[LegacyPM] Remove pipeline extension mechanism

[aeubanks]

Summary

Part of gradually removing the legacy PM optimization pipeline.

[aeubanks]

depends on https://reviews.llvm.org/D136621

[MaskRay]

LGTM.

[aeubanks]

I only tested with the X86 backend, forgot that other backends modify the passmanagerbuilder via adjustPassManager

[aeubanks]

remove adjustPassManager

[aeubanks]

rebase

llvm/docs/WritingAnLLVMPass.rst

 
 Lastly, we :ref:`register our class <writing-an-llvm-pass-registration>`
 ``Hello``, giving it a command line argument "``hello``", and a name "Hello
 World Pass".  The last two arguments describe its behavior: if a pass walks CFG
 without modifying it then the third argument is set to ``true``; if a pass is
 an analysis pass, for example dominator tree pass, then ``true`` is supplied as
 the fourth argument.
 
-If we want to register the pass as a step of an existing pipeline, some extension
-points are provided, e.g. ``PassManagerBuilder::EP_EarlyAsPossible`` to apply our
-pass before any optimization, or ``PassManagerBuilder::EP_FullLinkTimeOptimizationLast``
-to apply it after Link Time Optimizations.
-
-.. code-block:: c++
-
-    static llvm::RegisterStandardPasses Y(
-        llvm::PassManagerBuilder::EP_EarlyAsPossible,
-        [](const llvm::PassManagerBuilder &Builder,
-           llvm::legacy::PassManagerBase &PM) { PM.add(new Hello()); });
-
 As a whole, the ``.cpp`` file looks like:
 
 .. code-block:: c++
 
   #include "llvm/Pass.h"
   #include "llvm/IR/Function.h"
   #include "llvm/Support/raw_ostream.h"
 
.. code-block:: c++
   }; // end of struct Hello
   }  // end of anonymous namespace
 
   char Hello::ID = 0;
   static RegisterPass<Hello> X("hello", "Hello World Pass",
                                false /* Only looks at CFG */,
                                false /* Analysis Pass */);
 
-  static RegisterStandardPasses Y(
-      PassManagerBuilder::EP_EarlyAsPossible,
-      [](const PassManagerBuilder &Builder,
-         legacy::PassManagerBase &PM) { PM.add(new Hello()); });
-
 Now that it's all together, compile the file with a simple "``gmake``" command
 from the top level of your build directory and you should get a new file
 "``lib/LLVMHello.so``".  Note that everything in this file is
 contained in an anonymous namespace --- this reflects the fact that passes
 are self contained units that do not need external interfaces (although they
 can have them) to be useful.
 
 Running a pass with ``opt``

llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h

 public:
   /// Extensions are passed to the builder itself (so they can see how it is
   /// configured) as well as the pass manager to add stuff to.
   typedef std::function<void(const PassManagerBuilder &Builder,
                              legacy::PassManagerBase &PM)>
       ExtensionFn;
   typedef int GlobalExtensionID;
 
