[Lldb-commits] [lldb] f0c6d30 - [lldb][DWARFASTParserClang][NFC] Factor out unnamed bitfield creation into helper (#108196)
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Thu Sep 12 00:11:12 PDT 2024
Author: Michael Buch
Date: 2024-09-12T08:11:09+01:00
New Revision: f0c6d30a5d80dd42cb298f857987aa2c8f01e63e
URL: https://github.com/llvm/llvm-project/commit/f0c6d30a5d80dd42cb298f857987aa2c8f01e63e
DIFF: https://github.com/llvm/llvm-project/commit/f0c6d30a5d80dd42cb298f857987aa2c8f01e63e.diff
LOG: [lldb][DWARFASTParserClang][NFC] Factor out unnamed bitfield creation into helper (#108196)
This logic will need adjusting soon for
https://github.com/llvm/llvm-project/pull/108155
This patch pulls out the logic for detecting/creating unnamed bitfields
out of `ParseSingleMember` to make the latter (in my opinion) more
readable. Otherwise we have a large number of similarly named variables
in scope.
Added:
Modified:
lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h
Removed:
################################################################################
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index 4d688f9a1358b2..5b9de6f1566b05 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -2858,7 +2858,6 @@ void DWARFASTParserClang::ParseSingleMember(
}
const uint64_t character_width = 8;
- const uint64_t word_width = 32;
CompilerType member_clang_type = member_type->GetLayoutCompilerType();
const auto accessibility = attrs.accessibility == eAccessNone
@@ -2926,40 +2925,9 @@ void DWARFASTParserClang::ParseSingleMember(
detect_unnamed_bitfields =
die.GetCU()->Supports_unnamed_objc_bitfields();
- if (detect_unnamed_bitfields) {
- std::optional<FieldInfo> unnamed_field_info;
- uint64_t last_field_end =
- last_field_info.bit_offset + last_field_info.bit_size;
-
- if (!last_field_info.IsBitfield()) {
- // The last field was not a bit-field...
- // but if it did take up the entire word then we need to extend
- // last_field_end so the bit-field does not step into the last
- // fields padding.
- if (last_field_end != 0 && ((last_field_end % word_width) != 0))
- last_field_end += word_width - (last_field_end % word_width);
- }
-
- if (ShouldCreateUnnamedBitfield(last_field_info, last_field_end,
- this_field_info, layout_info)) {
- unnamed_field_info = FieldInfo{};
- unnamed_field_info->bit_size =
- this_field_info.bit_offset - last_field_end;
- unnamed_field_info->bit_offset = last_field_end;
- }
-
- if (unnamed_field_info) {
- clang::FieldDecl *unnamed_bitfield_decl =
- TypeSystemClang::AddFieldToRecordType(
- class_clang_type, llvm::StringRef(),
- m_ast.GetBuiltinTypeForEncodingAndBitSize(eEncodingSint,
- word_width),
- accessibility, unnamed_field_info->bit_size);
-
- layout_info.field_offsets.insert(std::make_pair(
- unnamed_bitfield_decl, unnamed_field_info->bit_offset));
- }
- }
+ if (detect_unnamed_bitfields)
+ AddUnnamedBitfieldToRecordTypeIfNeeded(layout_info, class_clang_type,
+ last_field_info, this_field_info);
last_field_info = this_field_info;
last_field_info.SetIsBitfield(true);
@@ -3764,6 +3732,43 @@ bool DWARFASTParserClang::ShouldCreateUnnamedBitfield(
return true;
}
+void DWARFASTParserClang::AddUnnamedBitfieldToRecordTypeIfNeeded(
+ ClangASTImporter::LayoutInfo &class_layout_info,
+ const CompilerType &class_clang_type, const FieldInfo &previous_field,
+ const FieldInfo ¤t_field) {
+ // TODO: get this value from target
+ const uint64_t word_width = 32;
+ uint64_t last_field_end = previous_field.bit_offset + previous_field.bit_size;
+
+ if (!previous_field.IsBitfield()) {
+ // The last field was not a bit-field...
+ // but if it did take up the entire word then we need to extend
+ // last_field_end so the bit-field does not step into the last
+ // fields padding.
+ if (last_field_end != 0 && ((last_field_end % word_width) != 0))
+ last_field_end += word_width - (last_field_end % word_width);
+ }
+
+ // Nothing to be done.
+ if (!ShouldCreateUnnamedBitfield(previous_field, last_field_end,
+ current_field, class_layout_info))
+ return;
+
+ // Place the unnamed bitfield into the gap between the previous field's end
+ // and the current field's start.
+ const uint64_t unnamed_bit_size = current_field.bit_offset - last_field_end;
+ const uint64_t unnamed_bit_offset = last_field_end;
+
+ clang::FieldDecl *unnamed_bitfield_decl =
+ TypeSystemClang::AddFieldToRecordType(
+ class_clang_type, llvm::StringRef(),
+ m_ast.GetBuiltinTypeForEncodingAndBitSize(eEncodingSint, word_width),
+ lldb::AccessType::eAccessPublic, unnamed_bit_size);
+
+ class_layout_info.field_offsets.insert(
+ std::make_pair(unnamed_bitfield_decl, unnamed_bit_offset));
+}
+
void DWARFASTParserClang::ParseRustVariantPart(
DWARFDIE &die, const DWARFDIE &parent_die,
const CompilerType &class_clang_type,
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h
index 2806fbbeb99d24..3809ee912cec6f 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h
@@ -266,7 +266,7 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
FieldInfo() = default;
void SetIsBitfield(bool flag) { is_bitfield = flag; }
- bool IsBitfield() { return is_bitfield; }
+ bool IsBitfield() const { return is_bitfield; }
void SetIsArtificial(bool flag) { is_artificial = flag; }
bool IsArtificial() const { return is_artificial; }
@@ -318,6 +318,35 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
FieldInfo const &this_field_info,
lldb_private::ClangASTImporter::LayoutInfo const &layout_info) const;
+ /// Tries to detect whether \ref class_clang_type contained an unnamed
+ /// bit-field between \ref previous_field and \ref current_field, and if
+ /// so, adds a clang::FieldDecl representing that bit-field to
+ /// \ref class_clang_type.
+ ///
+ /// This is necessary because Clang (and GCC) doesn't emit a DW_TAG_member
+ /// entry for unnamed bit-fields. So we derive it (with some exceptions),
+ /// by checking whether there is a gap between where the storage of a
+ /// DW_TAG_member ended and the subsequent DW_TAG_member began.
+ ///
+ /// \param[in,out] layout_info Layout information of all decls parsed by the
+ /// current parser. Will contain an entry for
+ /// the unnamed bit-field if this function created
+ /// one.
+ ///
+ /// \param[in] class_clang_type The RecordType to which the unnamed bit-field
+ /// will be added (if any).
+ ///
+ /// \param[in] previous_field FieldInfo of the previous DW_TAG_member
+ /// we parsed.
+ ///
+ /// \param[in] current_field FieldInfo of the current DW_TAG_member
+ /// being parsed.
+ ///
+ void AddUnnamedBitfieldToRecordTypeIfNeeded(
+ lldb_private::ClangASTImporter::LayoutInfo &class_layout_info,
+ const lldb_private::CompilerType &class_clang_type,
+ const FieldInfo &previous_field, const FieldInfo ¤t_field);
+
/// Parses a DW_TAG_APPLE_property DIE and appends the parsed data to the
/// list of delayed Objective-C properties.
///
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