[SandboxVec] Re-land "Use sbvec-passes flag to create a pipeline of Region passes after BottomUpVec. (llvm#111223)" (llvm#111772)

llvm#111223 was reverted because of
a build failure with `-DBUILD_SHARED_LIBS=on`.

The Passes component depends on Vectorizer (because PassBuilder needs to
be able to instantiate SandboxVectorizerPass). This resulted in CMake
doing this

1. when it builds lib/libLLVMVectorize.so.20.0git it adds
lib/libLLVMSandboxIR.so.20.0git to the command line, because it's listed
as a dependency (as expected)
2. when it's trying to build lib/libLLVMPasses.so.20.0git it adds
lib/libLLVMVectorize.so.20.0git to the command line, because it's listed
as a dependency (also as expected). But not libLLVMSandboxIR.so.

When SandboxVectorizerPass has its ctors/dtors defined inline, this
caused "undefined reference to vtable" linker errors. This change works
around that by moving ctors/dtors out of line.

Also fix a bazel build problem by adding the new
`llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/PassRegistry.def`
as a textual header in the Vectorizer target.

Author: slackito

llvm/include/llvm/SandboxIR/PassManager.h

@@ -18,6 +18,8 @@
 #ifndef LLVM_SANDBOXIR_PASSMANAGER_H
 #define LLVM_SANDBOXIR_PASSMANAGER_H
 
+#include <memory>
+
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/SandboxIR/Pass.h"
@@ -32,25 +34,65 @@ template <typename ParentPass, typename ContainedPass>
 class PassManager : public ParentPass {
 protected:
   /// The list of passes that this pass manager will run.
-  SmallVector<ContainedPass *> Passes;
+  SmallVector<std::unique_ptr<ContainedPass>> Passes;
 
   PassManager(StringRef Name) : ParentPass(Name) {}
   PassManager(const PassManager &) = delete;
+  PassManager(PassManager &&) = default;
   virtual ~PassManager() = default;
   PassManager &operator=(const PassManager &) = delete;
 
 public:
   /// Adds \p Pass to the pass pipeline.
-  void addPass(ContainedPass *Pass) {
+  void addPass(std::unique_ptr<ContainedPass> Pass) {
     // TODO: Check that Pass's class type works with this PassManager type.
-    Passes.push_back(Pass);
+    Passes.push_back(std::move(Pass));
+  }
+
+  using CreatePassFunc =
+      std::function<std::unique_ptr<ContainedPass>(StringRef)>;
+
+  /// Parses \p Pipeline as a comma-separated sequence of pass names and sets
+  /// the pass pipeline, using \p CreatePass to instantiate passes by name.
+  ///
+  /// After calling this function, the PassManager contains only the specified
+  /// pipeline, any previously added passes are cleared.
+  void setPassPipeline(StringRef Pipeline, CreatePassFunc CreatePass) {
+    static constexpr const char EndToken = '\0';
+    static constexpr const char PassDelimToken = ',';
+
+    assert(Passes.empty() &&
+           "setPassPipeline called on a non-empty sandboxir::PassManager");
+    // Add EndToken to the end to ease parsing.
+    std::string PipelineStr = std::string(Pipeline) + EndToken;
+    int FlagBeginIdx = 0;
+
+    for (auto [Idx, C] : enumerate(PipelineStr)) {
+      // Keep moving Idx until we find the end of the pass name.
+      bool FoundDelim = C == EndToken || C == PassDelimToken;
+      if (!FoundDelim)
+        continue;
+      unsigned Sz = Idx - FlagBeginIdx;
+      std::string PassName(&PipelineStr[FlagBeginIdx], Sz);
+      FlagBeginIdx = Idx + 1;
+
+      // Get the pass that corresponds to PassName and add it to the pass
+      // manager.
+      auto Pass = CreatePass(PassName);
+      if (Pass == nullptr) {
+        errs() << "Pass '" << PassName << "' not registered!\n";
+        exit(1);
+      }
+      addPass(std::move(Pass));
+    }
   }
+
 #ifndef NDEBUG
   void print(raw_ostream &OS) const override {
     OS << this->getName();
     OS << "(";
     // TODO: This should call Pass->print(OS) because Pass may be a PM.
-    interleave(Passes, OS, [&OS](auto *Pass) { OS << Pass->getName(); }, ",");
+    interleave(Passes, OS, [&OS](auto &Pass) { OS << Pass->getName(); }, ",");
     OS << ")";
   }
   LLVM_DUMP_METHOD void dump() const override {
@@ -79,38 +121,6 @@ class RegionPassManager final : public PassManager<RegionPass, RegionPass> {
   bool runOnRegion(Region &R) final;
 };
 
