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Re: [PATCH] Support signbit, signbitf and signbitl as GCC builtins
On Thu, Feb 05, 2004 at 03:13:23AM +0100, Ulrich Weigand wrote:
> The first alternative allows you to access any *low* part of a register
> (e.g. (subreg:QI (reg:SI) 3) or (subreg:HI (reg:SI) 2)), while the second
> alternative allows you to access any word of a multi-word value.
Quite right. Using subreg is *not* a substitute for an extraction.
If imode <= word_mode, and the signbit in imode is outside rmode,
you should use extract_bit_field on the imode version.
Indeed, it might be cleaner to just use extract_bit_field all the
time. It does force the result to 0/1 in the case we actually
store the value, but... that's ok too.