-  enum ExtensionPointTy {
-    /// EP_EarlyAsPossible - This extension point allows adding passes before
-    /// any other transformations, allowing them to see the code as it is coming
-    /// out of the frontend.
-    EP_EarlyAsPossible,
-
-    /// EP_ModuleOptimizerEarly - This extension point allows adding passes
-    /// just before the main module-level optimization passes.
-    EP_ModuleOptimizerEarly,
-
-    /// EP_LoopOptimizerEnd - This extension point allows adding loop passes to
-    /// the end of the loop optimizer.
-    EP_LoopOptimizerEnd,
-
-    /// EP_ScalarOptimizerLate - This extension point allows adding optimization
-    /// passes after most of the main optimizations, but before the last
-    /// cleanup-ish optimizations.
-    EP_ScalarOptimizerLate,
-
-    /// EP_OptimizerLast -- This extension point allows adding passes that
-    /// run after everything else.
-    EP_OptimizerLast,
-
-    /// EP_VectorizerStart - This extension point allows adding optimization
-    /// passes before the vectorizer and other highly target specific
-    /// optimization passes are executed.
-    EP_VectorizerStart,
-
-    /// EP_EnabledOnOptLevel0 - This extension point allows adding passes that
-    /// should not be disabled by O0 optimization level. The passes will be
-    /// inserted after the inlining pass.
-    EP_EnabledOnOptLevel0,
-
-    /// EP_Peephole - This extension point allows adding passes that perform
-    /// peephole optimizations similar to the instruction combiner. These passes
-    /// will be inserted after each instance of the instruction combiner pass.
-    EP_Peephole,
-
-    /// EP_LateLoopOptimizations - This extension point allows adding late loop
-    /// canonicalization and simplification passes. This is the last point in
-    /// the loop optimization pipeline before loop deletion. Each pass added
-    /// here must be an instance of LoopPass.
-    /// This is the place to add passes that can remove loops, such as target-
-    /// specific loop idiom recognition.
-    EP_LateLoopOptimizations,
-
-    /// EP_CGSCCOptimizerLate - This extension point allows adding CallGraphSCC
-    /// passes at the end of the main CallGraphSCC passes and before any
-    /// function simplification passes run by CGPassManager.
-    EP_CGSCCOptimizerLate,
-
-    /// EP_FullLinkTimeOptimizationEarly - This extensions point allow adding
-    /// passes that
-    /// run at Link Time, before Full Link Time Optimization.
-    EP_FullLinkTimeOptimizationEarly,
-
-    /// EP_FullLinkTimeOptimizationLast - This extensions point allow adding
-    /// passes that
-    /// run at Link Time, after Full Link Time Optimization.
-    EP_FullLinkTimeOptimizationLast,
-  };
-
   /// The Optimization Level - Specify the basic optimization level.
   ///    0 = -O0, 1 = -O1, 2 = -O2, 3 = -O3
   unsigned OptLevel;
 
   /// SizeLevel - How much we're optimizing for size.
   ///    0 = none, 1 = -Os, 2 = -Oz
   unsigned SizeLevel;
 
public:
   bool ForgetAllSCEVInLoopUnroll;
   bool VerifyInput;
   bool VerifyOutput;
   bool MergeFunctions;
   bool DivergentTarget;
   unsigned LicmMssaOptCap;
   unsigned LicmMssaNoAccForPromotionCap;
 
-private:
-  /// ExtensionList - This is list of all of the extensions that are registered.
-  std::vector<std::pair<ExtensionPointTy, ExtensionFn>> Extensions;
-
 public:
   PassManagerBuilder();
   ~PassManagerBuilder();
-  /// Adds an extension that will be used by all PassManagerBuilder instances.
-  /// This is intended to be used by plugins, to register a set of
-  /// optimisations to run automatically.
-  ///
-  /// \returns A global extension identifier that can be used to remove the
-  /// extension.
-  static GlobalExtensionID addGlobalExtension(ExtensionPointTy Ty,
-                                              ExtensionFn Fn);
-  /// Removes an extension that was previously added using addGlobalExtension.
-  /// This is also intended to be used by plugins, to remove any extension that
-  /// was previously registered before being unloaded.
-  ///
-  /// \param ExtensionID Identifier of the extension to be removed.
-  static void removeGlobalExtension(GlobalExtensionID ExtensionID);
-  void addExtension(ExtensionPointTy Ty, ExtensionFn Fn);
 
 private:
-  void addExtensionsToPM(ExtensionPointTy ETy,
-                         legacy::PassManagerBase &PM) const;
   void addInitialAliasAnalysisPasses(legacy::PassManagerBase &PM) const;
   void addFunctionSimplificationPasses(legacy::PassManagerBase &MPM);
   void addVectorPasses(legacy::PassManagerBase &PM, bool IsFullLTO);
 
 public:
   /// populateFunctionPassManager - This fills in the function pass manager,
   /// which is expected to be run on each function immediately as it is
   /// generated.  The idea is to reduce the size of the IR in memory.
   void populateFunctionPassManager(legacy::FunctionPassManager &FPM);
 
   /// populateModulePassManager - This sets up the primary pass manager.
   void populateModulePassManager(legacy::PassManagerBase &MPM);
 };
 
