On Tue, 4 Mar 2008, Andrew Pinski wrote: > On 3/4/08, Richard Guenther <[EMAIL PROTECTED]> wrote: > > I suggest to make sure that bit position and size are constants, the > > object referenced is of integral type (BIT_FIELD_REF should not be > > used as a way to circumvent aliasing) and the result type is of the > > same type as the operand zero type (and not a bitfield type of the > > referenced size -- in which case the BIT_FIELD_REF_UNSIGNED would > > be useless). The result would then be properly extended according > > to BIT_FIELD_REF_UNSIGNED. > > I tried non constant bit position with BIT_FIELD_REF of vector types > and it crashed in expand so I think this is the correct thing to do. > Though it would be nice if we have a VEC_EXTRACT tree instead of > overloading BIT_FIELD_REF for it that takes a non constant position so > we can do better optimization there in some cases (yes people write > code that extracts parts of vectors, trust me).
FWIW I agree. After all we also have REALPART_EXPR and IMAGPART_EXPR, a VEC_EXTRACT sounds fine (after all we already have a lot of VEC_ codes). At least BIT_FIELD_REF should not be VIEW_CONVERT_EXPR on steroids. Richard.
