19 files changed, 49 insertions, 14 deletions

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 507c3bfd334..d2bba5c8a74 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1277,6 +1277,10 @@ example:
     This function attribute indicates that the function never returns
     normally. This produces undefined behavior at runtime if the
     function ever does dynamically return.
+``norecurse``
+    This function attribute indicates that the function does not call itself
+    either directly or indirectly down any possible call path. This produces
+    undefined behavior at runtime if the function ever does recurse.
 ``nounwind``
     This function attribute indicates that the function never raises an
     exception. If the function does raise an exception, its runtime
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
index 08d88a20454..b79c2785a61 100644
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -466,7 +466,8 @@ enum { BITCODE_CURRENT_EPOCH = 0 };
     ATTR_KIND_SAFESTACK = 44,
     ATTR_KIND_ARGMEMONLY = 45,
     ATTR_KIND_SWIFT_SELF = 46,
-    ATTR_KIND_SWIFT_ERROR = 47
+    ATTR_KIND_SWIFT_ERROR = 47,
+    ATTR_KIND_NO_RECURSE = 48
   };
 
   enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.h b/llvm/include/llvm/IR/Attributes.h
index 15f48fa38d9..b3984330b17 100644
--- a/llvm/include/llvm/IR/Attributes.h
+++ b/llvm/include/llvm/IR/Attributes.h
@@ -86,6 +86,7 @@ public:
     NoDuplicate,           ///< Call cannot be duplicated
     NoImplicitFloat,       ///< Disable implicit floating point insts
     NoInline,              ///< inline=never
+    NoRecurse,             ///< The function does not recurse
     NonLazyBind,           ///< Function is called early and/or
                            ///< often, so lazy binding isn't worthwhile
     NonNull,               ///< Pointer is known to be not null
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index b8e22af4bfe..71822a462da 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -329,6 +329,15 @@ public:
     addFnAttr(Attribute::Convergent);
   }
 
+  /// Determine if the function is known not to recurse, directly or
+  /// indirectly.
+  bool doesNotRecurse() const {
+    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
+                                      Attribute::NoRecurse);
+  }
+  void setDoesNotRecurse() {
+    addFnAttr(Attribute::NoRecurse);
+  }  
 
