[RegionInfo] Add debug-time region viewer functions

[Meinersbur]

Summary

Analogously to Function::viewCFG(), RegionInfo::view() and RegionInfo::viewOnly() are meant to be called in debugging sessions. They open a viewer to show how RegionInfo currently understands the region hierarchy.

The functions viewRegion(Function*) and viewRegionOnly(Function*) invoke a fresh region analysis of the function in contrast to viewRegion(RegionInfo*) and viewRegionOnly(RegionInfo*) which show the current analysis result.

[grosser]

LGTM. Thanks for this nice debugging functionality.

include/llvm/Analysis/RegionInfo.h

856

visualization

include/llvm/Analysis/RegionPrinter.h

44

Maybe mention in the comments here that a new analysis is run (you mention this implicitly, but being explicit about this would be good).

61

Please be explicit about it running a new analysis.

[Meinersbur]

Addressed comments

[grosser]

Otherwise, this lucks good.

include/llvm/Analysis/RegionInfo.h

856

There is still a typo in visalization.

[Meinersbur]

Typo corrected in r244445

include/llvm/Analysis/RegionInfo.h

public:
 
   ~RegionInfo() override;
 
   // updateStatistics - Update statistic about created regions.
   void updateStatistics(Region *R) final;
 
   void recalculate(Function &F, DominatorTree *DT, PostDominatorTree *PDT,
                    DominanceFrontier *DF);
+
+#ifndef NDEBUG
+  /// @brief Opens a viewer to show the GraphViz visualization of the regions.
+  ///
+  /// Useful during debugging as an alternative to dump().
+  void view();
+
+  /// @brief Opens a viewer to show the GraphViz visalization of this region
+  /// without instructions in the BasicBlocks.
+  ///
+  /// Useful during debugging as an alternative to dump().
+  void viewOnly();
+#endif
 };
 
 class RegionInfoPass : public FunctionPass {
   RegionInfo RI;
 
 public:
   static char ID;
   explicit RegionInfoPass();

include/llvm/Analysis/RegionPrinter.h

 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_REGIONPRINTER_H
 #define LLVM_ANALYSIS_REGIONPRINTER_H
 
 namespace llvm {
   class FunctionPass;
+  class Function;
+  class RegionInfo;
+
   FunctionPass *createRegionViewerPass();
   FunctionPass *createRegionOnlyViewerPass();
   FunctionPass *createRegionPrinterPass();
   FunctionPass *createRegionOnlyPrinterPass();
+
+#ifndef NDEBUG
+  /// @brief Open a viewer to display the GraphViz vizualization of the analysis
+  /// result.
+  ///
+  /// Practical to call in the debugger.
+  /// Includes the instructions in each BasicBlock.
+  ///
+  /// @param RI The analysis to display.
+  void viewRegion(llvm::RegionInfo *RI);
+
+  /// @brief Analyze the regions of a function and open its GraphViz
+  /// visualization in a viewer.
+  ///
+  /// Useful to call in the debugger.
+  /// Includes the instructions in each BasicBlock.
+  /// The result of a new analysis may differ from the RegionInfo the pass
+  /// manager currently holds.
+  ///
+  /// @param F Function to analyze.
+  void viewRegion(const llvm::Function *F);
+
+  /// @brief Open a viewer to display the GraphViz vizualization of the analysis
+  /// result.
+  ///
+  /// Useful to call in the debugger.
+  /// Shows only the BasicBlock names without their instructions.
+  ///
+  /// @param RI The analysis to display.
+  void viewRegionOnly(llvm::RegionInfo *RI);
+
+  /// @brief Analyze the regions of a function and open its GraphViz
+  /// visualization in a viewer.
+  ///
+  /// Useful to call in the debugger.
+  /// Shows only the BasicBlock names without their instructions.
+  /// The result of a new analysis may differ from the RegionInfo the pass
+  /// manager currently holds.
+  ///
+  /// @param F Function to analyze.
+  void viewRegionOnly(const llvm::Function *F);
+#endif
 } // End llvm namespace
 
