[clang] [clang] Add bitint classification for __builtin_classify_type (PR #72036)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/72036

>From c7210706c0f45d3f4693e796970c73e3ef6dd48a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Sat, 11 Nov 2023 18:44:13 +0100
Subject: [PATCH] [clang] Add bitint classification for __builtin_classify_type

See #71911
---
 clang/docs/ReleaseNotes.rst                  | 2 ++
 clang/lib/AST/ExprConstant.cpp               | 8 +++++++-
 clang/test/Sema/builtin-classify-type.c      | 5 ++++-
 clang/test/SemaCXX/builtin-classify-type.cpp | 5 ++++-
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7a131cb520aa600..520b4035e001715 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -217,6 +217,8 @@ Non-comprehensive list of changes in this release
   (e.g., ``uint16x8_t``), this returns the constant number of elements at compile-time.
   For scalable vectors, e.g., SVE or RISC-V V, the number of elements is not known at compile-time and is
   determined at runtime.
+* ``__builtin_classify_type()`` now classifies ``_BitInt`` values as the return value ``18``,
+  to match GCC 14's behavior.
 
 New Compiler Flags
 ------------------
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e16fec6109e744e..2073679adf790fb 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -11486,6 +11486,7 @@ bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
 
 /// Values returned by __builtin_classify_type, chosen to match the values
 /// produced by GCC's builtin.
+/// The values can be found in gcc/typeclass.h in the GCC repository.
 enum class GCCTypeClass {
   None = -1,
   Void = 0,
@@ -11512,6 +11513,9 @@ enum class GCCTypeClass {
   // decay to pointer. (Prior to version 6 it was only used in C++ mode).
   // GCC reserves 15 for strings, but actually uses 5 (pointer) for string
   // literals.
+  // Lang = 16,
+  // OpaqueType = 17,
+  BitInt = 18
 };
 
 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
@@ -11644,11 +11648,13 @@ EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) {
   case Type::ObjCInterface:
   case Type::ObjCObjectPointer:
   case Type::Pipe:
-  case Type::BitInt:
     // GCC classifies vectors as None. We follow its lead and classify all
     // other types that don't fit into the regular classification the same way.
     return GCCTypeClass::None;
 
+  case Type::BitInt:
+    return GCCTypeClass::BitInt;
+
   case Type::LValueReference:
   case Type::RValueReference:
     llvm_unreachable("invalid type for expression");
diff --git a/clang/test/Sema/builtin-classify-type.c b/clang/test/Sema/builtin-classify-type.c
index a222ac8af0e32fd..9a4de34e823f231 100644
--- a/clang/test/Sema/builtin-classify-type.c
+++ b/clang/test/Sema/builtin-classify-type.c
@@ -11,7 +11,8 @@ enum gcc_type_class {
   function_type_class, method_type_class,
   record_type_class, union_type_class,
   array_type_class, string_type_class,
-  lang_type_class
+  lang_type_class, opaque_type_class,
+  bitint_type_class
 };
 
 void foo(void) {
@@ -45,6 +46,7 @@ void foo(void) {
   vint32_t3 vt5;
   typedef _BitInt(64) vint64_t3 __attribute__((vector_size(16)));
   vint64_t3 vt6;
+  _BitInt(16) bitint;
 
   _Atomic int atomic_i;
   _Atomic double atomic_d;
@@ -70,6 +72,7 @@ void foo(void) {
   int a17[__builtin_classify_type(atomic_d) == real_type_class ? 1 : -1];
   int a18[__builtin_classify_type(complex_i) == complex_type_class ? 1 : -1];
   int a19[__builtin_classify_type(complex_d) == complex_type_class ? 1 : -1];
+  int a20[__builtin_classify_type(bitint) == bitint_type_class ? 1 : -1];
 }
 
 extern int (^p)(void);
diff --git a/clang/test/SemaCXX/builtin-classify-type.cpp b/clang/test/SemaCXX/builtin-classify-type.cpp
index ebc81425e401f11..ed5430960001002 100644
--- a/clang/test/SemaCXX/builtin-classify-type.cpp
+++ b/clang/test/SemaCXX/builtin-classify-type.cpp
@@ -11,7 +11,8 @@ enum gcc_type_class {
   function_type_class, method_type_class,
   record_type_class, union_type_class,
   array_type_class, string_type_class,
-  lang_type_class
+  lang_type_class, opaque_type_class,
+  bitint_type_class
 };
 
 class cl {
@@ -42,6 +43,7 @@ void foo() {
   _Atomic double atomic_d;
   _Complex int complex_i;
   _Complex double complex_d;
+  _BitInt(32) bitint;
 
   int a1[__builtin_classify_type(f()) == void_type_class ? 1 : -1];
   int a2[__builtin_classify_type(i) == integer_type_class ? 1 : -1];
@@ -65,5 +67,6 @@ void foo() {
   int a20[__builtin_classify_type(atomic_d) == real_type_class ? 1 : -1];
   int a21[__builtin_classify_type(complex_i) == complex_type_class ? 1 : -1];
   int a22[__builtin_classify_type(complex_d) == complex_type_class ? 1 : -1];
+  int a23[__builtin_classify_type(bitint) == bitint_type_class ? 1 : -1];
 }