Index: lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- lib/Transforms/IPO/SampleProfile.cpp
+++ lib/Transforms/IPO/SampleProfile.cpp
@@ -253,6 +253,8 @@
     if (InstWeight > Weight)
       Weight = InstWeight;
   }
+  if (Weight > 0)
+    VisitedBlocks.insert(BB);
   Entry.first->second = Weight;
   return Weight;
 }
@@ -304,8 +306,7 @@
   for (auto *BB2 : Descendants) {
     bool IsDomParent = DomTree->dominates(BB2, BB1);
     bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
-    if (BB1 != BB2 && VisitedBlocks.insert(BB2).second && IsDomParent &&
-        IsInSameLoop) {
+    if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
       EquivalenceClass[BB2] = BB1;
 
       // If BB2 is heavier than BB1, make BB2 have the same weight
Index: test/Transforms/SampleProfile/Inputs/cfg.prof
===================================================================
--- /dev/null
+++ test/Transforms/SampleProfile/Inputs/cfg.prof
@@ -0,0 +1,10 @@
+main:15680:0
+1: 2500
+4: 1000
+5: 1000
+6: 800
+7: 500
+9: 10226
+10: 2243
+16: 0
+18: 0
Index: test/Transforms/SampleProfile/cfg.ll
===================================================================
--- /dev/null
+++ test/Transforms/SampleProfile/cfg.ll
@@ -0,0 +1,239 @@
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/cfg.prof | opt -analyze -branch-prob | FileCheck %s
+
+; Original C++ code for this test case:
+;
+; #include <stdio.h>
+; #include <stdlib.h>
+
+; int main(int argc, char *argv[]) {
+;   if (argc < 2)
+;     return 1;
+;   double result;
+;   int limit = atoi(argv[1]);
+;   if (limit > 100) {
+;     double s = 23.041968 * atoi(argv[2]);
+;     for (int u = 0; u < limit; u++) {
+;       double x = s;
+;       s = x + 3.049 + (double)u;
+;       s -= s + 3.94 / x * 0.32;
+;     }
+;     result = s;
+;   } else {
+;     result = atoi(argv[2]);
+;   }
+;   printf("result is %lf\n", result);
+;   return 0;
+; }
+
+@.str = private unnamed_addr constant [15 x i8] c"result is %lf\0A\00", align 1
+
+; Function Attrs: uwtable
+define i32 @main(i32 %argc, i8** %argv) #0 {
+; CHECK: Printing analysis 'Branch Probability Analysis' for function 'main':
+
+entry:
+  %retval = alloca i32, align 4
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 8
+  %result = alloca double, align 8
+  %limit = alloca i32, align 4
+  %s = alloca double, align 8
+  %u = alloca i32, align 4
+  %x = alloca double, align 8
+  store i32 0, i32* %retval, align 4
+  store i32 %argc, i32* %argc.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %argc.addr, metadata !16, metadata !17), !dbg !18
+  store i8** %argv, i8*** %argv.addr, align 8
+  call void @llvm.dbg.declare(metadata i8*** %argv.addr, metadata !19, metadata !17), !dbg !20
+  %0 = load i32, i32* %argc.addr, align 4, !dbg !21
+  %cmp = icmp slt i32 %0, 2, !dbg !23
+  br i1 %cmp, label %if.then, label %if.end, !dbg !24
+; CHECK:  edge entry -> if.then probability is 0x4ccccccd / 0x80000000 = 60.00%
+; CHECK:  edge entry -> if.end probability is 0x33333333 / 0x80000000 = 40.00%
+
+if.then:                                          ; preds = %entry
+  store i32 1, i32* %retval, align 4, !dbg !25
+  br label %return, !dbg !25
+
+if.end:                                           ; preds = %entry
+  call void @llvm.dbg.declare(metadata double* %result, metadata !26, metadata !17), !dbg !27
+  call void @llvm.dbg.declare(metadata i32* %limit, metadata !28, metadata !17), !dbg !29
+  %1 = load i8**, i8*** %argv.addr, align 8, !dbg !30
+  %arrayidx = getelementptr inbounds i8*, i8** %1, i64 1, !dbg !30
+  %2 = load i8*, i8** %arrayidx, align 8, !dbg !30
+  %call = call i32 @atoi(i8* %2) #4, !dbg !31
+  store i32 %call, i32* %limit, align 4, !dbg !29
+  %3 = load i32, i32* %limit, align 4, !dbg !32
+  %cmp1 = icmp sgt i32 %3, 100, !dbg !34
+  br i1 %cmp1, label %if.then.2, label %if.else, !dbg !35
+; CHECK: edge if.end -> if.then.2 probability is 0x66666666 / 0x80000000 = 80.00%
+; CHECK: edge if.end -> if.else probability is 0x1999999a / 0x80000000 = 20.00%
+
+if.then.2:                                        ; preds = %if.end
