On 9/4/19 2:53 PM, Richard Earnshaw (lists) wrote:
> On 15/08/2019 20:47, Bernd Edlinger wrote:
>> On 8/15/19 6:29 PM, Richard Biener wrote:
>>>>>
>>>>> Please split it into the parts for the PR and parts making the
>>>>> asserts not trigger.
>>>>>
>>>>
>>>> Yes, will do.
>>>>
>>
>> Okay, here is the rest of the PR 89544 fix,
>> actually just an optimization, making the larger stack alignment
>> known to the middle-end, and the test cases.
>>
>>
>> Boot-strapped and reg-tested on x86_64-pc-linux-gnu and arm-linux-gnueabihf.
>> Is it OK for trunk?
>>
>>
>> Thanks
>> Bernd.
>>
>
> Index: gcc/testsuite/gcc.target/arm/unaligned-argument-2.c
> ===================================================================
> --- gcc/testsuite/gcc.target/arm/unaligned-argument-2.c (Revision 0)
> +++ gcc/testsuite/gcc.target/arm/unaligned-argument-2.c (Arbeitskopie)
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target arm_arm_ok } */
> +/* { dg-require-effective-target arm_ldrd_strd_ok } */
> +/* { dg-options "-marm -mno-unaligned-access -O3" } */
> +
> +struct s {
> + int a, b;
> +} __attribute__((aligned(8)));
> +
> +struct s f0;
> +
> +void f(int a, int b, int c, int d, int e, struct s f)
> +{
> + f0 = f;
> +}
> +
> +/* { dg-final { scan-assembler-times "ldrd" 0 } } */
> +/* { dg-final { scan-assembler-times "strd" 0 } } */
> +/* { dg-final { scan-assembler-times "stm" 1 } } */
>
> I don't think this test is right. While we can't use an LDRD to load the
> argument off the stack, there's nothing wrong with using an STRD to then
> store the value to f0 (as that is 8-byte aligned). So the second and third
> scan-assembler tests are meaningless.
>
Ah, that is very similar to the unaligned-memcpy-2/3.c,
see https://gcc.gnu.org/ml/gcc-patches/2019-09/msg00157.html
initially that is a movdi,
then in subreg1 it is split in two movsi
which is then re-assembled as ldm
Not sure if that is intended in that way.
Bernd.
