1 files changed, 22 insertions, 6 deletions

diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index d2dfc20..d953e30 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -16,7 +16,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "loop-unroll"
 #include "llvm/Transforms/Utils/UnrollLoop.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/InstructionSimplify.h"
@@ -25,6 +24,8 @@
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Dominators.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
@@ -34,6 +35,8 @@
 #include "llvm/Transforms/Utils/SimplifyIndVar.h"
 using namespace llvm;
 
+#define DEBUG_TYPE "loop-unroll"
+
 // TODO: Should these be here or in LoopUnroll?
 STATISTIC(NumCompletelyUnrolled, "Number of loops completely unrolled");
 STATISTIC(NumUnrolled, "Number of loops unrolled (completely or otherwise)");
@@ -68,10 +71,10 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI,
   // pred, and if there is only one distinct successor of the predecessor, and
   // if there are no PHI nodes.
   BasicBlock *OnlyPred = BB->getSinglePredecessor();
-  if (!OnlyPred) return 0;
+  if (!OnlyPred) return nullptr;
 
   if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
-    return 0;
+    return nullptr;
 
   DEBUG(dbgs() << "Merging: " << *BB << "into: " << *OnlyPred);
 
@@ -227,20 +230,33 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
       (unsigned)GreatestCommonDivisor64(Count, TripMultiple);
   }
 
+  // Report the unrolling decision.
+  DebugLoc LoopLoc = L->getStartLoc();
+  Function *F = Header->getParent();
+  LLVMContext &Ctx = F->getContext();
+
   if (CompletelyUnroll) {
     DEBUG(dbgs() << "COMPLETELY UNROLLING loop %" << Header->getName()
           << " with trip count " << TripCount << "!\n");
+    emitOptimizationRemark(Ctx, DEBUG_TYPE, *F, LoopLoc,
+                           Twine("completely unrolled loop with ") +
+                               Twine(TripCount) + " iterations");
   } else {
     DEBUG(dbgs() << "UNROLLING loop %" << Header->getName()
           << " by " << Count);
+    Twine DiagMsg("unrolled loop by a factor of " + Twine(Count));
     if (TripMultiple == 0 || BreakoutTrip != TripMultiple) {
       DEBUG(dbgs() << " with a breakout at trip " << BreakoutTrip);
+      DiagMsg.concat(" with a breakout at trip " + Twine(BreakoutTrip));
     } else if (TripMultiple != 1) {
       DEBUG(dbgs() << " with " << TripMultiple << " trips per branch");
+      DiagMsg.concat(" with " + Twine(TripMultiple) + " trips per branch");
     } else if (RuntimeTripCount) {
       DEBUG(dbgs() << " with run-time trip count");
+      DiagMsg.concat(" with run-time trip count");
     }
     DEBUG(dbgs() << "!\n");
+    emitOptimizationRemark(Ctx, DEBUG_TYPE, *F, LoopLoc, DiagMsg);
   }
 
   bool ContinueOnTrue = L->contains(BI->getSuccessor(0));
@@ -411,7 +427,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
     }
   }
 
-  DominatorTree *DT = 0;
+  DominatorTree *DT = nullptr;
   if (PP) {
     // FIXME: Reconstruct dom info, because it is not preserved properly.
     // Incrementally updating domtree after loop unrolling would be easy.
@@ -458,7 +474,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
 
   Loop *OuterL = L->getParentLoop();
   // Remove the loop from the LoopPassManager if it's completely removed.
-  if (CompletelyUnroll && LPM != NULL)
+  if (CompletelyUnroll && LPM != nullptr)
     LPM->deleteLoopFromQueue(L);
 
   // If we have a pass and a DominatorTree we should re-simplify impacted loops
@@ -470,7 +486,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
       OuterL = L;
     if (OuterL) {
       ScalarEvolution *SE = PP->getAnalysisIfAvailable<ScalarEvolution>();
-      simplifyLoop(OuterL, DT, LI, PP, /*AliasAnalysis*/ 0, SE);
+      simplifyLoop(OuterL, DT, LI, PP, /*AliasAnalysis*/ nullptr, SE);
       formLCSSARecursively(*OuterL, *DT, SE);
     }
   }