-/// Owns the passes and provides an API to get a pass by its name.
-class PassRegistry {
-  SmallVector<std::unique_ptr<Pass>, 8> Passes;
-  DenseMap<StringRef, Pass *> NameToPassMap;
-
-public:
-  static constexpr const char PassDelimToken = ',';
-  PassRegistry() = default;
-  /// Registers \p PassPtr and takes ownership.
-  Pass &registerPass(std::unique_ptr<Pass> &&PassPtr) {
-    auto &PassRef = *PassPtr.get();
-    NameToPassMap[PassRef.getName()] = &PassRef;
-    Passes.push_back(std::move(PassPtr));
-    return PassRef;
-  }
-  /// \Returns the pass with name \p Name, or null if not registered.
-  Pass *getPassByName(StringRef Name) const {
-    auto It = NameToPassMap.find(Name);
-    return It != NameToPassMap.end() ? It->second : nullptr;
-  }
-  /// Creates a pass pipeline and returns the first pass manager.
-  FunctionPassManager &parseAndCreatePassPipeline(StringRef Pipeline);
-
-#ifndef NDEBUG
-  void print(raw_ostream &OS) const {
-    for (const auto &PassPtr : Passes)
-      OS << PassPtr->getName() << "\n";
-  }
-  LLVM_DUMP_METHOD void dump() const;
-#endif
-};
-
 } // namespace llvm::sandboxir
 
 #endif // LLVM_SANDBOXIR_PASSMANAGER_H

llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.h

@@ -15,18 +15,24 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/SandboxIR/Constant.h"
 #include "llvm/SandboxIR/Pass.h"
+#include "llvm/SandboxIR/PassManager.h"
 #include "llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h"
 
 namespace llvm::sandboxir {
 
+class RegionPassManager;
+
 class BottomUpVec final : public FunctionPass {
   bool Change = false;
   LegalityAnalysis Legality;
   void vectorizeRec(ArrayRef<Value *> Bndl);
   void tryVectorize(ArrayRef<Value *> Seeds);
 
+  // The PM containing the pipeline of region passes.
+  RegionPassManager RPM;
+
 public:
-  BottomUpVec() : FunctionPass("bottom-up-vec") {}
+  BottomUpVec();
   bool runOnFunction(Function &F) final;
 };
 

llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Passes/NullPass.h

@@ -0,0 +1,19 @@
+#ifndef LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_PASSES_NULLPASS_H
+#define LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_PASSES_NULLPASS_H
+
+#include "llvm/SandboxIR/Pass.h"
+
+namespace llvm::sandboxir {
+
+class Region;
+
+/// A Region pass that does nothing, for use as a placeholder in tests.
+class NullPass final : public RegionPass {
+public:
+  NullPass() : RegionPass("null") {}
+  bool runOnRegion(Region &R) final { return false; }
+};
+
+} // namespace llvm::sandboxir
+
+#endif // LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_PASSES_NULLPASS_H

llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/SandboxVectorizer.h

@@ -8,7 +8,10 @@
 #ifndef LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_SANDBOXVECTORIZER_H
 #define LLVM_TRANSFORMS_VECTORIZE_SANDBOXVECTORIZER_SANDBOXVECTORIZER_H
 
+#include <memory>
+
 #include "llvm/IR/PassManager.h"
+#include "llvm/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.h"
 
 namespace llvm {
 
@@ -17,10 +20,22 @@ class TargetTransformInfo;
 class SandboxVectorizerPass : public PassInfoMixin<SandboxVectorizerPass> {
   TargetTransformInfo *TTI = nullptr;
 
-public:
-  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  // The main vectorizer pass.
+  sandboxir::BottomUpVec BottomUpVecPass;
 
   bool runImpl(Function &F);
+
+public:
+  // Make sure the constructors/destructors are out-of-line. This works around a
+  // problem with -DBUILD_SHARED_LIBS=on where components that depend on the
+  // Vectorizer component can't find the vtable for classes like
+  // sandboxir::Pass. This way we don't have to make LLVMPasses add a direct
+  // dependency on SandboxIR.
+  SandboxVectorizerPass();
+  SandboxVectorizerPass(SandboxVectorizerPass &&);
+  ~SandboxVectorizerPass();
+
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
 
 } // namespace llvm

llvm/lib/SandboxIR/PassManager.cpp

@@ -8,11 +8,11 @@
 
 #include "llvm/SandboxIR/PassManager.h"
 
-using namespace llvm::sandboxir;
+namespace llvm::sandboxir {
 
 bool FunctionPassManager::runOnFunction(Function &F) {
   bool Change = false;
-  for (FunctionPass *Pass : Passes) {
+  for (auto &Pass : Passes) {
     Change |= Pass->runOnFunction(F);
     // TODO: run the verifier.
   }
@@ -22,48 +22,12 @@ bool FunctionPassManager::runOnFunction(Function &F) {
 
 bool RegionPassManager::runOnRegion(Region &R) {
   bool Change = false;
-  for (RegionPass *Pass : Passes) {
+  for (auto &Pass : Passes) {
     Change |= Pass->runOnRegion(R);
     // TODO: run the verifier.
   }
   // TODO: Check ChangeAll against hashes before/after.
   return Change;
 }
 
