Sure, b5cf892651812003e64c4a8f0dbf81f74a499016
On Mon, Jan 27, 2020 at 12:18 AM Raphael Isemann <risem...@apple.com> wrote: > > This commit fixes a *very* frequent crash when debugging Clang with LLDB 10. > Could we get that cherry-picked into the 10.x branch? > > I’ve been running the patch since more than a week and I haven’t found any > issues with it and the bots are also happy. > > Thanks! > - Raphael > > > On 23. Jan 2020, at 23:46, via lldb-commits <lldb-commits@lists.llvm.org> > > wrote: > > > > > > Author: shafik > > Date: 2020-01-23T14:46:24-08:00 > > New Revision: fcaf5f6c01a09f23b948afb8c91c4dd951d4525e > > > > URL: > > https://github.com/llvm/llvm-project/commit/fcaf5f6c01a09f23b948afb8c91c4dd951d4525e > > DIFF: > > https://github.com/llvm/llvm-project/commit/fcaf5f6c01a09f23b948afb8c91c4dd951d4525e.diff > > > > LOG: [LLDB] Fix the handling of unnamed bit-fields when parsing DWARF > > > > We ran into an assert when debugging clang and performing an expression on > > a class derived from DeclContext. The assert was indicating we were getting > > the offsets wrong for RecordDeclBitfields. We were getting both the size > > and offset of unnamed bit-field members wrong. We could fix this case with > > a quick change but as I extended the test suite to include more > > combinations we kept finding more cases that were being handled > > incorrectly. A fix that handled all the new cases as well as the cases > > already covered required a refactor of the existing technique. > > > > Differential Revision: https://reviews.llvm.org/D72953 > > > > Added: > > lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/Makefile > > > > lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/TestCppBitfields.py > > lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp > > > > Modified: > > lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp > > lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h > > > > Removed: > > > > > > > > ################################################################################ > > diff --git > > a/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/Makefile > > b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/Makefile > > new file mode 100644 > > index 000000000000..99998b20bcb0 > > --- /dev/null > > +++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/Makefile > > @@ -0,0 +1,3 @@ > > +CXX_SOURCES := main.cpp > > + > > +include Makefile.rules > > > > diff --git > > a/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/TestCppBitfields.py > > > > b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/TestCppBitfields.py > > new file mode 100644 > > index 000000000000..696e5647f13f > > --- /dev/null > > +++ > > b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/TestCppBitfields.py > > @@ -0,0 +1,105 @@ > > +"""Show bitfields and check that they display correctly.""" > > + > > +import lldb > > +from lldbsuite.test.decorators import * > > +from lldbsuite.test.lldbtest import * > > +from lldbsuite.test import lldbutil > > + > > + > > +class CppBitfieldsTestCase(TestBase): > > + > > + mydir = TestBase.compute_mydir(__file__) > > + > > + 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. > > + self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT, > > + substrs=['stopped', > > + 'stop reason = breakpoint']) > > + > > + # The breakpoint should have a hit count of 1. > > + self.expect("breakpoint list -f", BREAKPOINT_HIT_ONCE, > > + substrs=[' resolved, hit count = 1']) > > + > > + self.expect("expr (lba.a)", VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=['unsigned int', '2']) > > + self.expect("expr (lbb.b)", VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=['unsigned int', '3']) > > + self.expect("expr (lbc.c)", VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=['unsigned int', '4']) > > + self.expect("expr (lbd.a)", VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=['unsigned int', '5']) > > + self.expect("expr (clang_example.f.a)", > > VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=['uint64_t', '1']) > > + > > + self.expect( > > + "frame variable --show-types lba", > > + VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=[ > > + '(int:32) = ', > > + '(unsigned int:20) a = 2', > > + ]) > > + > > + self.expect( > > + "frame variable --show-types lbb", > > + VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=[ > > + '(unsigned int:1) a = 1', > > + '(int:31) =', > > + '(unsigned int:20) b = 3', > > + ]) > > + > > + self.expect( > > + "frame variable --show-types lbc", > > + VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=[ > > + '(int:22) =', > > + '(unsigned int:1) a = 1', > > + '(unsigned int:1) b = 0', > > + '(unsigned int:5) c = 4', > > + '(unsigned int:1) d = 1', > > + '(int:2) =', > > + '(unsigned int:20) e = 20', > > + ]) > > + > > + self.expect( > > + "frame variable --show-types lbd", > > + VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=[ > > + '(char [3]) arr = "abc"', > > + '(int:32) =', > > + '(unsigned int:20) a = 5', > > + ]) > > + > > + self.expect( > > + "frame variable --show-types clang_example", > > + VARIABLES_DISPLAYED_CORRECTLY, > > + substrs=[ > > + '(int:22) =', > > + '(uint64_t:1) a = 1', > > + '(uint64_t:1) b = 0', > > + '(uint64_t:1) c = 1', > > + '(uint64_t:1) d = 0', > > + '(uint64_t:1) e = 1', > > + '(uint64_t:1) f = 0', > > + '(uint64_t:1) g = 1', > > + '(uint64_t:1) h = 0', > > + '(uint64_t:1) i = 1', > > + '(uint64_t:1) j = 0', > > + '(uint64_t:1) k = 1', > > + ]) > > + > > > > diff --git > > a/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp > > b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp > > new file mode 100644 > > index 000000000000..975c0f05683c > > --- /dev/null > > +++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp > > @@ -0,0 +1,81 @@ > > +#include <stdint.h> > > + > > +int main(int argc, char const *argv[]) { > > + struct LargeBitsA { > > + unsigned int : 30, a : 20; > > + } lba; > > + > > + struct LargeBitsB { > > + unsigned int a : 1, : 11, : 12, b : 20; > > + } lbb; > > + > > + struct LargeBitsC { > > + unsigned int : 13, : 9, a : 1, b : 1, c : 5, d : 1, e : 20; > > + } lbc; > > + > > + struct LargeBitsD { > > + char arr[3]; > > + unsigned int : 30, a : 20; > > + } lbd; > > + > > + // This case came up when debugging clang and models RecordDeclBits > > + struct BitExampleFromClangDeclContext { > > + class fields { > > + uint64_t : 13; > > + uint64_t : 9; > > + > > + uint64_t a: 1; > > + uint64_t b: 1; > > + uint64_t c: 1; > > + uint64_t d: 1; > > + uint64_t e: 1; > > + uint64_t f: 1; > > + uint64_t g: 1; > > + uint64_t h: 1; > > + uint64_t i: 1; > > + uint64_t j: 1; > > + uint64_t k: 1; > > + > > + // In order to reproduce the crash for this case we need the > > + // members of fields to stay private :-( > > + friend struct BitExampleFromClangDeclContext; > > + }; > > + > > + union { > > + struct fields f; > > + }; > > + > > + BitExampleFromClangDeclContext() { > > + f.a = 1; > > + f.b = 0; > > + f.c = 1; > > + f.d = 0; > > + f.e = 1; > > + f.f = 0; > > + f.g = 1; > > + f.h = 0; > > + f.i = 1; > > + f.j = 0; > > + f.k = 1; > > + } > > + } clang_example; > > + > > + lba.a = 2; > > + > > + lbb.a = 1; > > + lbb.b = 3; > > + > > + lbc.a = 1; > > + lbc.b = 0; > > + lbc.c = 4; > > + lbc.d = 1; > > + lbc.e = 20; > > + > > + lbd.arr[0] = 'a'; > > + lbd.arr[1] = 'b'; > > + lbd.arr[2] = 'c'; > > + lbd.a = 5; > > + > > + > > + return 0; // Set break point at this line. > > +} > > > > diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp > > b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp > > index 1aa82ab67ce6..7a610e042b48 100644 > > --- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp > > +++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp > > @@ -85,35 +85,6 @@ static bool DeclKindIsCXXClass(clang::Decl::Kind > > decl_kind) { > > return false; > > } > > > > -struct BitfieldInfo { > > - uint64_t bit_size; > > - uint64_t bit_offset; > > - > > - BitfieldInfo() > > - : bit_size(LLDB_INVALID_ADDRESS), bit_offset(LLDB_INVALID_ADDRESS) {} > > - > > - void Clear() { > > - bit_size = LLDB_INVALID_ADDRESS; > > - bit_offset = LLDB_INVALID_ADDRESS; > > - } > > - > > - bool IsValid() const { > > - return (bit_size != LLDB_INVALID_ADDRESS) && > > - (bit_offset != LLDB_INVALID_ADDRESS); > > - } > > - > > - bool NextBitfieldOffsetIsValid(const uint64_t next_bit_offset) const { > > - if (IsValid()) { > > - // This bitfield info is valid, so any subsequent bitfields must not > > - // overlap and must be at a higher bit offset than any previous > > bitfield > > - // + size. > > - return (bit_size + bit_offset) <= next_bit_offset; > > - } else { > > - // If the this BitfieldInfo is not valid, then any offset isOK > > - return true; > > - } > > - } > > -}; > > > > ClangASTImporter &DWARFASTParserClang::GetClangASTImporter() { > > if (!m_clang_ast_importer_up) { > > @@ -2419,7 +2390,7 @@ void DWARFASTParserClang::ParseSingleMember( > > lldb::AccessType &default_accessibility, > > DelayedPropertyList &delayed_properties, > > lldb_private::ClangASTImporter::LayoutInfo &layout_info, > > - BitfieldInfo &last_field_info) { > > + FieldInfo &last_field_info) { > > ModuleSP module_sp = parent_die.GetDWARF()->GetObjectFile()->GetModule(); > > const dw_tag_t tag = die.Tag(); > > // Get the parent byte size so we can verify any members will fit > > @@ -2453,6 +2424,14 @@ void DWARFASTParserClang::ParseSingleMember( > > const dw_attr_t attr = attributes.AttributeAtIndex(i); > > DWARFFormValue form_value; > > if (attributes.ExtractFormValueAtIndex(i, form_value)) { > > + // DW_AT_data_member_location indicates the byte offset of the > > + // word from the base address of the structure. > > + // > > + // DW_AT_bit_offset indicates how many bits into the word > > + // (according to the host endianness) the low-order bit of the > > + // field starts. AT_bit_offset can be negative. > > + // > > + // DW_AT_bit_size indicates the size of the field in bits. > > switch (attr) { > > case DW_AT_name: > > name = form_value.AsCString(); > > @@ -2603,36 +2582,24 @@ void DWARFASTParserClang::ParseSingleMember( > > Type *member_type = die.ResolveTypeUID(encoding_form.Reference()); > > > > clang::FieldDecl *field_decl = nullptr; > > + const uint64_t character_width = 8; > > + const uint64_t word_width = 32; > > if (tag == DW_TAG_member) { > > if (member_type) { > > + CompilerType member_clang_type = > > member_type->GetLayoutCompilerType(); > > + > > if (accessibility == eAccessNone) > > accessibility = default_accessibility; > > member_accessibilities.push_back(accessibility); > > > > uint64_t field_bit_offset = > > (member_byte_offset == UINT32_MAX ? 0 : (member_byte_offset * > > 8)); > > - if (bit_size > 0) { > > > > - BitfieldInfo this_field_info; > > + if (bit_size > 0) { > > + FieldInfo this_field_info; > > this_field_info.bit_offset = field_bit_offset; > > this_field_info.bit_size = bit_size; > > > > - ///////////////////////////////////////////////////////////// > > - // How to locate a field given the DWARF debug information > > - // > > - // AT_byte_size indicates the size of the word in which the bit > > - // offset must be interpreted. > > - // > > - // AT_data_member_location indicates the byte offset of the > > - // word from the base address of the structure. > > - // > > - // AT_bit_offset indicates how many bits into the word > > - // (according to the host endianness) the low-order bit of the > > - // field starts. AT_bit_offset can be