[flang-commits] [clang] [flang] [llvm] [polly] [Plugins] Pass options to a pass plugin in -load-pass-plugin (PR #226773)

[Fangrui Song via flang-commits]

MaskRay wrote:

Revised based on the review. The interface is now:

```
opt -load-pass-plugin=Bye.so -plugin-arg=Bye,-wave-goodbye -passes=goodbye a.ll
opt -load-pass-plugin=LLVMPolly.so -plugin-arg=Polly,-polly-tile-sizes=64,1 ...
```

- `-load-pass-plugin=<file>` is a plain path, which may contain commas. opt, llc, and clang-linker-wrapper load plugins after `cl::ParseCommandLineOptions`, so a loaded plugin's options are no longer accepted as ordinary options.
- `-plugin-arg=<plugin>,<arg>` is split at the first comma, so `<arg>` may contain commas. The arguments go, in order, to the new `PassPluginLibraryInfo::ParseArguments` callback of the plugin with that name (`LLVM_PLUGIN_API_VERSION 3`). PassPlugin itself no longer calls cl::; plugins that define cl::opt (Bye, IRTransforms, Polly) call cl::ParseCommandLineOptions from the callback.
- Polly is migrated: `%{polly,}` expands to `-plugin-arg=Polly`, when Polly is a plugin and to nothing when it is linked into tools, where its options stay global. check-polly passes in both configurations (1137 linked, 1136 with LLVM_POLLY_LINK_INTO_TOOLS=OFF).


- -load-pass-plugin=<file> is a plain path again (commas in paths work as on main, and clang/flang/LTO are unchanged). opt, llc, and clang-linker-wrapper load plugins after cl::ParseCommandLineOptions, so a loaded plugin's options are no longer accepted as ordinary options.
- -plugin-arg=<plugin>,<arg> is split at the first comma only, so values may contain commas. All arguments naming a plugin are collected in command-line order and passed in one call to that plugin's ParseArguments callback. This mirrors clang's frontend plugins: clang -fplugin=foo.so -fplugin-arg-foo-<arg>, which the driver turns into cc1 -load foo.so -plugin-arg-foo <arg>. The plugin name moves into the value because a cl:: option can't have the plugin name in its spelling.
- PassPlugin itself no longer calls cl::. Plugins that define cl::opt (Bye, IRTransforms, Polly) call cl::ParseCommandLineOptions from the callback.
- PassPluginLibraryInfo gains Error `(*ParseArguments)(ArrayRef<const char *>)` after PreCodeGenCallback, so LLVM_PLUGIN_API_VERSION goes from 2 to 3, as its comment requires when callbacks are added. A plugin built against the old header is rejected with `Wrong API version on plugin '...'. Got version 2, supported version is 3`.
- Polly is migrated. In tests, each Polly option is prefixed with %{polly,}, which expands to `-plugin-arg=Polly,` when Polly is a plugin and to nothing when Polly is linked into tools, where its options stay global.

## Polly

```
; RUN: opt %loadNPMPolly %{polly,}-polly-tile-sizes=1,64 '-passes=polly-custom<opt-isl;ast>' %{polly,}-polly-print-ast -disable-output < %s | FileCheck %s
```

Linked into tools (unchanged from before):

```
opt -polly-process-unprofitable -polly-remarks-minimal -polly-use-llvm-names
    -polly-import-jscop-dir=.../ScheduleOptimizer -polly-codegen-verify
    -polly-tile-sizes=1,64 '-passes=polly-custom<opt-isl;ast>' -polly-print-ast -disable-output
```

As a plugin:

```
opt -load-pass-plugin=.../lib/LLVMPolly.so
    -plugin-arg=Polly,-polly-process-unprofitable -plugin-arg=Polly,-polly-remarks-minimal
    -plugin-arg=Polly,-polly-use-llvm-names -plugin-arg=Polly,-polly-import-jscop-dir=.../ScheduleOptimizer
    -plugin-arg=Polly,-polly-codegen-verify -plugin-arg=Polly,-polly-tile-sizes=1,64
    '-passes=polly-custom<opt-isl;ast>' -plugin-arg=Polly,-polly-print-ast -disable-output
```


https://github.com/llvm/llvm-project/pull/226773