[Lldb-commits] [lldb] DRAFT: [lldb][DWARFASTParserClang] Remove old workaround (PR #160132)
Michael Buch via lldb-commits
lldb-commits at lists.llvm.org
Mon Sep 29 07:02:59 PDT 2025
https://github.com/Michael137 updated https://github.com/llvm/llvm-project/pull/160132
>From 55de305f33e878e86706d5a2f3677a3d4ec28c81 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Mon, 22 Sep 2025 16:02:35 +0100
Subject: [PATCH] [lldb][DWARFASTParserClang] Simplify obsolete error condition
for malformed array member type offsets
First time check was introduced in fa3ab4599d717feedbb83e08e7f654913942520b to work around a debug-info generation bug in Clang. This bug was fixed in Clang-4. The check has since been adjusted (first in `808ff186f6a6ba1fd38cc7e00697cd82f4afe540`, and then most recently in `370db9c62910195e664e82dde6f0adb3e255a4fd`).
This check is getting quite convoluted, and all it does is turn an `array[1]` into an `array[0]` type when it is deemed correct. At this point the workaround probably never fires, apart from actually valid codegen. This patch removes the special conditions and emits the error specifically in those cases where we know the DWARF is malformed.
Added some shell tests for the error case.
---
.../SymbolFile/DWARF/DWARFASTParserClang.cpp | 45 ++------
...ncomplete-member-beyond-parent-bounds.yaml | 102 +++++++++++++++++
.../DWARF/member-beyond-parent-bounds.yaml | 107 ++++++++++++++++++
.../zero-sized-member-in-parent-bounds.yaml | 103 +++++++++++++++++
4 files changed, 321 insertions(+), 36 deletions(-)
create mode 100644 lldb/test/Shell/SymbolFile/DWARF/incomplete-member-beyond-parent-bounds.yaml
create mode 100644 lldb/test/Shell/SymbolFile/DWARF/member-beyond-parent-bounds.yaml
create mode 100644 lldb/test/Shell/SymbolFile/DWARF/zero-sized-member-in-parent-bounds.yaml
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index f1e73d73a733b..8f52242fd387d 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -3126,42 +3126,15 @@ void DWARFASTParserClang::ParseSingleMember(
if (!member_clang_type.IsCompleteType())
member_clang_type.GetCompleteType();
- {
- // Older versions of clang emit the same DWARF for array[0] and array[1]. If
- // the current field is at the end of the structure, then there is
- // definitely no room for extra elements and we override the type to
- // array[0]. This was fixed by f454dfb6b5af.
- CompilerType member_array_element_type;
- uint64_t member_array_size;
- bool member_array_is_incomplete;
-
- if (member_clang_type.IsArrayType(&member_array_element_type,
- &member_array_size,
- &member_array_is_incomplete) &&
- !member_array_is_incomplete) {
- uint64_t parent_byte_size =
- parent_die.GetAttributeValueAsUnsigned(DW_AT_byte_size, UINT64_MAX);
-
- // If the attrs.member_byte_offset is still set to UINT32_MAX this means
- // that the DW_TAG_member didn't have a DW_AT_data_member_location, so
- // don't emit an error if this is the case.
