[PM] Start sketching out the new module and function pass manager.

This is still just a skeleton. I'm trying to pull together the
experimentation I've done into committable chunks, and this is the first
coherent one. Others will follow in hopefully short order that move this
more toward a useful initial implementation. I still expect the design
to continue evolving in small ways as I work through the different
requirements and features needed here though.

Keep in mind, all of this is off by default.

Currently, this mostly exercises the use of a polymorphic smart pointer
and templates to hide the polymorphism for the pass manager from the
pass implementation. The next step will be more significant, adding the
first framework of analysis support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194325 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/PassManager.h

@@ -0,0 +1,118 @@
+//===- PassManager.h - LegacyContainer for Passes --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This header defines various interfaces for pass management in LLVM. There
+/// is no "pass" interface in LLVM per se. Instead, an instance of any class
+/// which supports a method to 'run' it over a unit of IR can be used as
+/// a pass. A pass manager is generally a tool to collect a sequence of passes
+/// which run over a particular IR construct, and run each of them in sequence
+/// over each such construct in the containing IR construct. As there is no
+/// containing IR construct for a Module, a manager for passes over modules
+/// forms the base case which runs its managed passes in sequence over the
+/// single module provided.
+///
+/// The core IR library provides managers for running passes over
+/// modules and functions.
+///
+/// * FunctionPassManager can run over a Module, runs each pass over
+///   a Function.
+/// * ModulePassManager must be directly run, runs each pass over the Module.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/polymorphic_ptr.h"
+#include "llvm/IR/Module.h"
+#include <vector>
+
+namespace llvm {
+
+class Module;
+class Function;
+
+/// \brief Implementation details of the pass manager interfaces.
+namespace detail {
+
+/// \brief Template for the abstract base class used to dispatch
+/// polymorphically over pass objects.
+template <typename T> struct PassConcept {
+  // Boiler plate necessary for the container of derived classes.
+  virtual ~PassConcept() {}
+  virtual PassConcept *clone() = 0;
+
+  /// \brief The polymorphic API which runs the pass over a given IR entity.
+  virtual bool run(T Arg) = 0;
+};
+
+/// \brief A template wrapper used to implement the polymorphic API.
+///
+/// Can be instantiated for any object which provides a \c run method
+/// accepting a \c T. It requires the pass to be a copyable
+/// object.
+template <typename T, typename PassT> struct PassModel : PassConcept<T> {
+  PassModel(PassT Pass) : Pass(llvm_move(Pass)) {}
+  virtual PassModel *clone() { return new PassModel(Pass); }
+  virtual bool run(T Arg) { return Pass.run(Arg); }
+  PassT Pass;
+};
+
+}
+
+class ModulePassManager {
+public:
+  ModulePassManager(Module *M) : M(M) {}
+
+  template <typename ModulePassT> void addPass(ModulePassT Pass) {
+    Passes.push_back(new ModulePassModel<ModulePassT>(llvm_move(Pass)));
+  }
+
+  void run() {
+    for (unsigned Idx = 0, Size = Passes.size(); Idx != Size; ++Idx)
+      Passes[Idx]->run(M);
+  }
+
+private:
+  // Pull in the concept type and model template specialized for modules.
+  typedef detail::PassConcept<Module *> ModulePassConcept;
+  template <typename PassT>
+  struct ModulePassModel : detail::PassModel<Module *, PassT> {
+    ModulePassModel(PassT Pass) : detail::PassModel<Module *, PassT>(Pass) {}
+  };
+
+  Module *M;
+  std::vector<polymorphic_ptr<ModulePassConcept> > Passes;
+};
+
+class FunctionPassManager {
+public:
+  template <typename FunctionPassT> void addPass(FunctionPassT Pass) {
+    Passes.push_back(new FunctionPassModel<FunctionPassT>(llvm_move(Pass)));
+  }
+
+  bool run(Module *M) {
+    bool Changed = false;
+    for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
+      for (unsigned Idx = 0, Size = Passes.size(); Idx != Size; ++Idx)
+        Changed |= Passes[Idx]->run(I);
+    return Changed;
+  }
+
+private:
+  // Pull in the concept type and model template specialized for functions.
+  typedef detail::PassConcept<Function *> FunctionPassConcept;
+  template <typename PassT>
+  struct FunctionPassModel : detail::PassModel<Function *, PassT> {
+    FunctionPassModel(PassT Pass)
+        : detail::PassModel<Function *, PassT>(Pass) {}
+  };
+
+  std::vector<polymorphic_ptr<FunctionPassConcept> > Passes;
+};
+
+}

unittests/IR/CMakeLists.txt

@@ -13,6 +13,7 @@ set(IRSources
   LegacyPassManagerTest.cpp
   MDBuilderTest.cpp
   MetadataTest.cpp
+  PassManagerTest.cpp
   PatternMatch.cpp
   TypeBuilderTest.cpp
   TypesTest.cpp

unittests/IR/PassManagerTest.cpp

@@ -0,0 +1,88 @@
+//===- llvm/unittest/IR/PassManager.cpp - PassManager tests ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Assembly/Parser.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Support/SourceMgr.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+struct TestModulePass {
+  TestModulePass(int &RunCount) : RunCount(RunCount) {}
+
+  bool run(Module *M) {
+    ++RunCount;
+    return true;
+  }
+
+  int &RunCount;
+};
+
+struct TestFunctionPass {
+  TestFunctionPass(int &RunCount) : RunCount(RunCount) {}
+
+  bool run(Function *F) {
+    ++RunCount;
+    return true;
+  }
+
+  int &RunCount;
+};
+
+Module *parseIR(const char *IR) {
+  LLVMContext &C = getGlobalContext();
+  SMDiagnostic Err;
+  return ParseAssemblyString(IR, 0, Err, C);
+}
+
+class PassManagerTest : public ::testing::Test {
+protected:
+  OwningPtr<Module> M;
+
+public:
+  PassManagerTest()
+      : M(parseIR("define void @f() {\n"
+                  "entry:\n"
+                  "  call void @g()\n"
+                  "  call void @h()\n"
+                  "  ret void\n"
+                  "}\n"
+                  "define void @g() {\n"
+                  "  ret void\n"
+                  "}\n"
+                  "define void @h() {\n"
+                  "  ret void\n"
+                  "}\n")) {}
+};
+
+TEST_F(PassManagerTest, Basic) {
+  ModulePassManager MPM(M.get());
+  FunctionPassManager FPM;
+
+  // Count the runs over a module.
+  int ModulePassRunCount = 0;
+  MPM.addPass(TestModulePass(ModulePassRunCount));
+
+  // Count the runs over a Function.
+  int FunctionPassRunCount = 0;
+  FPM.addPass(TestFunctionPass(FunctionPassRunCount));
+  MPM.addPass(FPM);
+
+  MPM.run();
+  EXPECT_EQ(1, ModulePassRunCount);
+  EXPECT_EQ(3, FunctionPassRunCount);
+}
+
+}