PM: Rephrase PrintLoopPass as a wrapper around a new-style pass. NFC

Splits PrintLoopPass into a new-style pass and a PrintLoopPassWrapper,
much like we already do for PrintFunctionPass and PrintModulePass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252085 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/LoopInfo.h

@@ -763,6 +763,19 @@ public:
   void getAnalysisUsage(AnalysisUsage &AU) const override;
 };
 
+/// \brief Pass for printing a loop's contents as LLVM's text IR assembly.
+class PrintLoopPass {
+  raw_ostream &OS;
+  std::string Banner;
+
+public:
+  PrintLoopPass();
+  PrintLoopPass(raw_ostream &OS, const std::string &Banner = "");
+
+  PreservedAnalyses run(Loop &L);
+  static StringRef name() { return "PrintLoopPass"; }
+};
+
 } // End llvm namespace
 
 #endif

lib/Analysis/LoopInfo.cpp

@@ -691,6 +691,20 @@ PreservedAnalyses LoopPrinterPass::run(Function &F,
   return PreservedAnalyses::all();
 }
 
+PrintLoopPass::PrintLoopPass() : OS(dbgs()) {}
+PrintLoopPass::PrintLoopPass(raw_ostream &OS, const std::string &Banner)
+    : OS(OS), Banner(Banner) {}
+
+PreservedAnalyses PrintLoopPass::run(Loop &L) {
+  OS << Banner;
+  for (auto *Block : L.blocks())
+    if (Block)
+      Block->print(OS);
+    else
+      OS << "Printing <null> block";
+  return PreservedAnalyses::all();
+}
+
 //===----------------------------------------------------------------------===//
 // LoopInfo implementation
 //

lib/Analysis/LoopPass.cpp

@@ -16,6 +16,7 @@
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
@@ -27,35 +28,26 @@ namespace {
 
 /// PrintLoopPass - Print a Function corresponding to a Loop.
 ///
-class PrintLoopPass : public LoopPass {
-private:
-  std::string Banner;
-  raw_ostream &Out;       // raw_ostream to print on.
+class PrintLoopPassWrapper : public LoopPass {
+  PrintLoopPass P;
 
 public:
   static char ID;
-  PrintLoopPass(const std::string &B, raw_ostream &o)
-      : LoopPass(ID), Banner(B), Out(o) {}
+  PrintLoopPassWrapper() : LoopPass(ID) {}
+  PrintLoopPassWrapper(raw_ostream &OS, const std::string &Banner)
+      : LoopPass(ID), P(OS, Banner) {}
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesAll();
   }
 
   bool runOnLoop(Loop *L, LPPassManager &) override {
-    Out << Banner;
-    for (Loop::block_iterator b = L->block_begin(), be = L->block_end();
-         b != be;
-         ++b) {
-      if (*b)
-        (*b)->print(Out);
-      else
-        Out << "Printing <null> block";
-    }
+    P.run(*L);
     return false;
   }
 };
 
-char PrintLoopPass::ID = 0;
+char PrintLoopPassWrapper::ID = 0;
 }
 
 //===----------------------------------------------------------------------===//
@@ -305,7 +297,7 @@ void LPPassManager::dumpPassStructure(unsigned Offset) {
 
 Pass *LoopPass::createPrinterPass(raw_ostream &O,
                                   const std::string &Banner) const {
-  return new PrintLoopPass(Banner, O);
+  return new PrintLoopPassWrapper(O, Banner);
 }
 
 // Check if this pass is suitable for the current LPPassManager, if