[PATCH] D66324: clang-misexpect: Profile Guided Validation of Performance Annotations in LLVM

[Paul Kirth via Phabricator via cfe-commits]

paulkirth updated this revision to Diff 217282.
paulkirth marked 3 inline comments as done.
paulkirth added a comment.

Address Code Review

- Give better names to extracted constants
- Remove extraneous call to getValue()
- Make integers const
- Remove extra braces
- Move NOps into branch
- Use std::plus


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66324/new/

https://reviews.llvm.org/D66324

Files:
  clang/include/clang/Basic/DiagnosticFrontendKinds.td
  clang/include/clang/Basic/DiagnosticGroups.td
  clang/lib/CodeGen/CodeGenAction.cpp
  clang/lib/CodeGen/CodeGenFunction.cpp
  clang/lib/Frontend/CompilerInvocation.cpp
  clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
  clang/test/Profile/Inputs/misexpect-branch.proftext
  clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
  clang/test/Profile/Inputs/misexpect-switch-default.proftext
  clang/test/Profile/Inputs/misexpect-switch.proftext
  clang/test/Profile/misexpect-branch-cold.c
  clang/test/Profile/misexpect-branch-nonconst-expected-val.c
  clang/test/Profile/misexpect-branch.c
  clang/test/Profile/misexpect-switch-default.c
  clang/test/Profile/misexpect-switch-nonconst.c
  clang/test/Profile/misexpect-switch-only-default-case.c
  clang/test/Profile/misexpect-switch.c
  llvm/include/llvm/IR/DiagnosticInfo.h
  llvm/include/llvm/IR/FixedMetadataKinds.def
  llvm/include/llvm/IR/MDBuilder.h
  llvm/include/llvm/Transforms/Utils/MisExpect.h
  llvm/lib/IR/DiagnosticInfo.cpp
  llvm/lib/IR/MDBuilder.cpp
  llvm/lib/Transforms/IPO/SampleProfile.cpp
  llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
  llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
  llvm/lib/Transforms/Utils/CMakeLists.txt
  llvm/lib/Transforms/Utils/MisExpect.cpp
  llvm/test/ThinLTO/X86/lazyload_metadata.ll
  llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
  llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch-correct.proftext
  llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch.proftext
  llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch-correct.proftext
  llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch.proftext
  llvm/test/Transforms/PGOProfile/misexpect-branch-correct.ll
  llvm/test/Transforms/PGOProfile/misexpect-branch.ll
  llvm/test/Transforms/PGOProfile/misexpect-switch-default.ll
  llvm/test/Transforms/PGOProfile/misexpect-switch.ll


