= assign
-- Assumptions:
+-- * Writes using Hp do not overlap with any other memory locations
+-- (An important invariant being relied on here is that we only ever
+-- use Hp to allocate values on the heap, which appears to be the
+-- case given hpReg usage, and that our heap writing code doesn't
+-- do anything stupid like overlapping writes.)
-- * Stack slots do not overlap with any other memory locations
--- * Non stack-slot stores always conflict with each other. (This is
--- not always the case; we could probably do something special for Hp)
-- * Stack slots for different areas do not overlap
-- * Stack slots within the same area and different offsets may
-- overlap; we need to do a size check (see 'overlaps').
-clobbers :: (CmmExpr, CmmExpr) -> (Unique, CmmExpr) -> Bool
+-- * Register slots only overlap with themselves. (But this shouldn't
+-- happen in practice, because we'll fail to inline a reload across
+-- the next spill.)
+-- * Non stack-slot stores always conflict with each other. (This is
+-- not always the case; we could probably do something special for Hp)
+clobbers :: (CmmExpr, CmmExpr) -- (lhs, rhs) of clobbering CmmStore
+ -> (Unique, CmmExpr) -- (register, expression) that may be clobbered
+ -> Bool
+clobbers (CmmRegOff (CmmGlobal Hp) _, _) (_, _) = False
+clobbers (CmmReg (CmmGlobal Hp), _) (_, _) = False
+-- ToDo: Also catch MachOp case
clobbers (ss@CmmStackSlot{}, CmmReg (CmmLocal r)) (u, CmmLoad (ss'@CmmStackSlot{}) _)
| getUnique r == u, ss == ss' = False -- No-op on the stack slot (XXX: Do we need this special case?)
clobbers (CmmStackSlot (CallArea a) o, rhs) (_, expr) = f expr
containsStackSlot (CmmMachOp _ es) = or (map containsStackSlot es)
containsStackSlot (CmmStackSlot{}) = True
containsStackSlot _ = False
+clobbers (CmmStackSlot (RegSlot l) _, _) (_, expr) = f expr
+ where f (CmmLoad (CmmStackSlot (RegSlot l') _) _) = l == l'
+ f _ = False
clobbers _ (_, e) = f e
where f (CmmLoad (CmmStackSlot _ _) _) = False
f (CmmLoad{}) = True -- conservative