[dpdk-dev] [RFC PATCH] lpm: add sve support for lookup on Arm platform

[Ruifeng Wang]

Added new path to do lpm4 lookup by using scalable vector extension.
The SVE path will be selected if compiler has flag SVE set.

Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
---
 lib/librte_eal/arm/include/rte_vect.h |  3 +
 lib/librte_lpm/meson.build            |  2 +-
 lib/librte_lpm/rte_lpm.h              |  4 ++
 lib/librte_lpm/rte_lpm_sve.h          | 83 +++++++++++++++++++++++++++
 4 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 lib/librte_lpm/rte_lpm_sve.h

diff --git a/lib/librte_eal/arm/include/rte_vect.h b/lib/librte_eal/arm/include/rte_vect.h
index a739e6e66..093e9122a 100644
--- a/lib/librte_eal/arm/include/rte_vect.h
+++ b/lib/librte_eal/arm/include/rte_vect.h
@@ -9,6 +9,9 @@
 #include "generic/rte_vect.h"
 #include "rte_debug.h"
 #include "arm_neon.h"
+#ifdef __ARM_FEATURE_SVE
+#include <arm_sve.h>
+#endif
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/lib/librte_lpm/meson.build b/lib/librte_lpm/meson.build
index 6cfc083c5..f93c86640 100644
--- a/lib/librte_lpm/meson.build
+++ b/lib/librte_lpm/meson.build
@@ -5,6 +5,6 @@ sources = files('rte_lpm.c', 'rte_lpm6.c')
 headers = files('rte_lpm.h', 'rte_lpm6.h')
 # since header files have different names, we can install all vector headers
 # without worrying about which architecture we actually need
-headers += files('rte_lpm_altivec.h', 'rte_lpm_neon.h', 'rte_lpm_sse.h')
+headers += files('rte_lpm_altivec.h', 'rte_lpm_neon.h', 'rte_lpm_sse.h', 'rte_lpm_sve.h')
 deps += ['hash']
 deps += ['rcu']
diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h
index 1afe55cdc..28b57683b 100644
--- a/lib/librte_lpm/rte_lpm.h
+++ b/lib/librte_lpm/rte_lpm.h
@@ -402,7 +402,11 @@ rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
 	uint32_t defv);
 
 #if defined(RTE_ARCH_ARM)
+#ifdef __ARM_FEATURE_SVE
+#include "rte_lpm_sve.h"
+#else
 #include "rte_lpm_neon.h"
+#endif
 #elif defined(RTE_ARCH_PPC_64)
 #include "rte_lpm_altivec.h"
 #else
diff --git a/lib/librte_lpm/rte_lpm_sve.h b/lib/librte_lpm/rte_lpm_sve.h
new file mode 100644
index 000000000..86576ec52
--- /dev/null
+++ b/lib/librte_lpm/rte_lpm_sve.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2020 Arm Limited
+ */
+
+#ifndef _RTE_LPM_SVE_H_
+#define _RTE_LPM_SVE_H_
+
+#include <rte_vect.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+__rte_internal
+static void
+__rte_lpm_lookup_vec(const struct rte_lpm *lpm, const uint32_t *ips,
+		uint32_t *__rte_restrict next_hops, const uint32_t n)
+{
+	uint32_t i = 0;
+	svuint32_t v_ip, v_idx, v_tbl24, v_tbl8, v_hop;
+	svuint32_t v_mask_xv, v_mask_v, v_mask_hop;
+	svbool_t pg = svwhilelt_b32(i, n);
+	svbool_t pv;
+
+	do {
+		v_ip = svld1(pg, &ips[i]);
+		/* Get indices for tbl24[] */
+		v_idx = svlsr_x(pg, v_ip, 8);
+		/* Extract values from tbl24[] */
+		v_tbl24 = svld1_gather_index(pg, (const uint32_t *)lpm->tbl24,
+						v_idx);
+
+		/* Create mask with valid set */
+		v_mask_v = svdup_u32_z(pg, RTE_LPM_LOOKUP_SUCCESS);
+		/* Create mask with valid and valid_group set */
+		v_mask_xv = svdup_u32_z(pg, RTE_LPM_VALID_EXT_ENTRY_BITMASK);
+		/* Create predicate for tbl24 entries: (valid && !valid_group) */
+		pv = svcmpeq(pg, svand_z(pg, v_tbl24, v_mask_xv), v_mask_v);
+		/* Create mask for next_hop in table entry */
+		v_mask_hop = svdup_u32_z(pg, 0x00ffffff);
+		/* Extract next_hop and write back */
+		v_hop = svand_x(pv, v_tbl24, v_mask_hop);
+		svst1(pv, &next_hops[i], v_hop);
+
+		/* Update predicate for tbl24 entries: (valid && valid_group) */
+		pv = svcmpeq(pg, svand_z(pg, v_tbl24, v_mask_xv), v_mask_xv);
+		/* Compute tbl8 index */
+		v_idx = svand_x(pv, v_tbl24, svdup_u32_z(pv, 0xff));
+		v_idx = svmul_x(pv, v_idx, RTE_LPM_TBL8_GROUP_NUM_ENTRIES);
+		v_idx = svadd_x(pv, svand_x(pv, v_ip, svdup_u32_z(pv, 0xff)),
+				v_idx);
+		/* Extract values from tbl8[] */
+		v_tbl8 = svld1_gather_index(pv, (const uint32_t *)lpm->tbl8,
+						v_idx);
+		/* Update predicate for tbl8 entries: (valid) */
+		pv = svcmpeq(pv, svand_z(pv, v_tbl8, v_mask_v), v_mask_v);
+		/* Extract next_hop and write back */
+		v_hop = svand_x(pv, v_tbl8, v_mask_hop);
+		svst1(pv, &next_hops[i], v_hop);
+
+		i += svlen(v_ip);
+		pg = svwhilelt_b32(i, n);
+	} while (svptest_any(svptrue_b32(), pg));
+}
+
+static inline void
+rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
+		uint32_t defv)
+{
+	uint32_t i, ips[4];
+
+	vst1q_s32((int32_t *)ips, ip);
+	for (i = 0; i < 4; i++)
+		hop[i] = defv;
+
+	__rte_lpm_lookup_vec(lpm, ips, hop, 4);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_LPM_SVE_H_ */
-- 
2.25.1