Index: llvm/test/Transforms/PGOProfile/misexpect-switch.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/misexpect-switch.ll
@@ -0,0 +1,293 @@
+
+; RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+; RUN: llvm-profdata merge %S/Inputs/misexpect-switch-correct.proftext -o %t.c.profdata
+
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+; New PM
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -S 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.c.profdata -S -pgo-warn-misexpect -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=CORRECT
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.c.profdata -pgo-warn-misexpect -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=CORRECT
+
+; WARNING-DAG: warning: misexpect-switch.c:26:5: 0.00%
+; WARNING-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; REMARK-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; REMARK-DAG: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; BOTH-DAG: warning: misexpect-switch.c:26:5: 0.00%
+; BOTH-DAG: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; DISABLED-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; DISABLED-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; DISABLED-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; DISABLED-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; CORRECT-NOT: warning: {{.*}}
+; CORRECT-NOT: remark: {{.*}}
+; CHECK-DAG: !{!"misexpect", i64 0, i64 2000, i64 1}
+
+
+
+; ModuleID = 'misexpect-switch.c'
+source_filename = "misexpect-switch.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@inner_loop = dso_local constant i32 1000, align 4, !dbg !0
+@outer_loop = dso_local constant i32 20, align 4, !dbg !6
+@arry_size = dso_local constant i32 25, align 4, !dbg !10
+@arry = dso_local global [25 x i32] zeroinitializer, align 16, !dbg !12
+
+; Function Attrs: nounwind uwtable
+define dso_local void @init_arry() #0 !dbg !21 {
+entry:
+  %i = alloca i32, align 4
+  %0 = bitcast i32* %i to i8*, !dbg !26
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #6, !dbg !26
+  call void @llvm.dbg.declare(metadata i32* %i, metadata !25, metadata !DIExpression()), !dbg !27
+  store i32 0, i32* %i, align 4, !dbg !28, !tbaa !30
+  br label %for.cond, !dbg !34
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %1 = load i32, i32* %i, align 4, !dbg !35, !tbaa !30
+  %cmp = icmp slt i32 %1, 25, !dbg !37
+  br i1 %cmp, label %for.body, label %for.end, !dbg !38
+
+for.body:                                         ; preds = %for.cond
+  %call = call i32 @rand() #6, !dbg !39
+  %rem = srem i32 %call, 10, !dbg !41
+  %2 = load i32, i32* %i, align 4, !dbg !42, !tbaa !30
+  %idxprom = sext i32 %2 to i64, !dbg !43
+  %arrayidx = getelementptr inbounds [25 x i32], [25 x i32]* @arry, i64 0, i64 %idxprom, !dbg !43
+  store i32 %rem, i32* %arrayidx, align 4, !dbg !44, !tbaa !30
+  br label %for.inc, !dbg !45
+
+for.inc:                                          ; preds = %for.body
+  %3 = load i32, i32* %i, align 4, !dbg !46, !tbaa !30
+  %inc = add nsw i32 %3, 1, !dbg !46
+  store i32 %inc, i32* %i, align 4, !dbg !46, !tbaa !30
+  br label %for.cond, !dbg !47, !llvm.loop !48
+
+for.end:                                          ; preds = %for.cond
+  %4 = bitcast i32* %i to i8*, !dbg !50
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %4) #6, !dbg !50
+  ret void, !dbg !50
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
+
+; Function Attrs: nounwind
+declare dso_local i32 @rand() #3
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
+
+; Function Attrs: nounwind uwtable
+define dso_local i32 @main() #0 !dbg !51 {
+entry:
+  %retval = alloca i32, align 4
+  %val = alloca i32, align 4
+  %j = alloca i32, align 4
+  %condition = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  call void @init_arry(), !dbg !62
+  %0 = bitcast i32* %val to i8*, !dbg !63
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #6, !dbg !63
+  call void @llvm.dbg.declare(metadata i32* %val, metadata !55, metadata !DIExpression()), !dbg !64
+  store i32 0, i32* %val, align 4, !dbg !64, !tbaa !30
+  %1 = bitcast i32* %j to i8*, !dbg !65
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1) #6, !dbg !65
+  call void @llvm.dbg.declare(metadata i32* %j, metadata !56, metadata !DIExpression()), !dbg !66
+  store i32 0, i32* %j, align 4, !dbg !67, !tbaa !30
+  br label %for.cond, !dbg !68
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %2 = load i32, i32* %j, align 4, !dbg !69, !tbaa !30
+  %cmp = icmp slt i32 %2, 20000, !dbg !70
+  br i1 %cmp, label %for.body, label %for.end, !dbg !71
+
+for.body:                                         ; preds = %for.cond
+  %3 = bitcast i32* %condition to i8*, !dbg !72
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %3) #6, !dbg !72
+  call void @llvm.dbg.declare(metadata i32* %condition, metadata !57, metadata !DIExpression()), !dbg !73
+  %call = call i32 @rand() #6, !dbg !74
+  %rem = srem i32 %call, 5, !dbg !75
+  store i32 %rem, i32* %condition, align 4, !dbg !73, !tbaa !30
+  %4 = load i32, i32* %condition, align 4, !dbg !76, !tbaa !30
+  %conv = zext i32 %4 to i64, !dbg !76
+  %expval = call i64 @llvm.expect.i64(i64 %conv, i64 0), !dbg !77
+  switch i64 %expval, label %sw.default [
+    i64 0, label %sw.bb
+    i64 1, label %sw.bb2
+    i64 2, label %sw.bb2
+    i64 3, label %sw.bb2
+    i64 4, label %sw.bb3
+  ], !dbg !78
+
+sw.bb:                                            ; preds = %for.body
+  %call1 = call i32 @sum(i32* getelementptr inbounds ([25 x i32], [25 x i32]* @arry, i64 0, i64 0), i32 25), !dbg !79
+  %5 = load i32, i32* %val, align 4, !dbg !81, !tbaa !30
+  %add = add nsw i32 %5, %call1, !dbg !81
+  store i32 %add, i32* %val, align 4, !dbg !81, !tbaa !30
+  br label %sw.epilog, !dbg !82
+
+sw.bb2:                                           ; preds = %for.body, %for.body, %for.body
+  br label %sw.epilog, !dbg !83
+
+sw.bb3:                                           ; preds = %for.body
+  %call4 = call i32 @random_sample(i32* getelementptr inbounds ([25 x i32], [25 x i32]* @arry, i64 0, i64 0), i32 25), !dbg !84
+  %6 = load i32, i32* %val, align 4, !dbg !85, !tbaa !30
+  %add5 = add nsw i32 %6, %call4, !dbg !85
+  store i32 %add5, i32* %val, align 4, !dbg !85, !tbaa !30
+  br label %sw.epilog, !dbg !86
+
+sw.default:                                       ; preds = %for.body
+  unreachable, !dbg !87
+
+sw.epilog:                                        ; preds = %sw.bb3, %sw.bb2, %sw.bb
+  %7 = bitcast i32* %condition to i8*, !dbg !88
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %7) #6, !dbg !88
+  br label %for.inc, !dbg !89
+
+for.inc:                                          ; preds = %sw.epilog
+  %8 = load i32, i32* %j, align 4, !dbg !90, !tbaa !30
+  %inc = add nsw i32 %8, 1, !dbg !90
+  store i32 %inc, i32* %j, align 4, !dbg !90, !tbaa !30
+  br label %for.cond, !dbg !91, !llvm.loop !92
+
+for.end:                                          ; preds = %for.cond
+  %9 = bitcast i32* %j to i8*, !dbg !94
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %9) #6, !dbg !94
+  %10 = bitcast i32* %val to i8*, !dbg !94
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %10) #6, !dbg !94
+  ret i32 0, !dbg !95
+}
+
+; Function Attrs: nounwind readnone willreturn
+declare i64 @llvm.expect.i64(i64, i64) #4
+
+declare dso_local i32 @sum(i32*, i32) #5
+
+declare dso_local i32 @random_sample(i32*, i32) #5
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { nounwind readnone speculatable willreturn }
+attributes #3 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind readnone willreturn }
+attributes #5 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #6 = { nounwind }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!17, !18, !19}
+!llvm.ident = !{!20}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "inner_loop", scope: !2, file: !3, line: 7, type: !8, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (sso://user/paulkirth/clang-misexpect 60b79b85b1763d3d25630261e5cd1adb7f0835bc)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "misexpect-switch.c", directory: "/usr/local/google/home/paulkirth/workspace/pgo_test/switchv2")
+!4 = !{}
+!5 = !{!0, !6, !10, !12}
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "outer_loop", scope: !2, file: !3, line: 8, type: !8, isLocal: false, isDefinition: true)
+!8 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !9)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DIGlobalVariableExpression(var: !11, expr: !DIExpression())
+!11 = distinct !DIGlobalVariable(name: "arry_size", scope: !2, file: !3, line: 9, type: !8, isLocal: false, isDefinition: true)
+!12 = !DIGlobalVariableExpression(var: !13, expr: !DIExpression())
+!13 = distinct !DIGlobalVariable(name: "arry", scope: !2, file: !3, line: 11, type: !14, isLocal: false, isDefinition: true)
+!14 = !DICompositeType(tag: DW_TAG_array_type, baseType: !9, size: 800, elements: !15)
+!15 = !{!16}
+!16 = !DISubrange(count: 25)
+!17 = !{i32 2, !"Dwarf Version", i32 4}
+!18 = !{i32 2, !"Debug Info Version", i32 3}
+!19 = !{i32 1, !"wchar_size", i32 4}
+!20 = !{!"clang version 10.0.0 (sso://user/paulkirth/clang-misexpect 60b79b85b1763d3d25630261e5cd1adb7f0835bc)"}
+!21 = distinct !DISubprogram(name: "init_arry", scope: !3, file: !3, line: 13, type: !22, scopeLine: 13, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !24)
+!22 = !DISubroutineType(types: !23)
+!23 = !{null}
+!24 = !{!25}
+!25 = !DILocalVariable(name: "i", scope: !21, file: !3, line: 14, type: !9)
+!26 = !DILocation(line: 14, column: 3, scope: !21)
+!27 = !DILocation(line: 14, column: 7, scope: !21)
+!28 = !DILocation(line: 15, column: 10, scope: !29)
+!29 = distinct !DILexicalBlock(scope: !21, file: !3, line: 15, column: 3)
+!30 = !{!31, !31, i64 0}
+!31 = !{!"int", !32, i64 0}
+!32 = !{!"omnipotent char", !33, i64 0}
+!33 = !{!"Simple C/C++ TBAA"}
+!34 = !DILocation(line: 15, column: 8, scope: !29)
+!35 = !DILocation(line: 15, column: 15, scope: !36)
+!36 = distinct !DILexicalBlock(scope: !29, file: !3, line: 15, column: 3)
+!37 = !DILocation(line: 15, column: 17, scope: !36)
+!38 = !DILocation(line: 15, column: 3, scope: !29)
+!39 = !DILocation(line: 16, column: 15, scope: !40)
+!40 = distinct !DILexicalBlock(scope: !36, file: !3, line: 15, column: 35)
+!41 = !DILocation(line: 16, column: 22, scope: !40)
+!42 = !DILocation(line: 16, column: 10, scope: !40)
+!43 = !DILocation(line: 16, column: 5, scope: !40)
+!44 = !DILocation(line: 16, column: 13, scope: !40)
+!45 = !DILocation(line: 17, column: 3, scope: !40)
+!46 = !DILocation(line: 15, column: 30, scope: !36)
+!47 = !DILocation(line: 15, column: 3, scope: !36)
+!48 = distinct !{!48, !38, !49}
+!49 = !DILocation(line: 17, column: 3, scope: !29)
+!50 = !DILocation(line: 18, column: 1, scope: !21)
+!51 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 20, type: !52, scopeLine: 20, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !54)
+!52 = !DISubroutineType(types: !53)
+!53 = !{!9}
+!54 = !{!55, !56, !57}
+!55 = !DILocalVariable(name: "val", scope: !51, file: !3, line: 22, type: !9)
+!56 = !DILocalVariable(name: "j", scope: !51, file: !3, line: 23, type: !9)
+!57 = !DILocalVariable(name: "condition", scope: !58, file: !3, line: 25, type: !61)
+!58 = distinct !DILexicalBlock(scope: !59, file: !3, line: 24, column: 49)
+!59 = distinct !DILexicalBlock(scope: !60, file: !3, line: 24, column: 3)
+!60 = distinct !DILexicalBlock(scope: !51, file: !3, line: 24, column: 3)
+!61 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
+!62 = !DILocation(line: 21, column: 3, scope: !51)
+!63 = !DILocation(line: 22, column: 3, scope: !51)
+!64 = !DILocation(line: 22, column: 7, scope: !51)
+!65 = !DILocation(line: 23, column: 3, scope: !51)
+!66 = !DILocation(line: 23, column: 7, scope: !51)
+!67 = !DILocation(line: 24, column: 10, scope: !60)
+!68 = !DILocation(line: 24, column: 8, scope: !60)
+!69 = !DILocation(line: 24, column: 15, scope: !59)
+!70 = !DILocation(line: 24, column: 17, scope: !59)
+!71 = !DILocation(line: 24, column: 3, scope: !60)
+!72 = !DILocation(line: 25, column: 5, scope: !58)
+!73 = !DILocation(line: 25, column: 14, scope: !58)
+!74 = !DILocation(line: 25, column: 26, scope: !58)
+!75 = !DILocation(line: 25, column: 33, scope: !58)
+!76 = !DILocation(line: 26, column: 30, scope: !58)
+!77 = !DILocation(line: 26, column: 13, scope: !58)
+!78 = !DILocation(line: 26, column: 5, scope: !58)
+!79 = !DILocation(line: 28, column: 14, scope: !80)
+!80 = distinct !DILexicalBlock(scope: !58, file: !3, line: 26, column: 45)
