On Wed, May 11, 2022 at 1:28 AM Honnappa Nagarahalli
<honnappa.nagaraha...@arm.com> wrote:
>
> <snip>
>
> >
> > 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.
> Is this still required given you have submitted [1]
>
> [1]
> http://patches.dpdk.org/project/dpdk/patch/20220510115758.457794-1-...@semihalf.com/
Correct, this patch is no longer necessary and marked as superseded in
patchwork. I did send v2 and v3 series without it. Thank you for
taking a look.
>
> >
> > Signed-off-by: Stanislaw Kardach <k...@semihalf.com>
> > Sponsored-by: Frank Zhao <frank.z...@starfivetech.com>
> > Sponsored-by: Sam Grove <sam.gr...@sifive.com>
> > ---
> > app/test/test_ring.c | 8 ++++++++
> > config/riscv/meson.build | 5 +++++
> > doc/guides/rel_notes/release_22_07.rst | 3 ++-
> > 3 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/app/test/test_ring.c b/app/test/test_ring.c index
> > bde33ab4a1..7d809c147b 100644
> > --- a/app/test/test_ring.c
> > +++ b/app/test/test_ring.c
> > @@ -955,6 +955,7 @@ test_ring_burst_bulk_tests4(unsigned int test_idx)
> > return -1;
> > }
> >
> > +#if !defined(RTE_RISCV_WO_DISABLE_RING_TESTS)
> > /*
> > * Test default, single element, bulk and burst APIs
> > */
> > @@ -1189,6 +1190,7 @@ test_ring_with_exact_size(void)
> > rte_ring_free(exact_sz_r);
> > return -1;
> > }
> > +#endif
> >
> > static int
> > test_ring(void)
> > @@ -1200,12 +1202,18 @@ test_ring(void)
> > if (test_ring_negative_tests() < 0)
> > goto test_fail;
> >
> > +/* Disable the following tests on RISC-V in debug mode. This is a
> > +work-around
> > + * GCC bug for RISC-V which fails to generate proper jumps for loops
> > +with large
> > + * bodies.
> > + */
> > +#if !defined(RTE_RISCV_WO_DISABLE_RING_TESTS)
> > /* Some basic operations */
> > if (test_ring_basic_ex() < 0)
> > goto test_fail;
> >
> > if (test_ring_with_exact_size() < 0)
> > goto test_fail;
> > +#endif
> >
> > /* Burst and bulk operations with sp/sc, mp/mc and default.
> > * The test cases are split into smaller test cases to diff --git
> > a/config/riscv/meson.build b/config/riscv/meson.build index
> > 0c16c31fc2..50d0b513bf 100644
> > --- a/config/riscv/meson.build
> > +++ b/config/riscv/meson.build
> > @@ -141,3 +141,8 @@ foreach flag: dpdk_flags endforeach message('Using
> > machine args: @0@'.format(machine_args))
> >
> > +# Enable work-around for ring unit tests in debug mode which fail to
> > +link # properly due to bad code generation by GCC.
> > +if get_option('optimization') == '0' or get_option('optimization') == 'g'
> > + add_project_arguments('-DRTE_RISCV_WO_DISABLE_RING_TESTS',
> > +language: 'c') endif
> > diff --git a/doc/guides/rel_notes/release_22_07.rst
> > b/doc/guides/rel_notes/release_22_07.rst
> > index 453591e568..4d64b68dfd 100644
> > --- a/doc/guides/rel_notes/release_22_07.rst
> > +++ b/doc/guides/rel_notes/release_22_07.rst
> > @@ -76,7 +76,8 @@ New Features
> > * Debug build of ``app/test/dpdk-test`` fails currently on RISC-V due to
> > seemingly invalid loop and goto jump code generation by GCC in
> > ``test_ring.c`` where extensive inlining increases the code size
> > beyond the
> > - capability of the generated instruction (JAL: +/-1MB PC-relative).
> > + capability of the generated instruction (JAL: +/-1MB PC-relative). The
> > + workaround is to disable ``test_ring_basic_ex()`` and
> > ``test_ring_with_exact_size()`` on RISC-V on ``-O0`` or ``-Og``.
> >
> > * **Updated Intel iavf driver.**
> >
> > --
> > 2.30.2
>
