[dpdk-dev] [PATCH v7 1/2] config/arm: select most suitable -march for kunpeng soc

[Chengwen Feng]

Currently, the soc_kunpeng930 declares '-march=armv8.2-a+crypto+sve',
but some compiler doesn't recognize the march because it doesn't
support sve.

To solve this bug we use the following scheme:
1. Define 'march_base' tuple which defines support march, it should
arrange from lower to higher.
e.g. 'march_base': ['-march=armv8.1-a', '-march=armv8.2-a']
2. Define 'march_feature' tuple which defines support feature.
e.g. 'march_feature': ['crypto', 'sve']
Note: If user defined 'march_feature', it also needs to define a valid
'march_base' because 'march_feature' depends on 'march_base' when
checking validity.
3. Select the most suitable march+feature combination based on
'march_base' and 'march_feature' tuples.
4. Use the selected march+feature combination as the default
machine_args.

Fixes: 7cf32a22b240 ("config/arm: add Hisilicon kunpeng")

Signed-off-by: Chengwen Feng <fengchengwen at huawei.com>
---
 config/arm/meson.build | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/config/arm/meson.build b/config/arm/meson.build
index 3f34ec9..044812f 100644
--- a/config/arm/meson.build
+++ b/config/arm/meson.build
@@ -158,7 +158,9 @@ implementer_hisilicon = {
             ]
         },
         '0xd02': {
-            'machine_args': ['-march=armv8.2-a+crypto+sve'],
+            'march_base': ['-march=armv8.2-a'],
+            'march_feature': ['crypto', 'sve'],
+            'machine_args': [],
             'flags': [
                 ['RTE_MACHINE', '"Kunpeng 930"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -449,8 +451,33 @@ else
     # add/overwrite flags in the proper order
     dpdk_flags = flags_common + implementer_config['flags'] + part_number_config.get('flags', []) + soc_flags
 
+    # select the most suitable march+feature combination
+    machine_march = []
+    if part_number_config.has_key('march_base')
+        tmp_machine_march = ''
+        march_valid = false
+        foreach march: part_number_config['march_base']
+            if cc.has_argument(march)
+                tmp_machine_march = march # Set the higher supported march as possible
+                march_valid = true
+            endif
+        endforeach
+        # select feature only when march valid
+        if march_valid and part_number_config.has_key('march_feature')
+            foreach feature: part_number_config['march_feature']
+                tmp_feature = tmp_machine_march + '+' + feature
+                if cc.has_argument(tmp_feature)
+                    tmp_machine_march = tmp_feature # Set the more supported feature as possible
+                endif
+            endforeach
+        endif
+        if march_valid
+            machine_march = [tmp_machine_march]
+        endif
+    endif
+
     # apply supported machine args
-    machine_args = [] # Clear previous machine args
+    machine_args = machine_march # Init with machine march which set above
     foreach flag: part_number_config['machine_args']
         if cc.has_argument(flag)
             machine_args += flag
-- 
2.8.1