* src/mcs51/ralloc.c (deassignLR),

[fw/sdcc] / src / mcs51 / ralloc.c

diff --git a/src/mcs51/ralloc.c b/src/mcs51/ralloc.c
index 8d7f6556abbf2b2751692400d97f1a6c67851840..ec01a64642e23b935a55a847a41fa9527828b4a5 100644 (file)
--- a/src/mcs51/ralloc.c
+++ b/src/mcs51/ralloc.c
@@ -981,6 +981,7 @@ deassignLRs (iCode * ic, eBBlock * ebp)
              (result = OP_SYMBOL (IC_RESULT (ic))) &&  /* has a result */
              result->liveTo > ic->seq &&       /* and will live beyond this */
              result->liveTo <= ebp->lSeq &&    /* does not go beyond this block */
+             result->liveFrom == ic->seq &&    /* does not start before here */
              result->regType == sym->regType &&        /* same register types */
              result->nRegs &&  /* which needs registers */
              !result->isspilt &&       /* and does not already have them */
@@ -1237,6 +1238,16 @@ serialRegAssign (eBBlock ** ebbs, int count)
                    spillThis (sym);
                    continue;                 
                }
+               
+               /* If the live range preceeds the point of definition 
+                  then ideally we must take into account registers that 
+                  have been allocated after sym->liveFrom but freed
+                  before ic->seq. This is complicated, so spill this
+                  symbol instead and let fillGaps handle the allocation. */
+               if (sym->liveFrom < ic->seq) {
+                   spillThis (sym);
+                   continue;                 
+               }
 
                /* if it has a spillocation & is used less than
                   all other live ranges then spill this */
@@ -1399,7 +1410,7 @@ static void fillGaps()
                bitVectBitValue(_G.totRegAssigned,i) == 0) /* and are still assigned to registers */
                continue ;
 
-               clr = hTabItemWithKey(liveRanges,i);
+           clr = hTabItemWithKey(liveRanges,i);
            assert(clr);
 
            /* mark these registers as used */