Mousius commented on a change in pull request #28: URL: https://github.com/apache/tvm-rfcs/pull/28#discussion_r726013981
########## File path: rfcs/0028-command-line-registry-composition.md ########## @@ -0,0 +1,153 @@ +- Feature Name: Command Line Composition from Internal Registry +- Start Date: 2021-08-24 +- RFC PR: [apache/tvm-rfcs#28](https://github.com/apache/tvm-rfcs/pull/28) +- GitHub Issue: [apache/tvm#0000](https://github.com/apache/tvm/issues/0000) + +# Summary +[summary]: #summary + +Introducing a standardised form for `tvmc` arguments to be populated from internal registries in TVM. + +# Motivation +[motivation]: #motivation + +Currently, when a user uses `tvmc`, they present a target string: +``` +tvmc --target="woofles -mcpu=woof, c -mattr=+mwoof" +``` + +Using a target string here means that the entire `--target` argument is used as an opaque pass-through to the internal `Target` string parser. Users coming to TVM should be able to compose these options and get meaningful help when doing that composition with `tvmc`. As an example, using the default `argparse` behaviour, the arguments can be registered as follows: +```python +import argparse +parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter) +parser.add_argument('--target', type=str, help='comma separated target list or target string') + +target_c = parser.add_argument_group('target c') +target_c.add_argument('--target-c-mcpu', type=str, help='target c mcpu string') +target_c.add_argument('--target-c-mattr', type=str, help='target c mattr string') + +target_llvm = parser.add_argument_group('target llvm') +target_llvm.add_argument('--target-llvm-mcpu', type=str, help='target llvm mcpu string') +target_llvm.add_argument('--target-llvm-mattr', type=str, help='target lvm mattr string') + +args = parser.parse_args() +print(args) +``` + +The user can get help for all available target options: +``` +usage: test.py [-h] [--target TARGET] [--target-c-mcpu TARGET_C_MCPU] [--target-c-mattr TARGET_C_MATTR] [--target-llvm-mcpu TARGET_LLVM_MCPU] [--target-llvm-mattr TARGET_LLVM_MATTR] + +optional arguments: + -h, --help show this help message and exit + --target TARGET comma separated target list or target string (default: None) + +target c: + --target-c-mcpu TARGET_C_MCPU + target c mcpu string (default: None) + --target-c-mattr TARGET_C_MATTR + target c mattr string (default: None) + +target llvm: + --target-llvm-mcpu TARGET_LLVM_MCPU + target llvm mcpu string (default: None) + --target-llvm-mattr TARGET_LLVM_MATTR + target lvm mattr string (default: None) +``` + +These are arranged in per-`Target` groups to allow the user to easily follow which are applicable and which aren't. The use can now replace their existing `Target` string, by using the documented `Target` options, with: +``` +tvmc --target=woofles,c \ + --target-woofles-mcpu=woof \ + --target-c-mattr=+mwoof +``` + +# Guide-level explanation +[guide-level-explanation]: #guide-level-explanation + +Alongside support for a target string, `tvmc` would populate a series of other arguments specific to targets which match the attributes found in the TargetKindRegistry in `target_kind.cc`. For example, consider a subset of the `c` `Target`: + +``` +TVM_REGISTER_TARGET_KIND("c", kDLCPU) + .add_attr_option<String>("mcpu") +``` + +This would be translated at the `tvmc` level to: +```bash +tvmc --target=c \ + --target-c-mcpu=cortex-m3 +``` + +Which would then allow the user to compose together these options, such as: + +```bash +tvmc --target=cmsisnn,c \ # Specifying multiple targets to enable in priority order + --target-cmsisnn-mattr=+dsp \ + --target-c-mcpu=cortex-m3 +``` + +# Reference-level explanation +[reference-level-explanation]: #reference-level-explanation + +There already exists a mechanism which provides Python with `PassConfig` information, via: + +```c++ +// Function Registry +TVM_REGISTER_GLOBAL("transform.ListConfigs").set_body_typed(PassContext::ListConfigs); +// Actual call +Map<String, Map<String, String>> PassContext::ListConfigs() { + return PassConfigManager::Global()->ListConfigs(); +} +// Implementation +Map<String, Map<String, String>> ListConfigs() { + Map<String, Map<String, String>> configs; + for (const auto& kv : key2vtype_) { + Map<String, String> metadata; + metadata.Set("type", kv.second.type_key); + configs.Set(kv.first, metadata); + } + return configs; +} +``` + +This can be replicated to provide the same information for `TargetKind` or any other registry and provide this information to generate arguments in `tvmc` using `argparse`: +``` +parser.add_argument(f"--target-{kind}-{attr}", ...) +``` + +# Drawbacks +[drawbacks]: #drawbacks + +# Rationale and alternatives +[rationale-and-alternatives]: #rationale-and-alternatives + +There's a number of alternative methods for injecting this information which have been used in other CLIs but obfuscate some of the information from the CLI arguments themselves: +- Continue using target strings +- Specify JSON + +# Prior art +[prior-art]: #prior-art + +This is not dissimilar to how `gcc` or `clang` provide options, [for example in gcc](https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html): +``` +gcc -fsanitize=address -fsanitize-address-use-after-scope +``` + +# Unresolved questions +[unresolved-questions]: #unresolved-questions + Review comment: Hi @areusch, Sorry, I'm totally missing something obvious I think, no other CLI parsing will be hurt in the process of introducing this, see: https://github.com/apache/tvm/pull/9218 Potentially this is related to https://github.com/apache/tvm-rfcs/pull/30 rather than this RFC? -- This is an automated message from the Apache Git Service. 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