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Posted to commits@tvm.apache.org by ar...@apache.org on 2021/10/12 17:53:13 UTC
[tvm-rfcs] branch main updated: Command Line Composition from
Internal Registry (#28)
This is an automated email from the ASF dual-hosted git repository.
areusch pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/tvm-rfcs.git
The following commit(s) were added to refs/heads/main by this push:
new 836250c Command Line Composition from Internal Registry (#28)
836250c is described below
commit 836250c17fee22b8aed00320a58b8f2ccde9f0d4
Author: Christopher Sidebottom <gi...@damouse.co.uk>
AuthorDate: Tue Oct 12 18:53:05 2021 +0100
Command Line Composition from Internal Registry (#28)
* Command Line Composition from Internal Registry
* Add additional demos to command line
* Provide more examples and clarification of scope
---
rfcs/0028-command-line-registry-composition.md | 178 +++++++++++++++++++++++++
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+- 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. This is currently limited to just the `Target` registry but with future work, such as [Migrating Target Attributes to IRModule](https://github.com/apache/tvm-rfcs/pull/29) there will be further options that require a standard CLI mechanism to interact with. The scope of this RFC is to define the pattern for translating between these internal registries and the CLI in a standard way which [...]
+
+# Motivation
+[motivation]: #motivation
+
+In order to motivate this, the `Target` will be used, as mentioned above this is a singular example of a general pattern - a core tenet of good UX is a series of well understood patterns that the user can re-apply through-out the use of a product.
+
+Coming to `tvmc` as a user 6-7 months ago, the `--target` is essentially magic compared to other CLI arguments which clearly detail the options available. Using a target string means that the entire `--target` argument is used as an opaque pass-through to the internal `Target` string parser, this obfuscates the options available to a `Target` and creates a non-standard sub-syntax for CLI users:
+```
+tvmc --target="woofles -mcpu=woof, c -mattr=+mwoof"
+```
+
+Users coming to TVM should be able to compose the available `Target` options and get meaningful help when doing that composition with `tvmc`, Such as:
+
+```bash
+$ tvmc --help
+usage: tvmc [-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)
+```
+
+The options are arranged in per-`Target` groups to allow the user to easily follow which are applicable and which aren't. The user can now replace their existing `Target` string, by using the documented `Target` options, with:
+```bash
+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 `argparse` parameters. 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_cmsisnn = parser.add_argument_group('target cmsisnn')
+target_cmsisnn.add_argument('--target-cmsisnn-mattr', type=str, help='target cmsisnn mattr string')
+
+args = parser.parse_args()
+print(args)
+```
+
+The user can get help for all available target options:
+```
+usage: tvmc [-h] [--target TARGET] [--target-c-mcpu TARGET_C_MCPU] [--target-c-mattr TARGET_C_MATTR] [--target-cmsisnn-mcpu TARGET_CMSISNN_MCPU] [--target-cmsisnn-mattr TARGET_CMSISNN_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 cmsisnn:
+ --target-cmsisnn-mattr TARGET_CMSISNN_MATTR
+ target lvm mattr string (default: None)
+```
+
+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
+```
+
+If a user tries to use an attribute of an unspecified `Target`, it is expected that it would error and provide feedback to the user, for example:
+
+```bash
+$ tvmc --target=cmsisnn,c \
+ --target-cmsisnn-mattr=+dsp \
+ --target-llvm-mcpu=cortex-m3 # Oh no, we asked for C but tried to configure LLVM
+Error: target llvm mcpu passed but target llvm not specified
+```
+
+# 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`:
+```python
+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):
+```shell
+gcc -fsanitize=address -fsanitize-address-use-after-scope
+```
+
+# Unresolved questions
+[unresolved-questions]: #unresolved-questions
+
+
+
+# Future possibilities
+[future-possibilities]: #future-possibilities
+
+## Pattern Re-use
+By creating the infrastructure to allow this composition and providing a standard pattern, we can allow `tvmc` users to compose other aspects of TVM in a similar way, such as `executor`:
+
+```
+tvmc --target=cmsisnn,c \ # Specifying multiple targets to enable in priority order
+ --target-cmsisnn-mattr=+dsp \
+ --target-c-mcpu=cortex-m3 \
+ --executor=aot \
+ --executor-aot-unpacked-api=1
+```
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