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* [PATCH 1/3] config/riscv: detect V extension
@ 2025-05-28 16:57 uk7b
  2025-06-04 11:49 ` [PATCH v2 0/3] Add RISC-V V extension detection and LPM optimization uk7b
                   ` (11 more replies)
  0 siblings, 12 replies; 19+ messages in thread
From: uk7b @ 2025-05-28 16:57 UTC (permalink / raw)
  To: dev; +Cc: sunyuechi, Stanislaw Kardach, Bruce Richardson

From: sunyuechi <sunyuechi@iscas.ac.cn>

This patch is derived from "config/riscv: detect presence of Zbc
extension with modifications".

The RISC-V C api defines architecture extension test macros
These let us detect whether the V extension is supported on the
compiler and -march we're building with. The C api also defines V
intrinsics we can use rather than inline assembly on newer versions of
GCC (14.1.0+) and Clang (18.1.0+).

If the V extension and intrinsics are both present and we can detect
the V extension at runtime, we define a flag, RTE_RISCV_FEATURE_V.

Signed-off-by: sunyuechi <sunyuechi@iscas.ac.cn>
---
 config/riscv/meson.build | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/config/riscv/meson.build b/config/riscv/meson.build
index 7562c6cb99..e3694cf2e6 100644
--- a/config/riscv/meson.build
+++ b/config/riscv/meson.build
@@ -119,6 +119,31 @@ foreach flag: arch_config['machine_args']
     endif
 endforeach
 
+# check if we can do buildtime detection of extensions supported by the target
+riscv_extension_macros = false
+if (cc.get_define('__riscv_arch_test', args: machine_args) == '1')
+  message('Detected architecture extension test macros')
+  riscv_extension_macros = true
+else
+  warning('RISC-V architecture extension test macros not available. Build-time detection of extensions not possible')
+endif
+
+# detect extensions
+# Requires intrinsics available in GCC 14.1.0+ and Clang 18.1.0+
+if (riscv_extension_macros and
+    (cc.get_define('__riscv_vector', args: machine_args) != ''))
+  if ((cc.get_id() == 'gcc' and cc.version().version_compare('>=14.1.0'))
+      or (cc.get_id() == 'clang' and cc.version().version_compare('>=18.1.0')))
+    if (cc.compiles('''#include <riscv_vector.h>
+        int main(void) { size_t vl = __riscv_vsetvl_e32m1(1); }''', args: machine_args))
+      message('Compiling with the V extension')
+      machine_args += ['-DRTE_RISCV_FEATURE_V']
+    endif
+  else
+    warning('Detected V extension but cannot use because intrinsics are not available (present in GCC 14.1.0+ and Clang 18.1.0+)')
+  endif
+endif
+
 # apply flags
 foreach flag: dpdk_flags
     if flag.length() > 0
-- 
2.49.0


^ permalink raw reply	[flat|nested] 19+ messages in thread
end of thread, other threads:[~2025-06-05 10:59 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2025-05-28 16:57 [PATCH 1/3] config/riscv: detect V extension uk7b
2025-06-04 11:49 ` [PATCH v2 0/3] Add RISC-V V extension detection and LPM optimization uk7b
2025-06-04 11:49 ` [PATCH v2 1/3] config/riscv: detect V extension uk7b
2025-06-04 19:54   ` Stephen Hemminger
2025-06-04 11:49 ` [PATCH v2 2/3] lib/lpm: R-V V rte_lpm_lookupx4 uk7b
2025-06-04 11:49 ` [PATCH v2 3/3] riscv: override machine_args only when default uk7b
2025-06-04 13:07 ` [PATCH v2 0/3] Add RISC-V V extension detection and LPM optimization uk7b
2025-06-04 13:16   ` 孙越池
2025-06-04 13:07 ` [PATCH v2 1/3] config/riscv: detect V extension uk7b
2025-06-04 13:07 ` [PATCH v2 2/3] lib/lpm: R-V V rte_lpm_lookupx4 uk7b
2025-06-04 13:07 ` [PATCH v2 3/3] riscv: override machine_args only when default uk7b
2025-06-04 15:47 ` [PATCH v3 0/3] Add RISC-V V extension detection and LPM optimization uk7b
     [not found] ` <20250604154720.3078131-1-uk7b@foxmail.com>
2025-06-04 15:47   ` [PATCH v3 1/3] config/riscv: detect V extension uk7b
2025-06-04 15:47   ` [PATCH v3 2/3] lib/lpm: R-V V rte_lpm_lookupx4 uk7b
2025-06-04 15:47   ` [PATCH v3 3/3] riscv: override machine_args only when default uk7b
2025-06-05 10:58 ` [PATCH v4 0/3] [PATCH v4 0/3] Add RISC-V V extension detection and LPM optimization uk7b
     [not found] ` <20250605105844.3931758-1-uk7b@foxmail.com>
2025-06-05 10:58   ` [PATCH v4 1/3] config/riscv: detect V extension uk7b
2025-06-05 10:58   ` [PATCH v4 2/3] lib/lpm: R-V V rte_lpm_lookupx4 uk7b
2025-06-05 10:58   ` [PATCH v4 3/3] riscv: override machine_args only when default uk7b

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