[LegacyPM] Remove pipeline extension mechanism

Part of gradually removing the legacy PM optimization pipeline.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D136622

Author: aeubanks

llvm/docs/WritingAnLLVMPass.rst

@@ -185,18 +185,6 @@ 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++
@@ -228,11 +216,6 @@ As a whole, the ``.cpp`` file looks like:
                                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

llvm/examples/Bye/Bye.cpp

@@ -44,17 +44,6 @@ static RegisterPass<LegacyBye> X("goodbye", "Good Bye World Pass",
                                  false /* Only looks at CFG */,
                                  false /* Analysis Pass */);
 
-/* Legacy PM Registration */
-static llvm::RegisterStandardPasses RegisterBye(
-    llvm::PassManagerBuilder::EP_VectorizerStart,
-    [](const llvm::PassManagerBuilder &Builder,
-       llvm::legacy::PassManagerBase &PM) { PM.add(new LegacyBye()); });
-
-static llvm::RegisterStandardPasses RegisterByeLTO(
-    llvm::PassManagerBuilder::EP_ModuleOptimizerEarly,
-    [](const llvm::PassManagerBuilder &Builder,
-       llvm::legacy::PassManagerBase &PM) { PM.add(new LegacyBye()); });
-
 /* New PM Registration */
 llvm::PassPluginLibraryInfo getByePluginInfo() {
   return {LLVM_PLUGIN_API_VERSION, "Bye", LLVM_VERSION_STRING,

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

@@ -63,68 +63,6 @@ class PassManagerBuilder {
       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;
@@ -168,32 +106,11 @@ class PassManagerBuilder {
   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);
@@ -208,27 +125,6 @@ class PassManagerBuilder {
   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);
 }

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -193,64 +193,6 @@ PassManagerBuilder::~PassManagerBuilder() {
   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 {
   switch (UseCFLAA) {
@@ -277,8 +219,6 @@ void PassManagerBuilder::addInitialAliasAnalysisPasses(
 
 void PassManagerBuilder::populateFunctionPassManager(
     legacy::FunctionPassManager &FPM) {
-  addExtensionsToPM(EP_EarlyAsPossible, FPM);
-
   // Add LibraryInfo if we have some.
   if (LibraryInfo)
     FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
@@ -341,7 +281,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   MPM.add(createInstructionCombiningPass());
   if (SizeLevel == 0 && !DisableLibCallsShrinkWrap)
     MPM.add(createLibCallsShrinkWrapPass());
-  addExtensionsToPM(EP_Peephole, MPM);
 
   // TODO: Investigate the cost/benefit of tail call elimination on debugging.
   if (OptLevel > 1)
@@ -391,7 +330,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   }
   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
-  addExtensionsToPM(EP_LateLoopOptimizations, MPM);
   MPM.add(createLoopDeletionPass());          // Delete dead loops
 
   if (EnableLoopInterchange)
@@ -400,7 +338,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   // 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.
@@ -424,7 +361,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   // Run instcombine after redundancy elimination to exploit opportunities
   // opened up by them.
   MPM.add(createInstructionCombiningPass());
-  addExtensionsToPM(EP_Peephole, MPM);
   if (OptLevel > 1) {
     if (EnableDFAJumpThreading && SizeLevel == 0)
       MPM.add(createDFAJumpThreadingPass());
@@ -442,8 +378,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
                            /*AllowSpeculation=*/true));
   }
 
-  addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
-
   if (RerollLoops)
     MPM.add(createLoopRerollPass());
 
@@ -452,7 +386,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
       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?
@@ -536,7 +469,6 @@ void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
   PM.add(createVectorCombinePass());
 
   if (!IsFullLTO) {
-    addExtensionsToPM(EP_Peephole, PM);
     PM.add(createInstructionCombiningPass());
 
     if (EnableUnrollAndJam && !DisableUnrollLoops) {
@@ -595,10 +527,6 @@ void PassManagerBuilder::populateModulePassManager(
     // 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;
@@ -617,8 +545,6 @@ void PassManagerBuilder::populateModulePassManager(
   if (AttributorRun & AttributorRunOption::MODULE)
     MPM.add(createAttributorLegacyPass());
 
-  addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
-
   if (OptLevel > 2)
     MPM.add(createCallSiteSplittingPass());
 
@@ -636,7 +562,6 @@ void PassManagerBuilder::populateModulePassManager(
   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
@@ -665,7 +590,6 @@ void PassManagerBuilder::populateModulePassManager(
 
   MPM.add(createPostOrderFunctionAttrsLegacyPass());
 
-  addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
   addFunctionSimplificationPasses(MPM);
 
   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
@@ -740,8 +664,6 @@ void PassManagerBuilder::populateModulePassManager(
     MPM.add(createEarlyCSEPass(false));
   }
 
-  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.
@@ -794,8 +716,6 @@ void PassManagerBuilder::populateModulePassManager(
   MPM.add(createCFGSimplificationPass(
       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
 
-  addExtensionsToPM(EP_OptimizerLast, MPM);
-
   MPM.add(createAnnotationRemarksLegacyPass());
 }