> It does make sense to give the target control over the mode used for > sizetype. Of course a global change of the default (for example to > use Pmode as Ada did) will require testing each affected target, > so I think it makes sense to keep the default as-is.
No disagreement here. > Btw, we still have the issue on which _precision_ we should use for > sizetype -- if we expect modulo-semantics of arithmetic using it > (thus basically sign-less arithmetic) then the precision has to match > the expectation the C frontend (and other frontends) assume how pointer > offsets are handled. Currently the C frontend gets this not correct > which means negative offsets will be not correctly handled. Is this theoritical or practical? Are you talking about GET_MODE_BITSIZE vs GET_MODE_PRECISION wrt TYPE_PRECISION? > Similar issues arise from the mode/precision chosen for the bitsize > types. We choose a way to wide precision for them, so the > modulo-semantics assumption does not usually hold for bitsize > quantities. Again because of GET_MODE_PRECISION vs GET_MODE_BITSIZE? Otherwise we round up the precision since GCC 4.5 so there should be no more weird precision. -- Eric Botcazo
