[clang][llvm][NFC] Change misexpect's tolerance option to be 32-bit

[paulkirth]

Summary

In D131869 we noticed that we jump through some hoops because we parse the
tolerance option used in MisExpect.cpp into a 64-bit integer. This is
unnecessary, since the value can only be in the range [0, 100).

This patch changes the underlying type to be 32-bit from where it is
parsed in Clang through to it's use in LLVM.

[jloser]

LGTM! Thanks for the follow-up cleanup. I'll rebase once this lands to avoid the cast in https://reviews.llvm.org/D131869 if that works for you.

clang/include/clang/Basic/CodeGenOptions.h

public:
   ///                    hotness threshold from profile summary during
   ///                    compilation.
   ///
   /// If threshold option is not specified, it is disabled by default.
   Optional<uint64_t> DiagnosticsHotnessThreshold = 0;
 
   /// The maximum percentage profiling weights can deviate from the expected
   /// values in order to be included in misexpect diagnostics.
-  Optional<uint64_t> DiagnosticsMisExpectTolerance = 0;
+  Optional<uint32_t> DiagnosticsMisExpectTolerance = 0;
 
 public:
   // Define accessors/mutators for code generation options of enumeration type.
 #define CODEGENOPT(Name, Bits, Default)
 #define ENUM_CODEGENOPT(Name, Type, Bits, Default) \
   Type get##Name() const { return static_cast<Type>(Name); } \
   void set##Name(Type Value) { Name = static_cast<unsigned>(Value); }
 #include "clang/Basic/CodeGenOptions.def"

clang/lib/Frontend/CompilerInvocation.cpp

 using namespace llvm::opt;
 
 //===----------------------------------------------------------------------===//
 // Helpers.
 //===----------------------------------------------------------------------===//
 
 // Parse misexpect tolerance argument value.
 // Valid option values are integers in the range [0, 100)
-inline Expected<Optional<uint64_t>> parseToleranceOption(StringRef Arg) {
-  int64_t Val;
+inline Expected<Optional<uint32_t>> parseToleranceOption(StringRef Arg) {
+  uint32_t Val;
   if (Arg.getAsInteger(10, Val))
     return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                    "Not an integer: %s", Arg.data());
   return Val;
 }
 
 //===----------------------------------------------------------------------===//
 // Initialization.

llvm/include/llvm/IR/LLVMContext.h

#undef LLVM_FIXED_MD_KIND
   /// diagnostics.
   bool getDiagnosticsHotnessRequested() const;
   /// Set if a code hotness metric should be included in optimization
   /// diagnostics.
   void setDiagnosticsHotnessRequested(bool Requested);
 
   bool getMisExpectWarningRequested() const;
   void setMisExpectWarningRequested(bool Requested);
-  void setDiagnosticsMisExpectTolerance(Optional<uint64_t> Tolerance);
-  uint64_t getDiagnosticsMisExpectTolerance() const;
+  void setDiagnosticsMisExpectTolerance(Optional<uint32_t> Tolerance);
+  uint32_t getDiagnosticsMisExpectTolerance() const;
 
   /// Return the minimum hotness value a diagnostic would need in order
   /// to be included in optimization diagnostics.
   ///
   /// Three possible return values:
   /// 0            - threshold is disabled. Everything will be printed out.
   /// positive int - threshold is set.
   /// UINT64_MAX   - threshold is not yet set, and needs to be synced from

llvm/lib/IR/LLVMContext.cpp

 }
 bool LLVMContext::getMisExpectWarningRequested() const {
   return pImpl->MisExpectWarningRequested;
 }
 uint64_t LLVMContext::getDiagnosticsHotnessThreshold() const {
   return pImpl->DiagnosticsHotnessThreshold.value_or(UINT64_MAX);
 }
 void LLVMContext::setDiagnosticsMisExpectTolerance(
-    Optional<uint64_t> Tolerance) {
+    Optional<uint32_t> Tolerance) {
   pImpl->DiagnosticsMisExpectTolerance = Tolerance;
 }
-uint64_t LLVMContext::getDiagnosticsMisExpectTolerance() const {
+uint32_t LLVMContext::getDiagnosticsMisExpectTolerance() const {
   return pImpl->DiagnosticsMisExpectTolerance.value_or(0);
 }
 
 bool LLVMContext::isDiagnosticsHotnessThresholdSetFromPSI() const {
   return !pImpl->DiagnosticsHotnessThreshold.has_value();
 }
 
 remarks::RemarkStreamer *LLVMContext::getMainRemarkStreamer() {

llvm/lib/IR/LLVMContextImpl.h

public:
   /// only allowed from 3 to 2, when the threshold is first synced with profile
   /// summary. This ensures that the threshold is set only once and stays
   /// constant.
   ///
   /// If threshold option is not specified, it is disabled (0) by default.
   Optional<uint64_t> DiagnosticsHotnessThreshold = 0;
 
   /// The percentage of difference between profiling branch weights and
-  // llvm.expect branch weights to tolerate when emiting MisExpect diagnostics
-  Optional<uint64_t> DiagnosticsMisExpectTolerance = 0;
+  /// llvm.expect branch weights to tolerate when emiting MisExpect diagnostics
+  Optional<uint32_t> DiagnosticsMisExpectTolerance = 0;
   bool MisExpectWarningRequested = false;
 
   /// The specialized remark streamer used by LLVM's OptimizationRemarkEmitter.
   std::unique_ptr<LLVMRemarkStreamer> LLVMRS;
 
   LLVMContext::YieldCallbackTy YieldCallback = nullptr;
   void *YieldOpaqueHandle = nullptr;
 

llvm/lib/Transforms/Utils/MisExpect.cpp

 
 // Command line option to enable/disable the warning when profile data suggests
 // a mismatch with the use of the llvm.expect intrinsic
 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 llvm.expect intrinsics."));
 
-static cl::opt<unsigned> MisExpectTolerance(
+static cl::opt<uint32_t> MisExpectTolerance(
     "misexpect-tolerance", cl::init(0),
     cl::desc("Prevents emiting diagnostics when profile counts are "
              "within N% of the threshold.."));
 
 } // namespace llvm
 
 namespace {
 
 bool isMisExpectDiagEnabled(LLVMContext &Ctx) {
   return PGOWarnMisExpect || Ctx.getMisExpectWarningRequested();
 }
 
 uint64_t getMisExpectTolerance(LLVMContext &Ctx) {
-  return std::max(static_cast<uint64_t>(MisExpectTolerance),
+  return std::max(static_cast<uint32_t>(MisExpectTolerance),
                   Ctx.getDiagnosticsMisExpectTolerance());
 }
 
 Instruction *getInstCondition(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());