[dpdk-dev] [PATCH v1] config/arm: split march cfg into arch and features

["Juraj Linkeš" <juraj.linkes@pantheon.tech>]

Older compilers may not support all arch versions and all features that
the target SoC supports, in which case it's better figure out the
highest arch version and features that the compiler supports. Implement
a way to achieve this:
1. Find the highest arch version that the compiler supports, keeping in
mind the SoC arch version we're building. For example, if the SoC arch
version is arm8.2-a, but the compiler only supports arm8.1-a, use
arm8.1-a. On the other hand, if the compiler supports arm8.3-a (or
higher), use armv8.2-a.
2. With the architecture version locked, iterate over SoC features and
use all that are supported.

In all cases, emit a warning if there's something unsupported by the
compiler.

Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
---
 config/arm/meson.build | 122 +++++++++++++++++++++++++++++++++--------
 1 file changed, 98 insertions(+), 24 deletions(-)

diff --git a/config/arm/meson.build b/config/arm/meson.build
index 9b147c0b93..9114d8a59c 100644
--- a/config/arm/meson.build
+++ b/config/arm/meson.build
@@ -37,20 +37,26 @@ implementer_generic = {
         ['RTE_MAX_NUMA_NODES', 4]
     ],
     'part_number_config': {
-        'generic': {'machine_args': ['-march=armv8-a+crc', '-moutline-atomics']}
+        'generic': {
+            'march': 'armv8-a',
+            'march_features': ['crc'],
+            'compiler_options': ['-moutline-atomics']
+        }
     }
 }
 
 part_number_config_arm = {
-    '0xd03': {'machine_args':  ['-mcpu=cortex-a53']},
-    '0xd04': {'machine_args':  ['-mcpu=cortex-a35']},
-    '0xd07': {'machine_args':  ['-mcpu=cortex-a57']},
-    '0xd08': {'machine_args':  ['-mcpu=cortex-a72']},
-    '0xd09': {'machine_args':  ['-mcpu=cortex-a73']},
-    '0xd0a': {'machine_args':  ['-mcpu=cortex-a75']},
-    '0xd0b': {'machine_args':  ['-mcpu=cortex-a76']},
+    '0xd03': {'compiler_options':  ['-mcpu=cortex-a53']},
+    '0xd04': {'compiler_options':  ['-mcpu=cortex-a35']},
+    '0xd07': {'compiler_options':  ['-mcpu=cortex-a57']},
+    '0xd08': {'compiler_options':  ['-mcpu=cortex-a72']},
+    '0xd09': {'compiler_options':  ['-mcpu=cortex-a73']},
+    '0xd0a': {'compiler_options':  ['-mcpu=cortex-a75']},
+    '0xd0b': {'compiler_options':  ['-mcpu=cortex-a76']},
     '0xd0c': {
-        'machine_args':  ['-march=armv8.2-a+crypto', '-mcpu=neoverse-n1'],
+        'march': 'armv8.2-a',
+        'march_features': ['crypto'],
+        'compiler_options':  ['-mcpu=neoverse-n1'],
         'flags': [
             ['RTE_MACHINE', '"neoverse-n1"'],
             ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -60,7 +66,8 @@ part_number_config_arm = {
         ]
     },
     '0xd49': {
-        'machine_args':  ['-march=armv8.5-a+crypto+sve2'],
+        'march': 'armv8.5-a',
+        'march_features': ['crypto', 'sve2'],
         'flags': [
             ['RTE_MACHINE', '"neoverse-n2"'],
             ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -94,19 +101,21 @@ implementer_cavium = {
     ],
     'part_number_config': {
         '0xa1': {
-            'machine_args': ['-mcpu=thunderxt88'],
+            'compiler_options': ['-mcpu=thunderxt88'],
             'flags': flags_part_number_thunderx
         },
         '0xa2': {
-            'machine_args': ['-mcpu=thunderxt81'],
+            'compiler_options': ['-mcpu=thunderxt81'],
             'flags': flags_part_number_thunderx
         },
         '0xa3': {
-            'machine_args': ['-mcpu=thunderxt83'],
+            'compiler_options': ['-mcpu=thunderxt83'],
             'flags': flags_part_number_thunderx
         },
         '0xaf': {
-            'machine_args': ['-march=armv8.1-a+crc+crypto', '-mcpu=thunderx2t99'],
+            'march': 'armv8.1-a',
+            'march_features': ['crc', 'crypto'],
+            'compiler_options': ['-mcpu=thunderx2t99'],
             'flags': [
                 ['RTE_MACHINE', '"thunderx2"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -116,7 +125,9 @@ implementer_cavium = {
             ]
         },
         '0xb2': {
-            'machine_args': ['-march=armv8.2-a+crc+crypto+lse', '-mcpu=octeontx2'],
+            'march': 'armv8.2-a',
+            'march_features': ['crc', 'crypto', 'lse'],
+            'compiler_options': ['-mcpu=octeontx2'],
             'flags': [
                 ['RTE_MACHINE', '"octeontx2"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -137,7 +148,11 @@ implementer_ampere = {
         ['RTE_MAX_NUMA_NODES', 1]
     ],
     'part_number_config': {
-        '0x0': {'machine_args':  ['-march=armv8-a+crc+crypto', '-mtune=emag']}
+        '0x0': {
+            'march': 'armv8-a',
+            'march_features': ['crc', 'crypto'],
+            'compiler_options':  ['-mtune=emag']
+        }
     }
 }
 
