Added some heuristic for register spilling

[fw/sdcc] / src / z80 / ralloc.c

diff --git a/src/z80/ralloc.c b/src/z80/ralloc.c
index 6dfca4cdf759663e5a65378a88e3b1c307c3a41c..a46ae56f197c034a89bbe03e6860fde654b3961d 100644 (file)
--- a/src/z80/ralloc.c
+++ b/src/z80/ralloc.c
@@ -1094,21 +1094,23 @@ serialRegAssign (eBBlock ** ebbs, int count)
 
              /* if it has a spillocation & is used less than
                 all other live ranges then spill this */
-             if (willCS && sym->usl.spillLoc)
-               {
-
-                 symbol *leastUsed =
-                 leastUsedLR (liveRangesWith (spillable,
-                                              allLRs,
-                                              ebbs[i],
-                                              ic));
-                 if (leastUsed &&
-                     leastUsed->used > sym->used)
-                   {
-                     spillThis (sym);
-                     continue;
-                   }
-               }
+             if (willCS) {
+                     if (sym->usl.spillLoc) {
+                             symbol *leastUsed = leastUsedLR (liveRangesWith (spillable,
+                                                                              allLRs, ebbs[i], ic));
+                             if (leastUsed && leastUsed->used > sym->used) {
+                                     spillThis (sym);
+                                     continue;
+                             }
+                     } else {
+                             /* if none of the liveRanges have a spillLocation then better
+                                to spill this one than anything else already assigned to registers */
+                             if (liveRangesWith(spillable,noSpilLoc,ebbs[i],ic)) {
+                                     spillThis (sym);
+                                     continue;
+                             }
+                     }
+             }
 
              /* else we assign registers to it */
              regAssigned = bitVectSetBit (regAssigned, sym->key);