[ItaniumDemangle] Demangle DF16b as bfloat16_t

This mangling is already supported in clang.

Author: frasercrmck

libcxxabi/src/demangle/ItaniumDemangle.h

@@ -1224,6 +1224,15 @@ class BinaryFPType final : public Node {
   }
 };
 
+class BFloat16Type final : public Node {
+public:
+  BFloat16Type() : Node(KBinaryFPType) {}
+
+  template <typename Fn> void match(Fn F) const { F(); }
+
+  void printLeft(OutputBuffer &OB) const override { OB += "bfloat16_t"; }
+};
+
 enum class TemplateParamKind { Type, NonType, Template };
 
 /// An invented name for a template parameter for which we don't have a
@@ -4330,9 +4339,12 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     case 'h':
       First += 2;
       return make<NameType>("half");
-    //                ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
+    //       ::= DF16b         # C++23 std::bfloat16_t
+    //       ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
     case 'F': {
       First += 2;
+      if (consumeIf("16b"))
+        return make<BFloat16Type>();
       Node *DimensionNumber = make<NameType>(parseNumber());
       if (!DimensionNumber)
         return nullptr;

libcxxabi/src/demangle/ItaniumNodes.def

@@ -100,5 +100,6 @@ NODE(ExprRequirement)
 NODE(TypeRequirement)
 NODE(NestedRequirement)
 NODE(ExplicitObjectParameter)
+NODE(BFloat16Type)
 
 #undef NODE

libcxxabi/test/test_demangle.pass.cpp

@@ -30245,6 +30245,8 @@ const char *cases[][2] = {
     {"_Z1fDSDRj", "f(_Sat unsigned _Fract)"},
     {"_Z1fDSDRl", "f(_Sat long _Fract)"},
     {"_Z1fDSDRm", "f(_Sat unsigned long _Fract)"},
+
+    {"_Z11bfloat16addDF16bDF16b", "bfloat16add(bfloat16_t, bfloat16_t)"},
     // clang-format on
 };
 

llvm/include/llvm/Demangle/ItaniumDemangle.h

@@ -1224,6 +1224,15 @@ class BinaryFPType final : public Node {
   }
 };
 
+class BFloat16Type final : public Node {
+public:
+  BFloat16Type() : Node(KBinaryFPType) {}
+
+  template <typename Fn> void match(Fn F) const { F(); }
+
+  void printLeft(OutputBuffer &OB) const override { OB += "bfloat16_t"; }
+};
+
 enum class TemplateParamKind { Type, NonType, Template };
 
 /// An invented name for a template parameter for which we don't have a
@@ -4330,9 +4339,12 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     case 'h':
       First += 2;
       return make<NameType>("half");
-    //                ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
+    //       ::= DF16b         # C++23 std::bfloat16_t
+    //       ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
     case 'F': {
       First += 2;
+      if (consumeIf("16b"))
+        return make<BFloat16Type>();
       Node *DimensionNumber = make<NameType>(parseNumber());
       if (!DimensionNumber)
         return nullptr;

llvm/include/llvm/Demangle/ItaniumNodes.def

@@ -100,5 +100,6 @@ NODE(ExprRequirement)
 NODE(TypeRequirement)
 NODE(NestedRequirement)
 NODE(ExplicitObjectParameter)
+NODE(BFloat16Type)
 
 #undef NODE