[sanitizer] Parse weighted sanitizer args and -fsanitize-skip-hot-cutoff (#121619)

This adds a function to parse weighted sanitizer flags (e.g.,
`-fsanitize-blah=undefined=0.5,null=0.3`) and adds the plumbing to apply
that to a new flag, `-fsanitize-skip-hot-cutoff`.

`-fsanitize-skip-hot-cutoff` currently has no effect; future work will
use it to generalize ubsan-guard-checks (originally introduced in
5f9ed2ff8364ff3e4fac410472f421299dafa793).

---------

Co-authored-by: Vitaly Buka <vitalybuka@google.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index d711df0..39bed84 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1453,6 +1453,18 @@ static SmallVector<StringRef, 4> serializeSanitizerKinds(SanitizerSet S) {
   return Values;
 }
 
+static SanitizerMaskCutoffs
+parseSanitizerWeightedKinds(StringRef FlagName,
+                            const std::vector<std::string> &Sanitizers,
+                            DiagnosticsEngine &Diags) {
+  SanitizerMaskCutoffs Cutoffs;
+  for (const auto &Sanitizer : Sanitizers) {
+    if (!parseSanitizerWeightedValue(Sanitizer, /*AllowGroups=*/false, Cutoffs))
+      Diags.Report(diag::err_drv_invalid_value) << FlagName << Sanitizer;
+  }
+  return Cutoffs;
+}
+
 static void parseXRayInstrumentationBundle(StringRef FlagName, StringRef Bundle,
                                            ArgList &Args, DiagnosticsEngine &D,
                                            XRayInstrSet &S) {
@@ -1813,6 +1825,11 @@ void CompilerInvocationBase::GenerateCodeGenArgs(const CodeGenOptions &Opts,
        serializeSanitizerKinds(Opts.SanitizeMergeHandlers))
     GenerateArg(Consumer, OPT_fsanitize_merge_handlers_EQ, Sanitizer);
 
+  SmallVector<std::string, 4> Values;
+  serializeSanitizerMaskCutoffs(Opts.SanitizeSkipHotCutoffs, Values);
+  for (std::string Sanitizer : Values)
+    GenerateArg(Consumer, OPT_fsanitize_skip_hot_cutoff_EQ, Sanitizer);
+
   if (!Opts.EmitVersionIdentMetadata)
     GenerateArg(Consumer, OPT_Qn);
 
@@ -2293,6 +2310,11 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
                       Args.getAllArgValues(OPT_fsanitize_merge_handlers_EQ),
                       Diags, Opts.SanitizeMergeHandlers);
 
+  // Parse -fsanitize-skip-hot-cutoff= arguments.
+  Opts.SanitizeSkipHotCutoffs = parseSanitizerWeightedKinds(
+      "-fsanitize-skip-hot-cutoff=",
+      Args.getAllArgValues(OPT_fsanitize_skip_hot_cutoff_EQ), Diags);
+
   Opts.EmitVersionIdentMetadata = Args.hasFlag(OPT_Qy, OPT_Qn, true);
 
   if (!LangOpts->CUDAIsDevice)