[VPlan] Add dump function to VPlan class.

This adds a dump() function to VPlan, which uses the existing
operator<<.

This method provides a convenient way to dump a VPlan while debugging,
e.g. from lldb.

Reviewers: hsaito, Ayal, gilr, rengolin

Reviewed By: hsaito

Differential Revision: https://reviews.llvm.org/D70920

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -468,6 +468,11 @@ void VPlan::execute(VPTransformState *State) {
     updateDominatorTree(State->DT, VectorPreHeaderBB, VectorLatchBB);
 }
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD
+void VPlan::dump() const { dbgs() << *this << '\n'; }
+#endif
+
 void VPlan::updateDominatorTree(DominatorTree *DT, BasicBlock *LoopPreHeaderBB,
                                 BasicBlock *LoopLatchBB) {
   BasicBlock *LoopHeaderBB = LoopPreHeaderBB->getSingleSuccessor();
@@ -527,8 +532,7 @@ void VPlanPrinter::dump() {
   if (!Plan.Value2VPValue.empty() || Plan.BackedgeTakenCount) {
     OS << ", where:";
     if (Plan.BackedgeTakenCount)
-      OS << "\\n"
-         << *Plan.getOrCreateBackedgeTakenCount() << " := BackedgeTakenCount";
+      OS << "\\n" << *Plan.BackedgeTakenCount << " := BackedgeTakenCount";
     for (auto Entry : Plan.Value2VPValue) {
       OS << "\\n" << *Entry.second;
       OS << DOT::EscapeString(" := ");
@@ -540,7 +544,7 @@ void VPlanPrinter::dump() {
   OS << "edge [fontname=Courier, fontsize=30]\n";
   OS << "compound=true\n";
 
-  for (VPBlockBase *Block : depth_first(Plan.getEntry()))
+  for (const VPBlockBase *Block : depth_first(Plan.getEntry()))
     dumpBlock(Block);
 
   OS << "}\n";

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -1387,6 +1387,9 @@ class VPlan {
   VPLoopInfo &getVPLoopInfo() { return VPLInfo; }
   const VPLoopInfo &getVPLoopInfo() const { return VPLInfo; }
 
+  /// Dump the plan to stderr (for debugging).
+  void dump() const;
+
 private:
   /// Add to the given dominator tree the header block and every new basic block
   /// that was created between it and the latch block, inclusive.
@@ -1398,20 +1401,20 @@ class VPlan {
 /// VPlanPrinter prints a given VPlan to a given output stream. The printing is
 /// indented and follows the dot format.
 class VPlanPrinter {
-  friend inline raw_ostream &operator<<(raw_ostream &OS, VPlan &Plan);
+  friend inline raw_ostream &operator<<(raw_ostream &OS, const VPlan &Plan);
   friend inline raw_ostream &operator<<(raw_ostream &OS,
                                         const struct VPlanIngredient &I);
 
 private:
   raw_ostream &OS;
-  VPlan &Plan;
+  const VPlan &Plan;
   unsigned Depth = 0;
   unsigned TabWidth = 2;
   std::string Indent;
   unsigned BID = 0;
   SmallDenseMap<const VPBlockBase *, unsigned> BlockID;
 
-  VPlanPrinter(raw_ostream &O, VPlan &P) : OS(O), Plan(P) {}
+  VPlanPrinter(raw_ostream &O, const VPlan &P) : OS(O), Plan(P) {}
 
   /// Handle indentation.
   void bumpIndent(int b) { Indent = std::string((Depth += b) * TabWidth, ' '); }
@@ -1458,13 +1461,12 @@ inline raw_ostream &operator<<(raw_ostream &OS, const VPlanIngredient &I) {
   return OS;
 }
 
-inline raw_ostream &operator<<(raw_ostream &OS, VPlan &Plan) {
+inline raw_ostream &operator<<(raw_ostream &OS, const VPlan &Plan) {
   VPlanPrinter Printer(OS, Plan);
   Printer.dump();
   return OS;
 }
 
-
 //===----------------------------------------------------------------------===//
 // VPlan Utilities
 //===----------------------------------------------------------------------===//