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[Bug tree-optimization/58570] [4.9 Regression] wrong code for bitfields at -O2 and above
- From: "bernd.edlinger at hotmail dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 08 Oct 2013 06:46:57 +0000
- Subject: [Bug tree-optimization/58570] [4.9 Regression] wrong code for bitfields at -O2 and above
- Auto-submitted: auto-generated
- References: <bug-58570-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58570
--- Comment #6 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to Eric Botcazou from comment #5)
> I think we just want to copy the following from
> nonoverlapping_component_refs_p:
>
> /* If we're left with accessing different fields of a structure, then
> no
> possible overlap, unless they are both bitfields. */
> if (TREE_CODE (typex) == RECORD_TYPE && fieldx != fieldy)
> return !(DECL_BIT_FIELD (fieldx) && DECL_BIT_FIELD (fieldy));
>
> over to nonoverlapping_component_refs_of_decl_p.
Yes.
Just one idea:
What if both bit fields have different DECL_BIT_FIELD_REPRESENTATIVE?
Then they can't possibly overlap?