+!81 = !DILocation(line: 28, column: 11, scope: !80)
+!82 = !DILocation(line: 29, column: 7, scope: !80)
+!83 = !DILocation(line: 33, column: 7, scope: !80)
+!84 = !DILocation(line: 35, column: 14, scope: !80)
+!85 = !DILocation(line: 35, column: 11, scope: !80)
+!86 = !DILocation(line: 36, column: 7, scope: !80)
+!87 = !DILocation(line: 38, column: 7, scope: !80)
+!88 = !DILocation(line: 40, column: 3, scope: !59)
+!89 = !DILocation(line: 40, column: 3, scope: !58)
+!90 = !DILocation(line: 24, column: 44, scope: !59)
+!91 = !DILocation(line: 24, column: 3, scope: !59)
+!92 = distinct !{!92, !71, !93}
+!93 = !DILocation(line: 40, column: 3, scope: !60)
+!94 = !DILocation(line: 43, column: 1, scope: !51)
+!95 = !DILocation(line: 42, column: 3, scope: !51)
Index: llvm/test/Transforms/PGOProfile/misexpect-switch-default.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/misexpect-switch-default.ll
@@ -0,0 +1,289 @@
+
+; RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+; New PM
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -S 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+; WARNING-DAG: warning: misexpect-switch.c:26:5: 0.00%
+; WARNING-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; REMARK-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; REMARK-DAG: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; BOTH-DAG: warning: misexpect-switch.c:26:5: 0.00%
+; BOTH-DAG: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; DISABLED-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; DISABLED-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; DISABLED-NOT: warning: misexpect-switch.c:26:5: 0.00%
+; DISABLED-NOT: remark: misexpect-switch.c:26:5: Potential performance regression from use of __builtin_expect(): Annotation was correct on 0.00% of profiled executions.
+
+; CORRECT-NOT: warning: {{.*}}
+; CORRECT-NOT: remark: {{.*}}
+; CHECK-DAG: !{!"misexpect", i64 0, i64 2000, i64 1}
+
+
+
+; ModuleID = 'misexpect-switch.c'
+source_filename = "misexpect-switch.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@inner_loop = dso_local constant i32 1000, align 4, !dbg !0
+@outer_loop = dso_local constant i32 20, align 4, !dbg !6
+@arry_size = dso_local constant i32 25, align 4, !dbg !10
+@arry = dso_local global [25 x i32] zeroinitializer, align 16, !dbg !12
+
+; Function Attrs: nounwind uwtable
+define dso_local void @init_arry() #0 !dbg !21 {
+entry:
+  %i = alloca i32, align 4
+  %0 = bitcast i32* %i to i8*, !dbg !26
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #6, !dbg !26
+  call void @llvm.dbg.declare(metadata i32* %i, metadata !25, metadata !DIExpression()), !dbg !27
+  store i32 0, i32* %i, align 4, !dbg !28, !tbaa !30
+  br label %for.cond, !dbg !34
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %1 = load i32, i32* %i, align 4, !dbg !35, !tbaa !30
+  %cmp = icmp slt i32 %1, 25, !dbg !37
+  br i1 %cmp, label %for.body, label %for.end, !dbg !38
+
+for.body:                                         ; preds = %for.cond
+  %call = call i32 @rand() #6, !dbg !39
+  %rem = srem i32 %call, 10, !dbg !41
+  %2 = load i32, i32* %i, align 4, !dbg !42, !tbaa !30
+  %idxprom = sext i32 %2 to i64, !dbg !43
+  %arrayidx = getelementptr inbounds [25 x i32], [25 x i32]* @arry, i64 0, i64 %idxprom, !dbg !43
+  store i32 %rem, i32* %arrayidx, align 4, !dbg !44, !tbaa !30
+  br label %for.inc, !dbg !45
+
+for.inc:                                          ; preds = %for.body
+  %3 = load i32, i32* %i, align 4, !dbg !46, !tbaa !30
+  %inc = add nsw i32 %3, 1, !dbg !46
+  store i32 %inc, i32* %i, align 4, !dbg !46, !tbaa !30
+  br label %for.cond, !dbg !47, !llvm.loop !48
+
+for.end:                                          ; preds = %for.cond
+  %4 = bitcast i32* %i to i8*, !dbg !50
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %4) #6, !dbg !50
+  ret void, !dbg !50
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
+
+; Function Attrs: nounwind
+declare dso_local i32 @rand() #3
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
+
+; Function Attrs: nounwind uwtable
+define dso_local i32 @main() #0 !dbg !51 {
+entry:
+  %retval = alloca i32, align 4
+  %val = alloca i32, align 4
+  %j = alloca i32, align 4
+  %condition = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  call void @init_arry(), !dbg !62
+  %0 = bitcast i32* %val to i8*, !dbg !63
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #6, !dbg !63
+  call void @llvm.dbg.declare(metadata i32* %val, metadata !55, metadata !DIExpression()), !dbg !64
+  store i32 0, i32* %val, align 4, !dbg !64, !tbaa !30
+  %1 = bitcast i32* %j to i8*, !dbg !65
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1) #6, !dbg !65
+  call void @llvm.dbg.declare(metadata i32* %j, metadata !56, metadata !DIExpression()), !dbg !66
+  store i32 0, i32* %j, align 4, !dbg !67, !tbaa !30
+  br label %for.cond, !dbg !68
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %2 = load i32, i32* %j, align 4, !dbg !69, !tbaa !30
+  %cmp = icmp slt i32 %2, 20000, !dbg !70
+  br i1 %cmp, label %for.body, label %for.end, !dbg !71
+
+for.body:                                         ; preds = %for.cond
+  %3 = bitcast i32* %condition to i8*, !dbg !72
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %3) #6, !dbg !72
+  call void @llvm.dbg.declare(metadata i32* %condition, metadata !57, metadata !DIExpression()), !dbg !73
+  %call = call i32 @rand() #6, !dbg !74
+  %rem = srem i32 %call, 5, !dbg !75
+  store i32 %rem, i32* %condition, align 4, !dbg !73, !tbaa !30
+  %4 = load i32, i32* %condition, align 4, !dbg !76, !tbaa !30
+  %conv = zext i32 %4 to i64, !dbg !76
+  %expval = call i64 @llvm.expect.i64(i64 %conv, i64 6), !dbg !77
+  switch i64 %expval, label %sw.default [
+    i64 0, label %sw.bb
+    i64 1, label %sw.bb2
+    i64 2, label %sw.bb2
+    i64 3, label %sw.bb2
+    i64 4, label %sw.bb3
+  ], !dbg !78
+
+sw.bb:                                            ; preds = %for.body
+  %call1 = call i32 @sum(i32* getelementptr inbounds ([25 x i32], [25 x i32]* @arry, i64 0, i64 0), i32 25), !dbg !79
+  %5 = load i32, i32* %val, align 4, !dbg !81, !tbaa !30
+  %add = add nsw i32 %5, %call1, !dbg !81
+  store i32 %add, i32* %val, align 4, !dbg !81, !tbaa !30
+  br label %sw.epilog, !dbg !82
+
+sw.bb2:                                           ; preds = %for.body, %for.body, %for.body
+  br label %sw.epilog, !dbg !83
+
+sw.bb3:                                           ; preds = %for.body
+  %call4 = call i32 @random_sample(i32* getelementptr inbounds ([25 x i32], [25 x i32]* @arry, i64 0, i64 0), i32 25), !dbg !84
+  %6 = load i32, i32* %val, align 4, !dbg !85, !tbaa !30
+  %add5 = add nsw i32 %6, %call4, !dbg !85
+  store i32 %add5, i32* %val, align 4, !dbg !85, !tbaa !30
+  br label %sw.epilog, !dbg !86
+
+sw.default:                                       ; preds = %for.body
+  unreachable, !dbg !87
+
+sw.epilog:                                        ; preds = %sw.bb3, %sw.bb2, %sw.bb
+  %7 = bitcast i32* %condition to i8*, !dbg !88
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %7) #6, !dbg !88
+  br label %for.inc, !dbg !89
+
+for.inc:                                          ; preds = %sw.epilog
+  %8 = load i32, i32* %j, align 4, !dbg !90, !tbaa !30
+  %inc = add nsw i32 %8, 1, !dbg !90
+  store i32 %inc, i32* %j, align 4, !dbg !90, !tbaa !30
+  br label %for.cond, !dbg !91, !llvm.loop !92
+
+for.end:                                          ; preds = %for.cond
+  %9 = bitcast i32* %j to i8*, !dbg !94
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %9) #6, !dbg !94
+  %10 = bitcast i32* %val to i8*, !dbg !94
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %10) #6, !dbg !94
+  ret i32 0, !dbg !95
+}
+
+; Function Attrs: nounwind readnone willreturn
+declare i64 @llvm.expect.i64(i64, i64) #4
+
+declare dso_local i32 @sum(i32*, i32) #5
+
+declare dso_local i32 @random_sample(i32*, i32) #5
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { nounwind readnone speculatable willreturn }
+attributes #3 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind readnone willreturn }
+attributes #5 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #6 = { nounwind }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!17, !18, !19}
+!llvm.ident = !{!20}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "inner_loop", scope: !2, file: !3, line: 7, type: !8, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (sso://user/paulkirth/clang-misexpect 60b79b85b1763d3d25630261e5cd1adb7f0835bc)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "misexpect-switch.c", directory: "/usr/local/google/home/paulkirth/workspace/pgo_test/switchv2")
+!4 = !{}
+!5 = !{!0, !6, !10, !12}
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "outer_loop", scope: !2, file: !3, line: 8, type: !8, isLocal: false, isDefinition: true)
+!8 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !9)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DIGlobalVariableExpression(var: !11, expr: !DIExpression())
+!11 = distinct !DIGlobalVariable(name: "arry_size", scope: !2, file: !3, line: 9, type: !8, isLocal: false, isDefinition: true)
+!12 = !DIGlobalVariableExpression(var: !13, expr: !DIExpression())
+!13 = distinct !DIGlobalVariable(name: "arry", scope: !2, file: !3, line: 11, type: !14, isLocal: false, isDefinition: true)
+!14 = !DICompositeType(tag: DW_TAG_array_type, baseType: !9, size: 800, elements: !15)
+!15 = !{!16}
+!16 = !DISubrange(count: 25)
+!17 = !{i32 2, !"Dwarf Version", i32 4}
+!18 = !{i32 2, !"Debug Info Version", i32 3}
+!19 = !{i32 1, !"wchar_size", i32 4}
+!20 = !{!"clang version 10.0.0 (sso://user/paulkirth/clang-misexpect 60b79b85b1763d3d25630261e5cd1adb7f0835bc)"}
+!21 = distinct !DISubprogram(name: "init_arry", scope: !3, file: !3, line: 13, type: !22, scopeLine: 13, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !24)
+!22 = !DISubroutineType(types: !23)
+!23 = !{null}
+!24 = !{!25}
+!25 = !DILocalVariable(name: "i", scope: !21, file: !3, line: 14, type: !9)
+!26 = !DILocation(line: 14, column: 3, scope: !21)
+!27 = !DILocation(line: 14, column: 7, scope: !21)
+!28 = !DILocation(line: 15, column: 10, scope: !29)
+!29 = distinct !DILexicalBlock(scope: !21, file: !3, line: 15, column: 3)
+!30 = !{!31, !31, i64 0}
+!31 = !{!"int", !32, i64 0}
+!32 = !{!"omnipotent char", !33, i64 0}
+!33 = !{!"Simple C/C++ TBAA"}
+!34 = !DILocation(line: 15, column: 8, scope: !29)
+!35 = !DILocation(line: 15, column: 15, scope: !36)
+!36 = distinct !DILexicalBlock(scope: !29, file: !3, line: 15, column: 3)
+!37 = !DILocation(line: 15, column: 17, scope: !36)
+!38 = !DILocation(line: 15, column: 3, scope: !29)
+!39 = !DILocation(line: 16, column: 15, scope: !40)
+!40 = distinct !DILexicalBlock(scope: !36, file: !3, line: 15, column: 35)
+!41 = !DILocation(line: 16, column: 22, scope: !40)
+!42 = !DILocation(line: 16, column: 10, scope: !40)
+!43 = !DILocation(line: 16, column: 5, scope: !40)
+!44 = !DILocation(line: 16, column: 13, scope: !40)
+!45 = !DILocation(line: 17, column: 3, scope: !40)
+!46 = !DILocation(line: 15, column: 30, scope: !36)
+!47 = !DILocation(line: 15, column: 3, scope: !36)
+!48 = distinct !{!48, !38, !49}
+!49 = !DILocation(line: 17, column: 3, scope: !29)
+!50 = !DILocation(line: 18, column: 1, scope: !21)
+!51 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 20, type: !52, scopeLine: 20, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !54)
+!52 = !DISubroutineType(types: !53)
+!53 = !{!9}
+!54 = !{!55, !56, !57}
+!55 = !DILocalVariable(name: "val", scope: !51, file: !3, line: 22, type: !9)
+!56 = !DILocalVariable(name: "j", scope: !51, file: !3, line: 23, type: !9)
+!57 = !DILocalVariable(name: "condition", scope: !58, file: !3, line: 25, type: !61)
+!58 = distinct !DILexicalBlock(scope: !59, file: !3, line: 24, column: 49)
+!59 = distinct !DILexicalBlock(scope: !60, file: !3, line: 24, column: 3)
+!60 = distinct !DILexicalBlock(scope: !51, file: !3, line: 24, column: 3)
+!61 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
+!62 = !DILocation(line: 21, column: 3, scope: !51)
+!63 = !DILocation(line: 22, column: 3, scope: !51)
+!64 = !DILocation(line: 22, column: 7, scope: !51)
+!65 = !DILocation(line: 23, column: 3, scope: !51)
+!66 = !DILocation(line: 23, column: 7, scope: !51)
+!67 = !DILocation(line: 24, column: 10, scope: !60)
+!68 = !DILocation(line: 24, column: 8, scope: !60)
+!69 = !DILocation(line: 24, column: 15, scope: !59)
+!70 = !DILocation(line: 24, column: 17, scope: !59)
+!71 = !DILocation(line: 24, column: 3, scope: !60)