negative. > > - // > > - // AT_bit_size indicates the size of the field in bits. > > - ///////////////////////////////////////////////////////////// > > - > > if (data_bit_offset != UINT64_MAX) { > > this_field_info.bit_offset = data_bit_offset; > > } else { > > @@ -2649,8 +2616,9 @@ void DWARFASTParserClang::ParseSingleMember( > > } > > > > if ((this_field_info.bit_offset >= parent_bit_size) || > > - !last_field_info.NextBitfieldOffsetIsValid( > > - this_field_info.bit_offset)) { > > + (last_field_info.IsBitfield() && > > + !last_field_info.NextBitfieldOffsetIsValid( > > + this_field_info.bit_offset))) { > > ObjectFile *objfile = die.GetDWARF()->GetObjectFile(); > > objfile->GetModule()->ReportWarning( > > "0x%8.8" PRIx64 ": %s bitfield named \"%s\" has invalid " > > @@ -2659,40 +2627,12 @@ void DWARFASTParserClang::ParseSingleMember( > > "compiler and include the preprocessed output for %s\n", > > die.GetID(), DW_TAG_value_to_name(tag), name, > > this_field_info.bit_offset, > > GetUnitName(parent_die).c_str()); > > - this_field_info.Clear(); > > return; > > } > > > > // Update the field bit offset we will report for layout > > field_bit_offset = this_field_info.bit_offset; > > > > - // If the member to be emitted did not start on a character > > - // boundary and there is empty space between the last field and > > - // this one, then we need to emit an anonymous member filling > > - // up the space up to its start. There are three cases here: > > - // > > - // 1 If the previous member ended on a character boundary, then > > - // we can emit an > > - // anonymous member starting at the most recent character > > - // boundary. > > - // > > - // 2 If the previous member did not end on a character boundary > > - // and the distance > > - // from the end of the previous member to the current member > > - // is less than a > > - // word width, then we can emit an anonymous member starting > > - // right after the > > - // previous member and right before this member. > > - // > > - // 3 If the previous member did not end on a character boundary > > - // and the distance > > - // from the end of the previous member to the current member > > - // is greater than > > - // or equal a word width, then we act as in Case 1. > > - > > - const uint64_t character_width = 8; > > - const uint64_t word_width = 32; > > - > > // Objective-C has invalid DW_AT_bit_offset values in older > > // versions of clang, so we have to be careful and only insert > > // unnamed bitfields if we have a new enough clang. > > @@ -2704,53 +2644,57 @@ void DWARFASTParserClang::ParseSingleMember( > > die.GetCU()->Supports_unnamed_objc_bitfields(); > > > > if (detect_unnamed_bitfields) { > > - BitfieldInfo anon_field_info; > > - > > - if ((this_field_info.bit_offset % character_width) != > > - 0) // not char aligned > > - { > > - uint64_t last_field_end = 0; > > - > > - if (last_field_info.IsValid()) > > - last_field_end = > > - last_field_info.bit_offset + > > last_field_info.bit_size; > > - > > - if (this_field_info.bit_offset != last_field_end) { > > - if (((last_field_end % character_width) == 0) || // case > > 1 > > - (this_field_info.bit_offset - last_field_end >= > > - word_width)) // case 3 > > - { > > - anon_field_info.bit_size = > > - this_field_info.bit_offset % character_width; > > - anon_field_info.bit_offset = > > - this_field_info.bit_offset - > > anon_field_info.bit_size; > > - } else // case 2 > > - { > > - anon_field_info.bit_size = > > - this_field_info.bit_offset - last_field_end; > > - anon_field_info.bit_offset = last_field_end; > > - } > > - } > > + clang::Optional<FieldInfo> unnamed_field_info; > > + uint64_t last_field_end = 0; > > + > > + 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 (anon_field_info.IsValid()) { > > + // If we have a gap between the last_field_end and the > > current > > + // field we have an unnamed bit-field > > + if (this_field_info.bit_offset != last_field_end && > > + !