regalloc: improve spilling and cleanup

Instead of spilling current interval when running out of registers,
spill the longest-lived active interval with a lower spill cost than
current. Spill costs are estimated based on multiplicative loop depth.
Also cleanup regalloc.c somewhat.
Update todo.txt too.

1 files changed, 1 insertions, 1 deletions

diff --git a/ir/ir.h b/ir/ir.h
index e7eb62a..ab3e474 100644
--- a/ir/ir.h
+++ b/ir/ir.h
@@ -295,7 +295,7 @@ void fillblkids(struct function *);
 #define startbbvisit() (void)(++visitmark)
 #define wasvisited(blk) ((blk)->visit == visitmark)
 #define markvisited(blk) ((blk)->visit = visitmark)
-void numberinstrs(struct function *);
+uint numberinstrs(struct function *);
 bool blkreachable(struct function *fn, struct block *blk);
 
 /** builder.c **/