[clang] Add flag fallow-runtime-check-skip-hot-cutoff

clang/include/clang/Basic/CodeGenOptions.h

@@ -399,6 +399,8 @@ class CodeGenOptions : public CodeGenOptionsBase {
   /// with extra debug info.
   SanitizerSet SanitizeAnnotateDebugInfo;
 
+  std::optional<double> AllowRuntimeCheckSkipHotCutoff;
+
   /// List of backend command-line options for -fembed-bitcode.
   std::vector<uint8_t> CmdArgs;
 

clang/include/clang/Driver/Options.td

@@ -2668,6 +2668,16 @@ def fsanitize_skip_hot_cutoff_EQ
 
 } // end -f[no-]sanitize* flags
 
+def fallow_runtime_check_skip_hot_cutoff_EQ
+    : Joined<["-"], "fallow-runtime-check-skip-hot-cutoff=">,
+      Group<f_clang_Group>,
+      Visibility<[ClangOption, CC1Option]>,
+      HelpText<"Exclude __allow_runtime_check for the top hottest code "
+               "responsible for "
+               "the given fraction of PGO counters "
+               "(0.0 [default] = skip none; 1/.0 = skip all). "
+               "Argument format: <value>">;
+
 def funsafe_math_optimizations : Flag<["-"], "funsafe-math-optimizations">,
   Group<f_Group>, Visibility<[ClangOption, CC1Option]>,
   HelpText<"Allow unsafe floating-point math optimizations which may decrease precision">,

clang/lib/CodeGen/BackendUtil.cpp

@@ -805,17 +805,21 @@ static void addSanitizers(const Triple &TargetTriple,
   // SanitizeSkipHotCutoffs: doubles with range [0, 1]
   // Opts.cutoffs: unsigned ints with range [0, 1000000]
   auto ScaledCutoffs = CodeGenOpts.SanitizeSkipHotCutoffs.getAllScaled(1000000);
-
+  uint64_t AllowRuntimeCheckSkipHotCutoff =
+      CodeGenOpts.AllowRuntimeCheckSkipHotCutoff.value_or(0.0) * 1000000;
   // TODO: remove IsRequested()
-  if (LowerAllowCheckPass::IsRequested() || ScaledCutoffs.has_value()) {
+  if (LowerAllowCheckPass::IsRequested() || ScaledCutoffs.has_value() ||
+      CodeGenOpts.AllowRuntimeCheckSkipHotCutoff.has_value()) {
     // We want to call it after inline, which is about OptimizerEarlyEPCallback.
     PB.registerOptimizerEarlyEPCallback(
-        [ScaledCutoffs](ModulePassManager &MPM, OptimizationLevel Level,
-                        ThinOrFullLTOPhase Phase) {
+        [ScaledCutoffs, AllowRuntimeCheckSkipHotCutoff](
+            ModulePassManager &MPM, OptimizationLevel Level,
+            ThinOrFullLTOPhase Phase) {
           LowerAllowCheckPass::Options Opts;
           // TODO: after removing IsRequested(), make this unconditional
           if (ScaledCutoffs.has_value())
             Opts.cutoffs = ScaledCutoffs.value();
+          Opts.runtime_check = AllowRuntimeCheckSkipHotCutoff;
           MPM.addPass(
               createModuleToFunctionPassAdaptor(LowerAllowCheckPass(Opts)));
         });

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6028,7 +6028,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // -fasynchronous-unwind-tables and -fnon-call-exceptions interact in more
   // complicated ways.
   auto SanitizeArgs = TC.getSanitizerArgs(Args);
-
+  Args.AddLastArg(CmdArgs,
+                  options::OPT_fallow_runtime_check_skip_hot_cutoff_EQ);
   bool IsAsyncUnwindTablesDefault =
       TC.getDefaultUnwindTableLevel(Args) == ToolChain::UnwindTableLevel::Asynchronous;
   bool IsSyncUnwindTablesDefault =

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1820,6 +1820,11 @@ void CompilerInvocationBase::GenerateCodeGenArgs(const CodeGenOptions &Opts,
   for (std::string Sanitizer : Values)
     GenerateArg(Consumer, OPT_fsanitize_skip_hot_cutoff_EQ, Sanitizer);
 
