aprantl created this revision.
aprantl added reviewers: jasonmolenda, davide, labath, clayborg.
Herald added a project: LLDB.
aprantl added a reviewer: jakubjelinek.
This patch adds basic support for DW_OP_convert[1] for integer types. Recent
versions of LLVM's optimizer may insert this opcode into DWARF expressions.
DW_OP_convert is effectively a type cast operation that takes a reference to a
base type DIE (or zero) and then casts the value at the top of the DWARF stack
to that type. Internally this works by changing the bit size of the APInt that
is used as backing storage for LLDB's DWARF stack.
I managed to write a unit test for this by implementing a mock YAML object file
/ module that takes debug info sections in yaml2obj format.
[1] Typed DWARF stack. http://www.dwarfstd.org/ShowIssue.php?issue=140425.1
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D67369
Files:
lldb/include/lldb/Core/Section.h
lldb/include/lldb/Utility/Scalar.h
lldb/source/Core/Section.cpp
lldb/source/Expression/DWARFExpression.cpp
lldb/source/Utility/Scalar.cpp
lldb/unittests/Expression/DWARFExpressionTest.cpp
Index: lldb/unittests/Expression/DWARFExpressionTest.cpp
===================================================================
--- lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -7,24 +7,105 @@
//===----------------------------------------------------------------------===//
#include "lldb/Expression/DWARFExpression.h"
+#include "../../source/Plugins/SymbolFile/DWARF/DWARFUnit.h"
+#include "../../source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/Section.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/dwarf.h"
+#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/StreamString.h"
#include "llvm/ADT/StringExtras.h"
+#include "llvm/ObjectYAML/DWARFEmitter.h"
#include "llvm/Testing/Support/Error.h"
#include "gtest/gtest.h"
using namespace lldb_private;
-static llvm::Expected<Scalar> Evaluate(llvm::ArrayRef<uint8_t> expr) {
+/// A mock module holding an object file parsed from YAML.
+class YAMLModule : public lldb_private::Module {
+public:
+ YAMLModule(ArchSpec &arch) : Module(FileSpec("test"), arch) {}
+ void SetObjectFile(lldb::ObjectFileSP obj_file) { m_objfile_sp = obj_file; }
+ ObjectFile *GetObjectFile() override { return m_objfile_sp.get(); }
+};
+
+/// A mock object file that can be parsed from YAML.
+class YAMLObjectFile : public lldb_private::ObjectFile {
+ const lldb::ModuleSP &m_module_sp;
+ llvm::StringMap<std::unique_ptr<llvm::MemoryBuffer>> &m_section_map;
+ /// Because there is only one DataExtractor in the ObjectFile
+ /// interface, all sections are copied into a contiguous buffer.
+ std::vector<char> m_buffer;
+
+public:
+ YAMLObjectFile(const lldb::ModuleSP &module_sp,
+ llvm::StringMap<std::unique_ptr<llvm::MemoryBuffer>> &map)
+ : ObjectFile(module_sp, &module_sp->GetFileSpec(), /*file_offset*/ 0,
+ /*length*/ 0, /*data_sp*/ nullptr, /*data_offset*/ 0),
+ m_module_sp(module_sp), m_section_map(map) {}
+ ConstString GetPluginName() override { return ConstString("YAMLObjectFile"); }
+ uint32_t GetPluginVersion() override { return 0; }
+ void Dump(Stream *s) override {}
+ uint32_t GetAddressByteSize() const override { return 8; }
+ uint32_t GetDependentModules(FileSpecList &file_list) override { return 0; }
+ bool IsExecutable() const override { return 0; }
+ ArchSpec GetArchitecture() override { return {}; }
+
+ void CreateSections(SectionList &unified_section_list) override {
+ lldb::offset_t total_bytes = 0;
+ for (auto &entry : m_section_map)
+ total_bytes += entry.getValue()->getBufferSize();
+ m_buffer.reserve(total_bytes);
+ m_data =
+ DataExtractor(m_buffer.data(), total_bytes, lldb::eByteOrderLittle, 4);
+
+ lldb::user_id_t sect_id = 1;
+ for (auto &entry : m_section_map) {
+ llvm::StringRef name = entry.getKey();
+ lldb::SectionType sect_type =
+ llvm::StringSwitch<lldb::SectionType>(name)
+ .Case("debug_info", lldb::eSectionTypeDWARFDebugInfo)
+ .Case("debug_abbrev", lldb::eSectionTypeDWARFDebugAbbrev);
+ auto &membuf = entry.getValue();
+ lldb::addr_t file_vm_addr = 0;
+ lldb::addr_t vm_size = 0;
+ lldb::offset_t file_offset = m_buffer.size();
+ lldb::offset_t file_size = membuf->getBufferSize();
+ m_buffer.resize(file_offset + file_size);
+ memcpy(m_buffer.data() + file_offset, membuf->getBufferStart(),
+ file_size);
+ uint32_t log2align = 0;
+ uint32_t flags = 0;
+ auto section_sp = std::make_shared<lldb_private::Section>(
+ m_module_sp, this, sect_id++, ConstString(name), sect_type,
+ file_vm_addr, vm_size, file_offset, file_size, log2align, flags);
+ unified_section_list.AddSection(section_sp);
+ }
+ }
+
+ Symtab *GetSymtab() override { return nullptr; }
+ bool IsStripped() override { return false; }
+ UUID GetUUID() override { return {}; }
+ lldb::ByteOrder GetByteOrder() const override {
+ return lldb::eByteOrderLittle;
+ }
+ bool ParseHeader() override { return false; }
+ Type CalculateType() override { return {}; }
+ Strata CalculateStrata() override { return {}; }
+};
+
+static llvm::Expected<Scalar> Evaluate(llvm::ArrayRef<uint8_t> expr,
+ lldb::ModuleSP module_sp = {},
+ DWARFUnit *unit = nullptr) {
DataExtractor extractor(expr.data(), expr.size(), lldb::eByteOrderLittle,
/*addr_size*/ 4);
Value result;
Status status;
if (!DWARFExpression::Evaluate(
- /*exe_ctx*/ nullptr, /*reg_ctx*/ nullptr, /*opcode_ctx*/ nullptr,
- extractor, /*dwarf_cu*/ nullptr, lldb::eRegisterKindLLDB,
+ /*exe_ctx*/ nullptr, /*reg_ctx*/ nullptr, module_sp, extractor, unit,
+ lldb::eRegisterKindLLDB,
/*initial_value_ptr*/ nullptr,
/*object_address_ptr*/ nullptr, result, &status))
return status.ToError();
@@ -32,6 +113,40 @@
return result.GetScalar();
}
+/// Unfortunately Scalar's operator==() is really picky.