 #endif

lib/Analysis/RegionInfo.cpp

 #include "llvm/Analysis/RegionInfoImpl.h"
 #include "llvm/Analysis/RegionIterator.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <iterator>
 #include <set>
+#ifndef NDEBUG
+#include "llvm/Analysis/RegionPrinter.h"
+#endif
 
 using namespace llvm;
 
 #define DEBUG_TYPE "region"
 
 namespace llvm {
 template class RegionBase<RegionTraits<Function>>;
 template class RegionNodeBase<RegionTraits<Function>>;
void RegionInfo::recalculate(Function &F, DominatorTree *DT_,
   DF = DF_;
 
   TopLevelRegion = new Region(&F.getEntryBlock(), nullptr,
                               this, DT, nullptr);
   updateStatistics(TopLevelRegion);
   calculate(F);
 }
 
+#ifndef NDEBUG
+void RegionInfo::view() { viewRegion(this); }
+
+void RegionInfo::viewOnly() { viewRegionOnly(this); }
+#endif
+
 //===----------------------------------------------------------------------===//
 // RegionInfoPass implementation
 //
 
 RegionInfoPass::RegionInfoPass() : FunctionPass(ID) {
   initializeRegionInfoPassPass(*PassRegistry::getPassRegistry());
 }
 

lib/Analysis/RegionPrinter.cpp

 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/DOTGraphTraitsPass.h"
 #include "llvm/Analysis/RegionInfo.h"
 #include "llvm/Analysis/RegionIterator.h"
 #include "llvm/Analysis/RegionPrinter.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
+#ifndef NDEBUG
+#include "llvm/IR/LegacyPassManager.h"
+#endif
 
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
 /// onlySimpleRegion - Show only the simple regions in the RegionViewer.
 static cl::opt<bool>
 onlySimpleRegions("only-simple-regions",
                   cl::desc("Show only simple regions in the graphviz viewer"),

 FunctionPass* llvm::createRegionViewerPass() {
   return new RegionViewer();
 }
 
 FunctionPass* llvm::createRegionOnlyViewerPass() {
   return new RegionOnlyViewer();
 }
 
+#ifndef NDEBUG
+static void viewRegionInfo(RegionInfo *RI, bool ShortNames) {
+  assert(RI && "Argument must be non-null");
+
+  llvm::Function *F = RI->getTopLevelRegion()->getEntry()->getParent();
+  std::string GraphName = DOTGraphTraits<RegionInfo *>::getGraphName(RI);
+
+  llvm::ViewGraph(RI, "reg", ShortNames,
+                  Twine(GraphName) + " for '" + F->getName() + "' function");
+}
+
+static void invokeFunctionPass(const Function *F, FunctionPass *ViewerPass) {
+  assert(F && "Argument must be non-null");
+  assert(!F->isDeclaration() && "Function must have an implementation");
+
+  // The viewer and analysis passes do not modify anything, so we can safely
+  // remove the const qualifier
+  auto NonConstF = const_cast<Function *>(F);
+
+  llvm::legacy::FunctionPassManager FPM(NonConstF->getParent());
+  FPM.add(ViewerPass);
+  FPM.doInitialization();
+  FPM.run(*NonConstF);
+  FPM.doFinalization();
+}
+
+void llvm::viewRegion(RegionInfo *RI) { viewRegionInfo(RI, false); }
+
+void llvm::viewRegion(const Function *F) {
+  invokeFunctionPass(F, createRegionViewerPass());
+}
+
+void llvm::viewRegionOnly(RegionInfo *RI) { viewRegionInfo(RI, true); }
+
+void llvm::viewRegionOnly(const Function *F) {
+  invokeFunctionPass(F, createRegionOnlyViewerPass());
+}
+#endif