[Lldb-commits] [lldb] ad6d808 - [lldb][DWARFASTParserClang] Make C++ method parsing aware of explicit object parameters (#124096)
via lldb-commits
lldb-commits at lists.llvm.org
Thu Jan 23 03:16:06 PST 2025
Author: Michael Buch
Date: 2025-01-23T11:16:02Z
New Revision: ad6d808906075c3386bbeada3c37d8d3e6afe248
URL: https://github.com/llvm/llvm-project/commit/ad6d808906075c3386bbeada3c37d8d3e6afe248
DIFF: https://github.com/llvm/llvm-project/commit/ad6d808906075c3386bbeada3c37d8d3e6afe248.diff
LOG: [lldb][DWARFASTParserClang] Make C++ method parsing aware of explicit object parameters (#124096)
LLDB deduces the CV-qualifiers and storage class of a C++ method from
the object parameter. Currently it assumes that parameter is implicit
(and is a pointer type with the name "this"). This isn't true anymore in
C++23 with explicit object parameters. To support those we can simply
check the `DW_AT_object_pointer` of the subprogram DIE (works for both
declarations and definitions) when searching for the object parameter.
We can also remove the check for `eEncodingIsPointerUID`, because in C++
an artificial parameter called `this` is only ever the implicit object
parameter (at least for all the major compilers).
Added:
Modified:
lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp
Removed:
################################################################################
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index f54b7fc9cdad24..682ee6d287bf5c 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -173,7 +173,9 @@ GetCXXObjectParameter(const DWARFDIE &subprogram,
if (!DeclKindIsCXXClass(containing_decl_ctx.getDeclKind()))
return {};
- // FIXME: if subprogram has a explicit DW_AT_object_pointer, use it.
+ if (DWARFDIE object_parameter =
+ subprogram.GetAttributeValueAsReferenceDIE(DW_AT_object_pointer))
+ return object_parameter;
// If no DW_AT_object_pointer was specified, assume the implicit object
// parameter is the first parameter to the function, is called "this" and is
@@ -215,11 +217,6 @@ static unsigned GetCXXMethodCVQuals(const DWARFDIE &subprogram,
return 0;
uint32_t encoding_mask = this_type->GetEncodingMask();
-
- // FIXME: explicit object parameters need not to be pointers
- if (!(encoding_mask & (1u << Type::eEncodingIsPointerUID)))
- return 0;
-
unsigned cv_quals = 0;
if (encoding_mask & (1u << Type::eEncodingIsConstUID))
cv_quals |= clang::Qualifiers::Const;
diff --git a/lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp b/lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp
index b31f56aa372d58..9c0300be08a78a 100644
--- a/lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp
@@ -902,3 +902,181 @@ TEST_F(DWARFASTParserClangTests, TestParseDWARFAttributes_ObjectPointer) {
EXPECT_TRUE(attrs.object_pointer.IsValid());
EXPECT_EQ(attrs.object_pointer, param_die);
}
+
+TEST_F(DWARFASTParserClangTests, TestParseSubroutine_ExplicitObjectParameter) {
+ // Tests parsing of a C++ non-static member function with an explicit object
+ // parameter that isn't called "this" and is not a pointer (but a CV-qualified
+ // rvalue reference instead).
