> 在 2015年1月30日，20:43，"Matwey V. Kornilov" <[email protected]> 写道： > > Hi, > > I have the following code > > int ret = 0; > unsigned long irqflags; > > spin_lock_irqsave(&lock, irqflags); > > //... > ret = hdl->count; > //... > > spin_unlock_irqrestore(&lock, irqflags); > return ret; > > I would like to be sure, that ret will not be optimized out. I think > compiler can convert the code to equivalent: > > unsigned long irqflags; > > spin_lock_irqsave(&lock, irqflags); > > //... > //... > > spin_unlock_irqrestore(&lock, irqflags); > return hdl->count; > > But this is not what I want, because I use lock to protect hdl and want > to return hdl->count value as it was in protected section. > > Please check the assembly code to double confirm the GCC behavior. Why will GCC change the order as what you mentioned? Only assembly code can tell you.
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