On 10/11/11 14:35, Richard Sandiford wrote: > No, reload 1 is inherited by a later instruction. And it's inherited > correctly, in terms of the register contents being what we expect. > (Reload 1 is the one that survives to the end of the instruction's > reload sequence. Reload 2, in contrast, is clobbered by reload 1, > so could not be inherited. So when we record inheritance information > in emit_reload_insns, reload_reg_reaches_end_p correctly stops us > from recording reload 2 but allows us to record reload 1.) > > The problem is that we record the wrong instruction for reload 1. > We say that reload 1 is performed by the instruction that performs > reload 2. So spill_reg_store[] contains the instruction for reload 2 > rather than the instruction for reload 1. We delete it in > delete_output_reload at the point of inheritance.
Ok. So, would the minimal fix of testing !new_spill_reg_store[..] before writing to it also work? Seems to me this would cope with the out-of-order writes by only allowing the first. If so, then I think I'd prefer that, but we could gcc_assert (reload_reg_reaches_end (..)) as a bit of a verification of that function. Bernd
