1 /*-------------------------------------------------------------------------
3 SDCCdflow.c - source file for data flow analysis and other utility
4 routines related to data flow.
6 Written By - Sandeep Dutta . sandeep.dutta@usa.net (1998)
8 This program is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by the
10 Free Software Foundation; either version 2, or (at your option) any
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22 In other words, you are welcome to use, share and improve this program.
23 You are forbidden to forbid anyone else to use, share and improve
24 what you give them. Help stamp out software-hoarding!
25 -------------------------------------------------------------------------*/
29 /*-----------------------------------------------------------------*/
30 /* ifKilledInBlock - will return 1 if the symbol is redefined in B */
31 /*-----------------------------------------------------------------*/
32 DEFSETFUNC (ifKilledInBlock)
35 V_ARG (eBBlock *, src);
38 /* if this is a global variable and this block
39 has a function call then delete it */
40 if (isOperandGlobal (cdp->sym) && src->hasFcall)
43 /* if this is pointer get then it will be killed
44 if there is a pointer set for the same pointer
46 if (POINTER_GET (cdp->diCode) &&
47 bitVectBitValue (src->ptrsSet,
48 IC_LEFT (cdp->diCode)->key))
51 /* if assignment to iTmep then if right is defined
52 elsewhere kill this one */
53 if (ASSIGNMENT (cdp->diCode) &&
54 !POINTER_SET (cdp->diCode) &&
55 IS_ITEMP (IC_RESULT (cdp->diCode)) &&
56 IS_SYMOP (IC_RIGHT (cdp->diCode)) &&
57 bitVectBitsInCommon (src->outDefs, OP_DEFS (IC_RIGHT (cdp->diCode))))
60 /* if we find it in the defSet of this block */
61 if (bitVectBitsInCommon (src->defSet, OP_DEFS (cdp->sym)))
64 /* if in the outdef we find a definition other than this one */
65 /* to do this we make a copy of the out definitions and turn */
66 /* this one off then check if there are other definitions */
67 bitVectUnSetBit (outs = bitVectCopy (src->outDefs),
69 if (bitVectBitsInCommon (outs, OP_DEFS (cdp->sym)))
71 setToNull ((void *) &outs);
75 setToNull ((void *) &outs);
77 /* if the operands of this one was changed in the block */
80 ((IS_SYMOP (IC_LEFT (cdp->diCode)) &&
81 bitVectBitsInCommon (src->defSet, OP_DEFS (IC_LEFT (cdp->diCode)))) ||
82 (IS_SYMOP (IC_RIGHT (cdp->diCode)) &&
83 bitVectBitsInCommon (src->defSet, OP_DEFS (IC_RIGHT (cdp->diCode))))))
89 /*-----------------------------------------------------------------*/
90 /* mergeInExprs - copy the in expression if it dominates */
91 /*-----------------------------------------------------------------*/
92 DEFSETFUNC (mergeInExprs)
95 V_ARG (eBBlock *, dest);
96 V_ARG (int *, firstTime);
98 /* if in the dominator list then */
99 if (bitVectBitValue (dest->domVect, ebp->bbnum) && dest != ebp)
101 /* if already present then intersect */
102 if (!dest->inExprs && *firstTime)
104 dest->inExprs = setFromSet (ebp->outExprs);
105 /* copy the pointer set from the dominator */
106 dest->inPtrsSet = bitVectCopy (ebp->ptrsSet);
107 dest->ndompset = bitVectCopy (ebp->ndompset);
111 dest->inExprs = intersectSets (dest->inExprs,
114 dest->inPtrsSet = bitVectUnion (dest->inPtrsSet, ebp->ptrsSet);
115 dest->ndompset = bitVectUnion (dest->ndompset, ebp->ndompset);
122 /* cseBBlock does a much more thorough analysis than */
123 /* ifKilledInBlock. Anything that is listed in inExprs */
124 /* but not in outExprs must have been killed somehow. */
125 for (expr=setFirstItem(ebp->inExprs); expr; expr=setNextItem(ebp->inExprs))
126 if (!isinSet(ebp->outExprs, expr))
127 deleteSetItem (&dest->inExprs, expr);
129 /* delete only if killed in this block */
130 deleteItemIf (&dest->inExprs, ifKilledInBlock, ebp);
131 /* union the ndompset with pointers set in this block */
132 dest->ndompset = bitVectUnion (dest->ndompset, ebp->ptrsSet);
140 /*-----------------------------------------------------------------*/
141 /* mergeInDefs - merge in incoming definitions */
142 /*-----------------------------------------------------------------*/
143 DEFSETFUNC (mergeInDefs)
146 V_ARG (eBBlock *, dest);
147 V_ARG (int *, firstTime);
149 /* the in definition is the union of the out */
150 /* of all blocks that come to this block */
151 if (!dest->inDefs && *firstTime)
152 dest->inDefs = bitVectCopy (ebp->outDefs);
154 dest->inDefs = bitVectUnion (dest->inDefs,
164 /*-----------------------------------------------------------------*/
165 /* computeDataFlow - does computations for data flow accross blocks */
166 /*-----------------------------------------------------------------*/