+!72 = !DILocation(line: 25, column: 5, scope: !58)
+!73 = !DILocation(line: 25, column: 14, scope: !58)
+!74 = !DILocation(line: 25, column: 26, scope: !58)
+!75 = !DILocation(line: 25, column: 33, scope: !58)
+!76 = !DILocation(line: 26, column: 30, scope: !58)
+!77 = !DILocation(line: 26, column: 13, scope: !58)
+!78 = !DILocation(line: 26, column: 5, scope: !58)
+!79 = !DILocation(line: 28, column: 14, scope: !80)
+!80 = distinct !DILexicalBlock(scope: !58, file: !3, line: 26, column: 45)
+!81 = !DILocation(line: 28, column: 11, scope: !80)
+!82 = !DILocation(line: 29, column: 7, scope: !80)
+!83 = !DILocation(line: 33, column: 7, scope: !80)
+!84 = !DILocation(line: 35, column: 14, scope: !80)
+!85 = !DILocation(line: 35, column: 11, scope: !80)
+!86 = !DILocation(line: 36, column: 7, scope: !80)
+!87 = !DILocation(line: 38, column: 7, scope: !80)
+!88 = !DILocation(line: 40, column: 3, scope: !59)
+!89 = !DILocation(line: 40, column: 3, scope: !58)
+!90 = !DILocation(line: 24, column: 44, scope: !59)
+!91 = !DILocation(line: 24, column: 3, scope: !59)
+!92 = distinct !{!92, !71, !93}
+!93 = !DILocation(line: 40, column: 3, scope: !60)
+!94 = !DILocation(line: 43, column: 1, scope: !51)
+!95 = !DILocation(line: 42, column: 3, scope: !51)
Index: llvm/test/Transforms/PGOProfile/misexpect-branch.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/misexpect-branch.ll
@@ -0,0 +1,130 @@
+
+; RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+
+
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect -pass-remarks=misexpect 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+; New PM
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -S 2>&1 | FileCheck %s --check-prefix=WARNING
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -pass-remarks=misexpect -S 2>&1 | FileCheck %s --check-prefix=BOTH
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -S 2>&1 | FileCheck %s --check-prefix=DISABLED
+
+
+
+; WARNING-DAG: warning: misexpect-branch.c:22:0: 19.98%
+; WARNING-NOT: remark: misexpect-branch.c:22:0: Potential performance regression from use of __builtin_expect(): Annotation was correct on 19.98% of profiled executions.
+
+; REMARK-NOT: warning: misexpect-branch.c:22:0: 19.98%
+; REMARK-DAG: remark: misexpect-branch.c:22:0: Potential performance regression from use of __builtin_expect(): Annotation was correct on 19.98% of profiled executions.
+
+; BOTH-DAG: warning: misexpect-branch.c:22:0: 19.98%
+; BOTH-DAG: remark: misexpect-branch.c:22:0: Potential performance regression from use of __builtin_expect(): Annotation was correct on 19.98% of profiled executions.
+
+; DISABLED-NOT: warning: misexpect-branch.c:22:0: 19.98%
+; DISABLED-NOT: remark: misexpect-branch.c:22:0: Potential performance regression from use of __builtin_expect(): Annotation was correct on 19.98% of profiled executions.
+
+; CHECK-DAG: !{!"misexpect", i64 1, i64 2000, i64 1}
+
+
+
+; ModuleID = 'misexpect-branch.c'
+source_filename = "misexpect-branch.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@inner_loop = constant i32 100, align 4
+@outer_loop = constant i32 2000, align 4
+
+; Function Attrs: nounwind
+define i32 @bar() #0 !dbg !6 {
+entry:
+  %rando = alloca i32, align 4
+  %x = alloca i32, align 4
+  %0 = bitcast i32* %rando to i8*, !dbg !9
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #4, !dbg !9
+  %call = call i32 (...) @buzz(), !dbg !9
+  store i32 %call, i32* %rando, align 4, !dbg !9, !tbaa !10
+  %1 = bitcast i32* %x to i8*, !dbg !14
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1) #4, !dbg !14
+  store i32 0, i32* %x, align 4, !dbg !14, !tbaa !10
+  %2 = load i32, i32* %rando, align 4, !dbg !15, !tbaa !10
+  %rem = srem i32 %2, 200000, !dbg !15
+  %cmp = icmp eq i32 %rem, 0, !dbg !15
+  %lnot = xor i1 %cmp, true, !dbg !15
+  %lnot1 = xor i1 %lnot, true, !dbg !15
+  %lnot.ext = zext i1 %lnot1 to i32, !dbg !15
+  %conv = sext i32 %lnot.ext to i64, !dbg !15
+  %expval = call i64 @llvm.expect.i64(i64 %conv, i64 1), !dbg !15
+  %tobool = icmp ne i64 %expval, 0, !dbg !15
+  br i1 %tobool, label %if.then, label %if.else, !dbg !15
+
+if.then:                                          ; preds = %entry
+  %3 = load i32, i32* %rando, align 4, !dbg !16, !tbaa !10
+  %call2 = call i32 @baz(i32 %3), !dbg !16
+  store i32 %call2, i32* %x, align 4, !dbg !16, !tbaa !10
+  br label %if.end, !dbg !17
+
+if.else:                                          ; preds = %entry
+  %call3 = call i32 @foo(i32 50), !dbg !18
+  store i32 %call3, i32* %x, align 4, !dbg !18, !tbaa !10
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  %4 = load i32, i32* %x, align 4, !dbg !19, !tbaa !10
+  %5 = bitcast i32* %x to i8*, !dbg !20
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %5) #4, !dbg !20
+  %6 = bitcast i32* %rando to i8*, !dbg !20
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %6) #4, !dbg !20
+  ret i32 %4, !dbg !19
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
+
+declare i32 @buzz(...) #2
+
+; Function Attrs: nounwind readnone willreturn
+declare i64 @llvm.expect.i64(i64, i64) #3
+
+declare i32 @baz(i32) #2
+
+declare i32 @foo(i32) #2
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { nounwind readnone willreturn }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (trunk c20270bfffc9d6965219de339d66c61e9fe7d82d)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "<stdin>", directory: ".")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{!"clang version 10.0.0 (trunk c20270bfffc9d6965219de339d66c61e9fe7d82d)"}
+!6 = distinct !DISubprogram(name: "bar", scope: !7, file: !7, line: 19, type: !8, scopeLine: 19, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!7 = !DIFile(filename: "misexpect-branch.c", directory: ".")
+!8 = !DISubroutineType(types: !2)
+!9 = !DILocation(line: 20, scope: !6)
+!10 = !{!11, !11, i64 0}
+!11 = !{!"int", !12, i64 0}
+!12 = !{!"omnipotent char", !13, i64 0}
+!13 = !{!"Simple C/C++ TBAA"}
+!14 = !DILocation(line: 21, scope: !6)
+!15 = !DILocation(line: 22, scope: !6)
+!16 = !DILocation(line: 23, scope: !6)
+!17 = !DILocation(line: 24, scope: !6)
+!18 = !DILocation(line: 25, scope: !6)
+!19 = !DILocation(line: 27, scope: !6)
+!20 = !DILocation(line: 28, scope: !6)
Index: llvm/test/Transforms/PGOProfile/misexpect-branch-correct.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/misexpect-branch-correct.ll
@@ -0,0 +1,109 @@
+; RUN: llvm-profdata merge %S/Inputs/misexpect-branch-correct.proftext -o %t.profdata
+
+; RUN: opt < %s -lower-expect -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -pgo-warn-misexpect -pass-remarks=misexpect 2>&1 | FileCheck %s
+
+; New PM
+; RUN: opt < %s -passes="function(lower-expect),pgo-instr-use" -pgo-test-profile-file=%t.profdata -pgo-warn-misexpect -pass-remarks=misexpect -S  2>&1 | FileCheck %s
+
+; CHECK-NOT: warning: {{.*}}
+; CHECK-NOT: remark: {{.*}}
+; CHECK: !{!"misexpect", i64 1, i64 2000, i64 1}
+
+
+; ModuleID = 'misexpect-branch-correct.c'
+source_filename = "misexpect-branch-correct.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@inner_loop = constant i32 100, align 4
+@outer_loop = constant i32 2000, align 4
+
+; Function Attrs: nounwind
+define i32 @bar() #0 !dbg !6 {
+entry:
+  %rando = alloca i32, align 4
+  %x = alloca i32, align 4
+  %0 = bitcast i32* %rando to i8*, !dbg !9
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #4, !dbg !9
+  %call = call i32 (...) @buzz(), !dbg !9
+  store i32 %call, i32* %rando, align 4, !dbg !9, !tbaa !10
+  %1 = bitcast i32* %x to i8*, !dbg !14
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1) #4, !dbg !14
+  store i32 0, i32* %x, align 4, !dbg !14, !tbaa !10
+  %2 = load i32, i32* %rando, align 4, !dbg !15, !tbaa !10
+  %rem = srem i32 %2, 200000, !dbg !15
+  %cmp = icmp eq i32 %rem, 0, !dbg !15
+  %lnot = xor i1 %cmp, true, !dbg !15
+  %lnot1 = xor i1 %lnot, true, !dbg !15
+  %lnot.ext = zext i1 %lnot1 to i32, !dbg !15
+  %conv = sext i32 %lnot.ext to i64, !dbg !15
+  %expval = call i64 @llvm.expect.i64(i64 %conv, i64 0), !dbg !15
+  %tobool = icmp ne i64 %expval, 0, !dbg !15
+  br i1 %tobool, label %if.then, label %if.else, !dbg !15
+
+if.then:                                          ; preds = %entry
+  %3 = load i32, i32* %rando, align 4, !dbg !16, !tbaa !10
+  %call2 = call i32 @baz(i32 %3), !dbg !16
+  store i32 %call2, i32* %x, align 4, !dbg !16, !tbaa !10
+  br label %if.end, !dbg !17
+
+if.else:                                          ; preds = %entry
+  %call3 = call i32 @foo(i32 50), !dbg !18
+  store i32 %call3, i32* %x, align 4, !dbg !18, !tbaa !10
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  %4 = load i32, i32* %x, align 4, !dbg !19, !tbaa !10
+  %5 = bitcast i32* %x to i8*, !dbg !20
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %5) #4, !dbg !20
+  %6 = bitcast i32* %rando to i8*, !dbg !20
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %6) #4, !dbg !20
+  ret i32 %4, !dbg !19
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
+
+declare i32 @buzz(...) #2
+
+; Function Attrs: nounwind readnone willreturn
+declare i64 @llvm.expect.i64(i64, i64) #3
+
+declare i32 @baz(i32) #2
+
+declare i32 @foo(i32) #2
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { nounwind readnone willreturn }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (sso://user/paulkirth/clang-misexpect c20270bfffc9d6965219de339d66c61e9fe7d82d)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "<stdin>", directory: "/usr/local/google/home/paulkirth/workspace/clang-misexpect/clang/test/Profile")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{!"clang version 10.0.0 (sso://user/paulkirth/clang-misexpect c20270bfffc9d6965219de339d66c61e9fe7d82d)"}
+!6 = distinct !DISubprogram(name: "bar", scope: !7, file: !7, line: 17, type: !8, scopeLine: 17, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!7 = !DIFile(filename: "misexpect-branch-correct.c", directory: "/usr/local/google/home/paulkirth/workspace/clang-misexpect/clang/test/Profile")
+!8 = !DISubroutineType(types: !2)
+!9 = !DILocation(line: 18, scope: !6)
+!10 = !{!11, !11, i64 0}
+!11 = !{!"int", !12, i64 0}
+!12 = !{!"omnipotent char", !13, i64 0}
+!13 = !{!"Simple C/C++ TBAA"}
+!14 = !DILocation(line: 19, scope: !6)
+!15 = !DILocation(line: 20, scope: !6)
+!16 = !DILocation(line: 21, scope: !6)
+!17 = !DILocation(line: 22, scope: !6)
+!18 = !DILocation(line: 23, scope: !6)
+!19 = !DILocation(line: 25, scope: !6)
+!20 = !DILocation(line: 26, scope: !6)
Index: llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch.proftext
@@ -0,0 +1,16 @@
+# IR level Instrumentation Flag
+:ir
+main
+# Func Hash:
+74054140268
+# Num Counters:
+7
+# Counter Values:
+3973
+3970
+0
+11889
+8111
+1
+0
+
Index: llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch-correct.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/misexpect-switch-correct.proftext
@@ -0,0 +1,16 @@
+# IR level Instrumentation Flag
+:ir
+main
+# Func Hash:
+74054140268
+# Num Counters:
+7
+# Counter Values:
+0
+0
+20000
+0
+0
+1
+0
+
Index: llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch.proftext
@@ -0,0 +1,38 @@
+# IR level Instrumentation Flag
+:ir
+bar
+# Func Hash:
+29667547796
+# Num Counters:
+2
+# Counter Values:
+399668
+1600332
+
+baz
+# Func Hash:
+12884901887
+# Num Counters:
+1
+# Counter Values:
+399668
+
+foo
+# Func Hash:
+29212902728
+# Num Counters:
+2
+# Counter Values:
+40803991
+1600332
+
+main
+# Func Hash:
+41605652536
+# Num Counters:
+3
+# Counter Values:
+2000000
+2000
+1
+
Index: llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch-correct.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/misexpect-branch-correct.proftext
@@ -0,0 +1,38 @@
+# IR level Instrumentation Flag
+:ir
+bar
+# Func Hash:
+29667547796
+# Num Counters:
+2
+# Counter Values:
+200000
+0
+
+baz
+# Func Hash:
+12884901887
+# Num Counters:
+1
+# Counter Values:
+399668
+
+foo
+# Func Hash:
+29212902728
+# Num Counters:
+2
+# Counter Values:
+40803991
+1600332
+
+main
+# Func Hash:
+41605652536
+# Num Counters:
+3
+# Counter Values:
+2000000
+2000
+1
+
Index: llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
===================================================================
--- llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
+++ llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
@@ -138,7 +138,7 @@
   %conv1 = sext i32 %conv to i64
   %expval = call i64 @llvm.expect.i64(i64 %conv1, i64 0)
   %tobool = icmp ne i64 %expval, 0
-; CHECK: !prof !1
+; CHECK: !prof !2
 ; CHECK-NOT: @llvm.expect
   br i1 %tobool, label %if.then, label %if.end
 
