[PATCH 09/11] test/ring: disable problematic tests for RISC-V

[Stanislaw Kardach <kda@semihalf.com>]

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>
---
 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