[Lldb-commits] [lldb] 0a0d497 - [lldb][TypeSystemClang] Added unique builtins types for __bf16 and _Float16 (#157674)

[via lldb-commits]

Author: Timur Golubovich
Date: 2025-10-01T11:20:58+01:00
New Revision: 0a0d4979935cc13ecafdb8c9b00dd74779651781

URL: https://github.com/llvm/llvm-project/commit/0a0d4979935cc13ecafdb8c9b00dd74779651781
DIFF: https://github.com/llvm/llvm-project/commit/0a0d4979935cc13ecafdb8c9b00dd74779651781.diff

LOG: [lldb][TypeSystemClang] Added unique builtins types for __bf16 and _Float16 (#157674)

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.

Added: 
    lldb/test/API/lang/cpp/floating-types-specialization/Makefile
    lldb/test/API/lang/cpp/floating-types-specialization/TestCppFloatingTypesSpecialization.py
    lldb/test/API/lang/cpp/floating-types-specialization/main.cpp

Modified: 
    lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
    lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index a5aaf1f9cb5af..21c265ede0bc5 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -960,6 +960,12 @@ 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 
diff erent formats.
@@ -1792,6 +1798,8 @@ 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() &&
+             "Base can't inherit from itself.");
       if (RecordHasFields(base_class->getType()->getAsCXXRecordDecl()))
         return true;
     }

diff  --git a/lldb/test/API/lang/cpp/floating-types-specialization/Makefile b/lldb/test/API/lang/cpp/floating-types-specialization/Makefile
new file mode 100644
index 0000000000000..99998b20bcb05
--- /dev/null
+++ b/lldb/test/API/lang/cpp/floating-types-specialization/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

diff  --git a/lldb/test/API/lang/cpp/floating-types-specialization/TestCppFloatingTypesSpecialization.py b/lldb/test/API/lang/cpp/floating-types-specialization/TestCppFloatingTypesSpecialization.py
new file mode 100644
index 0000000000000..9564a0bc31809
--- /dev/null
+++ b/lldb/test/API/lang/cpp/floating-types-specialization/TestCppFloatingTypesSpecialization.py
@@ -0,0 +1,22 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.cpp", False)
+        )
+
+        self.expect_expr("f0", result_type="Foo<__bf16>")
+        self.expect_expr("f1", result_type="Foo<__fp16>")
+
+        # Test sizeof to ensure while computing layout we don't do
+        # infinite recursion.
+        v = self.frame().EvaluateExpression("sizeof(f0)")
+        self.assertEqual(v.GetValueAsUnsigned() > 0, True)
+        v = self.frame().EvaluateExpression("sizeof(f1)")
+        self.assertEqual(v.GetValueAsUnsigned() > 0, True)

diff  --git a/lldb/test/API/lang/cpp/floating-types-specialization/main.cpp b/lldb/test/API/lang/cpp/floating-types-specialization/main.cpp
new file mode 100644
index 0000000000000..e3e8a3767fef8
--- /dev/null
+++ b/lldb/test/API/lang/cpp/floating-types-specialization/main.cpp
@@ -0,0 +1,11 @@
+template <typename T> struct Foo;
+
+template <> struct Foo<__bf16> {};
+
+template <> struct Foo<_Float16> : Foo<__bf16> {};
+
+int main() {
+  Foo<__bf16> f0;
+  Foo<_Float16> f1;
+  return 0; // break here
+}

diff  --git a/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py b/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
index eac7b5ef1099a..f26d382bf8582 100644
--- a/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
+++ b/lldb/test/API/lang/cpp/template-arguments/TestCppTemplateArguments.py
@@ -82,7 +82,7 @@ def test(self):
         value = self.expect_expr("temp7", result_type="Foo<__fp16, __fp16>")
         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>")