Add missing PassManager.h and fix .gitignore to not ignore src/include/

.gitignore

@@ -67,7 +67,7 @@ Thumbs.db
 # =========================
 # Local-only (not for grader)
 # =========================
-include
+/include
 third_party/antlr4-runtime-4.13.2/runtime/
 
 # =========================

src/include/ir/passes/PassManager.h

@@ -0,0 +1,83 @@
+#ifndef IR_PASSES_PASSMANAGER_H_
+#define IR_PASSES_PASSMANAGER_H_
+
+#include "ir/IR.h"
+
+#include <sstream>
+#include <string>
+
+namespace ir {
+
+void RunMem2Reg(Module& module);
+void RunLICM(Module* module);
+void RunConstFold(Module& module);
+void RunConstProp(Module& module);
+void RunDCE(Module& module);
+void RunCFGSimplify(Module& module);
+void RunCSE(Module& module);
+
+class PassManagerModule {
+ public:
+  explicit PassManagerModule(Module* module) : module_(module) {}
+
+  void Run() {
+    if (!module_) {
+      return;
+    }
+
+    RunMem2Reg(*module_);
+
+    RunLICM(module_);
+
+    bool changed = true;
+    int max_iterations = 10;
+    int iterations = 0;
+
+    while (changed && iterations < max_iterations) {
+      changed = false;
+      iterations++;
+
+      auto before = SerializeModule(*module_);
+
+      RunConstFold(*module_);
+      RunConstProp(*module_);
+      RunCFGSimplify(*module_);
+      RunCSE(*module_);
+      RunDCE(*module_);
+
+      auto after = SerializeModule(*module_);
+      changed = (before != after);
+    }
+  }
+
+ private:
+  std::string SerializeModule(const Module& module) {
+    std::ostringstream oss;
+    IRPrinter printer;
+    printer.Print(module, oss);
+    return oss.str();
+  }
+
+  Module* module_;
+};
+
+class PassManager {
+ public:
+  PassManager() = default;
+
+  void RunScalarOptimizationPasses(Module* module) {
+    if (!module) return;
+
+    RunMem2Reg(*module);
+
+    RunConstFold(*module);
+    RunDCE(*module);
+    RunCFGSimplify(*module);
+  }
+
+ private:
+};
+
+}  // namespace ir
+
+#endif  // IR_PASSES_PASSMANAGER_H_