Hi,
On Fri, Apr 15, 2011 at 05:28:49PM +0200, Richard Guenther wrote:
> On Fri, 15 Apr 2011, Martin Jambor wrote:
>
> > Hi,
> >
> > in order to speed up astar, I had to persuade the function that
> > decides whether a statement potentially modifies the dynamic type of
> > an object by storing a new value to the VMT pointer to consider the
> > following statement harmless (all types are integers of some sort):
> >
> > MEM[(i32 *)b2arp_3(D) + 8B] = 0;
> >
> > I'd like to experiment with this routine a bit more once I have some
> > other IPA-CP infrastructure in place but at the moment I opted for a
> > simple solution: All scalar non-pointer stores are deemed safe.
> >
> > VMT pointer is a compiler generated field which is a pointer so legal
> > user code is not able to store stuff there through some fancy type
> > casts and compiler generated code should have no reason whatsoever to
> > that either. Therefore I believe this change is safe and useful.
> >
> > I have bootstrapped and tested the patch on x886_64-linux. OK for
> > trunk?
>
> I think this should be only done for -fstrict-aliasing.
>
> Ok with that change.
OK, this is what I am testing and what I intend to commit if all goes
well.
Thanks,
Martin
2011-04-18 Martin Jambor <mjam...@suse.cz>
* ipa-prop.c (stmt_may_be_vtbl_ptr_store): Return false for scalar
non-pointer assignments.
Index: src/gcc/ipa-prop.c
===================================================================
*** src.orig/gcc/ipa-prop.c
--- src/gcc/ipa-prop.c
*************** stmt_may_be_vtbl_ptr_store (gimple stmt)
*** 405,417 ****
{
tree lhs = gimple_assign_lhs (stmt);
! if (TREE_CODE (lhs) == COMPONENT_REF
! && !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1))
! && !AGGREGATE_TYPE_P (TREE_TYPE (lhs)))
return false;
! /* In the future we might want to use get_base_ref_and_offset to find
! if there is a field corresponding to the offset and if so, proceed
! almost like if it was a component ref. */
}
return true;
}
--- 405,423 ----
{
tree lhs = gimple_assign_lhs (stmt);
! if (!AGGREGATE_TYPE_P (TREE_TYPE (lhs)))
! {
! if (flag_strict_aliasing
! && !POINTER_TYPE_P (TREE_TYPE (lhs)))
return false;
!
! if (TREE_CODE (lhs) == COMPONENT_REF
! && !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1)))
! return false;
! /* In the future we might want to use get_base_ref_and_offset to find
! if there is a field corresponding to the offset and if so, proceed
! almost like if it was a component ref. */
! }
}
return true;
}