-/// Registers a function for adding a standard set of passes.  This should be
-/// used by optimizer plugins to allow all front ends to transparently use
-/// them.  Create a static instance of this class in your plugin, providing a
-/// private function that the PassManagerBuilder can use to add your passes.
-class RegisterStandardPasses {
-  PassManagerBuilder::GlobalExtensionID ExtensionID;
-
-public:
-  RegisterStandardPasses(PassManagerBuilder::ExtensionPointTy Ty,
-                         PassManagerBuilder::ExtensionFn Fn) {
-    ExtensionID = PassManagerBuilder::addGlobalExtension(Ty, std::move(Fn));
-  }
-
-  ~RegisterStandardPasses() {
-    // If the collection holding the global extensions is destroyed after the
-    // plugin is unloaded, the extension has to be removed here. Indeed, the
-    // destructor of the ExtensionFn may reference code in the plugin.
-    PassManagerBuilder::removeGlobalExtension(ExtensionID);
-  }
-};
-
 inline PassManagerBuilder *unwrap(LLVMPassManagerBuilderRef P) {
     return reinterpret_cast<PassManagerBuilder*>(P);
 }
 
 inline LLVMPassManagerBuilderRef wrap(PassManagerBuilder *P) {
   return reinterpret_cast<LLVMPassManagerBuilderRef>(P);
 }
 
 } // end namespace llvm
 #endif

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

PassManagerBuilder::PassManagerBuilder() {
     CallGraphProfile = true;
 }
 
 PassManagerBuilder::~PassManagerBuilder() {
   delete LibraryInfo;
   delete Inliner;
 }
 
-/// Set of global extensions, automatically added as part of the standard set.
-static ManagedStatic<
-    SmallVector<std::tuple<PassManagerBuilder::ExtensionPointTy,
-                           PassManagerBuilder::ExtensionFn,
-                           PassManagerBuilder::GlobalExtensionID>,
-                8>>
-    GlobalExtensions;
-static PassManagerBuilder::GlobalExtensionID GlobalExtensionsCounter;
-
-/// Check if GlobalExtensions is constructed and not empty.
-/// Since GlobalExtensions is a managed static, calling 'empty()' will trigger
-/// the construction of the object.
-static bool GlobalExtensionsNotEmpty() {
-  return GlobalExtensions.isConstructed() && !GlobalExtensions->empty();
-}
-
-PassManagerBuilder::GlobalExtensionID
-PassManagerBuilder::addGlobalExtension(PassManagerBuilder::ExtensionPointTy Ty,
-                                       PassManagerBuilder::ExtensionFn Fn) {
-  auto ExtensionID = GlobalExtensionsCounter++;
-  GlobalExtensions->push_back(std::make_tuple(Ty, std::move(Fn), ExtensionID));
-  return ExtensionID;
-}
-
-void PassManagerBuilder::removeGlobalExtension(
-    PassManagerBuilder::GlobalExtensionID ExtensionID) {
-  // RegisterStandardPasses may try to call this function after GlobalExtensions
-  // has already been destroyed; doing so should not generate an error.
-  if (!GlobalExtensions.isConstructed())
-    return;
-
-  auto GlobalExtension =
-      llvm::find_if(*GlobalExtensions, [ExtensionID](const auto &elem) {
-        return std::get<2>(elem) == ExtensionID;
-      });
-  assert(GlobalExtension != GlobalExtensions->end() &&
-         "The extension ID to be removed should always be valid.");
-
-  GlobalExtensions->erase(GlobalExtension);
-}
-
-void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
-  Extensions.push_back(std::make_pair(Ty, std::move(Fn)));
-}
-
-void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
-                                           legacy::PassManagerBase &PM) const {
-  if (GlobalExtensionsNotEmpty()) {
-    for (auto &Ext : *GlobalExtensions) {
-      if (std::get<0>(Ext) == ETy)
-        std::get<1>(Ext)(*this, PM);
-    }
-  }
-  for (const auto &[PT, Fn] : Extensions)
-    if (PT == ETy)
-      Fn(*this, PM);
-}
-
 void PassManagerBuilder::addInitialAliasAnalysisPasses(
     legacy::PassManagerBase &PM) const {
   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
   // BasicAliasAnalysis wins if they disagree. This is intended to help
   // support "obvious" type-punning idioms.
   PM.add(createTypeBasedAAWrapperPass());
   PM.add(createScopedNoAliasAAWrapperPass());
 }
 
