((IC_LEFT(ic) && isOperandVolatile(IC_LEFT(ic), TRUE)) ||
483 (IC_RIGHT(ic) && isOperandVolatile(IC_RIGHT(ic), TRUE)))
489 /* if address of then it is an invariant */
490 if (ic->op == ADDRESS_OF &&
491 IS_SYMOP (IC_LEFT (ic)) &&
492 IS_AGGREGATE (operandType (IC_LEFT (ic))))
495 /* check if left operand is an invariant */
496 if ((lin = isOperandInvariant (IC_LEFT (ic), theLoop, lInvars)))
497 /* if this is a pointer get then make sure
498 that the pointer set does not exist in
500 if (POINTER_GET (ic) &&
501 (applyToSet (theLoop->regBlocks,
502 pointerAssigned, IC_LEFT (ic))))
506 /* do the same for right */
507 rin = isOperandInvariant (IC_RIGHT (ic), theLoop, lInvars);
509 /* if this is a POINTER_GET then special case, make sure all
510 usages within the loop are POINTER_GET any other usage
511 would mean that this is not an invariant , since the pointer
512 could then be passed as a parameter */
513 if (POINTER_GET (ic) &&
514 applyToSet (theLoop->regBlocks, hasNonPtrUse, IC_LEFT (ic)))
518 /* if both the left & right are invariants : then check that */
519 /* this definition exists in the out definition of all the */
520 /* blocks, this will ensure that this is not assigned any */
521 /* other value in the loop , and not used in this block */
522 /* prior to this definition which means only this definition */
523 /* is used in this loop */
524 if (lin && rin && IC_RESULT (ic))
527 set *lSet = setFromSet (theLoop->regBlocks);
529 /* if this block does not dominate all exits */
530 /* make sure this defintion is not used anywhere else */
534 if (isOperandGlobal (IC_RESULT (ic)))
536 /* for successors for all exits */
537 for (sBlock = setFirstItem (theLoop->exits); sBlock;
538 sBlock = setNextItem (theLoop->exits))
541 for (i = 0; i < count; ebbs[i++]->visited = 0);
543 if (applyToSet (sBlock->succList, isDefAlive, ic))
547 /* we have found usage */
552 /* now make sure this is the only definition */
553 for (sBlock = setFirstItem (lSet); sBlock;
554 sBlock = setNextItem (lSet))
556 /* if this is the block make sure the definition */
557 /* reaches the end of the block */
558 if (sBlock == lBlock)
560 if (!ifDiCodeIs (sBlock->outExprs, ic))
563 else if (bitVectBitsInCommon (sBlock->defSet, OP_DEFS (IC_RESULT (ic))))
568 continue; /* another definition present in the block */
570 /* now check if it exists in the in of this block */
571 /* if not then it was killed before this instruction */
572 if (!bitVectBitValue (lBlock->inDefs, ic->key))
575 /* now we know it is a true invariant */
576 /* remove it from the insts chain & put */
577 /* in the invariant set */
579 OP_SYMBOL (IC_RESULT (ic))->isinvariant = 1;
580 SPIL_LOC (IC_RESULT (ic)) = NULL;
581 remiCodeFromeBBlock (lBlock, ic);
583 /* maintain the data flow */
584 /* this means removing from definition from the */
585 /* defset of this block and adding it to the */
586 /* inexpressions of all blocks within the loop */
587 bitVectUnSetBit (lBlock->defSet, ic->key);
588 bitVectUnSetBit (lBlock->ldefs, ic->key);
589 ivar = newCseDef (IC_RESULT (ic), ic);
590 applyToSet (theLoop->regBlocks, addDefInExprs, ivar, ebbs, count);
591 addSet (&lInvars, ivar);
594 } /* for all loop blocks */
596 /* if we have some invariants then */
599 eBBlock *preHdr = theLoop->entry->preHeader;
600 iCode *icFirst = NULL, *icLast = NULL;
603 /* create an iCode chain from it */
604 for (cdp = setFirstItem (lInvars); cdp; cdp = setNextItem (lInvars))
607 /* maintain data flow .. add it to the */
608 /* ldefs defSet & outExprs of the preheader */
