Richard Earnshaw <richard.earns...@arm.com> writes:
> On 07/05/2025 13:57, Richard Sandiford wrote:
>> Kyrylo Tkachov <ktkac...@nvidia.com> writes:
>>>> On 7 May 2025, at 12:27, Karl Meakin <karl.mea...@arm.com> wrote:
>>>>
>>>> Commit the test file `cmpbr.c` before rules for generating the new
>>>> instructions are added, so that the changes in codegen are more obvious
>>>> in the next commit.
>>>
>>> I guess that’s an LLVM best practice.
>>> In GCC since we have the check-function-bodies mechanism we usually prefer
>>> to include the relevant test together with the patch that adds the
>>> optimization.
>>> But this is not wrong either.
>>>
>>>
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> * gcc.target/aarch64/cmpbr.c: New test.
>>>> ---
>>>> gcc/testsuite/gcc.target/aarch64/cmpbr.c | 1378 ++++++++++++++++++++++
>>>> 1 file changed, 1378 insertions(+)
>>>> create mode 100644 gcc/testsuite/gcc.target/aarch64/cmpbr.c
>>>>
>>>> diff --git a/gcc/testsuite/gcc.target/aarch64/cmpbr.c
>>>> b/gcc/testsuite/gcc.target/aarch64/cmpbr.c
>>>> new file mode 100644
>>>> index 00000000000..728d6ead91c
>>>> --- /dev/null
>>>> +++ b/gcc/testsuite/gcc.target/aarch64/cmpbr.c
>>>> @@ -0,0 +1,1378 @@
>>>> +/* Test that the instructions added by FEAT_CMPBR are emitted */
>>>> +/* { dg-do compile } */
>>>> +/* { dg-options "-march=armv9.5-a+cmpbr -O2" } */
>>>> +/* { dg-final { check-function-bodies "**" "" "" } } */
>>>
>>> As you’ll be adding new instructions to the compiler it’d be good to have
>>> it a dg-do assemble test where possible.
>>
>> Agreed FWIW, but:
>>
>>> For that you’ll need to create a new aarch64_asm_cmpbr_ok target and use it
>>> like so to fallback to dg-do compile when the assembler is too old:
>>> /* { dg-do compile { target aarch64_asm_cmpbr_ok } } */
>>
>> ...dg-do assemble for this one :)
>
> I don't think that works. If the first dg-do fails the test is just skipped.
>
> You need to replicate the test with separate dg-do directives, IIRC.
Hmm, can you remember the circumstances when you saw that?
We've been using the construct that Kyrill suggested with apparent
success in things like aarch64-sve2-acle-asm.exp. E.g.:
/* { dg-do assemble { target aarch64_asm_sve2p1_ok } } */
/* { dg-do compile { target { ! aarch64_asm_sve2p1_ok } } } */
/* { dg-final { check-function-bodies "**" "" "-DCHECK_ASM" } } */
If I run this normally, it picks the assemble route (tests run with -c).
If I force aarch64_asm_sve2p1_ok to false by mangling the test
instruction, the test picks the compile route (tests with run -S).
Thanks,
Richard