-FunctionPassManager &
-PassRegistry::parseAndCreatePassPipeline(StringRef Pipeline) {
-  static constexpr const char EndToken = '\0';
-  // Add EndToken to the end to ease parsing.
-  std::string PipelineStr = std::string(Pipeline) + EndToken;
-  int FlagBeginIdx = 0;
-  // Start with a FunctionPassManager.
-  auto &InitialPM = static_cast<FunctionPassManager &>(
-      registerPass(std::make_unique<FunctionPassManager>("init-fpm")));
-
-  for (auto [Idx, C] : enumerate(PipelineStr)) {
-    // Keep moving Idx until we find the end of the pass name.
-    bool FoundDelim = C == EndToken || C == PassDelimToken;
-    if (!FoundDelim)
-      continue;
-    unsigned Sz = Idx - FlagBeginIdx;
-    std::string PassName(&PipelineStr[FlagBeginIdx], Sz);
-    FlagBeginIdx = Idx + 1;
-
-    // Get the pass that corresponds to PassName and add it to the pass manager.
-    auto *Pass = getPassByName(PassName);
-    if (Pass == nullptr) {
-      errs() << "Pass '" << PassName << "' not registered!\n";
-      exit(1);
-    }
-    // TODO: This is safe for now, but would require proper upcasting once we
-    // add more Pass sub-classes.
-    InitialPM.addPass(static_cast<FunctionPass *>(Pass));
-  }
-  return InitialPM;
-}
-#ifndef NDEBUG
-void PassRegistry::dump() const {
-  print(dbgs());
-  dbgs() << "\n";
-}
-#endif // NDEBUG
+} // namespace llvm::sandboxir

llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp

@@ -10,10 +10,41 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/SandboxIR/Function.h"
 #include "llvm/SandboxIR/Instruction.h"
-
-using namespace llvm::sandboxir;
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Transforms/Vectorize/SandboxVectorizer/Passes/NullPass.h"
 
 namespace llvm::sandboxir {
+
+static cl::opt<bool>
+    PrintPassPipeline("sbvec-print-pass-pipeline", cl::init(false), cl::Hidden,
+                      cl::desc("Prints the pass pipeline and returns."));
+
+/// A magic string for the default pass pipeline.
+static const char *DefaultPipelineMagicStr = "*";
+
+static cl::opt<std::string> UserDefinedPassPipeline(
+    "sbvec-passes", cl::init(DefaultPipelineMagicStr), cl::Hidden,
+    cl::desc("Comma-separated list of vectorizer passes. If not set "
+             "we run the predefined pipeline."));
+
+static std::unique_ptr<RegionPass> createRegionPass(StringRef Name) {
+#define REGION_PASS(NAME, CREATE_PASS)                                         \
+  if (Name == NAME)                                                            \
+    return std::make_unique<decltype(CREATE_PASS)>(CREATE_PASS);
+#include "PassRegistry.def"
+  return nullptr;
+}
+
+BottomUpVec::BottomUpVec() : FunctionPass("bottom-up-vec"), RPM("rpm") {
+  // Create a pipeline to be run on each Region created by BottomUpVec.
+  if (UserDefinedPassPipeline == DefaultPipelineMagicStr) {
+    // TODO: Add default passes to RPM.
+  } else {
+    // Create the user-defined pipeline.
+    RPM.setPassPipeline(UserDefinedPassPipeline, createRegionPass);
+  }
+}
+
 // TODO: This is a temporary function that returns some seeds.
 //       Replace this with SeedCollector's function when it lands.
 static llvm::SmallVector<Value *, 4> collectSeeds(BasicBlock &BB) {
@@ -34,8 +65,6 @@ static SmallVector<Value *, 4> getOperand(ArrayRef<Value *> Bndl,
   return Operands;
 }
 
-} // namespace llvm::sandboxir
-
 void BottomUpVec::vectorizeRec(ArrayRef<Value *> Bndl) {
   auto LegalityRes = Legality.canVectorize(Bndl);
   switch (LegalityRes.getSubclassID()) {
@@ -53,14 +82,23 @@ void BottomUpVec::vectorizeRec(ArrayRef<Value *> Bndl) {
 void BottomUpVec::tryVectorize(ArrayRef<Value *> Bndl) { vectorizeRec(Bndl); }
 
 bool BottomUpVec::runOnFunction(Function &F) {
+  if (PrintPassPipeline) {
+    RPM.printPipeline(outs());
+    return false;
+  }
+
   Change = false;
   // TODO: Start from innermost BBs first
   for (auto &BB : F) {
     // TODO: Replace with proper SeedCollector function.
     auto Seeds = collectSeeds(BB);
     // TODO: Slice Seeds into smaller chunks.
+    // TODO: If vectorization succeeds, run the RegionPassManager on the
+    // resulting region.
     if (Seeds.size() >= 2)
       tryVectorize(Seeds);
   }
   return Change;
 }
+
+} // namespace llvm::sandboxir

llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/PassRegistry.def

@@ -0,0 +1,22 @@
+//===- PassRegistry.def - Registry of passes --------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is used as the registry of sub-passes that are part of the
+// SandboxVectorizer pass.
+//
+//===----------------------------------------------------------------------===//
+
+// NOTE: NO INCLUDE GUARD DESIRED!
+
+#ifndef REGION_PASS
+#define REGION_PASS(NAME, CREATE_PASS)
+#endif
+
+REGION_PASS("null", NullPass())
+
+#undef REGION_PASS