Show the reason a region is not a SCoP in the DOT graphs.

llvm-svn: 141458

polly/include/polly/ScopDetection.h

@@ -109,6 +109,7 @@ class ScopDetection : public FunctionPass {
   // Remember the invalid functions producted by backends;
   typedef std::set<const Function*> FunctionSet;
   FunctionSet InvalidFunctions;
+  mutable std::string LastFailure;
 
   // Try to expand the region R. If R can be expanded return the expanded
   // region, NULL otherwise.
@@ -233,6 +234,13 @@ public:
   /// @return Return true if R is the maximum Region in a Scop, false otherwise.
   bool isMaxRegionInScop(const Region &R) const;
 
+  /// @brief Get a message why a region is invalid
+  ///
+  /// @param R The region for which we get the error message
+  ///
+  /// @return The error or "" if no error appeared.
+  std::string regionIsInvalidBecause(const Region *R) const;
+
   /// @name Maximum Region In Scops Iterators
   ///
   /// These iterators iterator over all maximum region in Scops of this

polly/lib/Analysis/ScopDetection.cpp

@@ -77,6 +77,11 @@ STATISTIC(ValidRegion, "Number of regions that a valid part of Scop");
 
 #define INVALID(NAME, MESSAGE) \
   do { \
+    std::string Buf; \
+    raw_string_ostream fmt(Buf); \
+    fmt << MESSAGE; \
+    fmt.flush(); \
+    LastFailure = Buf; \
     DEBUG(dbgs() << MESSAGE); \
     DEBUG(dbgs() << "\n"); \
     STATSCOP(NAME); \
@@ -102,6 +107,14 @@ bool ScopDetection::isMaxRegionInScop(const Region &R) const {
   return ValidRegions.count(&R);
 }
 
+std::string ScopDetection::regionIsInvalidBecause(const Region *R) const {
+  if (!InvalidRegions.count(R))
+    return "";
+
+  return InvalidRegions.find(R)->second;
+}
+
+
 bool ScopDetection::isValidAffineFunction(const SCEV *S, Region &RefRegion,
                                           Value **BasePtr) const {
   assert(S && "S must not be null!");
@@ -438,6 +451,8 @@ void ScopDetection::findScops(Region &R) {
     return;
   }
 
+  InvalidRegions[&R] = LastFailure;
+
   for (Region::iterator I = R.begin(), E = R.end(); I != E; ++I)
     findScops(**I);
 
@@ -583,6 +598,7 @@ void ScopDetection::print(raw_ostream &OS, const Module *) const {
 
 void ScopDetection::releaseMemory() {
   ValidRegions.clear();
+  InvalidRegions.clear();
   // Do not clear the invalid function set.
 }
 

polly/lib/Analysis/ScopGraphPrinter.cpp

@@ -107,7 +107,8 @@ struct DOTGraphTraits<ScopDetection*> : public DOTGraphTraits<RegionNode*> {
                                  raw_ostream &O, unsigned depth = 0) {
     O.indent(2 * depth) << "subgraph cluster_" << static_cast<const void*>(R)
       << " {\n";
-    O.indent(2 * (depth + 1)) << "label = \"\";\n";
+    std::string ErrorMessage = SD->regionIsInvalidBecause(R);
+    O.indent(2 * (depth + 1)) << "label = \"" << ErrorMessage << "\";\n";
 
     if (SD->isMaxRegionInScop(*R)) {
       O.indent(2 * (depth + 1)) << "style = filled;\n";