+  if (Opts.AllowRuntimeCheckSkipHotCutoff) {
+    GenerateArg(Consumer, OPT_fallow_runtime_check_skip_hot_cutoff_EQ,
+                std::to_string(*Opts.AllowRuntimeCheckSkipHotCutoff));
+  }
+
   for (StringRef Sanitizer :
        serializeSanitizerKinds(Opts.SanitizeAnnotateDebugInfo))
     GenerateArg(Consumer, OPT_fsanitize_annotate_debug_info_EQ, Sanitizer);
@@ -2322,6 +2327,18 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
       Args.getAllArgValues(OPT_fsanitize_annotate_debug_info_EQ), Diags,
       Opts.SanitizeAnnotateDebugInfo);
 
+  if (StringRef V =
+          Args.getLastArgValue(OPT_fallow_runtime_check_skip_hot_cutoff_EQ);
+      !V.empty()) {
+    double A;
+    if (V.getAsDouble(A) || A < 0.0 || A > 1.0) {
+      Diags.Report(diag::err_drv_invalid_value)
+          << "-fallow-runtime-check-skip-hot-cutoff=" << V;
+    } else {
+      Opts.AllowRuntimeCheckSkipHotCutoff = A;
+    }
+  }
+
   Opts.EmitVersionIdentMetadata = Args.hasFlag(OPT_Qy, OPT_Qn, true);
 
   if (!LangOpts->CUDAIsDevice)

clang/test/CodeGen/fallow-runtime-check-skip-hot-cutoff.c

@@ -0,0 +1,15 @@
+// RUN: %clang -fallow-runtime-check-skip-hot-cutoff=1.0 -S -emit-llvm %s -o - -O2 | FileCheck --check-prefix=ONE %s
+// RUN: %clang -fallow-runtime-check-skip-hot-cutoff=0.0 -S -emit-llvm %s -o - -O2 | FileCheck --check-prefix=ZERO %s
+// RUN: not %clang -fallow-runtime-check-skip-hot-cutoff=6.0 -S -emit-llvm %s -o - -O2 2>&1 | FileCheck --check-prefix=SIX %s
+// RUN: not %clang -fallow-runtime-check-skip-hot-cutoff=-1.0 -S -emit-llvm %s -o - -O2 2>&1 | FileCheck --check-prefix=MINUSONE %s
+// RUN: not %clang -fallow-runtime-check-skip-hot-cutoff=string -S -emit-llvm %s -o - -O2 2>&1 | FileCheck --check-prefix=STRING %s
+
+// ONE: ret i32 0
+// ZERO: ret i32 1
+// SIX: invalid value '6.0' in '-fallow-runtime-check-skip-hot-cutoff='
+// MINUSONE: invalid value '-1.0' in '-fallow-runtime-check-skip-hot-cutoff='
+// STRING: invalid value 'string' in '-fallow-runtime-check-skip-hot-cutoff='
+
+int main(int argc, char** argv) {
+    return __builtin_allow_runtime_check("foo");
+}

clang/test/Driver/fallow-runtime-check-skip-hot-cutoff.c

@@ -0,0 +1,6 @@
+// RUN: %clang -### -fallow-runtime-check-skip-hot-cutoff=1.0 %s 2>&1 | FileCheck %s
+// CHECK: -fallow-runtime-check-skip-hot-cutoff=1.0
+
+int main(int argc, char** argv) {
+    return __builtin_allow_runtime_check("foo");
+}

llvm/include/llvm/Transforms/Instrumentation/LowerAllowCheckPass.h

@@ -27,6 +27,7 @@ class LowerAllowCheckPass : public PassInfoMixin<LowerAllowCheckPass> {
 public:
   struct Options {
     std::vector<unsigned int> cutoffs;
+    uint64_t runtime_check;
   };
 
   explicit LowerAllowCheckPass(LowerAllowCheckPass::Options Opts)

llvm/lib/Passes/PassBuilder.cpp

@@ -932,6 +932,19 @@ parseLowerAllowCheckPassOptions(StringRef Params) {
 
         Result.cutoffs[index] = cutoff;
       }
+    } else if (ParamName.starts_with("runtime_check")) {
+      StringRef ValueString;
+      std::tie(std::ignore, ValueString) = ParamName.split("=");
+      int runtime_check;
+      if (ValueString.getAsInteger(0, runtime_check)) {
+        return make_error<StringError>(
+            formatv("invalid LowerAllowCheck pass runtime_check parameter '{}' "
+                    "({})",
+                    ValueString, Params)
+                .str(),
+            inconvertibleErrorCode());
+      }
+      Result.runtime_check = runtime_check;
     } else {
       return make_error<StringError>(
           formatv("invalid LowerAllowCheck pass parameter '{}'", ParamName)

