gulfem updated this revision to Diff 302369.
gulfem added a comment.

Update the attribute documentation


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D90275/new/

https://reviews.llvm.org/D90275

Files:
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/lib/CodeGen/CGCall.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGen/attr-leaf.c
  clang/test/Misc/pragma-attribute-supported-attributes-list.test
  clang/test/Sema/attr-leaf.c
  llvm/include/llvm/Bitcode/LLVMBitCodes.h
  llvm/include/llvm/IR/Attributes.td
  llvm/lib/AsmParser/LLLexer.cpp
  llvm/lib/AsmParser/LLParser.cpp
  llvm/lib/AsmParser/LLToken.h
  llvm/lib/Bitcode/Reader/BitcodeReader.cpp
  llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
  llvm/lib/IR/Attributes.cpp
  llvm/lib/IR/Verifier.cpp
  llvm/lib/Transforms/Utils/CodeExtractor.cpp
  llvm/test/Bitcode/attributes.ll

Index: llvm/test/Bitcode/attributes.ll
===================================================================
--- llvm/test/Bitcode/attributes.ll
+++ llvm/test/Bitcode/attributes.ll
@@ -410,6 +410,12 @@
   ret void
 }
 
+; CHECK; define void @f70() #43
+define void @f70() nocallback
+{
+  ret void
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -453,4 +459,5 @@
 ; CHECK: attributes #40 = { null_pointer_is_valid }
 ; CHECK: attributes #41 = { mustprogress }
 ; CHECK: attributes #42 = { nossp }
+; CHECK: attributes #43 = { nocallback }
 ; CHECK: attributes #[[NOBUILTIN]] = { nobuiltin }
Index: llvm/lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -906,6 +906,7 @@
       case Attribute::NoRecurse:
       case Attribute::InlineHint:
       case Attribute::MinSize:
+      case Attribute::NoCallback:
       case Attribute::NoDuplicate:
       case Attribute::NoFree:
       case Attribute::NoImplicitFloat:
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -1572,6 +1572,7 @@
   case Attribute::NoReturn:
   case Attribute::NoSync:
   case Attribute::WillReturn:
+  case Attribute::NoCallback:
   case Attribute::NoCfCheck:
   case Attribute::NoUnwind:
   case Attribute::NoInline:
Index: llvm/lib/IR/Attributes.cpp
===================================================================
--- llvm/lib/IR/Attributes.cpp
+++ llvm/lib/IR/Attributes.cpp
@@ -371,6 +371,8 @@
     return "noalias";
   if (hasAttribute(Attribute::NoBuiltin))
     return "nobuiltin";
+  if (hasAttribute(Attribute::NoCallback))
+    return "nocallback";
   if (hasAttribute(Attribute::NoCapture))
     return "nocapture";
   if (hasAttribute(Attribute::NoDuplicate))
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -643,6 +643,8 @@
     return bitc::ATTR_KIND_NO_ALIAS;
   case Attribute::NoBuiltin:
     return bitc::ATTR_KIND_NO_BUILTIN;
+  case Attribute::NoCallback:
+    return bitc::ATTR_KIND_NO_CALLBACK;
   case Attribute::NoCapture:
     return bitc::ATTR_KIND_NO_CAPTURE;
   case Attribute::NoDuplicate:
Index: llvm/lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1433,6 +1433,8 @@
     return Attribute::NoAlias;
   case bitc::ATTR_KIND_NO_BUILTIN:
     return Attribute::NoBuiltin;
+  case bitc::ATTR_KIND_NO_CALLBACK:
+    return Attribute::NoCallback;
   case bitc::ATTR_KIND_NO_CAPTURE:
     return Attribute::NoCapture;
   case bitc::ATTR_KIND_NO_DUPLICATE:
Index: llvm/lib/AsmParser/LLToken.h
===================================================================
--- llvm/lib/AsmParser/LLToken.h
+++ llvm/lib/AsmParser/LLToken.h
@@ -198,6 +198,7 @@
   kw_noalias,
   kw_noundef,
   kw_nobuiltin,
+  kw_nocallback,
   kw_nocapture,
   kw_noduplicate,
   kw_nofree,
Index: llvm/lib/AsmParser/LLParser.cpp
===================================================================
--- llvm/lib/AsmParser/LLParser.cpp
+++ llvm/lib/AsmParser/LLParser.cpp
@@ -1314,6 +1314,9 @@
       break;
     case lltok::kw_naked: B.addAttribute(Attribute::Naked); break;
     case lltok::kw_nobuiltin: B.addAttribute(Attribute::NoBuiltin); break;
+    case lltok::kw_nocallback:
+      B.addAttribute(Attribute::NoCallback);
+      break;
     case lltok::kw_noduplicate: B.addAttribute(Attribute::NoDuplicate); break;
     case lltok::kw_nofree: B.addAttribute(Attribute::NoFree); break;
     case lltok::kw_noimplicitfloat:
Index: llvm/lib/AsmParser/LLLexer.cpp
===================================================================
--- llvm/lib/AsmParser/LLLexer.cpp
+++ llvm/lib/AsmParser/LLLexer.cpp
@@ -651,6 +651,7 @@
   KEYWORD(nest);
   KEYWORD(noalias);
   KEYWORD(nobuiltin);
+  KEYWORD(nocallback);
   KEYWORD(nocapture);
   KEYWORD(noduplicate);
   KEYWORD(nofree);
Index: llvm/include/llvm/IR/Attributes.td
===================================================================
--- llvm/include/llvm/IR/Attributes.td
+++ llvm/include/llvm/IR/Attributes.td
@@ -91,6 +91,9 @@
 /// Callee isn't recognized as a builtin.
 def NoBuiltin : EnumAttr<"nobuiltin">;
 