 void PassManagerBuilder::populateFunctionPassManager(
     legacy::FunctionPassManager &FPM) {
-  addExtensionsToPM(EP_EarlyAsPossible, FPM);
-
   // Add LibraryInfo if we have some.
   if (LibraryInfo)
     FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
 
   if (OptLevel == 0) return;
 
   addInitialAliasAnalysisPasses(FPM);
 
void PassManagerBuilder::addFunctionSimplificationPasses(
   }
   MPM.add(
       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
           true))); // Merge & remove BBs
   // Combine silly seq's
   MPM.add(createInstructionCombiningPass());
   if (SizeLevel == 0)
     MPM.add(createLibCallsShrinkWrapPass());
-  addExtensionsToPM(EP_Peephole, MPM);
 
   // TODO: Investigate the cost/benefit of tail call elimination on debugging.
   if (OptLevel > 1)
     MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
   MPM.add(
       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
           true)));                            // Merge & remove BBs
   MPM.add(createReassociatePass());           // Reassociate expressions
void PassManagerBuilder::addFunctionSimplificationPasses(
   // simplifycfg. Eventually loop-simplifycfg should be enhanced to replace the
   // need for this.
   MPM.add(createCFGSimplificationPass(
       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
   MPM.add(createInstructionCombiningPass());
   // We resume loop passes creating a second loop pipeline here.
   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
-  addExtensionsToPM(EP_LateLoopOptimizations, MPM);
   MPM.add(createLoopDeletionPass());          // Delete dead loops
 
   // Unroll small loops and perform peeling.
   MPM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
                                      ForgetAllSCEVInLoopUnroll));
-  addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
   // This ends the loop pass pipelines.
 
   // Break up allocas that may now be splittable after loop unrolling.
   MPM.add(createSROAPass());
 
   if (OptLevel > 1) {
     MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
     MPM.add(createGVNPass(DisableGVNLoadPRE));  // Remove redundancies
   }
   MPM.add(createSCCPPass());                  // Constant prop with SCCP
 
   // Delete dead bit computations (instcombine runs after to fold away the dead
   // computations, and then ADCE will run later to exploit any new DCE
   // opportunities that creates).
   MPM.add(createBitTrackingDCEPass());        // Delete dead bit computations
 
   // Run instcombine after redundancy elimination to exploit opportunities
   // opened up by them.
   MPM.add(createInstructionCombiningPass());
-  addExtensionsToPM(EP_Peephole, MPM);
   if (OptLevel > 1) {
     MPM.add(createJumpThreadingPass());         // Thread jumps
     MPM.add(createCorrelatedValuePropagationPass());
   }
   MPM.add(createAggressiveDCEPass()); // Delete dead instructions
 
   MPM.add(createMemCpyOptPass());               // Remove memcpy / form memset
   // TODO: Investigate if this is too expensive at O1.
   if (OptLevel > 1) {
     MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
                            /*AllowSpeculation=*/true));
   }
 
-  addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
-
   // Merge & remove BBs and sink & hoist common instructions.
   MPM.add(createCFGSimplificationPass(
       SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
   // Clean up after everything.
   MPM.add(createInstructionCombiningPass());
-  addExtensionsToPM(EP_Peephole, MPM);
 }
 
 /// FIXME: Should LTO cause any differences to this set of passes?
 void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
                                          bool IsFullLTO) {
   PM.add(createLoopVectorizePass(!LoopsInterleaved, !LoopVectorize));
 
   if (IsFullLTO) {
void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
   if (SLPVectorize) {
     PM.add(createSLPVectorizerPass());
   }
 
   // Enhance/cleanup vector code.
   PM.add(createVectorCombinePass());
 
   if (!IsFullLTO) {
-    addExtensionsToPM(EP_Peephole, PM);
     PM.add(createInstructionCombiningPass());
 
