Index: llvm/trunk/lib/Transforms/IPO/HotColdSplitting.cpp
===================================================================
--- llvm/trunk/lib/Transforms/IPO/HotColdSplitting.cpp
+++ llvm/trunk/lib/Transforms/IPO/HotColdSplitting.cpp
@@ -335,6 +335,7 @@
 HotColdSplitting::extractColdRegion(const SmallVectorImpl<BasicBlock *> &Region,
                                     DominatorTree *DT, BlockFrequencyInfo *BFI,
                                     OptimizationRemarkEmitter &ORE) {
+  assert(!Region.empty());
   LLVM_DEBUG(for (auto *BB : Region)
           llvm::dbgs() << "\nExtracting: " << *BB;);
 
@@ -348,6 +349,7 @@
   if (Outputs.size() > 0)
     return nullptr;
 
+  Function *OrigF = Region[0]->getParent();
   if (Function *OutF = CE.extractCodeRegion()) {
     User *U = *OutF->user_begin();
     CallInst *CI = cast<CallInst>(U);
@@ -359,6 +361,12 @@
     }
     CI->setIsNoInline();
     LLVM_DEBUG(llvm::dbgs() << "Outlined Region: " << *OutF);
+    ORE.emit([&]() {
+      return OptimizationRemark(DEBUG_TYPE, "HotColdSplit",
+                                &*Region[0]->begin())
+             << ore::NV("Original", OrigF) << " split cold code into "
+             << ore::NV("Split", OutF);
+    });
     return OutF;
   }
 
Index: llvm/trunk/test/Transforms/HotColdSplit/split-cold-2.ll
===================================================================
--- llvm/trunk/test/Transforms/HotColdSplit/split-cold-2.ll
+++ llvm/trunk/test/Transforms/HotColdSplit/split-cold-2.ll
@@ -1,9 +1,10 @@
-; RUN: opt -hotcoldsplit -S < %s | FileCheck %s
-; RUN: opt -passes=hotcoldsplit -S < %s | FileCheck %s
+; RUN: opt -hotcoldsplit -pass-remarks=hotcoldsplit -S < %s 2>&1 | FileCheck %s
+; RUN: opt -passes=hotcoldsplit -pass-remarks=hotcoldsplit -S < %s 2>&1 | FileCheck %s
 
 ; Make sure this compiles. This test used to fail with an invalid phi node: the
 ; two predecessors were outlined and the SSA representation was invalid.
 
+; CHECK: remark: <unknown>:0:0: fun split cold code into fun_if.else
 ; CHECK-LABEL: @fun
 ; CHECK: codeRepl:
 ; CHECK-NEXT: call void @fun_if.else