@@ -165,7 +165,7 @@
   %tmp = load i32, i32* %x.addr, align 4
   %conv = sext i32 %tmp to i64
   %expval = call i64 @llvm.expect.i64(i64 %conv, i64 1)
-; CHECK: !prof !2
+; CHECK: !prof !4
 ; CHECK-NOT: @llvm.expect
   switch i64 %expval, label %sw.epilog [
     i64 1, label %sw.bb
@@ -194,7 +194,7 @@
   %tmp = load i32, i32* %x.addr, align 4
   %conv = sext i32 %tmp to i64
   %expval = call i64 @llvm.expect.i64(i64 %conv, i64 1)
-; CHECK: !prof !3
+; CHECK: !prof !5
 ; CHECK-NOT: @llvm.expect
   switch i64 %expval, label %sw.epilog [
     i64 2, label %sw.bb
@@ -278,7 +278,7 @@
   %t7 = call i64 @llvm.expect.i64(i64 %t6, i64 0)
   %t8 = icmp ne i64 %t7, 0
   %t9 = select i1 %t8, i32 1, i32 2
-; CHECK: select{{.*}}, !prof !1
+; CHECK: select{{.*}}, !prof !2
   ret i32 %t9
 }
 
@@ -286,6 +286,6 @@
 declare i1 @llvm.expect.i1(i1, i1) nounwind readnone
 
 ; CHECK: !0 = !{!"branch_weights", i32 2000, i32 1}
-; CHECK: !1 = !{!"branch_weights", i32 1, i32 2000}
-; CHECK: !2 = !{!"branch_weights", i32 1, i32 2000, i32 1}
-; CHECK: !3 = !{!"branch_weights", i32 2000, i32 1, i32 1}
+; CHECK: !2 = !{!"branch_weights", i32 1, i32 2000}
+; CHECK: !4 = !{!"branch_weights", i32 1, i32 2000, i32 1}
+; CHECK: !5 = !{!"branch_weights", i32 2000, i32 1, i32 1}
Index: llvm/test/ThinLTO/X86/lazyload_metadata.ll
===================================================================
--- llvm/test/ThinLTO/X86/lazyload_metadata.ll
+++ llvm/test/ThinLTO/X86/lazyload_metadata.ll
@@ -10,13 +10,13 @@
 ; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t3.bc \
 ; RUN:          -o /dev/null -stats \
 ; RUN:  2>&1 | FileCheck %s -check-prefix=LAZY
-; LAZY: 61 bitcode-reader  - Number of Metadata records loaded
+; LAZY: 63 bitcode-reader  - Number of Metadata records loaded
 ; LAZY: 2 bitcode-reader  - Number of MDStrings loaded
 
 ; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t3.bc \
 ; RUN:          -o /dev/null -disable-ondemand-mds-loading -stats \
 ; RUN:  2>&1 | FileCheck %s -check-prefix=NOTLAZY
-; NOTLAZY: 70 bitcode-reader  - Number of Metadata records loaded
+; NOTLAZY: 72 bitcode-reader  - Number of Metadata records loaded
 ; NOTLAZY: 7 bitcode-reader  - Number of MDStrings loaded
 
 
Index: llvm/lib/Transforms/Utils/MisExpect.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Transforms/Utils/MisExpect.cpp
@@ -0,0 +1,167 @@
+//===--- MisExpect.cpp - Check Use of __builtin_expect() with PGO data ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). This utility extracts the threshold values from metadata
+// associated with the instrumented Branch or Switch. The threshold values are
+// then used to determin if a warning would be emmited.
+//
+// MisExpect metadata is generated when llvm.expect intrinsics are lowered see
+// LowerExpectIntrinsic.cpp
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/MisExpect.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/BranchProbability.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/FormatVariadic.h"
+#include <bits/stdint-uintn.h>
+#include <functional>
+#include <numeric>
+
+#define DEBUG_TYPE "misexpect"
+
+using namespace llvm;
+using namespace misexpect;
+
+namespace llvm {
+
+// Command line option to enable/disable the warning about missing profile
+// information.
+static cl::opt<bool> PGOWarnMisExpect(
+    "pgo-warn-misexpect", cl::init(false), cl::Hidden,
+    cl::desc("Use this option to turn on/off "
+             "warnings about incorrect usage of __builtin_expect."));
+
+} // namespace llvm
+
+namespace {
+
+Instruction *getOprndOrInst(Instruction *I) {
+  assert(I != nullptr && "MisExpect target Instruction cannot be nullptr");
+  Instruction *Ret = nullptr;
+  if (auto B = dyn_cast<BranchInst>(I)) {
+    Ret = dyn_cast<Instruction>(B->getCondition());
+  }
+  // TODO: Find a way to resolve condition location for switches
+  // Using the condition of the switch seems to often resolve to an earlier
+  // point in the program, i.e. the calculation of the switch condition, rather
+  // than the switches location in the source code. Thus, we should use the
+  // instruction to get source code locations rather than the condition to
+  // improve diagnostic output, such as the caret. If the same problem exists
+  // for branch instructions, then we should remove this function and directly
+  // use the instruction
+  //
+  // else if (auto S = dyn_cast<SwitchInst>(I)) {
+  // Ret = I;
+  //}
+  return Ret ? Ret : I;
+}
+
+void emitMisexpectDiagnostic(Instruction *I, LLVMContext &Ctx,
+                             double PercentageCorrect) {
+  auto PerString = formatv("{0:P}", PercentageCorrect);
+  auto RemStr = formatv(
+      "Potential performance regression from use of __builtin_expect(): "
+      "Annotation was correct on {0:P} of profiled executions.",
+      PercentageCorrect);
+  Twine Msg(PerString);
+  Instruction *Cond = getOprndOrInst(I);
+  if (PGOWarnMisExpect)
+    Ctx.diagnose(DiagnosticInfoMisExpect(Cond, Msg));
+  OptimizationRemarkEmitter ORE(I->getParent()->getParent());
+  ORE.emit(OptimizationRemark(DEBUG_TYPE, "misexpect", Cond) << RemStr.str());
+}
+
+} // namespace
+
+namespace llvm {
+namespace misexpect {
+
+void verifyMisExpect(Instruction *I, const SmallVector<uint32_t, 4> &Weights,
+                     LLVMContext &Ctx) {
+  if (auto *MisExpectData = I->getMetadata(LLVMContext::MD_misexpect)) {
+    auto *MisExpectDataName = dyn_cast<MDString>(MisExpectData->getOperand(0));
+    if (MisExpectDataName &&
+        MisExpectDataName->getString().equals("misexpect")) {
+      LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+      LLVM_DEBUG(llvm::dbgs()
+                 << "Function: " << I->getFunction()->getName() << "\n");
+      LLVM_DEBUG(llvm::dbgs() << "Instruction: " << *I << ":\n");
+      LLVM_DEBUG(for (int Idx = 0, Size = Weights.size(); Idx < Size; ++Idx) {
+        llvm::dbgs() << "Weights[" << Idx << "] = " << Weights[Idx] << "\n";
+      });
+
+      // extract values from misexpect metadata
+      const ConstantInt *IndexCint =
+          mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(1));
+      const ConstantInt *LikelyCInt =
+          mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(2));
+      const ConstantInt *UnlikelyCInt =
+          mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(3));
+
+      if (!IndexCint || !LikelyCInt || !UnlikelyCInt)
+        return;
+
+      const uint64_t Index = IndexCint->getZExtValue();
+      const uint64_t LikelyBranchWeight = LikelyCInt->getZExtValue();
+      const uint64_t UnlikelyBranchWeight = UnlikelyCInt->getZExtValue();
+      const uint64_t ProfileCount = Weights[Index];
+      const uint64_t CaseTotal = std::accumulate(
+          Weights.begin(), Weights.end(), (uint64_t)0, std::plus<uint64_t>());
+      const int NumUnlikelyTargets = Weights.size() - 1;
+
+      const uint64_t TotalBranchWeight =
+          LikelyBranchWeight + (UnlikelyBranchWeight * NumUnlikelyTargets);
+
+      double Percentage = (double)ProfileCount / (double)CaseTotal;
+
+      const llvm::BranchProbability LikelyThreshold(LikelyBranchWeight,
+                                                    TotalBranchWeight);
+      uint64_t ScaledThreshold = LikelyThreshold.scale(CaseTotal);
+
+      LLVM_DEBUG(llvm::dbgs()
+                 << "Unlikely Targets: " << NumUnlikelyTargets << ":\n");
+      LLVM_DEBUG(llvm::dbgs() << "Profile Count: " << ProfileCount << ":\n");
+      LLVM_DEBUG(llvm::dbgs()
+                 << "Scaled Threshold: " << ScaledThreshold << ":\n");
+      LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+      if (ProfileCount < ScaledThreshold)
+        emitMisexpectDiagnostic(I, Ctx, Percentage);
+    }
+  }
+}
+
+void checkClangInstrumentation(Instruction &I) {
+  if (auto *MD = I.getMetadata(LLVMContext::MD_prof)) {
+    // Operand 0 is a string tag "branch_weights"
+    if (MDString *Tag = cast<MDString>(MD->getOperand(0))) {
+      unsigned NOps = MD->getNumOperands();
+      if (NOps > 1 && Tag->getString().equals("branch_weights")) {
+        SmallVector<uint32_t, 4> RealWeights(NOps - 1);
+        for (unsigned i = 1; i < NOps; i++) {
+          ConstantInt *Value =
+              mdconst::dyn_extract<ConstantInt>(MD->getOperand(i));
+          RealWeights[i - 1] = Value->getZExtValue();
+        }
+        misexpect::verifyMisExpect(&I, RealWeights, I.getContext());
+      }
+    }
+  }
+}
+
+} // namespace misexpect
+} // namespace llvm
+#undef DEBUG_TYPE
Index: llvm/lib/Transforms/Utils/CMakeLists.txt
===================================================================
--- llvm/lib/Transforms/Utils/CMakeLists.txt
+++ llvm/lib/Transforms/Utils/CMakeLists.txt
@@ -40,6 +40,7 @@
   LowerSwitch.cpp
   Mem2Reg.cpp
   MetaRenamer.cpp
+  MisExpect.cpp
   ModuleUtils.cpp
   NameAnonGlobals.cpp
   PredicateInfo.cpp
Index: llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
+++ llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
 
 using namespace llvm;
 
@@ -71,15 +72,20 @@
   unsigned n = SI.getNumCases(); // +1 for default case.
   SmallVector<uint32_t, 16> Weights(n + 1, UnlikelyBranchWeight);
 
