[LLVM][rtsan] Add LLVM nosanitize_realtime attribute (#105447)

Author: cjappl

llvm/docs/LangRef.rst

@@ -2189,6 +2189,10 @@ example:
 ``nosanitize_coverage``
     This attribute indicates that SanitizerCoverage instrumentation is disabled
     for this function.
+``nosanitize_realtime``
+    This attribute indicates that the Realtime Sanitizer instrumentation is
+    disabled for this function.
+    This attribute is incompatible with the ``sanitize_realtime`` attribute.
 ``null_pointer_is_valid``
    If ``null_pointer_is_valid`` is set, then the ``null`` address
    in address-space 0 is considered to be a valid address for memory loads and
@@ -2315,6 +2319,7 @@ example:
     This attribute indicates that RealtimeSanitizer checks
     (realtime safety analysis - no allocations, syscalls or exceptions) are enabled
     for this function.
+    This attribute is incompatible with the ``nosanitize_realtime`` attribute.
 ``speculative_load_hardening``
     This attribute indicates that
     `Speculative Load Hardening <https://llvm.org/docs/SpeculativeLoadHardening.html>`_

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -759,6 +759,7 @@ enum AttributeKindCodes {
   ATTR_KIND_INITIALIZES = 94,
   ATTR_KIND_HYBRID_PATCHABLE = 95,
   ATTR_KIND_SANITIZE_REALTIME = 96,
+  ATTR_KIND_NO_SANITIZE_REALTIME = 97,
 };
 
 enum ComdatSelectionKindCodes {

llvm/include/llvm/IR/Attributes.td

@@ -212,6 +212,9 @@ def NoSanitizeBounds : EnumAttr<"nosanitize_bounds", [FnAttr]>;
 /// No SanitizeCoverage instrumentation.
 def NoSanitizeCoverage : EnumAttr<"nosanitize_coverage", [FnAttr]>;
 
+/// No SanitizeRealtime instrumentation.
+def NoSanitizeRealtime : EnumAttr<"nosanitize_realtime", [FnAttr]>;
+
 /// Null pointer in address space zero is valid.
 def NullPointerIsValid : EnumAttr<"null_pointer_is_valid", [FnAttr]>;
 

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2093,6 +2093,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::NoSanitizeBounds;
   case bitc::ATTR_KIND_NO_SANITIZE_COVERAGE:
     return Attribute::NoSanitizeCoverage;
+  case bitc::ATTR_KIND_NO_SANITIZE_REALTIME:
+    return Attribute::NoSanitizeRealtime;
   case bitc::ATTR_KIND_NULL_POINTER_IS_VALID:
     return Attribute::NullPointerIsValid;
   case bitc::ATTR_KIND_OPTIMIZE_FOR_DEBUGGING:

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -795,6 +795,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_NO_SANITIZE_BOUNDS;
   case Attribute::NoSanitizeCoverage:
     return bitc::ATTR_KIND_NO_SANITIZE_COVERAGE;
+  case llvm::Attribute::NoSanitizeRealtime:
+    return bitc::ATTR_KIND_NO_SANITIZE_REALTIME;
   case Attribute::NullPointerIsValid:
     return bitc::ATTR_KIND_NULL_POINTER_IS_VALID;
   case Attribute::OptimizeForDebugging:

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::NoSanitizeRealtime)),
+        "Attributes "
+        "'sanitize_realtime and nosanitize_realtime' are incompatible!",
+        V);
+
   if (Attrs.hasFnAttr(Attribute::OptimizeForDebugging)) {
     Check(!Attrs.hasFnAttr(Attribute::OptimizeForSize),
           "Attributes 'optsize and optdebug' are incompatible!", V);

llvm/lib/Transforms/Utils/CodeExtractor.cpp

@@ -937,6 +937,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
       case Attribute::NoUnwind:
       case Attribute::NoSanitizeBounds:
       case Attribute::NoSanitizeCoverage:
+      case Attribute::NoSanitizeRealtime:
       case Attribute::NullPointerIsValid:
       case Attribute::OptimizeForDebugging:
       case Attribute::OptForFuzzing:

llvm/test/Bitcode/attributes.ll

@@ -511,6 +511,12 @@ define void @f92() sanitize_realtime
         ret void;
 }
 
+; CHECK: define void @f93() #54
+define void @f93() nosanitize_realtime
+{
+        ret void;
+}
+
 ; CHECK: define void @f87() [[FNRETTHUNKEXTERN:#[0-9]+]]
 define void @f87() fn_ret_thunk_extern { ret void }
 
@@ -606,6 +612,7 @@ define void @initializes(ptr initializes((-4, 0), (4, 8)) %a) {
 ; CHECK: attributes #51 = { uwtable(sync) }
 ; CHECK: attributes #52 = { nosanitize_bounds }
 ; CHECK: attributes #53 = { sanitize_realtime }
+; CHECK: attributes #54 = { nosanitize_realtime }
 ; CHECK: attributes [[FNRETTHUNKEXTERN]] = { fn_ret_thunk_extern }
 ; CHECK: attributes [[SKIPPROFILE]] = { skipprofile }
 ; CHECK: attributes [[OPTDEBUG]] = { optdebug }

llvm/test/Bitcode/compatibility.ll

@@ -1562,7 +1562,7 @@ exit:
   ; CHECK: select <2 x i1> <i1 true, i1 false>, <2 x i8> <i8 2, i8 3>, <2 x i8> <i8 3, i8 2>
 
   call void @f.nobuiltin() builtin
-  ; CHECK: call void @f.nobuiltin() #53
+  ; CHECK: call void @f.nobuiltin() #54
 
   call fastcc noalias ptr @f.noalias() noinline
   ; CHECK: call fastcc noalias ptr @f.noalias() #12
@@ -1992,6 +1992,9 @@ declare void @f.sanitize_numerical_stability() sanitize_numerical_stability
 declare void @f.sanitize_realtime() sanitize_realtime
 ; CHECK: declare void @f.sanitize_realtime() #52
 
+declare void @f.nosanitize_realtime() nosanitize_realtime
+; CHECK: declare void @f.nosanitize_realtime() #53
+
 ; CHECK: declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
 declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
 
@@ -2115,7 +2118,8 @@ define float @nofpclass_callsites(float %arg) {
 ; CHECK: attributes #50 = { allockind("alloc,uninitialized") }
 ; CHECK: attributes #51 = { sanitize_numerical_stability }
 ; CHECK: attributes #52 = { sanitize_realtime }
-; CHECK: attributes #53 = { builtin }
+; CHECK: attributes #53 = { nosanitize_realtime }
+; CHECK: attributes #54 = { builtin }
 
 ;; Metadata
 

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 nosanitize_realtime' are incompatible!
+; CHECK-NEXT: ptr @sanitize_nosanitize
+define void @sanitize_nosanitize() #0 {
+  ret void
+}
+
+attributes #0 = { sanitize_realtime nosanitize_realtime }