[Bug target/57911] alignment of arrays allocated stack on ARM : 4 bytes ?

[rearnsha at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57911

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2013-07-23
     Ever confirmed|0                           |1

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
The ABI specifies *minimum* alignment constraints.  It can never specify a
maximum.  Compilers are entitled to place objects on whatever boundaries they
wish if they think it will lead to better results (better does not necessarily
mean faster).

Even when optimizing for size it can be the case that padding some objects up
to word boundaries will lead to smaller code (-Os is primarily aimed at
generating smaller code segments, not necessarily about minimizing stack
usage).  For example, it might allow LDM operations to be used to read multiple
words from the object at once.

If you have more details, then please supply pre-processed test case that we
can look at.