-  if (Case == *SI.case_default())
-    Weights[0] = LikelyBranchWeight;
-  else
-    Weights[Case.getCaseIndex() + 1] = LikelyBranchWeight;
+  uint64_t Index = (Case == *SI.case_default()) ? 0 : Case.getCaseIndex() + 1;
+  Weights[Index] = LikelyBranchWeight;
+
+  SI.setMetadata(
+      LLVMContext::MD_misexpect,
+      MDBuilder(CI->getContext())
+          .createMisExpect(Index, LikelyBranchWeight, UnlikelyBranchWeight));
+
+  SI.setCondition(ArgValue);
+  misexpect::checkClangInstrumentation(SI);
 
   SI.setMetadata(LLVMContext::MD_prof,
                  MDBuilder(CI->getContext()).createBranchWeights(Weights));
 
-  SI.setCondition(ArgValue);
   return true;
 }
 
@@ -280,19 +286,28 @@
 
   MDBuilder MDB(CI->getContext());
   MDNode *Node;
+  MDNode *ExpNode;
 
   if ((ExpectedValue->getZExtValue() == ValueComparedTo) ==
-      (Predicate == CmpInst::ICMP_EQ))
+      (Predicate == CmpInst::ICMP_EQ)) {
     Node = MDB.createBranchWeights(LikelyBranchWeight, UnlikelyBranchWeight);
-  else
+    ExpNode = MDB.createMisExpect(0, LikelyBranchWeight, UnlikelyBranchWeight);
+  } else {
     Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight);
+    ExpNode = MDB.createMisExpect(1, LikelyBranchWeight, UnlikelyBranchWeight);
+  }
 
-  BSI.setMetadata(LLVMContext::MD_prof, Node);
+  BSI.setMetadata(LLVMContext::MD_misexpect, ExpNode);
 
   if (CmpI)
     CmpI->setOperand(0, ArgValue);
   else
     BSI.setCondition(ArgValue);
+
+  misexpect::checkClangInstrumentation(BSI);
+
+  BSI.setMetadata(LLVMContext::MD_prof, Node);
+
   return true;
 }
 
Index: llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -108,6 +108,7 @@
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
@@ -1776,6 +1777,9 @@
                                            : Weights) {
     dbgs() << W << " ";
   } dbgs() << "\n";);
+
+  misexpect::verifyMisExpect(TI, Weights, TI->getContext());
+
   TI->setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
   if (EmitBranchProbability) {
     std::string BrCondStr = getBranchCondString(TI);
Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -72,6 +72,7 @@
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Utils/CallPromotionUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
@@ -1442,6 +1443,8 @@
       }
     }
 
+    misexpect::verifyMisExpect(TI, Weights, TI->getContext());
+
     uint64_t TempWeight;
     // Only set weights if there is at least one non-zero weight.
     // In any other case, let the analyzer set weights.
Index: llvm/lib/IR/MDBuilder.cpp
===================================================================
--- llvm/lib/IR/MDBuilder.cpp
+++ llvm/lib/IR/MDBuilder.cpp
@@ -309,3 +309,15 @@
   };
   return MDNode::get(Context, Vals);
 }
+
+MDNode *MDBuilder::createMisExpect(uint64_t Index, uint64_t LikleyWeight,
+                                   uint64_t UnlikleyWeight) {
+  auto IntType = Type::getInt64Ty(Context);
+  Metadata *Vals[] = {
+      createString("misexpect"),
+      createConstant(ConstantInt::get(IntType, Index)),
+      createConstant(ConstantInt::get(IntType, LikleyWeight)),
+      createConstant(ConstantInt::get(IntType, UnlikleyWeight)),
+  };
+  return MDNode::get(Context, Vals);
+}
Index: llvm/lib/IR/DiagnosticInfo.cpp
===================================================================
--- llvm/lib/IR/DiagnosticInfo.cpp
+++ llvm/lib/IR/DiagnosticInfo.cpp
@@ -370,5 +370,16 @@
   return OS.str();
 }
 
+DiagnosticInfoMisExpect::DiagnosticInfoMisExpect(const Instruction *Inst,
+                                                 Twine &Msg)
+    : DiagnosticInfoWithLocationBase(DK_MisExpect, DS_Warning,
+                                     *Inst->getParent()->getParent(),
+                                     Inst->getDebugLoc()),
+      Msg(Msg) {}
+
+void DiagnosticInfoMisExpect::print(DiagnosticPrinter &DP) const {
+  DP << getLocationStr() << ": " << getMsg();
+}
+
 void OptimizationRemarkAnalysisFPCommute::anchor() {}
 void OptimizationRemarkAnalysisAliasing::anchor() {}
Index: llvm/include/llvm/Transforms/Utils/MisExpect.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Transforms/Utils/MisExpect.h
@@ -0,0 +1,43 @@
+//===--- MisExpect.cpp - Check Use of __builtin_expect() with PGO data ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). This utility extracts the threshold values from metadata
+// associated with the instrumented Branch or Switch. The threshold values are
+// then used to determin if a warning would be emmited.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+
+namespace llvm {
+namespace misexpect {
+
+/// verifyMisExpect - compares PGO counters to the thresholds used for
+/// __builtin_expect and warns if the PGO counters are outside of the expected
+/// range.
+/// \param I The Instruction being checked
+/// \param Weights A vector of profile weights for each target block
+/// \param Ctx The current LLVM context
+void verifyMisExpect(llvm::Instruction *I,
+                     const llvm::SmallVector<uint32_t, 4> &Weights,
+                     llvm::LLVMContext &Ctx);
+
+/// checkClangInstrumentation - verify if __builtin_expect matches PGO profile
+/// This function checks the frontend instrumentation in the backend when
+/// lowering __builtin_expect intrinsics. It checks for existing metadata, and
+/// then validates the use of builtin-expect against the assigned branch
+/// weights.
+/// \param I the Instruction being checked
+void checkClangInstrumentation(Instruction &I);
+
+} // namespace misexpect
+} // namespace llvm
Index: llvm/include/llvm/IR/MDBuilder.h
===================================================================
--- llvm/include/llvm/IR/MDBuilder.h
+++ llvm/include/llvm/IR/MDBuilder.h
@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/Support/DataTypes.h"
 #include <utility>
@@ -75,6 +76,10 @@
   /// Return metadata containing the section prefix for a function.
   MDNode *createFunctionSectionPrefix(StringRef Prefix);
 
+  /// return metadata containing expected value
+  MDNode *createMisExpect(uint64_t Index, uint64_t LikelyWeight,
+                          uint64_t UnlikelyWeight);
+
   //===------------------------------------------------------------------===//
   // Range metadata.
   //===------------------------------------------------------------------===//
Index: llvm/include/llvm/IR/FixedMetadataKinds.def
===================================================================
--- llvm/include/llvm/IR/FixedMetadataKinds.def
+++ llvm/include/llvm/IR/FixedMetadataKinds.def
@@ -39,3 +39,4 @@
 LLVM_FIXED_MD_KIND(MD_access_group, "llvm.access.group", 25)
 LLVM_FIXED_MD_KIND(MD_callback, "callback", 26)
 LLVM_FIXED_MD_KIND(MD_preserve_access_index, "llvm.preserve.access.index", 27)
+LLVM_FIXED_MD_KIND(MD_misexpect, "misexpect", 28)
Index: llvm/include/llvm/IR/DiagnosticInfo.h
===================================================================
--- llvm/include/llvm/IR/DiagnosticInfo.h
+++ llvm/include/llvm/IR/DiagnosticInfo.h
@@ -75,7 +75,8 @@
   DK_MIRParser,
   DK_PGOProfile,
   DK_Unsupported,
-  DK_FirstPluginKind
+  DK_FirstPluginKind,
+  DK_MisExpect
 };
 
 /// Get the next available kind ID for a plugin diagnostic.
@@ -1002,6 +1003,31 @@
   void print(DiagnosticPrinter &DP) const override;
 };
 
+/// Diagnostic information for MisExpect analysis.
+class DiagnosticInfoMisExpect : public DiagnosticInfoWithLocationBase {
+public:
+  DiagnosticInfoMisExpect(const Function &Fn, const Twine &Msg,
+                          const DiagnosticLocation &Loc = DiagnosticLocation(),
+                          DiagnosticSeverity Severity = DS_Error)
+      : DiagnosticInfoWithLocationBase(DK_MisExpect, Severity, Fn, Loc),
+        Msg(Msg) {}
+
+  DiagnosticInfoMisExpect(const Instruction *Inst, Twine &Msg);
+
+  /// \see DiagnosticInfo::print.
+  void print(DiagnosticPrinter &DP) const override;
+
+  static bool classof(const DiagnosticInfo *DI) {
+    return DI->getKind() == DK_MisExpect;
+  }
+
+  const Twine &getMsg() const { return Msg; }
+
+private:
+  /// Message to report.
+  const Twine &Msg;
+};
+
 } // end namespace llvm
 
