[Bug middle-end/63991] redundant read when write to volatile member of packed structure

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63991

--- Comment #2 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
It looks like -fpack-struct cannot be used when -fstrict-volatile-bitfields is
in effect, i.e. on ARM EABI.  As for unaligned volatile fields on
strict-alignment
targets, they clearly ask for trouble.  Simply do not use -fpack-struct.