http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58041
Bug ID: 58041
Summary: Unaligned access to arrays in packed structure
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: bernd.edlinger at hotmail dot de
the attached test case shows unaligned accesses can be generated
on arm architecture, despite the -mno-unaligned-access option.
This does not happen at -O0 and -Og,
but it always happens at at -Os -O1 -O2 and -O3 to name a few.
assembler output for foo shows unaligned opcodes:
foo:
@ Function supports interworking.
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
add ip, r0, r1, asl #3
add r1, ip, #1
ldmia r1, {r0-r1}
str r2, [ip, #1]
str r3, [ip, #5]
bx lr
reproduced with latest trunk:
$ ../gcc-4.9-20130728/configure --target=arm-eabi
--prefix=/home/ed/gnu/arm-eabi --with-newlib --enable-languages=c,c++
--disable-hosted-libstdcxx --disable-__cxa_atexit
