[Bug target/51709] armv7 target is not using unaligned access to packed fields sometimes (halfwords, loads?)

johnvb at broadcom dot com gcc-bugzilla@gcc.gnu.org
Fri Jan 13 18:59:00 GMT 2012


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51709

--- Comment #5 from John A. Van Boxtel <johnvb at broadcom dot com> 2012-01-13 18:39:43 UTC ---
Sorry about not understanding CS vs GNU release numbering and time
relationship.  I now understand that CS versions may precede introduction into
the GNC source.  I will also try to work with CS on reporting the bug.

I noticed this bug was listed as a code generation enhancement which I could
understand in a strict sense, i.e. the code generated works.  But given that
the compiler does create unaligned access to half words sometimes and in armv7,
there is no unaligned restrictions on normal half (or full) word access, this
seems like a significant code geneation issue for armv7 and makes one wonder if
the root cause might be more serious.

Constrast this with an architecture like x86 where unaligned access has always
been legal but if somehow the code generator used byte acesses, shifts and
and/or's to access (half) words.  This would be view as pretty "buggy".

Bottom line: I am just trying to make sure that the "enhancement" attribute
doesn't disqualify this from the current release cycle.  From that point of
view this seems like a bug to be fixed, not a future enhancement request.

Regards,

John A. Van Boxtel



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