   /// @brief True if the ABI mandates (or the user requested) that this
   /// function be in a unwind table.
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index 2eb5f0bf45d..82d6eb7788c 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -616,6 +616,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   KEYWORD(noduplicate);
   KEYWORD(noimplicitfloat);
   KEYWORD(noinline);
+  KEYWORD(norecurse);
   KEYWORD(nonlazybind);
   KEYWORD(nonnull);
   KEYWORD(noredzone);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 1c219ad6cd8..7feb99d555c 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -998,6 +998,7 @@ bool LLParser::ParseFnAttributeValuePairs(AttrBuilder &B,
     case lltok::kw_nonlazybind: B.addAttribute(Attribute::NonLazyBind); break;
     case lltok::kw_noredzone: B.addAttribute(Attribute::NoRedZone); break;
     case lltok::kw_noreturn: B.addAttribute(Attribute::NoReturn); break;
+    case lltok::kw_norecurse: B.addAttribute(Attribute::NoRecurse); break;
     case lltok::kw_nounwind: B.addAttribute(Attribute::NoUnwind); break;
     case lltok::kw_optnone: B.addAttribute(Attribute::OptimizeNone); break;
     case lltok::kw_optsize: B.addAttribute(Attribute::OptimizeForSize); break;
diff --git a/llvm/lib/AsmParser/LLToken.h b/llvm/lib/AsmParser/LLToken.h
index 06b5f9b0800..ecd6481e6fa 100644
--- a/llvm/lib/AsmParser/LLToken.h
+++ b/llvm/lib/AsmParser/LLToken.h
@@ -123,6 +123,7 @@ namespace lltok {
     kw_noduplicate,
     kw_noimplicitfloat,
     kw_noinline,
+    kw_norecurse,
     kw_nonlazybind,
     kw_nonnull,
     kw_noredzone,
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 7c1b208c626..bc846192fcf 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1305,6 +1305,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::NoImplicitFloat;
   case bitc::ATTR_KIND_NO_INLINE:
     return Attribute::NoInline;
+  case bitc::ATTR_KIND_NO_RECURSE:
+    return Attribute::NoRecurse;
   case bitc::ATTR_KIND_NON_LAZY_BIND:
     return Attribute::NonLazyBind;
   case bitc::ATTR_KIND_NON_NULL:
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index c73b099e27f..941e54765f5 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -202,6 +202,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
   case Attribute::NoInline:
     return bitc::ATTR_KIND_NO_INLINE;
+  case Attribute::NoRecurse:
+    return bitc::ATTR_KIND_NO_RECURSE;
   case Attribute::NonLazyBind:
     return bitc::ATTR_KIND_NON_LAZY_BIND;
   case Attribute::NonNull:
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 2586cb54c3e..bdefe5917fe 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -232,6 +232,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
     return "noredzone";
   if (hasAttribute(Attribute::NoReturn))
     return "noreturn";
+  if (hasAttribute(Attribute::NoRecurse))
+    return "norecurse";
   if (hasAttribute(Attribute::NoUnwind))
     return "nounwind";
   if (hasAttribute(Attribute::OptimizeNone))
@@ -442,6 +444,7 @@ uint64_t AttributeImpl::getAttrMask(Attribute::AttrKind Val) {
   case Attribute::JumpTable:       return 1ULL << 45;
   case Attribute::Convergent:      return 1ULL << 46;
   case Attribute::SafeStack:       return 1ULL << 47;
+  case Attribute::NoRecurse:       return 1ULL << 48;
   case Attribute::Dereferenceable:
     llvm_unreachable("dereferenceable attribute not supported in raw format");
     break;
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 813f9ca6744..0fce50e8440 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -1233,7 +1233,8 @@ void Verifier::VerifyAttributeTypes(AttributeSet Attrs, unsigned Idx,
         I->getKindAsEnum() == Attribute::OptimizeNone ||
         I->getKindAsEnum() == Attribute::JumpTable ||
         I->getKindAsEnum() == Attribute::Convergent ||
-        I->getKindAsEnum() == Attribute::ArgMemOnly) {
+        I->getKindAsEnum() == Attribute::ArgMemOnly ||
+        I->getKindAsEnum() == Attribute::NoRecurse) {
       if (!isFunction) {
         CheckFailed("Attribute '" + I->getAsString() +
                     "' only applies to functions!", V);
diff --git a/llvm/test/Bindings/llvm-c/Inputs/invalid.ll.bc b/llvm/test/Bindings/llvm-c/Inputs/invalid.ll.bc
index a85c3644b3a..8f7474b9e46 100644
--- a/llvm/test/Bindings/llvm-c/Inputs/invalid.ll.bc
+++ b/llvm/test/Bindings/llvm-c/Inputs/invalid.ll.bc
diff --git a/llvm/test/Bindings/llvm-c/invalid-bitcode.test b/llvm/test/Bindings/llvm-c/invalid-bitcode.test
index 6318a9bf13d..9219f36eb24 100644
--- a/llvm/test/Bindings/llvm-c/invalid-bitcode.test
+++ b/llvm/test/Bindings/llvm-c/invalid-bitcode.test
@@ -1,3 +1,3 @@
 ; RUN: not llvm-c-test --module-dump < %S/Inputs/invalid.ll.bc 2>&1 | FileCheck %s
 
-CHECK: Error parsing bitcode: Unknown attribute kind (48)
+CHECK: Error parsing bitcode: Unknown attribute kind (50)
diff --git a/llvm/test/Bitcode/attributes.ll b/llvm/test/Bitcode/attributes.ll
index 0cf0745175e..e3eda4887b3 100644
--- a/llvm/test/Bitcode/attributes.ll
+++ b/llvm/test/Bitcode/attributes.ll
@@ -204,7 +204,7 @@ define void @f34()
 ; CHECK: define void @f34()
 {
         call void @nobuiltin() nobuiltin
-; CHECK: call void @nobuiltin() #27
+; CHECK: call void @nobuiltin() #28
         ret void;
 }
 
@@ -272,6 +272,11 @@ define "string_attribute_with_value"="value" void @f46(i32 "string_attribute_wit
   ret void
 }
 
+; CHECK: define void @f47() #27
+define void @f47() norecurse {
+  ret void
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -299,4 +304,5 @@ define "string_attribute_with_value"="value" void @f46(i32 "string_attribute_wit
 ; CHECK: attributes #24 = { jumptable }
 ; CHECK: attributes #25 = { convergent }
 ; CHECK: attributes #26 = { argmemonly }
-; CHECK: attributes #27 = { nobuiltin }
+; CHECK: attributes #27 = { norecurse }
+; CHECK: attributes #28 = { nobuiltin }
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
index 4c6349c803c..73c24f0370a 100644
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -501,6 +501,8 @@ declare void @f.uwtable() uwtable
 ; CHECK: declare void @f.uwtable() #30
 declare void @f.kvpair() "cpu"="cortex-a8"
 ; CHECK:declare void @f.kvpair() #31
+declare void @f.norecurse() norecurse
+; CHECK: declare void @f.norecurse() #32
 