- if (attrs.member_byte_offset != UINT32_MAX &&
- attrs.member_byte_offset >= parent_byte_size) {
- if (member_array_size != 1 &&
- (member_array_size != 0 ||
- attrs.member_byte_offset > parent_byte_size)) {
- module_sp->ReportError(
- "{0:x8}: DW_TAG_member '{1}' refers to type {2:x16}"
- " which extends beyond the bounds of {3:x8}",
- die.GetID(), attrs.name,
- attrs.encoding_form.Reference().GetOffset(), parent_die.GetID());
- }
-
- member_clang_type =
- m_ast.CreateArrayType(member_array_element_type, 0, false);
- }
- }
- }
+ if (attrs.member_byte_offset != UINT32_MAX &&
+ attrs.member_byte_offset >= parent_byte_size &&
+ llvm::expectedToOptional(member_clang_type.GetByteSize(nullptr))
+ .value_or(0) > 0)
+ module_sp->ReportError("{0:x8}: DW_TAG_member '{1}' refers to type {2:x16}"
+ " which extends beyond the bounds of {3:x8}",
+ die.GetID(), attrs.name,
+ attrs.encoding_form.Reference().GetOffset(),
+ parent_die.GetID());
TypeSystemClang::RequireCompleteType(member_clang_type);
diff --git a/lldb/test/Shell/SymbolFile/DWARF/incomplete-member-beyond-parent-bounds.yaml b/lldb/test/Shell/SymbolFile/DWARF/incomplete-member-beyond-parent-bounds.yaml
new file mode 100644
index 0000000000000..a032132ebc5c4
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/incomplete-member-beyond-parent-bounds.yaml
@@ -0,0 +1,102 @@
+# TODO
+#
+# DW_TAG_compile_unit
+# DW_AT_name ("main.cpp")
+# DW_AT_language (DW_LANG_C)
+#
+# DW_TAG_structure_type
+# DW_AT_name ("Incomplete")
+# DW_AT_external (true)
+#
+# DW_TAG_structure_type
+# DW_AT_name ("Foo")
+# DW_AT_byte_size (0x04)
+#
+# DW_TAG_member
+# DW_AT_name ("mem")
+# DW_AT_data_member_location ("0x04")
+# DW_AT_type (0x00000011 "Incomplete")
+#
+# NULL
+#
+# NULL
+
+# RUN: yaml2obj %s > %t
+# RUN: lldb-test symbols --name=Foo --find=type %t | FileCheck %s
+
+# CHECK: error: member-beyond-parent-bounds.yaml.tmp {{.*}}: DW_TAG_member 'mem' refers to type 0x0000000000000011 which extends beyond the bounds of 0x0000002b
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+DWARF:
+ debug_str:
+ - main.cpp
+ - Incomplete
+ - Foo
+ - mem
+ debug_abbrev:
+ - ID: 0
+ Table:
+ - Code: 0x1
+ Tag: DW_TAG_compile_unit
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_language
+ Form: DW_FORM_udata
+ - Code: 0x2
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_external
+ Form: DW_FORM_flag_present
+ - Code: 0x3
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_byte_size
+ Form: DW_FORM_data1
+ - Code: 0x4
+ Tag: DW_TAG_member
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Attribute: DW_AT_data_member_location
+ Form: DW_FORM_data1
+ debug_info:
+ - Version: 4
+ AbbrevTableID: 0
+ AbbrOffset: 0x0
+ AddrSize: 8
+ Entries:
+ - AbbrCode: 0x1
+ Values:
+ - Value: 0x0
+ - Value: 0x2
+ - AbbrCode: 0x2
+ Values:
+ - Value: 0x9
+ - AbbrCode: 0x3
+ Values:
+ - Value: 0x14
+ - Value: 0x04
+ - AbbrCode: 0x4
+ Values:
+ - Value: 0x18
+ - Value: 0x11
+ - Value: 0x04
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
+...
diff --git a/lldb/test/Shell/SymbolFile/DWARF/member-beyond-parent-bounds.yaml b/lldb/test/Shell/SymbolFile/DWARF/member-beyond-parent-bounds.yaml
new file mode 100644
index 0000000000000..ceb0cac82d5ef
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/member-beyond-parent-bounds.yaml
@@ -0,0 +1,107 @@
+# TODO
+#
+# DW_TAG_compile_unit
+# DW_AT_name ("main.cpp")
+# DW_AT_language (DW_LANG_C)
+#
+# DW_TAG_base_type
+# DW_AT_name ("int")
+# DW_AT_encoding (DW_ATE_signed_char)
+# DW_AT_byte_size (0x04)
+#
+# DW_TAG_structure_type
+# DW_AT_name ("Foo")
+# DW_AT_byte_size (0x04)
+#
