[Lldb-commits] [lldb] Make sure that the "TypeSystemClang::GetBuiltinTypeByName" method returns the correct value also for "_BitInt(...)" types. (PR #165857)

[Matej Košík via lldb-commits]

https://github.com/sedymrak created https://github.com/llvm/llvm-project/pull/165857

When trying to get the `SBType` object corresponding to the `_BitInt(...)` type name, we have noticed that the `SBTarget::FindFirstType` metod returns `nil`. This branch proposes:
- some test that demonstrate that the problem exists
- a possible fix

>From f9750d0fedc41532ffe7d5048c419cb91d223601 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matej=20Ko=C5=A1=C3=ADk?= <matej.kosik at codasip.com>
Date: Fri, 31 Oct 2025 10:37:26 +0100
Subject: [PATCH 1/3] [lldb] add more tests

---
 .../sbtype_basic_type/TestSBTypeBasicType.py       | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py b/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
index f8594dfc6b78d..99617cc68d19f 100644
--- a/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
+++ b/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
@@ -36,3 +36,17 @@ def test(self):
         # Check the size of the chosen aliases of basic types.
         self.assertEqual(self.target().FindFirstType("__int128_t").size, 16)
         self.assertEqual(self.target().FindFirstType("__uint128_t").size, 16)
+
+        # "_BitInt(...)" and "unsigned _BitInt(...)" are GNU C compiler extensions
+        # that are supported by LLVM C(++) compiler as well.
+        #
+        # We check that LLDB is able to map the names of these types
+        # (as reported by LLDB for variables of this type)
+        # to the corresponding SBType objects.
+        self.assertEqual(self.target().FindFirstType("_BitInt(65)").name, "_BitInt(65)")
+        self.assertEqual(self.target().FindFirstType("_BitInt(65)").size, 16)
+        self.assertEqual(
+            self.target().FindFirstType("unsigned _BitInt(65)").name,
+            "unsigned _BitInt(65)",
+        )
+        self.assertEqual(self.target().FindFirstType("unsigned _BitInt(65)").size, 16)

>From e46d8f3037eaf9c84dd8f0d875013ff574fc04af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matej=20Ko=C5=A1=C3=ADk?= <matej.kosik at codasip.com>
Date: Fri, 31 Oct 2025 10:37:51 +0100
Subject: [PATCH 2/3] [lldb] fix the "TypeSystemClang::GetBuiltinTypeByName"
 method

---
 .../Plugins/TypeSystem/Clang/TypeSystemClang.cpp      | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index 6ec054d5eac05..cfa936415d634 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -5498,6 +5498,17 @@ TypeSystemClang::GetNumChildren(lldb::opaque_compiler_type_t type,
 }
 
 CompilerType TypeSystemClang::GetBuiltinTypeByName(ConstString name) {
+  StringRef name_ref = name.GetStringRef();
+  llvm::Regex re("^(unsigned )?_BitInt\\((.*)\\)$");
+  llvm::SmallVector<llvm::StringRef, 4> matches;
+  bool is_bitint = re.match(name_ref, &matches);
+  if (is_bitint && matches.size() == 3) {
+    bool is_unsigned = matches[1] == "unsigned ";
+    llvm::APInt ap_bit_size;
+    if (!matches[2].getAsInteger(10, ap_bit_size))
+      return GetType(getASTContext().getBitIntType(is_unsigned,
+                                                   ap_bit_size.getZExtValue()));
+  }
   return GetBasicType(GetBasicTypeEnumeration(name));
 }
 

>From 0c91339d79e605e1ac1cc7ad5f882025d5138e25 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matej=20Ko=C5=A1=C3=ADk?= <matej.kosik at codasip.com>
Date: Fri, 31 Oct 2025 10:46:40 +0100
Subject: [PATCH 3/3] [lldb] some more (although unrelated) tests

---
 .../API/python_api/sbtype_basic_type/TestSBTypeBasicType.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py b/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
index 99617cc68d19f..07a4fae82677d 100644
--- a/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
+++ b/lldb/test/API/python_api/sbtype_basic_type/TestSBTypeBasicType.py
@@ -30,11 +30,17 @@ def test(self):
         self.assertEqual(d.GetType().GetBasicType(), int_basic_type)
 
         # Check the size of the chosen basic types.
+        self.assertEqual(self.target().FindFirstType("__int128").name, "__int128")
         self.assertEqual(self.target().FindFirstType("__int128").size, 16)
+        self.assertEqual(
+            self.target().FindFirstType("unsigned __int128").name, "unsigned __int128"
+        )
         self.assertEqual(self.target().FindFirstType("unsigned __int128").size, 16)
 
         # Check the size of the chosen aliases of basic types.
+        self.assertEqual(self.target().FindFirstType("__int128_t").name, "__int128_t")
         self.assertEqual(self.target().FindFirstType("__int128_t").size, 16)
+        self.assertEqual(self.target().FindFirstType("__uint128_t").name, "__uint128_t")
         self.assertEqual(self.target().FindFirstType("__uint128_t").size, 16)
 
         # "_BitInt(...)" and "unsigned _BitInt(...)" are GNU C compiler extensions