> On Feb 5, 2024, at 10:10 PM, Wathsala Wathawana Vithanage
> <wathsala.vithan...@arm.com> wrote:
>
> Hi Pavan,
>
>> The compiler options march and mtune are a subset of mcpu and will lead to
>> conflicts if improper march is chosen for a given mcpu.
>> To avoid conflicts, force part number march when mcpu is available and is
>> supported by the compiler.
>
> Why would one force the march specified in the part number when mcpu for
> that part number is also available and supported by the compiler?
>
It would be good to explain the use case or the problem being faced.
>>
>> Example:
>> march = armv9-a
>> mcpu = neoverse-n2
>>
>> mcpu supported, march supported
>> machine_args = ['-mcpu=neoverse-n2', '-march=armv9-a']
>
> -march restricts the compiler to baseline architecture of the -mcpu.
> For instance, Neoverse-n1's baseline architecture is armv8.2-a,
> but it has some extensions from armv8.3-a, armv8.4-a, and armv8.5-a.
> By setting -march to armv8.2-a the compiler will strictly omit extensions
> from 8.3, 8.4 and 8.5 resulting in a suboptimal outcome.
>
>>
>> mcpu supported, march not supported
>> machine_args = ['-mcpu=neoverse-n2']
>
> This will result in the best outcome.
>
>>
>> mcpu not supported, march supported
>> machine_args = ['-march=armv9-a']
>
> This too may result in a suboptimal outcome as optimization space
> is limited to the given march (not using extensions from later
> architectures when available).
>
>>
>> mcpu not supported, march not supported
>> machine_args = ['-march=armv8.6-a']
>
> Compiler knows nothing about the target CPU or the architecture.
> I think it's better to exit the build process with an error.
>
>>
>> Signed-off-by: Pavan Nikhilesh <pbhagavat...@marvell.com>
>> ---
>> v2 Changes:
>> - Cleanup march inconsistencies. (Juraj Linkes)
>> - Unify fallback march selection. (Juraj Linkes)
>> - Tag along ARM WFE patch.
>> v3 Changes:
>> - Fix missing 'fallback_march' key check.
>>
>> config/arm/meson.build | 108 +++++++++++++++++++++++++---------------
>> -
>> 1 file changed, 66 insertions(+), 42 deletions(-)
>>
>> diff --git a/config/arm/meson.build b/config/arm/meson.build index
>> 36f21d22599a..ba859bd060b5 100644
>> --- a/config/arm/meson.build
>> +++ b/config/arm/meson.build
>> @@ -58,18 +58,18 @@ implementer_generic = { }
>>
>> part_number_config_arm = {
>> - '0xd03': {'compiler_options': ['-mcpu=cortex-a53']},
>> - '0xd04': {'compiler_options': ['-mcpu=cortex-a35']},
>> - '0xd05': {'compiler_options': ['-mcpu=cortex-a55']},
>> - '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']},
>> + '0xd03': {'mcpu': 'cortex-a53'},
>> + '0xd04': {'mcpu': 'cortex-a35'},
>> + '0xd05': {'mcpu': 'cortex-a55'},
>> + '0xd07': {'mcpu': 'cortex-a57'},
>> + '0xd08': {'mcpu': 'cortex-a72'},
>> + '0xd09': {'mcpu': 'cortex-a73'},
>> + '0xd0a': {'mcpu': 'cortex-a75'},
>> + '0xd0b': {'mcpu': 'cortex-a76'},
>> '0xd0c': {
>> 'march': 'armv8.2-a',
>> 'march_features': ['crypto', 'rcpc'],
>> - 'compiler_options': ['-mcpu=neoverse-n1'],
>> + 'mcpu': 'neoverse-n1',
>> 'flags': [
>> ['RTE_MACHINE', '"neoverse-n1"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -81,7 +81,7 @@
>> part_number_config_arm = {
>> '0xd40': {
>> 'march': 'armv8.4-a',
>> 'march_features': ['sve'],
>> - 'compiler_options': ['-mcpu=neoverse-v1'],
>> + 'mcpu': 'neoverse-v1',
>> 'flags': [
>> ['RTE_MACHINE', '"neoverse-v1"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -92,8 +92,9 @@
>> part_number_config_arm = {
>> 'march': 'armv8.4-a',
>> },
>> '0xd49': {
>> + 'march': 'armv9-a',
>> 'march_features': ['sve2'],
>> - 'compiler_options': ['-mcpu=neoverse-n2'],
>> + 'mcpu': 'neoverse-n2',
>> 'flags': [
>> ['RTE_MACHINE', '"neoverse-n2"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -127,21 +128,23 @@
>> implementer_cavium = {
>> ],
>> 'part_number_config': {
>> '0xa1': {
>> - 'compiler_options': ['-mcpu=thunderxt88'],
>> + 'mcpu': 'thunderxt88',
>> 'flags': flags_part_number_thunderx
>> },
>> '0xa2': {
>> - 'compiler_options': ['-mcpu=thunderxt81'],
>> + 'mcpu': 'thunderxt81',
>> 'flags': flags_part_number_thunderx
>> },
>> '0xa3': {
>> - 'compiler_options': ['-march=armv8-a+crc', '-mcpu=thunderxt83'],
>> + 'march': 'armv8-a',
>> + 'march_features': ['crc'],
>> + 'mcpu': 'thunderxt83',
>> 'flags': flags_part_number_thunderx
