[Demangle] demangle builtin type transformations

Fixed: llvm#62127
https://reviews.llvm.org/D116203 introduced several compiler builtin
equivalents of the unary type traits. In some cases (e.g. template) those
builtin will be dependent and need to be mangle.
This patch add the check for `u{builtin}I{type}E` to demangle it.

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D148465

Author: HerrCai0907

libcxxabi/src/demangle/ItaniumDemangle.h

@@ -534,6 +534,23 @@ class ElaboratedTypeSpefType : public Node {
   }
 };
 
+class TransformedType : public Node {
+  StringView Transform;
+  Node *BaseType;
+public:
+  TransformedType(StringView Transform_, Node *BaseType_)
+      : Node(KTransformedType), Transform(Transform_), BaseType(BaseType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Transform, BaseType); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Transform;
+    OB += '(';
+    BaseType->print(OB);
+    OB += ')';
+  }
+};
+
 struct AbiTagAttr : Node {
   Node *Base;
   std::string_view Tag;
@@ -3894,7 +3911,15 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     // Typically, <builtin-type>s are not considered substitution candidates,
     // but the exception to that exception is vendor extended types (Itanium C++
     // ABI 5.9.1).
-    Result = make<NameType>(Res);
+    if (consumeIf('I')) {
+      Node *BaseType = parseType();
+      if (BaseType == nullptr)
+        return nullptr;
+      if (!consumeIf('E'))
+        return nullptr;
+      Result = make<TransformedType>(Res, BaseType);
+    } else
+      Result = make<NameType>(Res);
     break;
   }
   case 'D':

libcxxabi/src/demangle/ItaniumNodes.def

@@ -19,6 +19,7 @@ NODE(QualType)
 NODE(ConversionOperatorType)
 NODE(PostfixQualifiedType)
 NODE(ElaboratedTypeSpefType)
+NODE(TransformedType)
 NODE(NameType)
 NODE(AbiTagAttr)
 NODE(EnableIfAttr)

libcxxabi/test/test_demangle.pass.cpp

@@ -30114,6 +30114,9 @@ const char* cases[][2] =
      " std::allocator<char>>::basic_string()"},
     {"_ZN1SB8ctor_tagC2Ev", "S[abi:ctor_tag]::S()"},
     {"_ZN1SB8ctor_tagD2Ev", "S[abi:ctor_tag]::~S()"},
+
+    // clang builtin type transform
+    {"_Z2f5IiEvu7__decayIT_E", "void f5<int>(__decay(int))"},
 };
 
 const unsigned N = sizeof(cases) / sizeof(cases[0]);

llvm/include/llvm/Demangle/ItaniumDemangle.h

@@ -528,6 +528,23 @@ class ElaboratedTypeSpefType : public Node {
   }
 };
 
+class TransformedType : public Node {
+  StringView Transform;
+  Node *BaseType;
+public:
+  TransformedType(StringView Transform_, Node *BaseType_)
+      : Node(KTransformedType), Transform(Transform_), BaseType(BaseType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Transform, BaseType); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Transform;
+    OB += '(';
+    BaseType->print(OB);
+    OB += ')';
+  }
+};
+
 struct AbiTagAttr : Node {
   Node *Base;
   std::string_view Tag;
@@ -3889,7 +3906,15 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     // Typically, <builtin-type>s are not considered substitution candidates,
     // but the exception to that exception is vendor extended types (Itanium C++
     // ABI 5.9.1).
-    Result = make<NameType>(Res);
+    if (consumeIf('I')) {
+      Node *BaseType = parseType();
+      if (BaseType == nullptr)
+        return nullptr;
+      if (!consumeIf('E'))
+        return nullptr;
+      Result = make<TransformedType>(Res, BaseType);
+    } else
+      Result = make<NameType>(Res);
     break;
   }
   case 'D':

llvm/include/llvm/Demangle/ItaniumNodes.def

@@ -19,6 +19,7 @@ NODE(QualType)
 NODE(ConversionOperatorType)
 NODE(PostfixQualifiedType)
 NODE(ElaboratedTypeSpefType)
+NODE(TransformedType)
 NODE(NameType)
 NODE(AbiTagAttr)
 NODE(EnableIfAttr)