On Thu, 16 Jun 2011, H.J. Lu wrote: > On Thu, Jun 16, 2011 at 6:09 AM, Richard Guenther <rguent...@suse.de> wrote: > > > > For some reason I split out sanitizing sizetypes from the > > no-undefined-overflow-branch. In fact the following patch tries > > to only fix one thing - make unsigned sizetypes no longer sign-extended. > > > > This has (unfortunately) interesting side-effects, and some of them > > have been mitigated by already committed patches during the last half > > year. The main remaining issue I run into (and that sort-of blocks > > me from persuing this really really ...) is that there is a lot of > > code in GCC that assumes it can do modulo arithmetic on HOST_WIDE_INTs > > for sizetypes (pointers / offsets in general). Which happens to > > be wrong when a HOST_WIDE_INT is wider than sizetype (on -m32 multilib > > on x86_64 for example). It happens to work in almost all cases > > if we sign-extend from 32bit to 64bit HWI but not when we zero-extend. > > I'm not exactly sure how to proceeed here, other than adding fixups > > to various places (as seen in the patch below) and hope to catch > > all existing errors. [yes, I already tried making all sizetypes > > signed, really signed, but that has loads of fallout as well] > > > > That said, the fact that sizetypes are sign-extended has caused > > wrong-code bugs in the past, and TYPE_UNSIGNED is really used > > inconsistently. So I think this is definitely worth fixing. > > > > Eventually a first move would be to (finally) get rid of the > > requirement of sizetype offset arguments for POINTER_PLUS_EXPR. > > I didn't yet start on that project though. > > > > I remember the following bootstrapped fine on x86_64-unknown-linux-gnu > > at least for C, with a few remaining regressions. I'm trying > > a full all-lang bootstrap & regtest now. > > > > Comments? Questions? > > Any expected impacts on x32 branch after this changed is merged?
None that I'm aware of. But as I said above I'm not sure it'll be in mergeable state any time. Richard. > > Thanks, > > Richard. > > > > 2011-06-16 Richard Guenther <rguent...@suse.de> > > > > * fold-const.c (div_if_zero_remainder): sizetypes no longer > > sign-extend. > > * stor-layout.c (initialize_sizetypes): Likewise. > > * tree-ssa-ccp.c (bit_value_unop_1): Likewise. > > (bit_value_binop_1): Likewise. > > * tree.c (double_int_to_tree): Likewise. > > (double_int_fits_to_tree_p): Likewise. > > (force_fit_type_double): Likewise. > > (host_integerp): Likewise. > > (int_fits_type_p): Likewise. > > * expr.c (get_inner_reference): Sign-extend offset. > > * tree-ssa-structalias.c (get_constraint_for_ptr_offset): Likewise. > > * tree-cfg.c (verify_types_in_gimple_reference): Do not compare > > sizes by pointer. > > > > -- Richard Guenther <rguent...@suse.de> Novell / SUSE Labs SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746 GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer
