[Lldb-commits] [lldb] [lldb][TypeSystemClang] Added unique builtins types for __bf16 and _Float16 (PR #157674)

[via lldb-commits]

https://github.com/tgs-sc updated https://github.com/llvm/llvm-project/pull/157674

>From 5d80f548d4dd4a974d0b49573e7763fdd4a18aa4 Mon Sep 17 00:00:00 2001
From: Timur Golubovich <timur.golubovich at syntacore.com>
Date: Tue, 9 Sep 2025 13:39:33 +0000
Subject: [PATCH] [lldb][TypeSystemClang] Added unique builtins types for
 __bf16 and _Float16

During debugging applization with __bf16 and _Float16 float types it
was discovered that lldb creates the same CompilerType for them. This
can cause an infinite recursion error, if one tries to create two
struct specializations with these types and then inherit one
specialization from another. This is an example, provided by @Michael137:

```c++
template <typename T> struct Foo;

template <> struct Foo<__bf16> {};

template <> struct Foo<_Float16> : Foo<__bf16> {};

int main() {
  Foo<_Float16> f1;
  return 0;
}
```
---
 lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp   | 7 +++++++
 .../cpp/template-arguments/TestCppTemplateArguments.py     | 4 ++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index c4a917f59fb88..804ddd042574e 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -959,6 +959,12 @@ CompilerType TypeSystemClang::GetBuiltinTypeForDWARFEncodingAndBitSize(
     if (type_name == "long double" &&
         QualTypeMatchesBitSize(bit_size, ast, ast.LongDoubleTy))
       return GetType(ast.LongDoubleTy);
+    if (type_name == "__bf16" &&
+        QualTypeMatchesBitSize(bit_size, ast, ast.BFloat16Ty))
+      return GetType(ast.BFloat16Ty);
+    if (type_name == "_Float16" &&
+        QualTypeMatchesBitSize(bit_size, ast, ast.Float16Ty))
+      return GetType(ast.Float16Ty);
     // As Rust currently uses `TypeSystemClang`, match `f128` here as well so it
     // doesn't get misinterpreted as `long double` on targets where they are
     // the same size but different formats.
@@ -1791,6 +1797,7 @@ bool TypeSystemClang::RecordHasFields(const RecordDecl *record_decl) {
     for (base_class = cxx_record_decl->bases_begin(),
         base_class_end = cxx_record_decl->bases_end();
          base_class != base_class_end; ++base_class) {
+      assert(record_decl != base_class->getType()->getAsCXXRecordDecl());
       if (RecordHasFields(base_class->getType()->getAsCXXRecordDecl()))
         return true;
     }
diff --git a/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py b/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
index eac7b5ef1099a..cee6fcda08570 100644
--- a/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
+++ b/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
@@ -79,10 +79,10 @@ def test(self):
         self.assertFalse(value.GetType().GetTemplateArgumentValue(target, 1))
 
         # FIXME: support wider range of floating point types
-        value = self.expect_expr("temp7", result_type="Foo<__fp16, __fp16>")
+        value = self.expect_expr("temp7", result_type="Foo<_Float16, _Float16>")
         self.assertFalse(value.GetType().GetTemplateArgumentValue(target, 1))
 
-        value = self.expect_expr("temp8", result_type="Foo<__fp16, __fp16>")
+        value = self.expect_expr("temp8", result_type="Foo<__bf16, __bf16>")
         self.assertFalse(value.GetType().GetTemplateArgumentValue(target, 1))
 
         value = self.expect_expr("temp9", result_type="Bar<double, 1.200000e+00>")