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);
103 dest->inExprs = intersectSets (dest->inExprs,
106 /* copy the pointer set from the dominator */
107 dest->inPtrsSet = bitVectCopy(ebp->ptrsSet);
110 /* delete only if killed in this block */
111 deleteItemIf (&dest->inExprs,ifKilledInBlock, ebp);
118 /*-----------------------------------------------------------------*/
119 /* mergeInDefs - merge in incoming definitions */
120 /*-----------------------------------------------------------------*/
121 DEFSETFUNC(mergeInDefs)
123 eBBlock *ebp = item ;
124 V_ARG(eBBlock *,dest);
125 V_ARG(int *,firstTime);
127 /* the in definition is the union of the out */
128 /* of all blocks that come to this block */
129 if (!dest->inDefs && *firstTime)
130 dest->inDefs = bitVectCopy (ebp->outDefs);
132 dest->inDefs = bitVectUnion (dest->inDefs,
141 /*-----------------------------------------------------------------*/
142 /* computeDataFlow - does computations for data flow accross blocks*/
143 /*-----------------------------------------------------------------*/
144 void computeDataFlow (eBBlock **ebbs, int count)
154 for ( i = 0 ; i < count ; i++ ) {
161 /* if this is the entry block then continue */
162 /* since entry block can never have any inExprs */
166 /* get blocks that can come to this block */
167 pred = edgesTo(ebbs[i]);
169 /* make a copy of the outExpressions : to be */
170 /* used for iteration */
171 oldOut = setFromSet(ebbs[i]->outExprs);
172 setToNull ((void **)&ebbs[i]->inDefs);
174 /* indefitions are easy just merge them by union */
175 /* these are the definitions that can possibly */
176 /* reach this block */
178 applyToSet(pred,mergeInDefs,ebbs[i],&firstTime);
181 /* if none of the edges coming to this block */
182 /* dominate this block then add the immediate dominator */
183 /* of this block to the list of predecessors */
184 for ( pBlock = setFirstItem(pred); pBlock ;
185 pBlock = setNextItem(pred)) {
186 if (bitVectBitValue(ebbs[i]->domVect,pBlock->bbnum))
190 /* get the immediate dominator and put it there */
192 eBBlock *idom = immedDom(ebbs,ebbs[i]);
194 addSetHead (&pred,idom);
197 /* figure out the incoming expressions */
198 /* this is a little more complex */
199 setToNull ((void **)&ebbs[i]->inExprs);
201 applyToSet(pred,mergeInExprs,ebbs[i],&firstTime);
203 setToNull ((void **)&pred);
205 /* do cse with computeOnly flag set to TRUE */
206 /* this by far the quickest way of computing*/
207 cseBBlock(ebbs[i],TRUE,ebbs,count);
209 /* if it change we will need to iterate */
210 change += ! isSetsEqualWith(ebbs[i]->outExprs,oldOut,isCseDefEqual);
213 if (!change) /* iterate till no change */
220 /*-----------------------------------------------------------------*/
221 /* usedBetweenPoints - used between start & end */
222 /*-----------------------------------------------------------------*/
223 int usedBetweenPoints ( operand *op, iCode *start, iCode *end )
227 for (;lic != end; lic = lic->next) {
229 /* if the operand is a parameter */
230 /* then check for calls and return */
231 /* true if there is a call */
235 if ( isParameterToCall(IC_ARGS(lic),op))
241 /* if ifx then check the condition */
242 if (lic->op == IFX &&
243 IC_COND(lic)->key == op->key )
246 if (lic->op == JUMPTABLE &&
247 IC_JTCOND(lic)->key == op->key )
251 IC_RIGHT(lic)->key == op->key )
255 IC_LEFT(lic)->key == op->key )
258 /* for a pointer assignment usage */
259 if (POINTER_SET(lic) &&
260 op->key == IC_RESULT(lic)->key )
263 if (IC_RESULT(lic) && op->key == IC_RESULT(lic)->key)
272 /*-----------------------------------------------------------------*/
273 /* usedInRemaining - returns point of usage for an operand if found*/
274 /*-----------------------------------------------------------------*/
275 iCode *usedInRemaining (operand *op, iCode *ic)
282 for (;lic; lic = lic->next) {
284 /* if the operand is a parameter */
285 /* then check for calls and return */
286 /* true if there is a call */
287 /* if this is a global variable then
289 if ( lic->op == CALL || lic->op == PCALL ) {
292 isParameterToCall(IC_ARGS(lic),op)) ||
293 isOperandGlobal (op))
297 if (ic->op == SEND &&
298 isOperandEqual (IC_LEFT(lic),op))
304 /* if ifx then check the condition */
305 if (lic->op == IFX &&
306 isOperandEqual (IC_COND(lic),op))
309 if (lic->op == JUMPTABLE &&
310 isOperandEqual (IC_JTCOND(lic),op) )
314 isOperandEqual(IC_RIGHT(lic),op))
318 isOperandEqual(IC_LEFT(lic),op) )
321 /* for a pointer assignment usage */
322 if (POINTER_SET(lic) &&
323 isOperandEqual (op,IC_RESULT(lic)))
326 if (IC_RESULT(lic) && isOperandEqual(IC_RESULT(lic),op))
335 /*-----------------------------------------------------------------*/
336 /* isDefAlive - will return true if definiton reaches a block & used */
337 /*-----------------------------------------------------------------*/
338 DEFSETFUNC(isDefAlive)
341 V_ARG(iCode *,diCode);
348 /* if this definition is used in the block */
349 if (bitVectBitValue(ebp->usesDefs,diCode->key))
352 return applyToSet(ebp->succList,isDefAlive,diCode);