(this_field_info.bit_offset < last_field_end)) { > > + 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, anon_field_info.bit_size); > > + accessibility, unnamed_field_info->bit_size); > > > > layout_info.field_offsets.insert(std::make_pair( > > - unnamed_bitfield_decl, anon_field_info.bit_offset)); > > + unnamed_bitfield_decl, > > unnamed_field_info->bit_offset)); > > } > > } > > + > > last_field_info = this_field_info; > > + last_field_info.SetIsBitfield(true); > > } else { > > - last_field_info.Clear(); > > + last_field_info.bit_offset = field_bit_offset; > > + > > + if (llvm::Optional<uint64_t> clang_type_size = > > + member_clang_type.GetByteSize(nullptr)) { > > + last_field_info.bit_size = *clang_type_size * > > character_width; > > + } > > + > > + last_field_info.SetIsBitfield(false); > > } > > > > - CompilerType member_clang_type = > > member_type->GetLayoutCompilerType(); > > if (!member_clang_type.IsCompleteType()) > > member_clang_type.GetCompleteType(); > > > > @@ -2885,7 +2829,7 @@ bool DWARFASTParserClang::ParseChildMembers( > > if (!parent_die) > > return false; > > > > - BitfieldInfo last_field_info; > > + FieldInfo last_field_info; > > > > ModuleSP module_sp = parent_die.GetDWARF()->GetObjectFile()->GetModule(); > > TypeSystemClang *ast = > > > > diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h > > b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h > > index 299281876d6c..6cd2dc8bf558 100644 > > --- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h > > +++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h > > @@ -170,33 +170,20 @@ class DWARFASTParserClang : public DWARFASTParser { > > lldb::ModuleSP GetModuleForType(const DWARFDIE &die); > > > > private: > > - struct BitfieldInfo { > > - uint64_t bit_size; > > - uint64_t bit_offset; > > + struct FieldInfo { > > + uint64_t bit_size = 0; > > + uint64_t bit_offset = 0; > > + bool is_bitfield = false; > > > > - BitfieldInfo() > > - : bit_size(LLDB_INVALID_ADDRESS), bit_offset(LLDB_INVALID_ADDRESS) > > {} > > + FieldInfo() = default; > > > > - void Clear() { > > - bit_size = LLDB_INVALID_ADDRESS; > > - bit_offset = LLDB_INVALID_ADDRESS; > > - } > > - > > - bool IsValid() const { > > - return (bit_size != LLDB_INVALID_ADDRESS) && > > - (bit_offset != LLDB_INVALID_ADDRESS); > > - } > > + void SetIsBitfield(bool flag) { is_bitfield = flag; } > > + bool IsBitfield() { return is_bitfield; } > > > > bool NextBitfieldOffsetIsValid(const uint64_t next_bit_offset) const { > > - if (IsValid()) { > > - // This bitfield info is valid, so any subsequent bitfields must > > not > > - // overlap and must be at a higher bit offset than any previous > > bitfield > > - // + size. > > - return (bit_size + bit_offset) <= next_bit_offset; > > - } else { > > - // If the this BitfieldInfo is not valid, then any offset isOK > > - return true; > > - } > > + // Any subsequent bitfields must not overlap and must be at a higher > > + // bit offset than any previous bitfield + size. > > + return (bit_size + bit_offset) <= next_bit_offset; > > } > > }; > > > > @@ -208,7 +195,7 @@ class DWARFASTParserClang : public DWARFASTParser { > > lldb::AccessType &default_accessibility, > > DelayedPropertyList &delayed_properties, > > lldb_private::ClangASTImporter::LayoutInfo &layout_info, > > - BitfieldInfo &last_field_info); > > + FieldInfo &last_field_info); > > > > bool CompleteRecordType(const DWARFDIE &die, lldb_private::Type *type, > > lldb_private::CompilerType &clang_type); > > > > > > > > _______________________________________________ > > lldb-commits mailing list > > lldb-commits@lists.llvm.org > > https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits > _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
