On 30 May 10:45, Jeff Law wrote:
> On 05/29/14 04:53, Ilya Enkovich wrote:
> >Hi,
> >
> >This patch tries to keep bounds initial values when it may be needed. Even
> >if initial value is not fully known (e.g. we know only low bound) it still
> >may help to remove some redundant checks.
> >
> >Bootstrapped and tested on linux-x86_64.
> >
> >Thanks,
> >Ilya
> >--
> >gcc/
> >
> >2013-05-29 Ilya Enkovich <ilya.enkov...@intel.com>
> >
> > * ipa.c (symtab_remove_unreachable_nodes): Kepp initial values for
> > pointer bounds to be used for checks eliminations.
> > * lto-cgraph.c (compute_ltrans_boundary): Likewise.
> > * add_references_to_partition (add_references_to_partition): Add
> > references to pointer bounds vars.
> Typo in the ChangeLog "kepp" -> "keep".
>
> OK for the trunk when the rest of the stuff is approved, though I'm
> curious how, for example, keeping the initial value for an
> unreachable node in symtab_remove_unreachable_nodes helps eliminate
> redundant checks.
Consider we have some var 'arr' and static bounds '__chkp_bounds_of_arr'
holding its bounds. Upper bound may be unknown at compile time and therefore
'__chkp_bounds_of_arr' is not a candidate for constant folding. But we always
know low bound which is '&arr'. It means we may remove checks of low bound when
value of '__chkp_bounds_of_arr' is used in checks. That is why I want to keep
initials for all static bounds vars.
Here is fixed ChangeLog.
Thanks,
Ilya
--
gcc/
2014-06-02 Ilya Enkovich <ilya.enkov...@intel.com>
* ipa.c (symtab_remove_unreachable_nodes): Keep initial values for
pointer bounds to be used for checks eliminations.
* lto-cgraph.c (compute_ltrans_boundary): Likewise.
* add_references_to_partition (add_references_to_partition): Add
references to pointer bounds vars.
>
> Jeff
>
