[Bug middle-end/66661] incorrect memory access in optimization with flexible array member

["P at draigBrady dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66661

--- Comment #9 from Pádraig Brady <P at draigBrady dot com> ---
I'm not understanding completely TBH. Are flexible array members not special?
Should the optimizations be restricted on access through the flexible array,
because I presume most/all existing allocation code is not considering this
alignment/padding issue. I certainly didn't notice any examples when looking
into a workaround which I came up with independently. For my reference there
are some notes RE GCC's divergence from C99 re padding and flexi arrays at:
https://sites.google.com/site/embeddedmonologue/home/c-programming/data-alig
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From: "mwahab at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/64783] -march=armv8.1-a should be supported
Date: Thu, 25 Jun 2015 11:49:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd783

--- Comment #3 from mwahab at gcc dot gnu.org ---
I've just noticed this has been assigned to me. Support for -march=armv8.1-a
has been added to the Aarch64 backend, the ARM backend is still to be done.

Author: mwahab
Date: Tue Jun 16 13:38:37 2015
New Revision: 224519

URL: https://gcc.gnu.org/viewcvs?rev"4519&root=gcc&view=rev
Log:
2015-06-16  Matthew Wahab  <matthew.wahab@arm.com>

        * config/aarch64/aarch64-arches.def: Add "armv8.1-a".
        * config/aarch64/aarch64-options-extensions.def: Update "fP",
        "simd" and "crypto".  Add "lse", "pan", "lor" and "rdma".
        * gcc/config/aarch64/aarch64.h (AARCH64_FL_LSE): New.
        (AARCH64_FL_PAN): New.
        (AARCH64_FL_LOR): New.
        (AARCH64_FL_RDMA): New.
        (AARCH64_FL_FOR_ARCH8_1): New.
        * doc/invoke.texi (AArch64 Options): Add "armv8.1-a" to
        -march. Add "lse", "pan", "lor", "rdma" to feature modifiers.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/aarch64/aarch64-arches.def
    trunk/gcc/config/aarch64/aarch64-option-extensions.def
    trunk/gcc/config/aarch64/aarch64.h
    trunk/gcc/doc/invoke.texi