+# DW_TAG_member
+# DW_AT_name ("mem")
+# DW_AT_data_member_location ("0x04")
+# DW_AT_type (0x00000011 "int")
+#
+# NULL
+#
+# NULL
+
+# RUN: yaml2obj %s > %t
+# RUN: lldb-test symbols --name=Foo --find=type %t | FileCheck %s
+
+# CHECK: error: member-beyond-parent-bounds.yaml.tmp {{.*}}: DW_TAG_member 'mem' refers to type 0x0000000000000011 which extends beyond the bounds of 0x0000002b
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+DWARF:
+ debug_str:
+ - main.cpp
+ - int
+ - Foo
+ - mem
+ debug_abbrev:
+ - ID: 0
+ Table:
+ - Code: 0x1
+ Tag: DW_TAG_compile_unit
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_language
+ Form: DW_FORM_udata
+ - Code: 0x2
+ Tag: DW_TAG_base_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_encoding
+ Form: DW_FORM_data1
+ - Attribute: DW_AT_byte_size
+ Form: DW_FORM_data1
+ - Code: 0x3
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_byte_size
+ Form: DW_FORM_data1
+ - Code: 0x4
+ Tag: DW_TAG_member
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Attribute: DW_AT_data_member_location
+ Form: DW_FORM_data1
+ debug_info:
+ - Version: 4
+ AbbrevTableID: 0
+ AbbrOffset: 0x0
+ AddrSize: 8
+ Entries:
+ - AbbrCode: 0x1
+ Values:
+ - Value: 0x0
+ - Value: 0x2
+ - AbbrCode: 0x2
+ Values:
+ - Value: 0x9
+ - Value: 0x6
+ - Value: 0x4
+ - AbbrCode: 0x3
+ Values:
+ - Value: 0x0d
+ - Value: 0x04
+ - AbbrCode: 0x4
+ Values:
+ - Value: 0x11
+ - Value: 0x11
+ - Value: 0x04
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
+...
diff --git a/lldb/test/Shell/SymbolFile/DWARF/zero-sized-member-in-parent-bounds.yaml b/lldb/test/Shell/SymbolFile/DWARF/zero-sized-member-in-parent-bounds.yaml
new file mode 100644
index 0000000000000..de1e31bf48f23
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/zero-sized-member-in-parent-bounds.yaml
@@ -0,0 +1,103 @@
+# TODO
+#
+# DW_TAG_compile_unit
+# DW_AT_name ("main.cpp")
+# DW_AT_language (DW_LANG_C)
+#
+# DW_TAG_structure_type
+# DW_AT_name ("Bar")
+# DW_AT_byte_size (0x00)
+#
+# DW_TAG_structure_type
+# DW_AT_name ("Foo")
+# DW_AT_byte_size (0x04)
+#
+# DW_TAG_member
+# DW_AT_name ("mem")
+# DW_AT_data_member_location ("0x04")
+# DW_AT_type (0x00000011 "Bar")
+#
+# NULL
+#
+# NULL
+
+# RUN: yaml2obj %s > %t
+# RUN: lldb-test symbols --name=Foo --find=type %t | FileCheck %s
+
+# CHECK: error: member-beyond-parent-bounds.yaml.tmp {{.*}}: DW_TAG_member 'mem' refers to type 0x0000000000000011 which extends beyond the bounds of 0x0000002b
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+DWARF:
+ debug_str:
+ - main.cpp
+ - Bar
+ - Foo
+ - mem
+ debug_abbrev:
+ - ID: 0
+ Table:
+ - Code: 0x1
+ Tag: DW_TAG_compile_unit
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_language
+ Form: DW_FORM_udata
+ - Code: 0x2
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_byte_size
+ Form: DW_FORM_data1
+ - Code: 0x3
+ Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_byte_size
+ Form: DW_FORM_data1
+ - Code: 0x4
+ Tag: DW_TAG_member
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_strp
+ - Attribute: DW_AT_type
+ Form: DW_FORM_ref4
+ - Attribute: DW_AT_data_member_location
+ Form: DW_FORM_data1
+ debug_info:
+ - Version: 4
+ AbbrevTableID: 0
+ AbbrOffset: 0x0
+ AddrSize: 8
+ Entries:
+ - AbbrCode: 0x1
+ Values:
+ - Value: 0x0
+ - Value: 0x2
+ - AbbrCode: 0x2
+ Values:
+ - Value: 0x9
+ - Value: 0x0
+ - AbbrCode: 0x3
+ Values:
+ - Value: 0x0d
+ - Value: 0x04
+ - AbbrCode: 0x4
+ Values:
+ - Value: 0x11
+ - Value: 0x11
+ - Value: 0x04
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
+...
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