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))))))
86 /* kill if cseBBlock() found a case we missed here */
87 if (isinSetWith(src->killedExprs, cdp, isCseDefEqual))
93 /*-----------------------------------------------------------------*/
94 /* mergeInExprs - copy the in expression if it dominates */
95 /*-----------------------------------------------------------------*/
96 DEFSETFUNC (mergeInExprs)
99 V_ARG (eBBlock *, dest);
100 V_ARG (int *, firstTime);
102 dest->killedExprs = unionSets (dest->killedExprs, ebp->killedExprs, THROW_DEST);
104 /* if in the dominator list then */
105 if (bitVectBitValue (dest->domVect, ebp->bbnum) && dest != ebp)
107 /* if already present then intersect */
108 if (!dest->inExprs && *firstTime)
110 dest->inExprs = setFromSet (ebp->outExprs);
111 /* copy the pointer set from the dominator */
112 dest->inPtrsSet = bitVectCopy (ebp->ptrsSet);
113 dest->ndompset = bitVectCopy (ebp->ndompset);
117 dest->inExprs = intersectSets (dest->inExprs,
120 dest->inPtrsSet = bitVectUnion (dest->inPtrsSet, ebp->ptrsSet);
121 dest->ndompset = bitVectUnion (dest->ndompset, ebp->ndompset);
126 /* delete only if killed in this block*/
127 deleteItemIf (&dest->inExprs, ifKilledInBlock, ebp);
128 /* union the ndompset with pointers set in this block */
129 dest->ndompset = bitVectUnion (dest->ndompset, ebp->ptrsSet);
137 /*-----------------------------------------------------------------*/
138 /* mergeInDefs - merge in incoming definitions */
139 /*-----------------------------------------------------------------*/
140 DEFSETFUNC (mergeInDefs)
143 V_ARG (eBBlock *, dest);
144 V_ARG (int *, firstTime);
146 /* the in definition is the union of the out */
147 /* of all blocks that come to this block */
148 if (!dest->inDefs && *firstTime)
149 dest->inDefs = bitVectCopy (ebp->outDefs);
151 dest->inDefs = bitVectUnion (dest->inDefs,
161 /*-----------------------------------------------------------------*/
162 /* computeDataFlow - does computations for data flow accross blocks */
163 /*-----------------------------------------------------------------*/
165 computeDataFlow (eBBlock ** ebbs, int count)
170 for (i = 0; i < count; i++)
171 ebbs[i]->killedExprs = NULL;
178 for (i = 0; i < count; i++)
182 set *oldOutExprs = NULL;
183 set *oldKilledExprs = 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 and outDefs : to be */
197 /* used for iteration */
198 if (optimize.global_cse)
200 oldOutExprs = setFromSet (ebbs[i]->outExprs);
201 oldKilledExprs = setFromSet (ebbs[i]->killedExprs);
203 oldOutDefs = bitVectCopy (ebbs[i]->outDefs);
204 setToNull ((void *) &ebbs[i]->inDefs);
206 /* indefitions are easy just merge them by union */
207 /* these are the definitions that can possibly */
208 /* reach this block */
210 applyToSet (pred, mergeInDefs, ebbs[i], &firstTime);
212 /* if none of the edges coming to this block */
213 /* dominate this block then add the immediate dominator */
214 /* of this block to the list of predecessors */
215 for (pBlock = setFirstItem (pred); pBlock;
216 pBlock = setNextItem (pred))
218 if (bitVectBitValue (ebbs[i]->domVect, pBlock->bbnum))
222 /* get the immediate dominator and put it there */
225 eBBlock *idom = immedDom (ebbs, ebbs[i]);
227 addSetHead (&pred, idom);
230 /* figure out the incoming expressions */
231 /* this is a little more complex */
232 setToNull ((void *) &ebbs[i]->inExprs);
233 if (optimize.global_cse)
236 applyToSet (pred, mergeInExprs, ebbs[i], &firstTime);
238 setToNull ((void *) &pred);
240 /* do cse with computeOnly flag set to TRUE */
241 /* this by far the quickest way of computing */
242 cseBBlock (ebbs[i], TRUE, ebbs, count);
244 /* if it change we will need to iterate */
245 if (optimize.global_cse)
247 change += !isSetsEqualWith (ebbs[i]->outExprs, oldOutExprs, isCseDefEqual);
248 change += !isSetsEqualWith (ebbs[i]->killedExprs, oldKilledExprs, isCseDefEqual);
250 change += !bitVectEqual (ebbs[i]->outDefs, oldOutDefs);
253 if (!change) /* iterate till no change */
260 /*-----------------------------------------------------------------*/
261 /* usedBetweenPoints - used between start & end */
262 /*-----------------------------------------------------------------*/
264 usedBetweenPoints (operand * op, iCode * start, iCode * end)
268 for (; lic != end; lic = lic->next)
271 /* if the operand is a parameter */
272 /* then check for calls and return */
273 /* true if there is a call */
278 if (lic->op == CALL) {
279 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type);
281 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type->next);
283 if (isParameterToCall (args, op))
290 /* if ifx then check the condition */
291 if (lic->op == IFX &&
292 IC_COND (lic)->key == op->key)
295 if (lic->op == JUMPTABLE &&
296 IC_JTCOND (lic)->key == op->key)
299 if (IC_RIGHT (lic) &&
300 IC_RIGHT (lic)->key == op->key)
304 IC_LEFT (lic)->key == op->key)
307 /* for a pointer assignment usage */
308 if (POINTER_SET (lic) &&
309 op->key == IC_RESULT (lic)->key)
311 else if (IC_RESULT (lic) && op->key == IC_RESULT (lic)->key)
320 /*-----------------------------------------------------------------*/
321 /* usedInRemaining - returns point of usage for an operand if found */
322 /*-----------------------------------------------------------------*/
324 usedInRemaining (operand * op, iCode * ic)
331 for (; lic; lic = lic->next)
334 /* if the operand is a parameter */
335 /* then check for calls and return */
336 /* true if there is a call */
337 /* if this is a global variable then
339 if (lic->op == CALL || lic->op == PCALL)
342 if (lic->op == CALL) {
343 args=FUNC_ARGS(OP_SYMBOL(IC_LEFT(lic))->type);
345 args=FUNC_ARGS(operandType(IC_LEFT(lic))->next);
348 isParameterToCall (args, op)) ||
349 isOperandGlobal (op))
353 if (ic->op == SEND &&
354 isOperandEqual (IC_LEFT (lic), op))
360 /* if ifx then check the condition */
361 if (lic->op == IFX &&
362 isOperandEqual (IC_COND (lic), op))
365 if (lic->op == JUMPTABLE &&
366 isOperandEqual (IC_JTCOND (lic), op))
369 if (IC_RIGHT (lic) &&
370 isOperandEqual (IC_RIGHT (lic), op))
374 isOperandEqual (IC_LEFT (lic), op))
377 /* for a pointer assignment usage */
378 if (POINTER_SET (lic) &&
379 isOperandEqual (op, IC_RESULT (lic)))
381 else if (IC_RESULT (lic) && isOperandEqual (IC_RESULT (lic), op))
390 /*-----------------------------------------------------------------*/
391 /* isDefAlive - will return true if definiton reaches a block & used */
392 /*-----------------------------------------------------------------*/
393 DEFSETFUNC (isDefAlive)
396 V_ARG (iCode *, diCode);
403 /* if this definition is used in the block */
404 if (bitVectBitValue (ebp->usesDefs, diCode->key))
407 return applyToSet (ebp->succList, isDefAlive, diCode);