Revert "[LegacyPM] Remove pipeline extension mechanism"

This reverts commit 4ea6ffb.

Breaks various backends.

Author: aeubanks

llvm/docs/WritingAnLLVMPass.rst

@@ -185,6 +185,18 @@ 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++
@@ -216,6 +228,11 @@ 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

@@ -44,6 +44,17 @@ 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

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

@@ -193,6 +193,64 @@ 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) {
@@ -219,6 +277,8 @@ 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));
@@ -281,6 +341,7 @@ 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)
@@ -330,6 +391,7 @@ 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)
@@ -338,6 +400,7 @@ 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.
@@ -361,6 +424,7 @@ 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());
@@ -378,6 +442,8 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
                            /*AllowSpeculation=*/true));
   }
 
+  addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
+
   if (RerollLoops)
     MPM.add(createLoopRerollPass());
 
@@ -386,6 +452,7 @@ 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?
@@ -469,6 +536,7 @@ void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
   PM.add(createVectorCombinePass());
 
   if (!IsFullLTO) {
+    addExtensionsToPM(EP_Peephole, PM);
     PM.add(createInstructionCombiningPass());
 
     if (EnableUnrollAndJam && !DisableUnrollLoops) {
@@ -527,6 +595,10 @@ 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;
@@ -545,6 +617,8 @@ void PassManagerBuilder::populateModulePassManager(
   if (AttributorRun & AttributorRunOption::MODULE)
     MPM.add(createAttributorLegacyPass());
 
+  addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
+
   if (OptLevel > 2)
     MPM.add(createCallSiteSplittingPass());
 
@@ -562,6 +636,7 @@ 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
@@ -590,6 +665,7 @@ 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
@@ -664,6 +740,8 @@ 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.
@@ -716,6 +794,8 @@ void PassManagerBuilder::populateModulePassManager(
   MPM.add(createCFGSimplificationPass(
       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
 
+  addExtensionsToPM(EP_OptimizerLast, MPM);
+
   MPM.add(createAnnotationRemarksLegacyPass());
 }