+
+ const char *yamldata = R"(
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_AARCH64
+DWARF:
+ debug_str:
+ - Context
+ - func
+ - mySelf
+ debug_abbrev:
+ - ID: 0
+ Table:
+ - Code: 0x1
+ Tag: DW_TAG_compile_unit
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_language
+ Form: DW_FORM_data2
+ - Code: 0x2
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Code: 0x3
+ Tag: DW_TAG_subprogram
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_declaration
+ Form: DW_FORM_flag_present
+ - Attribute: DW_AT_object_pointer
+ Form: DW_FORM_ref4
+ - Attribute: DW_AT_external
+ Form: DW_FORM_flag_present
+ - Code: 0x4
+ Tag: DW_TAG_formal_parameter
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Code: 0x5
+ Tag: DW_TAG_rvalue_reference_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Code: 0x6
+ Tag: DW_TAG_const_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Code: 0x7
+ Tag: DW_TAG_volatile_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ debug_info:
+ - Version: 5
+ UnitType: DW_UT_compile
+ AddrSize: 8
+ Entries:
+
+# DW_TAG_compile_unit
+# DW_AT_language [DW_FORM_data2] (DW_LANG_C_plus_plus)
+
+ - AbbrCode: 0x1
+ Values:
+ - Value: 0x04
+
+# DW_TAG_structure_type
+# DW_AT_name [DW_FORM_strp] ("Context")
+
+ - AbbrCode: 0x2
+ Values:
+ - Value: 0x0
+
+# DW_TAG_subprogram
+# DW_AT_name [DW_FORM_strp] ("func")
+# DW_AT_object_pointer [DW_FORM_ref4]
+ - AbbrCode: 0x3
+ Values:
+ - Value: 0x8
+ - Value: 0x1
+ - Value: 0x1d
+ - Value: 0x1
+
+# DW_TAG_formal_parameter
+# DW_AT_name [DW_FORM_strp] ("mySelf")
+# DW_AT_type [DW_FORM_ref4] (const volatile Context &&)
+ - AbbrCode: 0x4
+ Values:
+ - Value: 0xd
+ - Value: 0x28
+
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
+
+# DW_TAG_rvalue_reference_type
+# DW_AT_type [DW_FORM_ref4] ("const volatile Context")
+
+ - AbbrCode: 0x5
+ Values:
+ - Value: 0x2d
+
+# DW_TAG_const_type
+# DW_AT_type [DW_FORM_ref4] ("volatile Context")
+
+ - AbbrCode: 0x6
+ Values:
+ - Value: 0x32
+
+# DW_TAG_volatile_type
+# DW_AT_type [DW_FORM_ref4] ("Context")
+
+ - AbbrCode: 0x7
+ Values:
+ - Value: 0xf
+
+ - AbbrCode: 0x0
+...
+)";
+ YAMLModuleTester t(yamldata);
+
+ DWARFUnit *unit = t.GetDwarfUnit();
+ ASSERT_NE(unit, nullptr);
+ const DWARFDebugInfoEntry *cu_entry = unit->DIE().GetDIE();
+ ASSERT_EQ(cu_entry->Tag(), DW_TAG_compile_unit);
+ ASSERT_EQ(unit->GetDWARFLanguageType(), DW_LANG_C_plus_plus);
+ DWARFDIE cu_die(unit, cu_entry);
+
+ auto ts_or_err =
+ cu_die.GetDWARF()->GetTypeSystemForLanguage(eLanguageTypeC_plus_plus);
+ auto *parser =
+ static_cast<DWARFASTParserClang *>((*ts_or_err)->GetDWARFParser());
+
+ auto context_die = cu_die.GetFirstChild();
+ ASSERT_TRUE(context_die.IsValid());
+ ASSERT_EQ(context_die.Tag(), DW_TAG_structure_type);
+
+ SymbolContext sc;
+ bool new_type;
+ auto context_type_sp = parser->ParseTypeFromDWARF(sc, context_die, &new_type);
+ ASSERT_NE(context_type_sp, nullptr);
+
+ ASSERT_TRUE(
+ parser->CompleteTypeFromDWARF(context_die, context_type_sp.get(),
+ context_type_sp->GetForwardCompilerType()));
+
+ auto *record_decl = llvm::dyn_cast_or_null<clang::CXXRecordDecl>(
+ ClangUtil::GetAsTagDecl(context_type_sp->GetForwardCompilerType()));
+ ASSERT_NE(record_decl, nullptr);
+
+ auto method_it = record_decl->method_begin();
+ ASSERT_NE(method_it, record_decl->method_end());
+
+ // Check that we didn't parse the function as static.
+ EXPECT_FALSE(method_it->isStatic());
+
+ // Check that method qualifiers were correctly set.
+ EXPECT_EQ(method_it->getMethodQualifiers(),
+ clang::Qualifiers::fromCVRMask(clang::Qualifiers::Const |
+ clang::Qualifiers::Volatile));
+}
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