Index: llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -544,6 +544,12 @@
   const std::string infoString() const {
     return (Twine("Index=") + Twine(Index)).str();
   }
+
+  // Empty function -- only applicable to UseBBInfo.
+  void addOutEdge(PGOEdge *E LLVM_ATTRIBUTE_UNUSED) {}
+
+  // Empty function -- only applicable to UseBBInfo.
+  void addInEdge(PGOEdge *E LLVM_ATTRIBUTE_UNUSED) {}
 };
 
 // This class implements the CFG edges. Note the CFG can be a multi-graph.
@@ -748,7 +754,7 @@
 }
 
 // Collect all the BBs that will be instruments and return them in
-// InstrumentBBs.
+// InstrumentBBs and setup InEdges/OutEdge for UseBBInfo.
 template <class Edge, class BBInfo>
 void FuncPGOInstrumentation<Edge, BBInfo>::getInstrumentBBs(
     std::vector<BasicBlock *> &InstrumentBBs) {
@@ -763,6 +769,18 @@
     if (InstrBB)
       InstrumentBBs.push_back(InstrBB);
   }
+
+  // Set up InEdges/OutEdges for all BBs.
+  for (auto &E : MST.AllEdges) {
+    if (E->Removed)
+      continue;
+    const BasicBlock *SrcBB = E->SrcBB;
+    const BasicBlock *DestBB = E->DestBB;
+    BBInfo &SrcInfo = getBBInfo(SrcBB);
+    BBInfo &DestInfo = getBBInfo(DestBB);
+    SrcInfo.addOutEdge(E.get());
+    DestInfo.addInEdge(E.get());
+  }
 }
 
 // Given a CFG E to be instrumented, find which BB to place the instrumented
@@ -780,19 +798,25 @@
   if (DestBB == nullptr)
     return SrcBB;
 
+  auto canInstrument = [this](BasicBlock *BB) -> BasicBlock * {
+    // There are basic blocks (such as catchswitch) cannot be instrumented.
+    // If the returned first insertion point is the end of BB, skip this BB.
+    if (BB->getFirstInsertionPt() == BB->end()) {
+      LLVM_DEBUG(dbgs() << "Cannot instrument BB index=" << getBBInfo(BB).Index
+                        << "\n");
+      return nullptr;
+    }
+    return BB;
+  };
+
   // Instrument the SrcBB if it has a single successor,
   // otherwise, the DestBB if this is not a critical edge.
   Instruction *TI = SrcBB->getTerminator();
   if (TI->getNumSuccessors() <= 1)
-    return SrcBB;
+    return canInstrument(SrcBB);
   if (!E->IsCritical)
-    return DestBB;
+    return canInstrument(DestBB);
 
-  // For a critical edge, we have to split. Instrument the newly
-  // created BB.
-  IsCS ? NumOfCSPGOSplit++ : NumOfPGOSplit++;
-  LLVM_DEBUG(dbgs() << "Split critical edge: " << getBBInfo(SrcBB).Index
-                    << " --> " << getBBInfo(DestBB).Index << "\n");
   unsigned SuccNum = GetSuccessorNumber(SrcBB, DestBB);
   BasicBlock *InstrBB = SplitCriticalEdge(TI, SuccNum);
   if (!InstrBB) {
@@ -800,6 +824,11 @@
         dbgs() << "Fail to split critical edge: not instrument this edge.\n");
     return nullptr;
   }
+  // For a critical edge, we have to split. Instrument the newly
+  // created BB.
+  IsCS ? NumOfCSPGOSplit++ : NumOfPGOSplit++;
+  LLVM_DEBUG(dbgs() << "Split critical edge: " << getBBInfo(SrcBB).Index
+                    << " --> " << getBBInfo(DestBB).Index << "\n");
   // Need to add two new edges. First one: Add new edge of SrcBB->InstrBB.
   MST.addEdge(SrcBB, InstrBB, 0);
   // Second one: Add new edge of InstrBB->DestBB.
@@ -807,7 +836,7 @@
   NewEdge1.InMST = true;
   E->Removed = true;
 
-  return InstrBB;
+  return canInstrument(InstrBB);
 }
 
 // Visit all edge and instrument the edges not in MST, and do value profiling.
@@ -925,6 +954,18 @@
       return BBInfo::infoString();
     return (Twine(BBInfo::infoString()) + "  Count=" + Twine(CountValue)).str();
   }
+
+  // Add an OutEdge and update the edge count.
+  void addOutEdge(PGOUseEdge *E) {
+    OutEdges.push_back(E);
+    UnknownCountOutEdge++;
+  }
+
+  // Add an InEdge and update the edge count.
+  void addInEdge(PGOUseEdge *E) {
+    InEdges.push_back(E);
+    UnknownCountInEdge++;
+  }
 };
 
