[mlir-opt] Add '-p' as an alias for '-pass-pipeline'

[rkayaith]

Summary

The pipeline strings have been getting more verbose over time, adding an alias for the option should help improve the ergonomics a bit.

[mehdi_amini]

I'm not sure about this: isn't there a high risk of conflicts with another CL option named -p?

[rriddle]

In D137347#3906084, @mehdi_amini wrote:

I'm not sure about this: isn't there a high risk of conflicts with another CL option named -p?

We could consider prefix here (which would match the model for our other commands). I think it would be nice to have simpler syntax here, though the library situation makes it slightly tricky I suppose.

[rkayaith]

In D137347#3906084, @mehdi_amini wrote:

I'm not sure about this: isn't there a high risk of conflicts with another CL option named -p?

It's registered with llvm::cl::DefaultOption, which should allow other options to shadow this one: https://llvm.org/docs/CommandLine.html#miscellaneous-option-modifiers
And when I tried that out locally it seemed to work.

Another option would be making PassPipelineCLParser::passPipeline public and only registering the alias in mlir-opt

[rriddle]

In D137347#3906104, @rkayaith wrote:

In D137347#3906084, @mehdi_amini wrote:

I'm not sure about this: isn't there a high risk of conflicts with another CL option named -p?

It's registered with llvm::cl::DefaultOption, which should allow other options to shadow this one: https://llvm.org/docs/CommandLine.html#miscellaneous-option-modifiers
And when I tried that out locally it seemed to work.

Another option would be making PassPipelineCLParser::passPipeline public and only registering the alias in mlir-opt

We could also have an optional "registerAliases" or similar method on PassPipelineCLParser that could be called by users that want easier args. Then, users could specify what they want as alias, which might be nice anyways.

[mehdi_amini]

To me there is diminish return to the added complexity, and I'm not sure this is all pulling its weight.

[rkayaith]

• slightly different approach

[rkayaith]

The alias name is now an argument to the PassPipelineCLParser constructor so users can configure it, and it's now opt-in so this no longer affects other PassPipelineCLParser users

I think this should resolve the concerns about option name conflicts, and I don't think it adds significant complexity here.

mlir/include/mlir/Pass/PassRegistry.h

 /// options for each of the passes and pipelines that have been registered with
 /// the pass registry; Meaning that `-cse` will refer to the CSE pass in MLIR.
 /// It also registers an argument, `pass-pipeline`, that supports parsing a
 /// textual description of a pipeline. This option is mutually exclusive with
 /// the individual pass options.
 class PassPipelineCLParser {
 public:
   /// Construct a pass pipeline parser with the given command line description.
+  /// Optionally registers an alias for the `pass-pipeline` option.
   PassPipelineCLParser(StringRef arg, StringRef description);
+  PassPipelineCLParser(StringRef arg, StringRef description, StringRef alias);
   ~PassPipelineCLParser();
 
   /// Returns true if this parser contains any valid options to add.
   bool hasAnyOccurrences() const;
 
   /// Returns true if the given pass registry entry was registered at the
   /// top-level of the parser, i.e. not within an explicit textual pipeline.
   bool contains(const PassRegistryEntry *entry) const;
 
   /// Adds the passes defined by this parser entry to the given pass manager.
   /// Returns failure() if the pass could not be properly constructed due
   /// to options parsing.
   LogicalResult
   addToPipeline(OpPassManager &pm,
                 function_ref<LogicalResult(const Twine &)> errorHandler) const;
 
 private:
   std::unique_ptr<detail::PassPipelineCLParserImpl> impl;
 
   llvm::cl::opt<std::string> passPipeline;
+  Optional<llvm::cl::alias> passPipelineAlias;
 };
 
 /// This class implements a command-line parser specifically for MLIR pass
 /// names. It registers a cl option with a given argument and description that
 /// accepts a comma delimited list of pass names.
 class PassNameCLParser {
 public:
   /// Construct a parser with the given command line description.

mlir/lib/Pass/PassRegistry.cpp

 };
 } // namespace cl
 } // namespace llvm
 
 namespace {
 
 /// The name for the command line option used for parsing the textual pass
 /// pipeline.
-static constexpr StringLiteral passPipelineArg = "pass-pipeline";
+#define PASS_PIPELINE_ARG "pass-pipeline"
 
