[1/1] test/ring: remove excessive inlining

  Forcing inlining in test_ring_enqueue and test_ring_dequeue can cause
the compiled code to grow extensively when compiled with no optimization
(-O0 or -Og). This is default in the meson's debug configuration. This
can collide with compiler bugs and cause issues during linking of unit
tests where the api_type or esize are non-const variables causing
inlining cascade. In perf tests this is not the case in perf-tests as
esize and api_type are const values.

One such case was discovered when porting DPDK to RISC-V. GCC 11.2 (and
no fix still in 12.1) is generating a short relative jump instruction
(J <offset>) for goto and for loops. When loop body grows extensively in
ring test, the target offset goes beyond supported offfset of +/- 1MB
from PC. This is an obvious bug in the GCC as RISC-V has a
two-instruction construct to jump to any absolute address (AUIPC+JALR).

However there is no reason to force inlining as the test code works
perfectly fine without it.

Fixes: a9fe152363 test/ring: add custom element size functional tests

Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
---
 app/test/test_ring.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
  

+ Bruce, Stephen

<snip>

> 
> Forcing inlining in test_ring_enqueue and test_ring_dequeue can cause the
> compiled code to grow extensively when compiled with no optimization
> (-O0 or -Og). This is default in the meson's debug configuration. This can collide
> with compiler bugs and cause issues during linking of unit tests where the
> api_type or esize are non-const variables causing inlining cascade. In perf tests
> this is not the case in perf-tests as esize and api_type are const values.
> 
> One such case was discovered when porting DPDK to RISC-V. GCC 11.2 (and no
> fix still in 12.1) is generating a short relative jump instruction (J <offset>) for
> goto and for loops. When loop body grows extensively in ring test, the target
> offset goes beyond supported offfset of +/- 1MB from PC. This is an obvious
> bug in the GCC as RISC-V has a two-instruction construct to jump to any
> absolute address (AUIPC+JALR).
Is there a bug report created for this? Is it possible to add a link to the bug report?

> 
> However there is no reason to force inlining as the test code works perfectly
> fine without it.
If this solves the problem, I prefer this as it is test code.

> 
> Fixes: a9fe152363 test/ring: add custom element size functional tests
> 
> Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
> ---
>  app/test/test_ring.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/app/test/test_ring.h b/app/test/test_ring.h index
> c8bfec8399..45c263f3ff 100644
> --- a/app/test/test_ring.h
> +++ b/app/test/test_ring.h
> @@ -97,7 +97,7 @@ test_ring_copy_from(struct rte_ring_zc_data *zcd, void
> *dst, int esize,
>  	}
>  }
> 
> -static __rte_always_inline unsigned int
> +static inline unsigned int
>  test_ring_enqueue(struct rte_ring *r, void **obj, int esize, unsigned int n,
>  			unsigned int api_type)
>  {
> @@ -158,7 +158,7 @@ test_ring_enqueue(struct rte_ring *r, void **obj, int
> esize, unsigned int n,
>  		}
>  }
> 
> -static __rte_always_inline unsigned int
> +static inline unsigned int
>  test_ring_dequeue(struct rte_ring *r, void **obj, int esize, unsigned int n,
>  			unsigned int api_type)
>  {
> @@ -222,7 +222,7 @@ test_ring_dequeue(struct rte_ring *r, void **obj, int
> esize, unsigned int n,
>  /* This function is placed here as it is required for both
>   * performance and functional tests.
>   */
> -static __rte_always_inline void *
> +static inline void *
>  test_ring_calloc(unsigned int rsize, int esize)  {
>  	unsigned int sz;
> --
> 2.30.2
  

On Tue, May 10, 2022 at 11:23:53PM +0000, Honnappa Nagarahalli wrote:
> + Bruce, Stephen
> 
> <snip>
> 
> > 
> > Forcing inlining in test_ring_enqueue and test_ring_dequeue can cause the
> > compiled code to grow extensively when compiled with no optimization
> > (-O0 or -Og). This is default in the meson's debug configuration. This can collide
> > with compiler bugs and cause issues during linking of unit tests where the
> > api_type or esize are non-const variables causing inlining cascade. In perf tests
> > this is not the case in perf-tests as esize and api_type are const values.
> > 
> > One such case was discovered when porting DPDK to RISC-V. GCC 11.2 (and no
> > fix still in 12.1) is generating a short relative jump instruction (J <offset>) for
> > goto and for loops. When loop body grows extensively in ring test, the target
> > offset goes beyond supported offfset of +/- 1MB from PC. This is an obvious
> > bug in the GCC as RISC-V has a two-instruction construct to jump to any
> > absolute address (AUIPC+JALR).
> Is there a bug report created for this? Is it possible to add a link to the bug report?
> 
> > 
> > However there is no reason to force inlining as the test code works perfectly
> > fine without it.
> If this solves the problem, I prefer this as it is test code.
> 
+1 to this. I'm quite wary of changing the ring code itself.
  

On Wed, May 11, 2022 at 1:24 AM Honnappa Nagarahalli
<Honnappa.Nagarahalli@arm.com> wrote:
<snip>
> Is there a bug report created for this? Is it possible to add a link to the bug report?
I have found a bug for a similar issue (with "if" conditional):
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93062
I'll add it in v2.