 } // end anonymous namespace
@@ -1069,24 +1110,50 @@
   if (NumCounters != CountFromProfile.size()) {
     return false;
   }
+  // Set the profile count to the Instrumented BBs.
   uint32_t I = 0;
   for (BasicBlock *InstrBB : InstrumentBBs) {
     uint64_t CountValue = CountFromProfile[I++];
     UseBBInfo &Info = getBBInfo(InstrBB);
     Info.setBBInfoCount(CountValue);
-    // If only one in-edge, the edge profile count should be the same as BB
-    // profile count.
-    if (Info.InEdges.size() == 1) {
-      Info.InEdges[0]->setEdgeCount(CountValue);
-    }
+  }
+  ProfileCountSize = CountFromProfile.size();
+  CountPosition = I;
+
+  // Set the edge count and update the count of unknown edges for BBs.
+  auto setEdgeCount = [this](PGOUseEdge *E, uint64_t Value) -> void {
+    E->setEdgeCount(Value);
+    this->getBBInfo(E->SrcBB).UnknownCountOutEdge--;
+    this->getBBInfo(E->DestBB).UnknownCountInEdge--;
+  };
+
+  // Set the profile count the Instrumented edges. There are BBs that not in
+  // MST but not instrumented. Need to set the edge count value so that we can
+  // populate the profile counts later.
+  for (auto &E : FuncInfo.MST.AllEdges) {
+    if (E->Removed || E->InMST)
+      continue;
+    const BasicBlock *SrcBB = E->SrcBB;
+    UseBBInfo &SrcInfo = getBBInfo(SrcBB);
+
     // If only one out-edge, the edge profile count should be the same as BB
     // profile count.
-    if (Info.OutEdges.size() == 1) {
-      Info.OutEdges[0]->setEdgeCount(CountValue);
+    if (SrcInfo.CountValid && SrcInfo.OutEdges.size() == 1)
+      setEdgeCount(E.get(), SrcInfo.CountValue);
+    else {
+      const BasicBlock *DestBB = E->DestBB;
+      UseBBInfo &DestInfo = getBBInfo(DestBB);
+      // If only one in-edge, the edge profile count should be the same as BB
+      // profile count.
+      if (DestInfo.CountValid && DestInfo.InEdges.size() == 1)
+        setEdgeCount(E.get(), DestInfo.CountValue);
     }
+    if (E->CountValid)
+      continue;
+    // E's count should have been set from profile. If not, this meenas E skips
+    // the instrumentation. We set the count to 0.
+    setEdgeCount(E.get(), 0);
   }
-  ProfileCountSize = CountFromProfile.size();
-  CountPosition = I;
   return true;
 }
 
@@ -1180,26 +1247,6 @@
 // Populate the counters from instrumented BBs to all BBs.
 // In the end of this operation, all BBs should have a valid count value.
 void PGOUseFunc::populateCounters() {
-  // First set up Count variable for all BBs.
-  for (auto &E : FuncInfo.MST.AllEdges) {
-    if (E->Removed)
-      continue;
-
-    const BasicBlock *SrcBB = E->SrcBB;
-    const BasicBlock *DestBB = E->DestBB;
-    UseBBInfo &SrcInfo = getBBInfo(SrcBB);
-    UseBBInfo &DestInfo = getBBInfo(DestBB);
-    SrcInfo.OutEdges.push_back(E.get());
-    DestInfo.InEdges.push_back(E.get());
-    SrcInfo.UnknownCountOutEdge++;
-    DestInfo.UnknownCountInEdge++;
-
-    if (!E->CountValid)
-      continue;
-    DestInfo.UnknownCountInEdge--;
-    SrcInfo.UnknownCountOutEdge--;
-  }
-
   bool Changes = true;
   unsigned NumPasses = 0;
   while (Changes) {
Index: llvm/test/Transforms/PGOProfile/Inputs/PR41279.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/PR41279.proftext
@@ -0,0 +1,9 @@
+:ir
+foo
+60927483247
+4
+3
+2
+3
+2
+
Index: llvm/test/Transforms/PGOProfile/Inputs/PR41279_2.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/PR41279_2.proftext
@@ -0,0 +1,7 @@
+:ir
+f
+62077759478
+2
+3
+2
+
Index: llvm/test/Transforms/PGOProfile/PR41279.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/PR41279.ll
+++ llvm/test/Transforms/PGOProfile/PR41279.ll
@@ -1,6 +1,9 @@
 ; Test that instrumentaiton works fine for the case of failing the split critical edges.
 ; RUN: opt < %s -pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
 ; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
+; RUN: llvm-profdata merge %S/Inputs/PR41279.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
 
 declare void @f3({ i8*, i64 }*, { i8*, i64 }*, i64)
 declare { i8*, i64 } @f0({ i8*, i64 }*)
@@ -9,17 +12,22 @@
 declare void @invok1({ i8*, i64 }*, { i8*, i64 }*, i64)
 declare i32 @__CxxFrameHandler3(...)
 