 /// Adds command line option for each registered pass or pass pipeline, as well
 /// as textual pass pipelines.
 struct PassNameParser : public llvm::cl::parser<PassArgData> {
   PassNameParser(llvm::cl::Option &opt) : llvm::cl::parser<PassArgData>(opt) {}
 
   void initialize();
   void printOptionInfo(const llvm::cl::Option &opt,

 } // namespace detail
 } // namespace mlir
 
 /// Construct a pass pipeline parser with the given command line description.
 PassPipelineCLParser::PassPipelineCLParser(StringRef arg, StringRef description)
     : impl(std::make_unique<detail::PassPipelineCLParserImpl>(
           arg, description, /*passNamesOnly=*/false)),
       passPipeline(
-          StringRef(passPipelineArg),
+          PASS_PIPELINE_ARG,
           llvm::cl::desc("Textual description of the pass pipeline to run")) {}
+
+PassPipelineCLParser::PassPipelineCLParser(StringRef arg, StringRef description,
+                                           StringRef alias)
+    : PassPipelineCLParser(arg, description) {
+  passPipelineAlias.emplace(alias,
+                            llvm::cl::desc("Alias for --" PASS_PIPELINE_ARG),
+                            llvm::cl::aliasopt(passPipeline));
+}
+
 PassPipelineCLParser::~PassPipelineCLParser() = default;
 
 /// Returns true if this parser contains any valid options to add.
 bool PassPipelineCLParser::hasAnyOccurrences() const {
   return passPipeline.getNumOccurrences() != 0 ||
          impl->passList.getNumOccurrences() != 0;
 }
 
 /// Returns true if the given pass registry entry was registered at the
 /// top-level of the parser, i.e. not within an explicit textual pipeline.
 bool PassPipelineCLParser::contains(const PassRegistryEntry *entry) const {
   return impl->contains(entry);
 }
 
 /// Adds the passes defined by this parser entry to the given pass manager.
 LogicalResult PassPipelineCLParser::addToPipeline(
     OpPassManager &pm,
     function_ref<LogicalResult(const Twine &)> errorHandler) const {
   if (passPipeline.getNumOccurrences()) {
     if (impl->passList.getNumOccurrences())
       return errorHandler(
-          "'-" + passPipelineArg +
+          "'-" PASS_PIPELINE_ARG
           "' option can't be used with individual pass options");
     std::string errMsg;
     llvm::raw_string_ostream os(errMsg);
     FailureOr<OpPassManager> parsed = parsePassPipeline(passPipeline, os);
     if (failed(parsed))
       return errorHandler(errMsg);
     pm = std::move(*parsed);
     return success();

mlir/lib/Tools/mlir-opt/MlirOptMain.cpp

LogicalResult mlir::MlirOptMain(int argc, char **argv, llvm::StringRef toolName,
   InitLLVM y(argc, argv);
 
   // Register any command line options.
   registerAsmPrinterCLOptions();
   registerMLIRContextCLOptions();
   registerPassManagerCLOptions();
   registerDefaultTimingManagerCLOptions();
   DebugCounter::registerCLOptions();
-  PassPipelineCLParser passPipeline("", "Compiler passes to run");
+  PassPipelineCLParser passPipeline("", "Compiler passes to run", "p");
 
   // Build the list of dialects as a header for the --help message.
   std::string helpHeader = (toolName + "\nAvailable Dialects: ").str();
   {
     llvm::raw_string_ostream os(helpHeader);
     interleaveComma(registry.getDialectNames(), os,
                     [&](auto name) { os << name; });
   }

mlir/test/mlir-opt/commandline.mlir

 // CHECK-NEXT: spirv
 // CHECK-NEXT: tensor
 // CHECK-NEXT: test
 // CHECK-NEXT: test_dyn
 // CHECK-NEXT: tosa
 // CHECK-NEXT: transform
 // CHECK-NEXT: vector
 // CHECK-NEXT: x86vector
+
+// RUN: mlir-opt --help-hidden | FileCheck %s -check-prefix=CHECK-HELP
+// CHECK-HELP: -p - Alias for --pass-pipeline