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)
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))) {
70 setToNull((void **) &outs);
74 setToNull((void **) &outs);
76 /* if the operands of this one was changed in the block */
79 ( (IS_SYMOP(IC_LEFT(cdp->diCode)) &&
80 bitVectBitsInCommon (src->defSet,OP_DEFS(IC_LEFT(cdp->diCode)))) ||
81 (IS_SYMOP(IC_RIGHT(cdp->diCode)) &&
82 bitVectBitsInCommon (src->defSet,OP_DEFS(IC_RIGHT(cdp->diCode)))) ))
88 /*-----------------------------------------------------------------*/
89 /* mergeInExprs - copy the in expression if it dominates */
90 /*-----------------------------------------------------------------*/
91 DEFSETFUNC(mergeInExprs)
94 V_ARG(eBBlock *,dest);
95 V_ARG(int *,firstTime);
97 /* if in the dominator list then */
98 if (bitVectBitValue(dest->domVect,ebp->bbnum) && dest != ebp) {
99 /* if already present then intersect */
100 if (!dest->inExprs && *firstTime) {
101 dest->inExprs = setFromSet(ebp->outExprs);
102 /* copy the pointer set from the dominator */
103 dest->inPtrsSet = bitVectCopy(ebp->ptrsSet);
104 dest->ndompset = bitVectCopy(ebp->ndompset);
107 dest->inExprs = intersectSets (dest->inExprs,
110 dest->inPtrsSet = bitVectUnion(dest->inPtrsSet,ebp->ptrsSet);
111 dest->ndompset = bitVectUnion(dest->ndompset,ebp->ndompset);
115 /* delete only if killed in this block */
116 deleteItemIf (&dest->inExprs,ifKilledInBlock, ebp);
117 /* union the ndompset with pointers set in this block*/
118 dest->ndompset = bitVectUnion(dest->ndompset,ebp->ptrsSet);
126 /*-----------------------------------------------------------------*/
127 /* mergeInDefs - merge in incoming definitions */
128 /*-----------------------------------------------------------------*/
129 DEFSETFUNC(mergeInDefs)
131 eBBlock *ebp = item ;
132 V_ARG(eBBlock *,dest);
133 V_ARG(int *,firstTime);
135 /* the in definition is the union of the out */
136 /* of all blocks that come to this block */
137 if (!dest->inDefs && *firstTime)
138 dest->inDefs = bitVectCopy (ebp->outDefs);
140 dest->inDefs = bitVectUnion (dest->inDefs,
149 /*-----------------------------------------------------------------*/
150 /* computeDataFlow - does computations for data flow accross blocks*/
151 /*-----------------------------------------------------------------*/
152 void computeDataFlow (eBBlock **ebbs, int count)
162 for ( i = 0 ; i < count ; i++ ) {
169 /* if this is the entry block then continue */
170 /* since entry block can never have any inExprs */
174 /* get blocks that can come to this block */
175 pred = edgesTo(ebbs[i]);
177 /* make a copy of the outExpressions : to be */
178 /* used for iteration */
179 oldOut = setFromSet(ebbs[i]->outExprs);
180 setToNull ((void **)&ebbs[i]->inDefs);
182 /* indefitions are easy just merge them by union */
183 /* these are the definitions that can possibly */
184 /* reach this block */
186 applyToSet(pred,mergeInDefs,ebbs[i],&firstTime);
189 /* if none of the edges coming to this block */
190 /* dominate this block then add the immediate dominator */
191 /* of this block to the list of predecessors */
192 for ( pBlock = setFirstItem(pred); pBlock ;
193 pBlock = setNextItem(pred)) {
194 if (bitVectBitValue(ebbs[i]->domVect,pBlock->bbnum))
198 /* get the immediate dominator and put it there */
200 eBBlock *idom = immedDom(ebbs,ebbs[i]);
202 addSetHead (&pred,idom);
205 /* figure out the incoming expressions */
206 /* this is a little more complex */
207 setToNull ((void **)&ebbs[i]->inExprs);
209 applyToSet(pred,mergeInExprs,ebbs[i],&firstTime);
211 setToNull ((void **)&pred);
213 /* do cse with computeOnly flag set to TRUE */
214 /* this by far the quickest way of computing*/
215 cseBBlock(ebbs[i],TRUE,ebbs,count);
217 /* if it change we will need to iterate */
218 change += ! isSetsEqualWith(ebbs[i]->outExprs,oldOut,isCseDefEqual);
221 if (!change) /* iterate till no change */
228 /*-----------------------------------------------------------------*/
229 /* usedBetweenPoints - used between start & end */
230 /*-----------------------------------------------------------------*/
231 int usedBetweenPoints ( operand *op, iCode *start, iCode *end )
235 for (;lic != end; lic = lic->next) {
237 /* if the operand is a parameter */
238 /* then check for calls and return */
239 /* true if there is a call */
243 if ( isParameterToCall(IC_ARGS(lic),op))
249 /* if ifx then check the condition */
250 if (lic->op == IFX &&
251 IC_COND(lic)->key == op->key )
254 if (lic->op == JUMPTABLE &&
255 IC_JTCOND(lic)->key == op->key )
259 IC_RIGHT(lic)->key == op->key )
263 IC_LEFT(lic)->key == op->key )
266 /* for a pointer assignment usage */
267 if (POINTER_SET(lic) &&
268 op->key == IC_RESULT(lic)->key )
271 if (IC_RESULT(lic) && op->key == IC_RESULT(lic)->key)
280 /*-----------------------------------------------------------------*/
281 /* usedInRemaining - returns point of usage for an operand if found*/
282 /*-----------------------------------------------------------------*/
283 iCode *usedInRemaining (operand *op, iCode *ic)
290 for (;lic; lic = lic->next) {
292 /* if the operand is a parameter */
293 /* then check for calls and return */
294 /* true if there is a call */
295 /* if this is a global variable then
297 if ( lic->op == CALL || lic->op == PCALL ) {
300 isParameterToCall(IC_ARGS(lic),op)) ||
301 isOperandGlobal (op))
305 if (ic->op == SEND &&
306 isOperandEqual (IC_LEFT(lic),op))
312 /* if ifx then check the condition */
313 if (lic->op == IFX &&
314 isOperandEqual (IC_COND(lic),op))
317 if (lic->op == JUMPTABLE &&
318 isOperandEqual (IC_JTCOND(lic),op) )
322 isOperandEqual(IC_RIGHT(lic),op))
326 isOperandEqual(IC_LEFT(lic),op) )
329 /* for a pointer assignment usage */
330 if (POINTER_SET(lic) &&
331 isOperandEqual (op,IC_RESULT(lic)))
334 if (IC_RESULT(lic) && isOperandEqual(IC_RESULT(lic),op))
343 /*-----------------------------------------------------------------*/
344 /* isDefAlive - will return true if definiton reaches a block & used */
345 /*-----------------------------------------------------------------*/
346 DEFSETFUNC(isDefAlive)
349 V_ARG(iCode *,diCode);
356 /* if this definition is used in the block */
357 if (bitVectBitValue(ebp->usesDefs,diCode->key))
360 return applyToSet(ebp->succList,isDefAlive,diCode);