On Thu, 5 May 2022 19:30:01 +0200
Stanislaw Kardach <kda@semihalf.com> wrote:
> When compiling for RISC-V in debug mode the large amount of inlining in
> test_ring_basic_ex() and test_ring_with_exact_size() (in test_ring.c)
> leads to large loop bodies. This causes 'goto' and 'for' loop
> PC-relative jumps generated by the compiler to go beyond the architecture
> limitation of +/-1MB offset (the 'j <offset>' instruction). This
> instruction should not be generated by the compiler since C language does
> not limit the maximum distance for 'goto' or 'for' loop jumps.
>
> This only happens in the unit test for ring which tries to perform long
> loops with ring enqueue/dequeue and it seems to be caused by excessive
> __rte_always_inline usage. ring perf test compiles just fine under
> debug.
>
> To work around this, disable the offending tests in debug mode.
>
> Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
> Sponsored-by: Frank Zhao <Frank.Zhao@starfivetech.com>
> Sponsored-by: Sam Grove <sam.grove@sifive.com>
> ---
It seems to me that fixing the excessive inlining in the ring code
could benefit all architectures, rather than neutering the tests
on RISCV.
True. Since this only happened in the tests that I've mentioned, my other approach was to introduce a "slow" wrapper over test_ring_dequeue|enqueue() which did not force inlining via __rte_always_inline and use it in functional test functions. However after talking with Thomas Monjalon we've decided to guard the debug build of RISC-V only.
Another thing is that this is a clear bug in the compiler, the relaxation of the jump should not be done since RISC-V has long jump construct for arbitrary jumps (auipc+jalr).