609 preHdr->defSet = bitVectSetBit (preHdr->defSet, cdp->diCode->key);
610 preHdr->ldefs = bitVectSetBit (preHdr->ldefs, cdp->diCode->key);
611 cdp->diCode->lineno = preHdr->ech->lineno;
612 addSetHead (&preHdr->outExprs, cdp);
616 icFirst = cdp->diCode;
619 icLast->next = cdp->diCode;
620 cdp->diCode->prev = icLast;
621 icLast = cdp->diCode;
624 icLast = cdp->diCode;
628 /* add the instruction chain to the end of the
629 preheader for this loop, preheaders will always
630 have atleast a label */
631 preHdr->ech->next = icFirst;
632 icFirst->prev = preHdr->ech;
633 preHdr->ech = icLast;
640 /*-----------------------------------------------------------------*/
641 /* addressTaken - returns true if the symbol is found in the addrof */
642 /*-----------------------------------------------------------------*/
644 addressTaken (set * sset, operand * sym)
650 for (loop = sset; loop; loop = loop->next)
656 if (isOperandEqual ((operand *) loop2->item, sym))
666 /*-----------------------------------------------------------------*/
667 /* findInduction :- returns 1 & the item if the induction is found */
668 /*-----------------------------------------------------------------*/
669 DEFSETFUNC (findInduction)
671 induction *ip = item;
672 V_ARG (operand *, sym);
673 V_ARG (induction **, ipp);
675 if (isOperandEqual (ip->sym, sym))
684 /*-----------------------------------------------------------------*/
685 /* findDefInRegion - finds the definition within the region */
686 /*-----------------------------------------------------------------*/
688 findDefInRegion (set * regBlocks, operand * defOp, eBBlock ** owner)
692 /* for all blocks in the region */
693 for (lBlock = setFirstItem (regBlocks); lBlock;
694 lBlock = setNextItem (regBlocks))
697 /* if a definition for this exists */
698 if (bitVectBitsInCommon (lBlock->defSet, OP_DEFS (defOp)))
702 /* go thru the instruction chain to find it */
703 for (ic = lBlock->sch; ic; ic = ic->next)
704 if (bitVectBitValue (OP_DEFS (defOp), ic->key))
716 /*-----------------------------------------------------------------*/
717 /* basicInduction - finds the basic induction variables in a loop */
718 /*-----------------------------------------------------------------*/
720 basicInduction (region * loopReg, eBBlock ** ebbs, int count)
725 /* i.e. all assignments of the form a := a +/- const */
726 /* for all blocks within the loop do */
727 for (lBlock = setFirstItem (loopReg->regBlocks); lBlock;
728 lBlock = setNextItem (loopReg->regBlocks))
733 /* for all instructions in the blocks do */
734 for (ic = lBlock->sch; ic; ic = ic->next)
738 unsigned long litValue;
741 eBBlock *owner = NULL;
744 /* look for assignments of the form */
745 /* symbolVar := iTempNN */
749 if (!IS_TRUE_SYMOP (IC_RESULT (ic)) &&
750 !OP_SYMBOL (IC_RESULT (ic))->isreqv)
753 if (isOperandGlobal (IC_RESULT (ic)))
756 if (!IS_ITEMP (IC_RIGHT (ic)))
759 /* if it has multiple assignments within the loop then skip */
760 if (assignmentsToSym (loopReg->regBlocks, IC_RESULT (ic)) > 1)
763 /* if the address of this was taken inside the loop then continue */
764 if (addressTaken (loopReg->regBlocks, IC_RESULT (ic)))
767 /* find the definition for the result in the block */
768 if (!(dic = findDefInRegion (setFromSet (loopReg->regBlocks),
769 IC_RIGHT (ic), &owner)))
772 /* if not +/- continue */
773 if (dic->op != '+' && dic->op != '-')
776 /* make sure definition is of the form a +/- c */
777 if (!IS_OP_LITERAL (IC_LEFT (dic)) && !IS_OP_LITERAL (IC_RIGHT (dic)))
780 aSym = (IS_OP_LITERAL (IC_RIGHT (dic)) ?