>> },
>> '0xaf': {
>> 'march': 'armv8.1-a',
>> 'march_features': ['crc', 'crypto'],
>> - 'compiler_options': ['-mcpu=thunderx2t99'],
>> + 'mcpu': 'thunderx2t99',
>> 'flags': [
>> ['RTE_MACHINE', '"thunderx2"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -153,7 +156,7 @@
>> implementer_cavium = {
>> '0xb2': {
>> 'march': 'armv8.2-a',
>> 'march_features': ['crc', 'crypto', 'lse'],
>> - 'compiler_options': ['-mcpu=octeontx2'],
>> + 'mcpu': 'octeontx2',
>> 'flags': [
>> ['RTE_MACHINE', '"cn9k"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -176,7 +179,7 @@
>> implementer_ampere = {
>> '0x0': {
>> 'march': 'armv8-a',
>> 'march_features': ['crc', 'crypto'],
>> - 'compiler_options': ['-mtune=emag'],
>> + 'mcpu': 'emag',
>> 'flags': [
>> ['RTE_MACHINE', '"eMAG"'],
>> ['RTE_MAX_LCORE', 32],
>> @@ -186,7 +189,7 @@ implementer_ampere = {
>> '0xac3': {
>> 'march': 'armv8.6-a',
>> 'march_features': ['crc', 'crypto'],
>> - 'compiler_options': ['-mcpu=ampere1'],
>> + 'mcpu': 'ampere1',
>> 'flags': [
>> ['RTE_MACHINE', '"AmpereOne"'],
>> ['RTE_MAX_LCORE', 320], @@ -206,7 +209,7 @@
>> implementer_hisilicon = {
>> '0xd01': {
>> 'march': 'armv8.2-a',
>> 'march_features': ['crypto'],
>> - 'compiler_options': ['-mtune=tsv110'],
>> + 'mcpu': 'tsv110',
>> 'flags': [
>> ['RTE_MACHINE', '"Kunpeng 920"'],
>> ['RTE_ARM_FEATURE_ATOMICS', true], @@ -695,11 +698,21 @@ if
>> update_flags
>>
>> machine_args = [] # Clear previous machine args
>>
>> + candidate_mcpu = ''
>> + if part_number_config.has_key('mcpu')
>> + mcpu = part_number_config['mcpu']
>> + if (cc.has_argument('-mcpu=' + mcpu))
>> + candidate_mcpu = mcpu
>> + endif
>> + endif
>> +
>> # probe supported archs and their features
>> candidate_march = ''
>> if part_number_config.has_key('march')
>> - if part_number_config.get('force_march', false)
>> - candidate_march = part_number_config['march']
>> + if part_number_config.get('force_march', false) or candidate_mcpu
>> != ''
>> + if cc.has_argument('-march=' + part_number_config['march'])
>> + candidate_march = part_number_config['march']
>> + endif
>> else
>> supported_marchs = ['armv8.6-a', 'armv8.5-a', 'armv8.4-a',
>> 'armv8.3-
>> a',
>> 'armv8.2-a', 'armv8.1-a', 'armv8-a'] @@
>> -717,32 +730,43
>> @@ if update_flags
>> endif
>> endforeach
>> endif
>> - if candidate_march == ''
>> - error('No suitable armv8 march version found.')
>> - endif
>> +
>> 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))
>> + warning('Configuration march version is @0@, not supported.'
>> + .format(part_number_config['march']))
>> + if candidate_march != ''
>> + warning('Using march version @0@.'.format(candidate_march))
>> + endif
>> endif
>> - candidate_march = '-march=' + candidate_march
>>
>> - march_features = []
>> - if part_number_config.has_key('march_features')
>> - march_features += part_number_config['march_features']
>> - endif
>> - if soc_config.has_key('extra_march_features')
>> - march_features += soc_config['extra_march_features']
>> + if candidate_march == '' and candidate_mcpu == ''
>> + error('No suitable ARM march/mcpu version found.')
>> endif
>> - foreach feature: march_features
>> - if cc.has_argument('+'.join([candidate_march, feature]))
>> - candidate_march = '+'.join([candidate_march, feature])
>> - else
>> - warning('The compiler does not support feature @0@'
>> - .format(feature))
>> +
>> + if candidate_march != ''
>> + candidate_march = '-march=' + candidate_march
>> + march_features = []
>> + if part_number_config.has_key('march_features')
>> + march_features += part_number_config['march_features']
>> endif
>> - endforeach
>> - machine_args += candidate_march
>> + if soc_config.has_key('extra_march_features')
>> + march_features += soc_config['extra_march_features']
>> + endif
>> + foreach feature: march_features
>> + if cc.has_argument('+'.join([candidate_march, feature]))
>> + candidate_march = '+'.join([candidate_march, feature])
>> + else
>> + warning('The compiler does not support feature @0@'
>> + .format(feature))
>> + endif
>> + endforeach
>> + machine_args += candidate_march
>> + endif
>> + endif
>> +
>> + if candidate_mcpu != ''
>> + candidate_mcpu = '-mcpu=' + candidate_mcpu
>> + machine_args += candidate_mcpu
>> endif
>>
>> # apply supported compiler options
>> --
>> 2.43.0
>
