-----Original Message-----
From: Juraj Linkeš <redacted>
Sent: Monday, July 12, 2021 9:02 PM
To: thomas@monjalon.net; david.marchand@redhat.com;
bruce.richardson@intel.com; Honnappa Nagarahalli
[off-list ref]; Ruifeng Wang
[off-list ref]; fengchengwen@huawei.com;
ferruh.yigit@intel.com; jerinjacobk@gmail.com; jerinj@marvell.com
Cc: dev@dpdk.org; Juraj Linkeš <redacted>
Subject: [PATCH v3] config/arm: split march cfg into arch and features

Older compilers may not support all arch versions and all features that the
target SoC supports, in which case it's better to 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 <redacted>
---
v3: rebase
---
 config/arm/meson.build | 125 ++++++++++++++++++++++++++++++++-----
----
 1 file changed, 100 insertions(+), 25 deletions(-)

diff --git a/config/arm/meson.build b/config/arm/meson.build index

14987c634a..f5cd30f4f0 100644

--- a/config/arm/meson.build
+++ b/config/arm/meson.build

@@ -38,7 +38,9 @@ implementer_generic = {
     ],
     'part_number_config': {
         'generic': {
-            'machine_args': ['-march=armv8-a+crc', '-moutline-atomics']
+            'march': 'armv8-a',
+            'march_features': ['crc'],
+            'compiler_options': ['-moutline-atomics']
         },
         'generic_aarch32': {
             'machine_args': ['-march=armv8-a', '-mfpu=neon'], @@ -53,15 +55,17

@@ implementer_generic = {  }

 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], @@ -71,7 +75,8 @@

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], @@ -105,19 +110,21 @@
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], @@ -127,7 +134,9 @@
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], @@ -148,7 +157,11 @@
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']
+        }
     }
 }

@@ -160,7 +173,9 @@ 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], @@ -169,7 +184,8 @@

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], @@ -190,8 +206,14 @@
implementer_qualcomm = {
         ['RTE_MAX_NUMA_NODES', 1]
     ],
     'part_number_config': {
-        '0x800': {'machine_args':  ['-march=armv8-a+crc']},
-        '0xc00': {'machine_args':  ['-march=armv8-a+crc']},
+        '0x800': {
+            'march': 'armv8-a',
+            'march_features': ['crc']
+        },
+        '0xc00': {
+            'march': 'armv8-a',
+            'march_features': ['crc']
+        }
     }
 }

@@ -500,13 +522,66 @@ if update_flags
     # 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