     // Unroll small loops
     PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
                                 ForgetAllSCEVInLoopUnroll));
 
     if (!DisableUnrollLoops) {
       // LoopUnroll may generate some redundency to cleanup.
if (OptLevel == 0) {
 
     // FIXME: The BarrierNoopPass is a HACK! The inliner pass above implicitly
     // creates a CGSCC pass manager, but we don't want to add extensions into
     // that pass manager. To prevent this we insert a no-op module pass to reset
     // the pass manager to get the same behavior as EP_OptimizerLast in non-O0
     // builds. The function merging pass is
     if (MergeFunctions)
       MPM.add(createMergeFunctionsPass());
-    else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
-      MPM.add(createBarrierNoopPass());
-
-    addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
 
     MPM.add(createAnnotationRemarksLegacyPass());
     return;
   }
 
   // Add LibraryInfo if we have some.
   if (LibraryInfo)
     MPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
 
   addInitialAliasAnalysisPasses(MPM);
 
   // Infer attributes about declarations if possible.
   MPM.add(createInferFunctionAttrsLegacyPass());
 
-  addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
-
   if (OptLevel > 2)
     MPM.add(createCallSiteSplittingPass());
 
   MPM.add(createIPSCCPPass());          // IP SCCP
   MPM.add(createCalledValuePropagationPass());
 
   MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
   // Promote any localized global vars.
   MPM.add(createPromoteMemoryToRegisterPass());
 
   MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
 
   MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
-  addExtensionsToPM(EP_Peephole, MPM);
   MPM.add(
       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
           true))); // Clean up after IPCP & DAE
 
   // We add a module alias analysis pass here. In part due to bugs in the
   // analysis infrastructure this "works" in that the analysis stays alive
   // for the entire SCC pass run below.
   MPM.add(createGlobalsAAWrapperPass());
 
   // Start of CallGraph SCC passes.
   bool RunInliner = false;
   if (Inliner) {
     MPM.add(Inliner);
     Inliner = nullptr;
     RunInliner = true;
   }
 
   // Try to perform OpenMP specific optimizations. This is a (quick!) no-op if
   // there are no OpenMP runtime calls present in the module.
   if (OptLevel > 1)
     MPM.add(createOpenMPOptCGSCCLegacyPass());
 
   MPM.add(createPostOrderFunctionAttrsLegacyPass());
 
-  addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
   addFunctionSimplificationPasses(MPM);
 
   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
   // pass manager that we are specifically trying to avoid. To prevent this
   // we must insert a no-op module pass to reset the pass manager.
   MPM.add(createBarrierNoopPass());
 
   if (OptLevel > 1)
void PassManagerBuilder::populateModulePassManager(
   // this to work. Fortunately, it is trivial to preserve AliasAnalysis
   // (doing nothing preserves it as it is required to be conservatively
   // correct in the face of IR changes).
   MPM.add(createGlobalsAAWrapperPass());
 
   MPM.add(createFloat2IntPass());
   MPM.add(createLowerConstantIntrinsicsPass());
 
-  addExtensionsToPM(EP_VectorizerStart, MPM);
-
   // Re-rotate loops in all our loop nests. These may have fallout out of
   // rotated form due to GVN or other transformations, and the vectorizer relies
   // on the rotated form. Disable header duplication at -Oz.
   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1, false));
 
   // Distribute loops to allow partial vectorization.  I.e. isolate dependences
   // into separate loop that would otherwise inhibit vectorization.  This is
   // currently only performed for loops marked with the metadata
void PassManagerBuilder::populateModulePassManager(
   // flattening of blocks.
   MPM.add(createDivRemPairsPass());
 
   // LoopSink (and other loop passes since the last simplifyCFG) might have
   // resulted in single-entry-single-exit or empty blocks. Clean up the CFG.
   MPM.add(createCFGSimplificationPass(
       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
 
-  addExtensionsToPM(EP_OptimizerLast, MPM);
-
   MPM.add(createAnnotationRemarksLegacyPass());
 }
 
 LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
   PassManagerBuilder *PMB = new PassManagerBuilder();
   return wrap(PMB);
 }