llvm/lib/Transforms/Instrumentation/LowerAllowCheckPass.cpp

@@ -74,7 +74,7 @@ static void emitRemark(IntrinsicInst *II, OptimizationRemarkEmitter &ORE,
 static bool removeUbsanTraps(Function &F, const BlockFrequencyInfo &BFI,
                              const ProfileSummaryInfo *PSI,
                              OptimizationRemarkEmitter &ORE,
-                             const std::vector<unsigned int> &cutoffs) {
+                             const LowerAllowCheckPass::Options &Opts) {
   SmallVector<std::pair<IntrinsicInst *, bool>, 16> ReplaceWithValue;
   std::unique_ptr<RandomNumberGenerator> Rng;
 
@@ -89,8 +89,10 @@ static bool removeUbsanTraps(Function &F, const BlockFrequencyInfo &BFI,
       return HotPercentileCutoff;
     else if (II->getIntrinsicID() == Intrinsic::allow_ubsan_check) {
       auto *Kind = cast<ConstantInt>(II->getArgOperand(0));
-      if (Kind->getZExtValue() < cutoffs.size())
-        return cutoffs[Kind->getZExtValue()];
+      if (Kind->getZExtValue() < Opts.cutoffs.size())
+        return Opts.cutoffs[Kind->getZExtValue()];
+    } else if (II->getIntrinsicID() == Intrinsic::allow_runtime_check) {
+      return Opts.runtime_check;
     }
 
     return 0;
@@ -157,7 +159,7 @@ PreservedAnalyses LowerAllowCheckPass::run(Function &F,
   OptimizationRemarkEmitter &ORE =
       AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
 
-  return removeUbsanTraps(F, BFI, PSI, ORE, Opts.cutoffs)
+  return removeUbsanTraps(F, BFI, PSI, ORE, Opts)
              // We do not change the CFG, we only replace the intrinsics with
              // true or false.
              ? PreservedAnalyses::none().preserveSet<CFGAnalyses>()
@@ -182,14 +184,22 @@ void LowerAllowCheckPass::printPipeline(
   // correctness.
   // TODO: print shorter output by combining adjacent runs, etc.
   int i = 0;
+  bool printed = false;
   for (unsigned int cutoff : Opts.cutoffs) {
     if (cutoff > 0) {
       if (i > 0)
         OS << ";";
       OS << "cutoffs[" << i << "]=" << cutoff;
+      printed = true;
     }
 
     i++;
   }
+  if (Opts.runtime_check) {
+    if (printed)
+      OS << ";";
+    OS << "runtime_check=" << Opts.runtime_check;
+  }
+
   OS << '>';
 }

llvm/test/Transforms/lower-builtin-allow-check-remarks.ll

@@ -4,12 +4,21 @@
 ; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check)' -lower-allow-check-percentile-cutoff-hot=0 -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s
 ; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check)' -lower-allow-check-percentile-cutoff-hot=1000000 -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=REMOVE
 
+; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check<cutoffs[7]=0;runtime_check=1000000>)' -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=MIXED
+; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check<cutoffs[7]=1000000;runtime_check=0>)' -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=MIXED2
+
 ; CHECK: remark: <unknown>:0:0: Allowed check: Kind=test_check F=test_runtime BB=entry1
 ; CHECK: remark: <unknown>:0:0: Allowed check: Kind=7 F=test_ubsan BB=entry2
 
 ; REMOVE: remark: <unknown>:0:0: Removed check: Kind=test_check F=test_runtime BB=entry1
 ; REMOVE: remark: <unknown>:0:0: Removed check: Kind=7 F=test_ubsan BB=entry2
 
+; MIXED: remark: <unknown>:0:0: Removed check: Kind=test_check F=test_runtime BB=entry1
+; MIXED: remark: <unknown>:0:0: Allowed check: Kind=7 F=test_ubsan BB=entry2
+
+; MIXED2: remark: <unknown>:0:0: Allowed check: Kind=test_check F=test_runtime BB=entry1
+; MIXED2: remark: <unknown>:0:0: Removed check: Kind=7 F=test_ubsan BB=entry2
+
 target triple = "x86_64-pc-linux-gnu"
 
 define i1 @test_runtime() local_unnamed_addr {