Add sanitize_realtime_unsafe attribute verification

Author: davidtrevelyan

llvm/include/llvm/IR/Attributes.td

@@ -300,8 +300,8 @@ def SanitizeNumericalStability : EnumAttr<"sanitize_numerical_stability", [FnAtt
 /// RealtimeSanitizer is on.
 def SanitizeRealtime : EnumAttr<"sanitize_realtime", [FnAttr]>;
 
-/// RealtimeSanitizer should error if an realtime_unsafe function is called
-/// during a sanitize_realtime function.
+/// RealtimeSanitizer should error if a real-time unsafe function is invoked
+/// during a real-time sanitized function (see `sanitize_realtime`).
 def SanitizeRealtimeUnsafe : EnumAttr<"sanitize_realtime_unsafe", [FnAttr]>;
 
 /// Speculative Load Hardening is enabled.

llvm/lib/IR/Verifier.cpp

@@ -2223,6 +2223,12 @@ void Verifier::verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,
           "Attributes 'optdebug and optnone' are incompatible!", V);
   }
 
+  Check(!(Attrs.hasFnAttr(Attribute::SanitizeRealtime) &&
+          Attrs.hasFnAttr(Attribute::SanitizeRealtimeUnsafe)),
+        "Attributes "
+        "'sanitize_realtime and sanitize_realtime_unsafe' are incompatible!",
+        V);
+
   if (Attrs.hasFnAttr(Attribute::OptimizeForDebugging)) {
     Check(!Attrs.hasFnAttr(Attribute::OptimizeForSize),
           "Attributes 'optsize and optdebug' are incompatible!", V);

llvm/test/Verifier/rtsan-attrs.ll

@@ -0,0 +1,9 @@
+; RUN: not llvm-as -disable-output %s 2>&1 | FileCheck %s
+
+; CHECK: Attributes 'sanitize_realtime and sanitize_realtime_unsafe' are incompatible!
+; CHECK-NEXT: ptr @sanitize_unsafe
+define void @sanitize_unsafe() #0 {
+  ret void
+}
+
+attributes #0 = { sanitize_realtime sanitize_realtime_unsafe }