 ; Functions -- section
 declare void @f.section() section "80"
@@ -559,7 +561,7 @@ declare void @f.prologuearray() prologue [4 x i32] [i32 0, i32 1, i32 2, i32 3]
 
 ; Functions -- Personality constant
 declare void @llvm.donothing() nounwind readnone
-; CHECK: declare void @llvm.donothing() #32
+; CHECK: declare void @llvm.donothing() #33
 define void @f.no_personality() personality i8 3 {
 ; CHECK: define void @f.no_personality() personality i8 3
   invoke void @llvm.donothing() to label %normal unwind label %exception
@@ -1125,7 +1127,7 @@ 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() #36
+  ; CHECK: call void @f.nobuiltin() #37
 
   call fastcc noalias i32* @f.noalias() noinline
   ; CHECK: call fastcc noalias i32* @f.noalias() #12
@@ -1497,11 +1499,12 @@ normal:
 ; CHECK: attributes #29 = { "thunk" }
 ; CHECK: attributes #30 = { uwtable }
 ; CHECK: attributes #31 = { "cpu"="cortex-a8" }
-; CHECK: attributes #32 = { nounwind readnone }
-; CHECK: attributes #33 = { nounwind readonly argmemonly }
-; CHECK: attributes #34 = { nounwind argmemonly }
-; CHECK: attributes #35 = { nounwind readonly }
-; CHECK: attributes #36 = { builtin }
+; CHECK: attributes #32 = { norecurse }
+; CHECK: attributes #33 = { nounwind readnone }
+; CHECK: attributes #34 = { nounwind readonly argmemonly }
+; CHECK: attributes #35 = { nounwind argmemonly }
+; CHECK: attributes #36 = { nounwind readonly }
+; CHECK: attributes #37 = { builtin }
 
 ;; Metadata
 
diff --git a/llvm/test/Bitcode/invalid.ll b/llvm/test/Bitcode/invalid.ll
index df9fec8772d..2f2eca94321 100644
--- a/llvm/test/Bitcode/invalid.ll
+++ b/llvm/test/Bitcode/invalid.ll
@@ -1,6 +1,6 @@
 ; RUN:  not llvm-dis < %s.bc 2>&1 | FileCheck %s
 
-; CHECK: llvm-dis{{(\.EXE|\.exe)?}}: error: Unknown attribute kind (48)
+; CHECK: llvm-dis{{(\.EXE|\.exe)?}}: error: Unknown attribute kind (50)
 
 ; invalid.ll.bc has an invalid attribute number.
 ; The test checks that LLVM reports the error and doesn't access freed memory
diff --git a/llvm/test/Bitcode/invalid.ll.bc b/llvm/test/Bitcode/invalid.ll.bc
index a85c3644b3a..8f7474b9e46 100644
--- a/llvm/test/Bitcode/invalid.ll.bc
+++ b/llvm/test/Bitcode/invalid.ll.bc
diff --git a/llvm/test/LTO/X86/Inputs/invalid.ll.bc b/llvm/test/LTO/X86/Inputs/invalid.ll.bc
index a85c3644b3a..8f7474b9e46 100644
--- a/llvm/test/LTO/X86/Inputs/invalid.ll.bc
+++ b/llvm/test/LTO/X86/Inputs/invalid.ll.bc
diff --git a/llvm/test/LTO/X86/invalid.ll b/llvm/test/LTO/X86/invalid.ll
index 5b6996d4ad3..3de11112c71 100644
--- a/llvm/test/LTO/X86/invalid.ll
+++ b/llvm/test/LTO/X86/invalid.ll
@@ -1,4 +1,4 @@
 ; RUN: not llvm-lto %S/Inputs/invalid.ll.bc 2>&1 | FileCheck %s
 
 
-; CHECK: llvm-lto{{.*}}: error loading file '{{.*}}/Inputs/invalid.ll.bc': Unknown attribute kind (48)
+; CHECK: llvm-lto{{.*}}: error loading file '{{.*}}/Inputs/invalid.ll.bc': Unknown attribute kind (50)