+  call void @llvm.dbg.declare(metadata double* %s, metadata !36, metadata !17), !dbg !38
+  %4 = load i8**, i8*** %argv.addr, align 8, !dbg !39
+  %arrayidx3 = getelementptr inbounds i8*, i8** %4, i64 2, !dbg !39
+  %5 = load i8*, i8** %arrayidx3, align 8, !dbg !39
+  %call4 = call i32 @atoi(i8* %5) #4, !dbg !40
+  %conv = sitofp i32 %call4 to double, !dbg !40
+  %mul = fmul double 0x40370ABE6A337A81, %conv, !dbg !41
+  store double %mul, double* %s, align 8, !dbg !38
+  call void @llvm.dbg.declare(metadata i32* %u, metadata !42, metadata !17), !dbg !44
+  store i32 0, i32* %u, align 4, !dbg !44
+  br label %for.cond, !dbg !45
+
+for.cond:                                         ; preds = %for.inc, %if.then.2
+  %6 = load i32, i32* %u, align 4, !dbg !46
+  %7 = load i32, i32* %limit, align 4, !dbg !48
+  %cmp5 = icmp slt i32 %6, %7, !dbg !49
+  br i1 %cmp5, label %for.body, label %for.end, !dbg !50
+
+for.body:                                         ; preds = %for.cond
+  call void @llvm.dbg.declare(metadata double* %x, metadata !51, metadata !17), !dbg !53
+  %8 = load double, double* %s, align 8, !dbg !54
+  store double %8, double* %x, align 8, !dbg !53
+  %9 = load double, double* %x, align 8, !dbg !55
+  %add = fadd double %9, 3.049000e+00, !dbg !56
+  %10 = load i32, i32* %u, align 4, !dbg !57
+  %conv6 = sitofp i32 %10 to double, !dbg !57
+  %add7 = fadd double %add, %conv6, !dbg !58
+  store double %add7, double* %s, align 8, !dbg !59
+  %11 = load double, double* %s, align 8, !dbg !60
+  %12 = load double, double* %x, align 8, !dbg !61
+  %div = fdiv double 3.940000e+00, %12, !dbg !62
+  %mul8 = fmul double %div, 3.200000e-01, !dbg !63
+  %add9 = fadd double %11, %mul8, !dbg !64
+  %13 = load double, double* %s, align 8, !dbg !65
+  %sub = fsub double %13, %add9, !dbg !65
+  store double %sub, double* %s, align 8, !dbg !65
+  br label %for.inc, !dbg !66
+
+for.inc:                                          ; preds = %for.body
+  %14 = load i32, i32* %u, align 4, !dbg !67
+  %inc = add nsw i32 %14, 1, !dbg !67
+  store i32 %inc, i32* %u, align 4, !dbg !67
+  br label %for.cond, !dbg !68
+
+for.end:                                          ; preds = %for.cond
+  %15 = load double, double* %s, align 8, !dbg !69
+  store double %15, double* %result, align 8, !dbg !70
+  br label %if.end.13, !dbg !71
+
+if.else:                                          ; preds = %if.end
+  %16 = load i8**, i8*** %argv.addr, align 8, !dbg !72
+  %arrayidx10 = getelementptr inbounds i8*, i8** %16, i64 2, !dbg !72
+  %17 = load i8*, i8** %arrayidx10, align 8, !dbg !72
+  %call11 = call i32 @atoi(i8* %17) #4, !dbg !74
+  %conv12 = sitofp i32 %call11 to double, !dbg !74
+  store double %conv12, double* %result, align 8, !dbg !75
+  br label %if.end.13
+
+if.end.13:                                        ; preds = %if.else, %for.end
+  %18 = load double, double* %result, align 8, !dbg !76
+  %call14 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str, i32 0, i32 0), double %18), !dbg !77
+  store i32 0, i32* %retval, align 4, !dbg !78
+  br label %return, !dbg !78
+
+return:                                           ; preds = %if.end.13, %if.then
+  %19 = load i32, i32* %retval, align 4, !dbg !79
+  ret i32 %19, !dbg !79
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readonly
+declare i32 @atoi(i8*) #2
+
+declare i32 @printf(i8*, ...) #3
+
+attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind readonly "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind readonly }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!13, !14}
+!llvm.ident = !{!15}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 248211) (llvm/trunk 248217)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !3, subprograms: !5)
+!1 = !DIFile(filename: "test.cc", directory: "/ssd/llvm_commit")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIBasicType(name: "double", size: 64, align: 64, encoding: DW_ATE_float)
+!5 = !{!6}
+!6 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 4, type: !7, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: false, function: i32 (i32, i8**)* @main, variables: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !9, !10}