168 computeDataFlow (eBBlock ** ebbs, int count)
179 for (i = 0; i < count; i++)
183 set *oldOutExprs = NULL;
184 bitVect *oldOutDefs = NULL;
188 /* if this is the entry block then continue */
189 /* since entry block can never have any inExprs */
193 /* get blocks that can come to this block */
194 pred = edgesTo (ebbs[i]);
196 /* make a copy of the outExpressions or outDefs : to be */
197 /* used for iteration */
198 if (optimize.global_cse)
199 oldOutExprs = setFromSet (ebbs[i]->outExprs);
201 oldOutDefs = bitVectCopy (ebbs[i]->outDefs);
202 setToNull ((void *) &ebbs[i]->inDefs);
204 /* indefitions are easy just merge them by union */
205 /* these are the definitions that can possibly */
206 /* reach this block */
208 applyToSet (pred, mergeInDefs, ebbs[i], &firstTime);
210 /* if none of the edges coming to this block */
211 /* dominate this block then add the immediate dominator */
212 /* of this block to the list of predecessors */
213 for (pBlock = setFirstItem (pred); pBlock;
214 pBlock = setNextItem (pred))
216 if (bitVectBitValue (ebbs[i]->domVect, pBlock->bbnum))
220 /* get the immediate dominator and put it there */
223 eBBlock *idom = immedDom (ebbs, ebbs[i]);
225 addSetHead (&pred, idom);
228 /* figure out the incoming expressions */
229 /* this is a little more complex */
230 setToNull ((void *) &ebbs[i]->inExprs);
231 if (optimize.global_cse)
234 applyToSet (pred, mergeInExprs, ebbs[i], &firstTime);
236 setToNull ((void *) &pred);
238 /* do cse with computeOnly flag set to TRUE */
239 /* this by far the quickest way of computing */
240 cseBBlock (ebbs[i], TRUE, ebbs, count);
242 /* if it change we will need to iterate */
243 if (optimize.global_cse)
244 change += !isSetsEqualWith (ebbs[i]->outExprs, oldOutExprs, isCseDefEqual);
246 change += !bitVectEqual (ebbs[i]->outDefs, oldOutDefs);
249 if (!change) /* iterate till no change */
256 /*-----------------------------------------------------------------*/
257 /* usedBetweenPoints - used between start & end */
258 /*-----------------------------------------------------------------*/
260 usedBetweenPoints (operand * op, iCode * start, iCode * end)
264 for (; lic != end; lic = lic->next)
267 /* if the operand is a parameter */
268 /* then check for calls and return */
269 /* true if there is a call */
274 if (lic->op == CALL) {
275 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type);
277 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type->next);
279 if (isParameterToCall (args, op))
286 /* if ifx then check the condition */
287 if (lic->op == IFX &&
288 IC_COND (lic)->key == op->key)
291 if (lic->op == JUMPTABLE &&
292 IC_JTCOND (lic)->key == op->key)
295 if (IC_RIGHT (lic) &&
296 IC_RIGHT (lic)->key == op->key)
300 IC_LEFT (lic)->key == op->key)
303 /* for a pointer assignment usage */
304 if (POINTER_SET (lic) &&
305 op->key == IC_RESULT (lic)->key)
307 else if (IC_RESULT (lic) && op->key == IC_RESULT (lic)->key)
316 /*-----------------------------------------------------------------*/
317 /* usedInRemaining - returns point of usage for an operand if found */
318 /*-----------------------------------------------------------------*/
320 usedInRemaining (operand * op, iCode * ic)
327 for (; lic; lic = lic->next)
330 /* if the operand is a parameter */
331 /* then check for calls and return */
332 /* true if there is a call */
333 /* if this is a global variable then
335 if (lic->op == CALL || lic->op == PCALL)
338 if (lic->op == CALL) {
339 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type);
341 args=FUNC_ARGS(operandType(IC_LEFT(lic))->next);
344 isParameterToCall (args, op)) ||
345 isOperandGlobal (op))
349 if (ic->op == SEND &&
350 isOperandEqual (IC_LEFT (lic), op))
356 /* if ifx then check the condition */
357 if (lic->op == IFX &&
358 isOperandEqual (IC_COND (lic), op))
361 if (lic->op == JUMPTABLE &&
362 isOperandEqual (IC_JTCOND (lic), op))
365 if (IC_RIGHT (lic) &&
366 isOperandEqual (IC_RIGHT (lic), op))
370 isOperandEqual (IC_LEFT (lic), op))
373 /* for a pointer assignment usage */
374 if (POINTER_SET (lic) &&
375 isOperandEqual (op, IC_RESULT (lic)))
377 else if (IC_RESULT (lic) && isOperandEqual (IC_RESULT (lic), op))
386 /*-----------------------------------------------------------------*/
387 /* isDefAlive - will return true if definiton reaches a block & used */
388 /*-----------------------------------------------------------------*/
389 DEFSETFUNC (isDefAlive)
392 V_ARG (iCode *, diCode);
399 /* if this definition is used in the block */
400 if (bitVectBitValue (ebp->usesDefs, diCode->key))
403 return applyToSet (ebp->succList, isDefAlive, diCode);