+ -- Invariant: Sp is always greater than SpLim. Thus, if
+ -- the high water mark is zero, we can optimize away the
+ -- conditional branch. Relies on dead code elimination
+ -- to get rid of the dead GC blocks.
+ -- EZY: Maybe turn this into a guard that checks if a
+ -- statement is stack-check ish? Maybe we should make
+ -- an actual mach-op for it, so there's no chance of
+ -- mixing this up with something else...
+ replSlot _ (CmmMachOp (MO_U_Lt _)
+ [CmmMachOp (MO_Sub _)
+ [ CmmReg (CmmGlobal Sp)
+ , CmmLit (CmmInt 0 _)],
+ CmmReg (CmmGlobal SpLim)]) = CmmLit (CmmInt 0 wordWidth)