781 (litValue = (unsigned long) operandLitValue (IC_RIGHT (dic)), IC_LEFT (dic)) :
782 (litValue = (unsigned long) operandLitValue (IC_LEFT (dic)), IC_RIGHT (dic)));
784 if (!isOperandEqual (IC_RESULT (ic), aSym) &&
785 !isOperandEqual (IC_RIGHT (ic), aSym))
788 /* find the definition for this and check */
789 if (!(ddic = findDefInRegion (setFromSet (loopReg->regBlocks),
796 if (!isOperandEqual (IC_RESULT (ddic), aSym) ||
797 !isOperandEqual (IC_RIGHT (ddic), IC_RESULT (ic)))
801 /* if the right hand side has more than one usage then
802 don't make it an induction (will have to think some more) */
803 if (bitVectnBitsOn (OP_USES (IC_RIGHT (ic))) > 1)
806 /* if the definition is volatile then it cannot be
807 an induction object */
808 if (isOperandVolatile (IC_RIGHT (ic), FALSE) ||
809 isOperandVolatile (IC_RESULT (ic), FALSE))
812 /* whew !! that was a lot of work to find the definition */
813 /* create an induction object */
814 indIc = newiCode ('=', NULL, IC_RESULT (ic));
815 indIc->lineno = ic->lineno;
816 IC_RESULT (indIc) = operandFromOperand (IC_RIGHT (ic));
817 IC_RESULT (indIc)->isaddr = 0;
818 OP_SYMBOL (IC_RESULT (indIc))->isind = 1;
819 ip = newInduction (IC_RIGHT (ic), dic->op, litValue, indIc, NULL);
821 /* replace the inducted variable by the iTemp */
822 replaceSymBySym (loopReg->regBlocks, IC_RESULT (ic), IC_RIGHT (ic));
824 /* if it has only one exit then remove it from here
825 and put it in the exit block */
826 nexits = elementsInSet (loopReg->exits);
829 eBBlock *exit = setFirstItem (loopReg->exits);
830 /* if it is the same block then there is no
831 need to move it about */
834 iCode *saveic = ic->prev;
836 remiCodeFromeBBlock (lBlock, ic);
837 /* clear the definition */
838 bitVectUnSetBit (lBlock->defSet, ic->key);
839 /* add it to the exit */
840 addiCodeToeBBlock (exit, ic, NULL);
841 /* set the definition bit */
842 exit->defSet = bitVectSetBit (exit->defSet, ic->key);
847 /* if the number of exits is greater than one then
848 we use another trick ; we will create an intersection
849 of succesors of the exits, then take those that are not
850 part of the loop and have dfNumber greater loop entry
851 and insert a new definition in them */
855 bitVect *loopSuccs = intersectLoopSucc (loopReg->exits, ebbs);
857 /* loopSuccs now contains intersection
858 of all the loops successors */
862 for (i = 0; i < loopSuccs->size; i++)
864 if (bitVectBitValue (loopSuccs, i))
867 eBBlock *eblock = NULL;
870 /* Need to search for bbnum == i since ebbs is */
871 /* sorted by dfnum; a direct index won't do. */
872 for (j=0; j<count; j++)
873 if (ebbs[j]->bbnum == 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_DEST);
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);
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);
1191 /* now create all the exits .. also */
1192 /* create an ordered set of loops */
1193 /* i.e. we process loops in the inner to outer order */
1194 for (lp = setFirstItem (allRegion); lp; lp = setNextItem (allRegion))
1196 applyToSet (lp->regBlocks, addToExitsMarkDepth,
1197 lp->regBlocks, &lp->exits,
1198 (maxDepth - lp->containsLoops), lp);
1200 hTabAddItem (&orderedLoops, lp->containsLoops, lp);
1203 return orderedLoops;
1206 /*-----------------------------------------------------------------*/
1207 /* loopOptimizations - identify region & remove invariants & ind */
1208 /*-----------------------------------------------------------------*/
1210 loopOptimizations (hTab * orderedLoops, eBBlock ** ebbs, int count)
1216 /* if no loop optimizations requested */
1217 if (!optimize.loopInvariant &&
1218 !optimize.loopInduction)
1221 /* now we process the loops inner to outer order */
1222 /* this is essential to maintain data flow information */
1223 /* the other choice is an ugly iteration for the depth */
1224 /* of the loops would hate that */
1225 for (lp = hTabFirstItem (orderedLoops, &k); lp;
1226 lp = hTabNextItem (orderedLoops, &k))
1229 if (optimize.loopInvariant)
1230 change += loopInvariants (lp, ebbs, count);
1232 if (optimize.loopInduction)
1233 change += loopInduction (lp, ebbs, count);