[lldb] Encode `bool` as unsigned int

[werat]

Summary

bool is considered to be unsigned according to std::is_unsigned<bool>::value (and Type::GetTypeInfo). Encoding it as signed int works fine for normal variables and fields, but breaks when reading the values of boolean bitfields. If the field is declared as bool b : 1 and has a value of 0b1, the call to SBValue::GetValueAsSigned() will return -1.

[teemperor]

Nice, and it's not even my birthday. Just some nits that don't need another round of review.

lldb/test/API/lang/cpp/bitfields/TestCppBitfields.py

21

Please land that as it's own commit (from what I understand from the bug report this worked before and you just remove the skipIf here)

134

You might want to assert that bb.IsValid() after this call (otherwise the GetValueAs* calls just return 0 and that's a confusing error).

[werat]

Keep @skipIfWindows for now
Add more checks in tests

[werat]

Thanks for a quick review!

lldb/test/API/lang/cpp/bitfields/TestCppBitfields.py

21

Okay, will submit this in a follow up commit

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

case clang::Type::DependentExtInt:
     return qual_type->isUnsignedIntegerType() ? lldb::eEncodingUint
                                               : lldb::eEncodingSint;
 
   case clang::Type::Builtin:
     switch (llvm::cast<clang::BuiltinType>(qual_type)->getKind()) {
     case clang::BuiltinType::Void:
       break;
 
-    case clang::BuiltinType::Bool:
     case clang::BuiltinType::Char_S:
     case clang::BuiltinType::SChar:
     case clang::BuiltinType::WChar_S:
     case clang::BuiltinType::Short:
     case clang::BuiltinType::Int:
     case clang::BuiltinType::Long:
     case clang::BuiltinType::LongLong:
     case clang::BuiltinType::Int128:
       return lldb::eEncodingSint;
 
+    case clang::BuiltinType::Bool:
     case clang::BuiltinType::Char_U:
     case clang::BuiltinType::UChar:
     case clang::BuiltinType::WChar_U:
     case clang::BuiltinType::Char8:
     case clang::BuiltinType::Char16:
     case clang::BuiltinType::Char32:
     case clang::BuiltinType::UShort:
     case clang::BuiltinType::UInt:

lldb/test/API/lang/cpp/bitfields/TestCppBitfields.py

class CppBitfieldsTestCase(TestBase):
     def setUp(self):
         # Call super's setUp().
         TestBase.setUp(self)
         # Find the line number to break inside main().
         self.line = line_number('main.cpp', '// Set break point at this line.')
 
     # BitFields exhibit crashes in record layout on Windows
     # (http://llvm.org/pr21800)
     @skipIfWindows
     def test_and_run_command(self):
         """Test 'frame variable ...' on a variable with bitfields."""
         self.build()
 
         lldbutil.run_to_source_breakpoint(self, '// Set break point at this line.',
           lldb.SBFileSpec("main.cpp", False))
 
         # The stop reason of the thread should be breakpoint.
def test_and_run_command(self):
 
         self.expect(
             "frame variable --show-types derived",
             VARIABLES_DISPLAYED_CORRECTLY,
             substrs=[
                 '(uint32_t) b_a = 2',
                 '(uint32_t:1) d_a = 1',
                 ])
+
+        self.expect(
+            "frame variable --show-types bb",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=[
+                '(bool:1) a = true',
+                '(bool:1) b = false',
+                '(bool:2) c = true',
+                '(bool:2) d = true',
+                ])
+
+        bb = self.frame().FindVariable('bb')
+        self.assertTrue(bb.IsValid())
+
+        bb_a = bb.GetChildAtIndex(0)
+        self.assertTrue(bb_a.IsValid())
+        self.assertEqual(bb_a.GetValueAsUnsigned(), 1)
+        self.assertEqual(bb_a.GetValueAsSigned(), 1)
+
+        bb_b = bb.GetChildAtIndex(1)
+        self.assertTrue(bb_b.IsValid())
+        self.assertEqual(bb_b.GetValueAsUnsigned(), 0)
+        self.assertEqual(bb_b.GetValueAsSigned(), 0)
+
+        bb_c = bb.GetChildAtIndex(2)
+        self.assertTrue(bb_c.IsValid())
+        self.assertEqual(bb_c.GetValueAsUnsigned(), 1)
+        self.assertEqual(bb_c.GetValueAsSigned(), 1)
+
+        bb_d = bb.GetChildAtIndex(3)
+        self.assertTrue(bb_d.IsValid())
+        self.assertEqual(bb_d.GetValueAsUnsigned(), 1)
+        self.assertEqual(bb_d.GetValueAsSigned(), 1)

lldb/test/API/lang/cpp/bitfields/main.cpp

int main(int argc, char const *argv[]) {
   lbd.a = 5;
 
   derived.b_a = 2;
   derived.d_a = 1;
 
   uwbf.x = 0xFFFFFFFF;
   uwubf.x = 0xFFFFFFFF;
 
+  struct BoolBits {
+    bool a : 1;
+    bool b : 1;
+    bool c : 2;
+    bool d : 2;
+  } bb;
+
+  bb.a = 0b1;
+  bb.b = 0b0;
+  bb.c = 0b11;
+  bb.d = 0b01;
+
   return 0; // Set break point at this line.
 }