Added function computeClash - also moved NULLING out of spillocation

to computeClash since this is more accurate

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@1541 4a8a32a2-be11-0410-ad9d-d568d2c75423

diff --git a/src/SDCClrange.c b/src/SDCClrange.c
index 75242d192e6a1ca0b0c54a5cb09d65509ec7b6f3..9207338affba3d2cc6a3a54d087461471bf41472 100644 (file)
--- a/src/SDCClrange.c
+++ b/src/SDCClrange.c
@@ -545,44 +545,86 @@ markLiveRanges (eBBlock * ebp, eBBlock ** ebbs, int count)
 void 
 rlivePoint (eBBlock ** ebbs, int count)
 {
-       int i;
-
-       /* for all blocks do */
-       for (i = 0; i < count; i++) {
-               iCode *ic;
-
-               /* for all instruction in the block do */
-               for (ic = ebbs[i]->sch; ic; ic = ic->next) {
-                       symbol *lrange;
-                       int k;
-
-                       ic->rlive = newBitVect (operandKey);
-                       /* for all symbols in the liverange table */
-                       for (lrange = hTabFirstItem (liveRanges, &k); lrange;
-                            lrange = hTabNextItem (liveRanges, &k)) {
-
-                               /* if it is live then add the lrange to ic->rlive */
-                               if (lrange->liveFrom <= ic->seq &&
-                                   lrange->liveTo >= ic->seq) {
-                                       lrange->isLiveFcall |= (ic->op == CALL || ic->op == PCALL || ic->op == SEND);
-                                       ic->rlive = bitVectSetBit (ic->rlive, lrange->key);
-                               }
-                       }
-                       /* overlapping live ranges should be eliminated */
-                       if (ASSIGN_ITEMP_TO_ITEMP (ic)) {
-
-                               if (SPIL_LOC(IC_RIGHT(ic)) == SPIL_LOC(IC_RESULT(ic))   && /* left & right share the same spil location */
-                                   OP_SYMBOL(IC_RESULT(ic))->isreqv                    && /* left of assign is a register requivalent */
-                                   !OP_SYMBOL(IC_RIGHT(ic))->isreqv                    && /* right side is not */
-                                   OP_SYMBOL(IC_RIGHT(ic))->liveTo > ic->key           && /* right side live beyond this point */
-                                   bitVectnBitsOn(OP_DEFS(IC_RESULT(ic))) > 1 )        {  /* left has multiple definitions */
-                                       SPIL_LOC(IC_RIGHT(ic)) = NULL; /* then cannot share */
-                               }
-                       }
+    int i;
+    
+    /* for all blocks do */
+    for (i = 0; i < count; i++) {
+       iCode *ic;
+       
+       /* for all instruction in the block do */
+       for (ic = ebbs[i]->sch; ic; ic = ic->next) {
+           symbol *lrange;
+           int k;
+           
+           ic->rlive = newBitVect (operandKey);
+           /* for all symbols in the liverange table */
+           for (lrange = hTabFirstItem (liveRanges, &k); lrange;
+                lrange = hTabNextItem (liveRanges, &k)) {
+               
+               /* if it is live then add the lrange to ic->rlive */
+               if (lrange->liveFrom <= ic->seq &&
+                   lrange->liveTo >= ic->seq) {
+                   lrange->isLiveFcall |= (ic->op == CALL || ic->op == PCALL || ic->op == SEND);
+                   ic->rlive = bitVectSetBit (ic->rlive, lrange->key);
                }
+           }
        }
+    }
 }
 
+/*-----------------------------------------------------------------*/
+/* computeClash - find out which live ranges collide with others   */
+/*-----------------------------------------------------------------*/
+static void computeClash ()
+{
+    hTab *lRangeCopy = newHashTable(hTabMaxKey(liveRanges));
+    void *item;
+    symbol *outer, *inner;
+    int key, key1;
+
+    /* have to make a copy of the liveRanges hashTable :: UGHH .*/
+    for (item = hTabFirstItem(liveRanges,&key); item ; 
+        item = hTabNextItem(liveRanges,&key)) {
+       hTabAddItem(&lRangeCopy,key,item);
+    }
+   
+    /* outerloop : for each liverange do */
+    for (outer = hTabFirstItem(liveRanges,&key); outer ; 
+        outer = hTabNextItem(liveRanges,&key)) {
+
+       /* if the liveFrom & To are the same then skip, 
+          could happen for unused return values from functions */
+       if (outer->liveFrom == outer->liveTo) continue;
+
+       /* innerloop : for the inner loop we can start from the
+          item after the outer loop */
+       inner = hTabFirstItemWK (lRangeCopy,outer->key);
+       inner = hTabNextItem (lRangeCopy,&key1 );
+       for (; inner ; inner = hTabNextItem( lRangeCopy ,&key1)) {
+
+           if (inner->liveFrom == inner->liveTo) continue;
+           if (inner->liveTo < outer->liveFrom)  continue;
+           if (inner->liveFrom > outer->liveTo)  continue;
+           
+           /* if one of them are being defined where the other
+              one end , then no overlap (i.e. they can goto same registers */
+           if (inner->liveFrom == outer->liveTo ||
+               outer->liveFrom == inner->liveTo) continue;
+
+           /* so they overlap : set both their clashes */
+           inner->clashes = bitVectSetBit(inner->clashes,outer->key);
+           outer->clashes = bitVectSetBit(outer->clashes,inner->key);
+           
+           /* check if they share the same spillocation */
+           if (SYM_SPIL_LOC(inner) && SYM_SPIL_LOC(outer)) {
+               if (inner->reqv && !outer->reqv) SYM_SPIL_LOC(outer)=NULL;
+               else if (outer->reqv && !inner->reqv) SYM_SPIL_LOC(inner)=NULL;
+               else if (inner->used > outer->used) SYM_SPIL_LOC(outer)=NULL;
+               else SYM_SPIL_LOC(inner)=NULL;
+           }
+       }
+    }
+}
 
 /*-----------------------------------------------------------------*/
 /* computeLiveRanges - computes the live ranges for variables      */
@@ -607,4 +649,7 @@ computeLiveRanges (eBBlock ** ebbs, int count)
 
   /* mark the ranges live for each point */
   rlivePoint (ebbs, count);
+
+  /* compute which overlaps with what */
+  computeClash();
 }