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Re: Need help with PR71976 combine.c::get_last_value returns a wrong result


On Fri, Jul 29, 2016 at 11:05:13AM +0200, Georg-Johann Lay wrote:
> There might still problems linger around if hard-regs are used:
> 
> Suppose we set the reg in DImode and then get_last_value is called for the 
> same reg in SImode.  Using the DI value might be wrong, e.g. if it is used 
> to compute the sign (on little endian) or the number of sign bit copies.

rtlanal.c:num_sign_bit_copies1, see the part after
  /* For a smaller object, just ignore the high bits.  */

Cheers,


Segher


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