+!9 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, align: 64)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64, align: 64)
+!12 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!13 = !{i32 2, !"Dwarf Version", i32 4}
+!14 = !{i32 2, !"Debug Info Version", i32 3}
+!15 = !{!"clang version 3.8.0 (trunk 248211) (llvm/trunk 248217)"}
+!16 = !DILocalVariable(name: "argc", arg: 1, scope: !6, file: !1, line: 4, type: !9)
+!17 = !DIExpression()
+!18 = !DILocation(line: 4, column: 15, scope: !6)
+!19 = !DILocalVariable(name: "argv", arg: 2, scope: !6, file: !1, line: 4, type: !10)
+!20 = !DILocation(line: 4, column: 27, scope: !6)
+!21 = !DILocation(line: 5, column: 8, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !6, file: !1, line: 5, column: 8)
+!23 = !DILocation(line: 5, column: 13, scope: !22)
+!24 = !DILocation(line: 5, column: 8, scope: !6)
+!25 = !DILocation(line: 6, column: 6, scope: !22)
+!26 = !DILocalVariable(name: "result", scope: !6, file: !1, line: 7, type: !4)
+!27 = !DILocation(line: 7, column: 11, scope: !6)
+!28 = !DILocalVariable(name: "limit", scope: !6, file: !1, line: 8, type: !9)
+!29 = !DILocation(line: 8, column: 8, scope: !6)
+!30 = !DILocation(line: 8, column: 21, scope: !6)
+!31 = !DILocation(line: 8, column: 16, scope: !6)
+!32 = !DILocation(line: 9, column: 8, scope: !33)
+!33 = distinct !DILexicalBlock(scope: !6, file: !1, line: 9, column: 8)
+!34 = !DILocation(line: 9, column: 14, scope: !33)
+!35 = !DILocation(line: 9, column: 8, scope: !6)
+!36 = !DILocalVariable(name: "s", scope: !37, file: !1, line: 10, type: !4)
+!37 = distinct !DILexicalBlock(scope: !33, file: !1, line: 9, column: 21)
+!38 = !DILocation(line: 10, column: 13, scope: !37)
+!39 = !DILocation(line: 10, column: 34, scope: !37)
+!40 = !DILocation(line: 10, column: 29, scope: !37)
+!41 = !DILocation(line: 10, column: 27, scope: !37)
+!42 = !DILocalVariable(name: "u", scope: !43, file: !1, line: 11, type: !9)
+!43 = distinct !DILexicalBlock(scope: !37, file: !1, line: 11, column: 6)
+!44 = !DILocation(line: 11, column: 15, scope: !43)
+!45 = !DILocation(line: 11, column: 11, scope: !43)
+!46 = !DILocation(line: 11, column: 22, scope: !47)
+!47 = distinct !DILexicalBlock(scope: !43, file: !1, line: 11, column: 6)
+!48 = !DILocation(line: 11, column: 26, scope: !47)
+!49 = !DILocation(line: 11, column: 24, scope: !47)
+!50 = !DILocation(line: 11, column: 6, scope: !43)
+!51 = !DILocalVariable(name: "x", scope: !52, file: !1, line: 12, type: !4)
+!52 = distinct !DILexicalBlock(scope: !47, file: !1, line: 11, column: 38)
+!53 = !DILocation(line: 12, column: 15, scope: !52)
+!54 = !DILocation(line: 12, column: 19, scope: !52)
+!55 = !DILocation(line: 13, column: 12, scope: !52)
+!56 = !DILocation(line: 13, column: 14, scope: !52)
+!57 = !DILocation(line: 13, column: 32, scope: !52)
+!58 = !DILocation(line: 13, column: 22, scope: !52)
+!59 = !DILocation(line: 13, column: 10, scope: !52)
+!60 = !DILocation(line: 14, column: 13, scope: !52)
+!61 = !DILocation(line: 14, column: 24, scope: !52)
+!62 = !DILocation(line: 14, column: 22, scope: !52)
+!63 = !DILocation(line: 14, column: 26, scope: !52)
+!64 = !DILocation(line: 14, column: 15, scope: !52)
+!65 = !DILocation(line: 14, column: 10, scope: !52)
+!66 = !DILocation(line: 15, column: 6, scope: !52)
+!67 = !DILocation(line: 11, column: 34, scope: !47)
+!68 = !DILocation(line: 11, column: 6, scope: !47)
+!69 = !DILocation(line: 16, column: 15, scope: !37)
+!70 = !DILocation(line: 16, column: 13, scope: !37)
+!71 = !DILocation(line: 17, column: 4, scope: !37)
+!72 = !DILocation(line: 18, column: 20, scope: !73)
+!73 = distinct !DILexicalBlock(scope: !33, file: !1, line: 17, column: 11)
+!74 = !DILocation(line: 18, column: 15, scope: !73)
+!75 = !DILocation(line: 18, column: 13, scope: !73)
+!76 = !DILocation(line: 20, column: 30, scope: !6)
+!77 = !DILocation(line: 20, column: 4, scope: !6)
+!78 = !DILocation(line: 21, column: 4, scope: !6)
+!79 = !DILocation(line: 22, column: 2, scope: !6)