@@ -149,7 +164,9 @@ implementer_hisilicon = {
     ],
     'part_number_config': {
         '0xd01': {
-            'machine_args': ['-march=armv8.2-a+crypto', '-mtune=tsv110'],
+            'march': 'armv8.2-a',
+            'march_features': ['crypto'],
+            'compiler_options': ['-mtune=tsv110'],
             'flags': [
                 ['RTE_MACHINE', '"Kunpeng 920"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -158,7 +175,8 @@ implementer_hisilicon = {
             ]
         },
         '0xd02': {
-            'machine_args': ['-march=armv8.2-a+crypto+sve'],
+            'march': 'armv8.2-a',
+            'march_features': ['crypto', 'sve'],
             'flags': [
                 ['RTE_MACHINE', '"Kunpeng 930"'],
                 ['RTE_ARM_FEATURE_ATOMICS', true],
@@ -179,7 +197,10 @@ implementer_qualcomm = {
         ['RTE_MAX_NUMA_NODES', 1]
     ],
     'part_number_config': {
-        '0xc00': {'machine_args':  ['-march=armv8-a+crc']}
+        '0xc00': {
+            'march': 'armv8-a',
+            'march_features': ['crc']
+        }
     }
 }
 
@@ -458,13 +479,66 @@ else
     # add/overwrite flags in the proper order
     dpdk_flags = flags_common + implementer_config['flags'] + part_number_config.get('flags', []) + soc_flags
 
-    # apply supported machine args
     machine_args = [] # Clear previous machine args
-    foreach flag: part_number_config['machine_args']
-        if cc.has_argument(flag)
-            machine_args += flag
+
+    # probe supported marchs and their features
+    candidate_march = ''
+    if part_number_config.has_key('march')
+        supported_marchs = ['armv8.6-a', 'armv8.5-a', 'armv8.4-a', 'armv8.3-a',
+                            'armv8.2-a', 'armv8.1-a', 'armv8-a']
+        check_compiler_support = false
+        foreach supported_march: supported_marchs
+            if supported_march == part_number_config['march']
+                # start checking from this version downwards
+                check_compiler_support = true
+            endif
+            if check_compiler_support and
+                cc.has_argument('-march=' + supported_march)
+                candidate_march = supported_march
+                # highest supported march version found
+                break
+            endif
+        endforeach
+        if candidate_march == ''
+            error('No suitable armv8 march version found.')
+        else
+            if candidate_march != part_number_config['march']
+                warning('Configuration march version is ' +
+                        '@0@, but the compiler supports only @1@.'
+                        .format(part_number_config['march'], candidate_march))
+            endif
+            candidate_march = '-march=' + candidate_march
         endif
-    endforeach
+        if part_number_config.has_key('march_features')
+            feature_unsupported = false
+            foreach feature: part_number_config['march_features']
+                if cc.has_argument('+'.join([candidate_march, feature]))
+                    candidate_march = '+'.join([candidate_march, feature])
+                else
+                    feature_unsupported = true
+                endif
+            endforeach
+            if feature_unsupported
+                warning('Configuration march features are ' +
+                        '@0@, but the compiler supports only @1@.'
+                        .format(part_number_config['march_features'],
+                                candidate_march))
+            endif
+        endif
+        machine_args += candidate_march
+    endif
+
+    # apply supported compiler options
+    if part_number_config.has_key('compiler_options')
+        foreach flag: part_number_config['compiler_options']
+            if cc.has_argument(flag)
+                machine_args += flag
+            else
+                warning('Configuration compiler option ' +
+                        '@0@ isn\'t supported.'.format(flag))
+            endif
+        endforeach
+    endif
 
     # apply flags
     foreach flag: dpdk_flags
-- 
2.20.1