-define internal void @foo({ i8*, i64 }*, { i8*, i64 }*) personality i32 (...)* @__CxxFrameHandler3 {
+define void @foo({ i8*, i64 }*, { i8*, i64 }*) personality i32 (...)* @__CxxFrameHandler3 {
+; USE-LABEL: @foo
+; USE-SAME: !prof ![[FUNC_ENTRY_COUNT:[0-9]+]]
+
   %3 = alloca i8, align 1
   store i8 0, i8* %3, align 1
   %4 = call i64 @f1()
   %5 = icmp ult i64 %4, 32
   br i1 %5, label %7, label %13
+; USE: br i1 %5, label %7, label %13
+; USE-SAME: !prof ![[BW_ENTRY1:[0-9]+]]
 
 6:
   cleanupret from %17 unwind to caller
 ; GEN: 6:
-; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__profn__stdin__foo, i32 0, i32 0), i64 60927483247, i32 4, i32 2)
+; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 60927483247, i32 4, i32 2)
 
 7:
   store i8 1, i8* %3, align 1
@@ -42,13 +50,13 @@
   store i8 0, i8* %3, align 1
   br label %14
 ; GEN: 12:
-; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__profn__stdin__foo, i32 0, i32 0), i64 60927483247, i32 4, i32 1)
+; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 60927483247, i32 4, i32 1)
 
 13:
   call void @f3({ i8*, i64 }* %0, { i8*, i64 }* %1, i64 1)
   br label %14
 ; GEN: 13:
-; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__profn__stdin__foo, i32 0, i32 0), i64 60927483247, i32 4, i32 0)
+; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 60927483247, i32 4, i32 0)
 
 14:
   ret void
@@ -57,11 +65,20 @@
   store i8 0, i8* %3, align 1
   br label %6
 ; GEN: 15:
-; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__profn__stdin__foo, i32 0, i32 0), i64 60927483247, i32 4, i32 3)
+; GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 60927483247, i32 4, i32 3)
 
 16:
   %17 = cleanuppad within none []
   %18 = load i8, i8* %3, align 1
   %19 = trunc i8 %18 to i1
   br i1 %19, label %15, label %6
+; USE: br i1 %19, label %15, label %6
+; USE-SAME: !prof ![[BW_ENTRY2:[0-9]+]]
 }
+
+; USE-DAG: {{![0-9]+}} = !{i32 1, !"ProfileSummary", {{![0-9]+}}}
+; USE-DAG: {{![0-9]+}} = !{!"DetailedSummary", {{![0-9]+}}}
+; USE-DAG: ![[FUNC_ENTRY_COUNT]] = !{!"function_entry_count", i64 8}
+; USE_DAG: ![[BW_ENTRY1]] = !{!"branch_weights", i32 5, i32 3}
+; USE_DAG: ![[BW_ENTRY2]] = !{!"branch_weights", i32 2, i32 1}
+
Index: llvm/test/Transforms/PGOProfile/PR41279_2.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/PR41279_2.ll
@@ -0,0 +1,68 @@
+; Test that instrumentaiton works fine for the case of catchswitch stmts.
+; RUN: opt < %s -pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
+; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
+; RUN: llvm-profdata merge %S/Inputs/PR41279_2.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
+
+
+define dso_local void @f() personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*) {
+; USE-LABEL: @f
+; USE-SAME: !prof ![[FUNC_ENTRY_COUNT:[0-9]+]]
+; USE-DAG: {{![0-9]+}} = !{i32 1, !"ProfileSummary", {{![0-9]+}}}
+; USE-DAG: {{![0-9]+}} = !{!"DetailedSummary", {{![0-9]+}}}
+; USE-DAG: ![[FUNC_ENTRY_COUNT]] = !{!"function_entry_count", i64 5}
+entry:
+  %__exception_code = alloca i32, align 4
+  %__exception_code2 = alloca i32, align 4
+  invoke void @f() #2
+          to label %invoke.cont unwind label %catch.dispatch
+
+catch.dispatch:
+  %0 = catchswitch within none [label %__except] unwind to caller
+
+__except:
+  %1 = catchpad within %0 [i8* null]
+  catchret from %1 to label %__except1
+
+__except1:
+  %2 = call i32 @llvm.eh.exceptioncode(token %1)
+  store i32 %2, i32* %__exception_code, align 4
+  br label %__try.cont7
+;GEN:  _except1:
+;GEN:    call void @llvm.instrprof.increment(i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__profn_f, i32 0, i32 0), i64 62077759478, i32 2, i32 1)
+
+invoke.cont:
+  br label %__try.cont
+
+__try.cont:
+  invoke void @f()
+          to label %invoke.cont3 unwind label %catch.dispatch4
+
+catch.dispatch4:
+  %3 = catchswitch within none [label %__except5] unwind to caller
+; GEN: catch.dispatch4:
+; GEN-NOT: call void @llvm.instrprof.increment
+
+__except5:
+  %4 = catchpad within %3 [i8* null]
+  catchret from %4 to label %__except6
+
+__except6:
+  %5 = call i32 @llvm.eh.exceptioncode(token %4)
+  store i32 %5, i32* %__exception_code2, align 4
+  br label %__try.cont7
+
+__try.cont7:
+  ret void
+
+invoke.cont3:
+  br label %__try.cont7
+;GEN: invoke.cont3:
+;GEN:  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__profn_f, i32 0, i32 0), i64 62077759478, i32 2, i32 0)
+
+}
+
+declare dso_local i32 @__C_specific_handler(...)
+
+declare i32 @llvm.eh.exceptioncode(token)