- (shortcut_blocks, others) = partitionWith split blocks
- split (BasicBlock id [insn]) | Just dest <- canShortcut insn
- = Left (id,dest)
- split other = Right other
+ -- Don't completely eliminate loops here -- that can leave a dangling jump!
+ (_, shortcut_blocks, others) = foldl split (emptyBlockSet, [], []) blocks
+ split (s, shortcut_blocks, others) b@(BasicBlock id [insn])
+ | Just (DestBlockId dest) <- canShortcut insn,
+ (elemBlockSet dest s) || dest == id -- loop checks
+ = (s, shortcut_blocks, b : others)
+ split (s, shortcut_blocks, others) (BasicBlock id [insn])
+ | Just dest <- canShortcut insn
+ = (extendBlockSet s id, (id,dest) : shortcut_blocks, others)
+ split (s, shortcut_blocks, others) other = (s, shortcut_blocks, other : others)
+