 #endif // LLVM_IR_DIAGNOSTICINFO_H
Index: clang/test/Profile/misexpect-switch.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch.c
@@ -0,0 +1,41 @@
+// Test that misexpect detects mis-annotated switch statements
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect -debug-info-kind=line-tables-only
+
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+  init_arry();
+  int val = 0;
+
+  int j, k;
+  for (j = 0; j < outer_loop; ++j) {
+    for (k = 0; k < inner_loop; ++k) {
+      unsigned condition = rand() % 10000;
+      switch (__builtin_expect(condition, 0)) { // expected-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+      case 0:
+        val += sum(arry, arry_size);
+        break;
+      case 1:
+      case 2:
+      case 3:
+        break;
+      default:
+        val += random_sample(arry, arry_size);
+        break;
+      } // end switch
+    }   // end inner_loop
+  }     // end outer_loop
+
+  return 0;
+}
Index: clang/test/Profile/misexpect-switch-only-default-case.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-only-default-case.c
@@ -0,0 +1,35 @@
+// Test that misexpect emits no warning when there is only one switch case
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch-default-only.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect -debug-info-kind=line-tables-only
+
+// expected-no-diagnostics
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+  init_arry();
+  int val = 0;
+
+  int j, k;
+  for (j = 0; j < outer_loop; ++j) {
+    for (k = 0; k < inner_loop; ++k) {
+      unsigned condition = rand() % 10000;
+      switch (__builtin_expect(condition, 0)) {
+      default:
+        val += random_sample(arry, arry_size);
+        break;
+      }; // end switch
+    }    // end inner_loop
+  }      // end outer_loop
+
+  return 0;
+}
Index: clang/test/Profile/misexpect-switch-nonconst.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-nonconst.c
@@ -0,0 +1,43 @@
+// Test that misexpect emits no warning when switch condition is non-const
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect
+
+// expected-no-diagnostics
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+  init_arry();
+  int val = 0;
+
+  int j, k;
+  for (j = 0; j < outer_loop; ++j) {
+    for (k = 0; k < inner_loop; ++k) {
+      unsigned condition = rand() % 10000;
+      switch (__builtin_expect(condition, rand())) {
+      case 0:
+        val += sum(arry, arry_size);
+        break;
+      case 1:
+      case 2:
+      case 3:
+      case 4:
+        val += random_sample(arry, arry_size);
+        break;
+      default:
+        __builtin_unreachable();
+      } // end switch
+    }   // end inner_loop
+  }     // end outer_loop
+
+  return 0;
+}
Index: clang/test/Profile/misexpect-switch-default.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-default.c
@@ -0,0 +1,40 @@
+// Test that misexpect detects mis-annotated switch statements for default case
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch-default.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect -debug-info-kind=line-tables-only
+
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+  init_arry();
+  int val = 0;
+  int j;
+  for (j = 0; j < outer_loop * inner_loop; ++j) {
+    unsigned condition = rand() % 5;
+    switch (__builtin_expect(condition, 6)) { // expected-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+    case 0:
+      val += sum(arry, arry_size);
+      break;
+    case 1:
+    case 2:
+    case 3:
+      break;
+    case 4:
+      val += random_sample(arry, arry_size);
+      break;
+    default:
+      __builtin_unreachable();
+    } // end switch
+  }   // end outer_loop
+
+  return 0;
+}
Index: clang/test/Profile/misexpect-branch.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch.c
@@ -0,0 +1,28 @@
+// Test that misexpect detects mis-annotated branches
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify=imprecise -Wmisexpect
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify=exact -Wmisexpect -debug-info-kind=line-tables-only
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify=foo
+
+// foo-no-diagnostics
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() { // imprecise-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+  int rando = buzz();
+  int x = 0;
+  if (likely(rando % (outer_loop * inner_loop) == 0)) { // exact-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+    x = baz(rando);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
Index: clang/test/Profile/misexpect-branch-nonconst-expected-val.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch-nonconst-expected-val.c
@@ -0,0 +1,23 @@
+// Test that misexpect emits no warning when condition is not a compile-time constant
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch-nonconst-expect-arg.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect
+
+// expected-no-diagnostics
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+  int rando = buzz();
+  int x = 0;
+  if (__builtin_expect(rando % (outer_loop * inner_loop) == 0, buzz())) {
+    x = baz(rando);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
Index: clang/test/Profile/misexpect-branch-cold.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch-cold.c
@@ -0,0 +1,27 @@
+// Test that misexpect emits no warning when prediction is correct
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -Wmisexpect
+
+// expected-no-diagnostics
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+  int rando = buzz();
+  int x = 0;
+  if (unlikely(rando % (outer_loop * inner_loop) == 0)) {
+    x = baz(rando);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
+
Index: clang/test/Profile/Inputs/misexpect-switch.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-switch.proftext
@@ -0,0 +1,16 @@
+main
+# Func Hash:
+1965403898329309329
+# Num Counters:
+9
+# Counter Values:
+1
+20
+20000
+20000
+12
+26
+0
+0
+19962
+
Index: clang/test/Profile/Inputs/misexpect-switch-default.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-switch-default.proftext
@@ -0,0 +1,17 @@
+main
+# Func Hash:
+8712453512413296413
+# Num Counters:
+9
+# Counter Values:
+1
+20000
+20000
+4066
+11889
+0
+0
+4045
+0
+
+
Index: clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
@@ -0,0 +1,12 @@
+main
+# Func Hash:
+79676873694057560
+# Num Counters:
+5
+# Counter Values:
+1
+20
+20000
+20000
+20000
+
Index: clang/test/Profile/Inputs/misexpect-branch.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-branch.proftext
@@ -0,0 +1,9 @@
+bar
+# Func Hash:
+45795613684824
+# Num Counters:
+2
+# Counter Values:
+200000
+0
+
Index: clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
@@ -0,0 +1,9 @@
+bar
+# Func Hash:
+11262309464
+# Num Counters:
+2
+# Counter Values:
+200000
+2
+
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -3448,6 +3448,13 @@
     }
   }
 
+const std::vector<std::string> &warnings =
+      Res.getDiagnosticOpts().Warnings;
+  if (std::find(warnings.begin(), warnings.end(), "misexpect") !=
+      warnings.end()) {
+    Res.FrontendOpts.LLVMArgs.push_back("-pgo-warn-misexpect");
+  }
+
   LangOpts.FunctionAlignment =
       getLastArgIntValue(Args, OPT_function_alignment, 0, Diags);
 
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -33,6 +33,7 @@
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Operator.h"
@@ -1357,8 +1358,6 @@
   return true;
 }
 
-
-
 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
 /// statement) to the specified blocks.  Based on the condition, this might try
 /// to simplify the codegen of the conditional based on the branch.
Index: clang/lib/CodeGen/CodeGenAction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenAction.cpp
+++ clang/lib/CodeGen/CodeGenAction.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclGroup.h"
+#include "clang/Basic/DiagnosticFrontend.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/LangStandard.h"
 #include "clang/Basic/SourceManager.h"
@@ -365,6 +366,7 @@
     bool StackSizeDiagHandler(const llvm::DiagnosticInfoStackSize &D);
     /// Specialized handler for unsupported backend feature diagnostic.
     void UnsupportedDiagHandler(const llvm::DiagnosticInfoUnsupported &D);
+    void MisExpectDiagHandler(const llvm::DiagnosticInfoMisExpect &D);
     /// Specialized handlers for optimization remarks.
     /// Note that these handlers only accept remarks and they always handle
     /// them.
@@ -617,6 +619,25 @@
         << Filename << Line << Column;
 }
 
+void BackendConsumer::MisExpectDiagHandler(
+    const llvm::DiagnosticInfoMisExpect &D) {
+  StringRef Filename;
+  unsigned Line, Column;
+  bool BadDebugInfo = false;
+  FullSourceLoc Loc =
+      getBestLocationFromDebugLoc(D, BadDebugInfo, Filename, Line, Column);
+
+  Diags.Report(Loc, diag::warn_profile_data_misexpect) << D.getMsg().str();
+
+  if (BadDebugInfo)
+    // If we were not able to translate the file:line:col information
+    // back to a SourceLocation, at least emit a note stating that
+    // we could not translate this location. This can happen in the
+    // case of #line directives.
+    Diags.Report(Loc, diag::note_fe_backend_invalid_loc)
+        << Filename << Line << Column;
+}
+
 void BackendConsumer::EmitOptimizationMessage(
     const llvm::DiagnosticInfoOptimizationBase &D, unsigned DiagID) {
   // We only support warnings and remarks.
@@ -787,6 +808,9 @@
   case llvm::DK_Unsupported:
     UnsupportedDiagHandler(cast<DiagnosticInfoUnsupported>(DI));
     return;
+  case llvm::DK_MisExpect:
+    MisExpectDiagHandler(cast<DiagnosticInfoMisExpect>(DI));
+    return;
   default:
     // Plugin IDs are not bound to any value as they are set dynamically.
     ComputeDiagRemarkID(Severity, backend_plugin, DiagID);
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -1034,6 +1034,7 @@
 def ProfileInstrMissing : DiagGroup<"profile-instr-missing">;
 def ProfileInstrOutOfDate : DiagGroup<"profile-instr-out-of-date">;
 def ProfileInstrUnprofiled : DiagGroup<"profile-instr-unprofiled">;
+def MisExpect : DiagGroup<"misexpect">;
 
 // AddressSanitizer frontend instrumentation remarks.
 def SanitizeAddressRemarks : DiagGroup<"sanitize-address">;
Index: clang/include/clang/Basic/DiagnosticFrontendKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -275,7 +275,12 @@
 def warn_profile_data_unprofiled : Warning<
   "no profile data available for file \"%0\"">,
   InGroup<ProfileInstrUnprofiled>;
-
+def warn_profile_data_misexpect : Warning<
+  "Potential performance regression from use of __builtin_expect(): "
+  "Annotation was correct on %0 of profiled executions.">,
+  BackendInfo,
+  InGroup<MisExpect>,
+  DefaultIgnore;
 } // end of instrumentation issue category
 
 }

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