https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102162
--- Comment #8 from deller at gmx dot de ---
On 9/1/21 11:19 PM, dave.anglin at bell dot net wrote:
>> I think the problem with your testcase is, that the compiler doesn't know the
>> alignment of the parameter "p" in your f_unaligned() function.
>> So it will generate byte-accesses.
> I think it's the type rather than the alignment. If type is char, one gets
> byte accesses. If type is short, one gets 16-bit accesses.
>
> The alignment is being ignored.
You are right.
It's even worse!
short evil;
int f_unaligned2(void)
{ return get_unaligned(&evil); }
gives:
00000000 <f_unaligned2>:
0: 2b 60 00 00 addil L%0,dp,r1
4: 44 3c 00 00 ldh 0(r1),ret0
8: e8 40 c0 00 bv r0(rp)
c: d3 9c 1f f0 extrw,s ret0,31,16,ret0
The "ldh" loads only the first two bytes, and extends it into the upper 32bits
with "extrw,s".
So, only 16bits instead of 32bits are loaded from the address where "evil"
is...
