[LLVM][rtsan] Add LLVM nonblocking attribute for realtime sanitizer

Author: cjappl

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -758,6 +758,7 @@ enum AttributeKindCodes {
   ATTR_KIND_SANITIZE_NUMERICAL_STABILITY = 93,
   ATTR_KIND_INITIALIZES = 94,
   ATTR_KIND_HYBRID_PATCHABLE = 95,
+  ATTR_KIND_NONBLOCKING = 96,
 };
 
 enum ComdatSelectionKindCodes {

llvm/include/llvm/IR/Attributes.td

@@ -239,6 +239,9 @@ def ReadNone : EnumAttr<"readnone", [ParamAttr]>;
 /// Function only reads from memory.
 def ReadOnly : EnumAttr<"readonly", [ParamAttr]>;
 
+/// Function is marked to be non-blocking
+def NonBlocking : EnumAttr<"nonblocking", [FnAttr]>;
+
 /// Return value is always equal to this argument.
 def Returned : EnumAttr<"returned", [ParamAttr]>;
 

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2109,6 +2109,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::ReadOnly;
   case bitc::ATTR_KIND_RETURNED:
     return Attribute::Returned;
+  case bitc::ATTR_KIND_NONBLOCKING:
+    return Attribute::NonBlocking;
   case bitc::ATTR_KIND_RETURNS_TWICE:
     return Attribute::ReturnsTwice;
   case bitc::ATTR_KIND_S_EXT:

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -805,6 +805,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
   case Attribute::OptimizeNone:
     return bitc::ATTR_KIND_OPTIMIZE_NONE;
+  case Attribute::NonBlocking:
+    return bitc::ATTR_KIND_NONBLOCKING;
   case Attribute::ReadNone:
     return bitc::ATTR_KIND_READ_NONE;
   case Attribute::ReadOnly:

llvm/lib/Transforms/Utils/CodeExtractor.cpp

@@ -946,6 +946,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
       case Attribute::NoUnwind:
       case Attribute::NoSanitizeBounds:
       case Attribute::NoSanitizeCoverage:
+      case Attribute::NonBlocking:
       case Attribute::NullPointerIsValid:
       case Attribute::OptimizeForDebugging:
       case Attribute::OptForFuzzing:

llvm/test/Bitcode/attributes.ll

@@ -505,6 +505,12 @@ define void @f86() nosanitize_bounds
         ret void;
 }
 
+; CHECK: define void @f92() #53
+define void @f92() nonblocking
+{
+        ret void;
+}
+
 ; CHECK: define void @f87() [[FNRETTHUNKEXTERN:#[0-9]+]]
 define void @f87() fn_ret_thunk_extern { ret void }
 
@@ -599,6 +605,7 @@ define void @initializes(ptr initializes((-4, 0), (4, 8)) %a) {
 ; CHECK: attributes #50 = { disable_sanitizer_instrumentation }
 ; CHECK: attributes #51 = { uwtable(sync) }
 ; CHECK: attributes #52 = { nosanitize_bounds }
+; CHECK: attributes #53 = { nonblocking }
 ; CHECK: attributes [[FNRETTHUNKEXTERN]] = { fn_ret_thunk_extern }
 ; CHECK: attributes [[SKIPPROFILE]] = { skipprofile }
 ; CHECK: attributes [[OPTDEBUG]] = { optdebug }

llvm/test/Bitcode/compatibility.ll

@@ -1564,7 +1564,7 @@ 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() #52
+  ; CHECK: call void @f.nobuiltin() #53
 
   call fastcc noalias ptr @f.noalias() noinline
   ; CHECK: call fastcc noalias ptr @f.noalias() #12
@@ -1991,6 +1991,9 @@ declare void @f.allockind() allockind("alloc,uninitialized")
 declare void @f.sanitize_numerical_stability() sanitize_numerical_stability
 ; CHECK: declare void @f.sanitize_numerical_stability() #51
 
+declare void @f.nonblocking() nonblocking
+; CHECK: declare void @f.nonblocking() #52
+
 ; CHECK: declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
 declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
 
@@ -2113,7 +2116,8 @@ define float @nofpclass_callsites(float %arg) {
 ; CHECK: attributes #49 = { nosanitize_bounds }
 ; CHECK: attributes #50 = { allockind("alloc,uninitialized") }
 ; CHECK: attributes #51 = { sanitize_numerical_stability }
-; CHECK: attributes #52 = { builtin }
+; CHECK: attributes #52 = { nonblocking }
+; CHECK: attributes #53 = { builtin }
 
 ;; Metadata