+/// Function cannot enter into caller's translation unit.
+def NoCallback : EnumAttr<"nocallback">;
+
 /// Function creates no aliases of pointer.
 def NoCapture : EnumAttr<"nocapture">;
 
Index: llvm/include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -652,6 +652,7 @@
   ATTR_KIND_BYREF = 69,
   ATTR_KIND_MUSTPROGRESS = 70,
   ATTR_KIND_NO_STACK_PROTECT = 71,
+  ATTR_KIND_NO_CALLBACK = 72,
 };
 
 enum ComdatSelectionKindCodes {
Index: clang/test/Sema/attr-leaf.c
===================================================================
--- /dev/null
+++ clang/test/Sema/attr-leaf.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+// expected-no-diagnostics
+
+void f(void) __attribute__((leaf));
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -68,6 +68,7 @@
 // CHECK-NEXT: InitPriority (SubjectMatchRule_variable)
 // CHECK-NEXT: InternalLinkage (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record)
 // CHECK-NEXT: LTOVisibilityPublic (SubjectMatchRule_record)
+// CHECK-NEXT: Leaf (SubjectMatchRule_function)
 // CHECK-NEXT: LoaderUninitialized (SubjectMatchRule_variable_is_global)
 // CHECK-NEXT: Lockable (SubjectMatchRule_record)
 // CHECK-NEXT: MIGServerRoutine (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_block)
Index: clang/test/CodeGen/attr-leaf.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/attr-leaf.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -emit-llvm -Oz -o - %s | FileCheck %s
+
+// CHECK: define void @f() local_unnamed_addr [[ATTRS:#[0-9]+]] {
+void f() __attribute__((leaf));
+
+void f()
+{
+}
+
+// CHECK: attributes [[ATTRS]] = { {{.*}}nocallback{{.*}} }
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -7590,6 +7590,9 @@
   case ParsedAttr::AT_AnyX86NoCfCheck:
     handleNoCfCheckAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_Leaf:
+    handleSimpleAttribute<LeafAttr>(S, D, AL);
+    break;
   case ParsedAttr::AT_NoThrow:
     if (!AL.isUsedAsTypeAttr())
       handleSimpleAttribute<NoThrowAttr>(S, D, AL);
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1988,6 +1988,8 @@
       FuncAttrs.addAttribute("no_caller_saved_registers");
     if (TargetDecl->hasAttr<AnyX86NoCfCheckAttr>())
       FuncAttrs.addAttribute(llvm::Attribute::NoCfCheck);
+    if (TargetDecl->hasAttr<LeafAttr>())
+      FuncAttrs.addAttribute(llvm::Attribute::NoCallback);
 
     HasOptnone = TargetDecl->hasAttr<OptimizeNoneAttr>();
     if (auto *AllocSize = TargetDecl->getAttr<AllocSizeAttr>()) {
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -3901,6 +3901,22 @@
   }];
 }
 
+def LeafDocs : Documentation {
+  let Category = DocCatVariable;
+  let Content = [{
+
+The ``leaf`` attribute is used as a compiler hint to improve dataflow analysis
+in library functions. Functions marked with the ``leaf`` attribute are not allowed
+to jump back into the caller's translation unit, whether through invoking a
+callback function, a direct external function call, use of ``longjmp``, or other means.
+Therefore, they cannot use or modify any data that does not escape the caller function's
+compilation unit.
+
+For more information see
+`gcc documentation <https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>`
+}];
+}
+
 def NoStackProtectorDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1430,6 +1430,13 @@
   let Documentation = [LayoutVersionDocs];
 }
 
+def Leaf : InheritableAttr {
+  let Spellings = [GCC<"leaf">];
+  let Subjects = SubjectList<[Function]>;
+  let Documentation = [LeafDocs];
+  let SimpleHandler = 1;
+}
+
 def LifetimeBound : DeclOrTypeAttr {
   let Spellings = [Clang<"lifetimebound", 0>];
   let Subjects = SubjectList<[ParmVar, ImplicitObjectParameter], ErrorDiag>;
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