[clang] [sanitizer] Parse weighted sanitizer args and -fno-sanitize-top-hot (PR #121619)

[Vitaly Buka via cfe-commits]

================
@@ -3615,9 +3616,12 @@ void CodeGenFunction::EmitCheck(
 
     if (!CGM.getCodeGenOpts().SanitizeMergeHandlers.has(Checked[i].second))
       NoMerge = true;
+
+    if (!CGM.getCodeGenOpts().NoSanitizeTopHot.has(Checked[i].second))
+      SanitizeGuardChecks = true;
   }
 
-  if (ClSanitizeGuardChecks) {
+  if (SanitizeGuardChecks) {
     llvm::Value *Allow =
         Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::allow_ubsan_check),
                            llvm::ConstantInt::get(CGM.Int8Ty, CheckHandler));
----------------
vitalybuka wrote:

It's maybe not important for the patch, but we will have  a problem here.

LLVM pass will need to lookup fraction by the argument,
but the argument is `CheckHandler` which is not the same as NoSanitizeTopHot.

but maybe we need to think a little bit now.

Assuming very few `Checked.size() > 1` also `Checked[i].second` is usually 1 bit.
Probably correct approach will be to apply llvm::Intrinsic::allow_ubsan_check on line 3606?
And use the bit with with highest sanitizer coverage as ID.

WDYT?



https://github.com/llvm/llvm-project/pull/121619