[mlir] Add macro for enabling all generated pass declarations

[rkayaith]

Summary

Currently the generated pass declarations have to be enabled per-pass
using multiple GEN_PASS_DECL_{PASSNAME} defines. This adds
GEN_PASS_DECL, which enables the declarations for all passes in the
group with a single macro. This is convenient for cases where a single
header is used for all passes in the group.

[mscuttari]

LGTM. What about doing this also for the definitions?

[rkayaith]

In D134766#3820116, @mscuttari wrote:

LGTM. What about doing this also for the definitions?

Might be worth adding for consistency, but I don't have a use case for that at the moment. Typically I see the pass definitions for a group being spread across multiple files.

[mscuttari]

In D134766#3821105, @rkayaith wrote:

Might be worth adding for consistency, but I don't have a use case for that at the moment. Typically I see the pass definitions for a group being spread across multiple files.

Right. We can add it later if the need will never arise.

mlir/docs/PassManagement.md

void registerMyPasses() {
 
   // Register `MyPass` specifically.
   foo::registerMyPass();
 }
 ```
 
 The second is to provide a way to configure the pass options. These classes are
 named in the form of `MyPassOptions`, where `MyPass` is the name of the pass
-definition in tablegen. The configurable parameters reflect the options
-declared in the tablegen file. Differently from the registration hooks, these
-classes can be enabled on a per-pass basis by defining the
-`GEN_PASS_DECL_PASSNAME` macro, where `PASSNAME` is the uppercase version of
-the name specified in tablegen.
+definition in tablegen. The configurable parameters reflect the options declared
+in the tablegen file. These declarations can be enabled for the whole group of
+passes by defining the `GEN_PASS_DECL` macro, or on a per-pass basis by defining
+`GEN_PASS_DECL_PASSNAME` where `PASSNAME` is the uppercase version of the name
+specified in tablegen.
 
 ```c++
 // .h.inc
 
 #ifdef GEN_PASS_DECL_MYPASS
 
 struct MyPassOptions {
     bool option = true;

 struct MyPass : foo::impl::MyPassBase<MyPass> {
   using MyPassBase::MyPassBase;
 
   /// The definitions of the options and statistics are now generated within
   /// the base class, but are accessible in the same way.
 };
 ```
 
-Similarly to the previous cases, the definitions can be enabled on a per-pass
-basis by defining the appropriate preprocessor `GEN_PASS_DEF_PASSNAME` macro,
-with `PASSNAME` equal to the uppercase version of the name of the pass
-definition in tablegen.
+These definitions can be enabled on a per-pass basis by defining the appropriate
+preprocessor `GEN_PASS_DEF_PASSNAME` macro, with `PASSNAME` equal to the
+uppercase version of the name of the pass definition in tablegen.
 If the `constructor` field has not been specified in tablegen, then the default
 constructors are also defined and expect the name of the actual pass class to
 be equal to the name defined in tablegen.
 
 Using the `gen-pass-doc` generator, markdown documentation for each of the
 passes can be generated. See [Passes.md](Passes.md) for example output of real
 MLIR passes.
 

mlir/tools/mlir-tblgen/PassGen.cpp

if (Optional<StringRef> defaultVal = opt.getDefaultValue())
       os << " = " << defaultVal;
 
     os << ";\n";
   }
 
   os << "};\n";
 }
 
+static std::string getPassDeclVarName(const Pass &pass) {
+  return "GEN_PASS_DECL_" + pass.getDef()->getName().upper();
+}
+
 /// Emit the code to be included in the public header of the pass.
 static void emitPassDecls(const Pass &pass, raw_ostream &os) {
   StringRef passName = pass.getDef()->getName();
-  std::string enableVarName = "GEN_PASS_DECL_" + passName.upper();
+  std::string enableVarName = getPassDeclVarName(pass);
 
   os << "#ifdef " << enableVarName << "\n";
   emitPassOptionsStruct(pass, os);
 
   if (StringRef constructor = pass.getConstructor(); constructor.empty()) {
     // Default constructor declaration.
     os << "std::unique_ptr<::mlir::Pass> create" << passName << "();\n";
 
static void emitOldPassDecl(const Pass &pass, raw_ostream &os) {
   os << "};\n";
 }
 
 static void emitPasses(const llvm::RecordKeeper &recordKeeper,
                        raw_ostream &os) {
   std::vector<Pass> passes = getPasses(recordKeeper);
   os << "/* Autogenerated by mlir-tblgen; don't manually edit */\n";
 
+  os << "\n";
+  os << "#ifdef GEN_PASS_DECL\n";
+  os << "// Generate declarations for all passes.\n";
+  for (const Pass &pass : passes)
+    os << "#define " << getPassDeclVarName(pass) << "\n";
+  os << "#undef GEN_PASS_DECL\n";
+  os << "#endif // GEN_PASS_DECL\n";
+
   for (const Pass &pass : passes)
     emitPass(pass, os);
 
   emitRegistrations(passes, os);
 
   // TODO: Drop old pass declarations.
   // Emit the old code until all the passes have switched to the new design.
   os << "// Deprecated. Please use the new per-pass macros.\n";

mlir/unittests/TableGen/PassGenTest.cpp

 //===- PassGenTest.cpp - TableGen PassGen Tests ---------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Pass/Pass.h"
 #include "llvm/ADT/STLExtras.h"
 
 #include "gmock/gmock.h"
 
 std::unique_ptr<mlir::Pass> createTestPassWithCustomConstructor(int v = 0);
 
-#define GEN_PASS_DECL_TESTPASS
-#define GEN_PASS_DECL_TESTPASSWITHOPTIONS
-#define GEN_PASS_DECL_TESTPASSWITHCUSTOMCONSTRUCTOR
+#define GEN_PASS_DECL
 #define GEN_PASS_REGISTRATION
 #include "PassGenTest.h.inc"
 
 #define GEN_PASS_DEF_TESTPASS
 #define GEN_PASS_DEF_TESTPASSWITHOPTIONS
 #define GEN_PASS_DEF_TESTPASSWITHCUSTOMCONSTRUCTOR
 #include "PassGenTest.h.inc"