+static Scalar GetScalar(unsigned bits, uint64_t value, bool sign) {
+ Scalar scalar;
+ auto type = Scalar::GetBestType(bits, sign);
+ switch (type) {
+ case Scalar::e_sint:
+ scalar = Scalar((int)value);
+ break;
+ case Scalar::e_slong:
+ scalar = Scalar((long)value);
+ break;
+ case Scalar::e_slonglong:
+ scalar = Scalar((long long)value);
+ break;
+ case Scalar::e_uint:
+ scalar = Scalar((unsigned int)value);
+ break;
+ case Scalar::e_ulong:
+ scalar = Scalar((unsigned long)value);
+ break;
+ case Scalar::e_ulonglong:
+ scalar = Scalar((unsigned long long)value);
+ break;
+ default:
+ llvm_unreachable("not implemented");
+ }
+ scalar.TruncOrExtendTo(type, bits);
+ if (sign)
+ scalar.MakeSigned();
+ else
+ scalar.MakeUnsigned();
+ return scalar;
+}
+
TEST(DWARFExpression, DW_OP_pick) {
EXPECT_THAT_EXPECTED(Evaluate({DW_OP_lit1, DW_OP_lit0, DW_OP_pick, 0}),
llvm::HasValue(0));
@@ -40,3 +155,159 @@
EXPECT_THAT_EXPECTED(Evaluate({DW_OP_lit1, DW_OP_lit0, DW_OP_pick, 2}),
llvm::Failed());
}
+
+TEST(DWARFExpression, DW_OP_convert) {
+ const char *yamldata =
+ "debug_abbrev:\n"
+ " - Code: 0x00000001\n"
+ " Tag: DW_TAG_compile_unit\n"
+ " Children: DW_CHILDREN_yes\n"
+ " Attributes:\n"
+ " - Attribute: DW_AT_language\n"
+ " Form: DW_FORM_data2\n"
+ " - Code: 0x00000002\n"
+ " Tag: DW_TAG_base_type\n"
+ " Children: DW_CHILDREN_no\n"
+ " Attributes:\n"
+ " - Attribute: DW_AT_encoding\n"
+ " Form: DW_FORM_data1\n"
+ " - Attribute: DW_AT_byte_size\n"
+ " Form: DW_FORM_data1\n"
+ "debug_info:\n"
+ " - Length:\n"
+ " TotalLength: 0\n"
+ " Version: 4\n"
+ " AbbrOffset: 0\n"
+ " AddrSize: 8\n"
+ " Entries:\n"
+ " - AbbrCode: 0x00000001\n"
+ " Values:\n"
+ " - Value: 0x000000000000000C\n"
+ // 0x0000000e:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x0000000000000007\n" // DW_ATE_unsigned
+ " - Value: 0x0000000000000004\n"
+ // 0x00000011:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x0000000000000007\n" // DW_ATE_unsigned
+ " - Value: 0x0000000000000008\n"
+ // 0x00000014:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x0000000000000005\n" // DW_ATE_signed
+ " - Value: 0x0000000000000008\n"
+ // 0x00000017:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x0000000000000008\n" // DW_ATE_unsigned_char
+ " - Value: 0x0000000000000001\n"
+ // 0x0000001a:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x0000000000000006\n" // DW_ATE_signed_char
+ " - Value: 0x0000000000000001\n"
+ // 0x0000001d:
+ " - AbbrCode: 0x00000002\n"
+ " Values:\n"
+ " - Value: 0x000000000000000b\n" // DW_ATE_numeric_string
+ " - Value: 0x0000000000000001\n"
+ ""
+ " - AbbrCode: 0x00000000\n"
+ " Values: []\n";
+ uint8_t offs_uint32_t = 0x0000000e;
+ uint8_t offs_uint64_t = 0x00000011;
+ uint8_t offs_sint64_t = 0x00000014;
+ uint8_t offs_uchar = 0x00000017;
+ uint8_t offs_schar = 0x0000001a;
+
+ auto sections_map = llvm::DWARFYAML::EmitDebugSections(yamldata, true);
+ ASSERT_TRUE((bool)sections_map);
+ ArchSpec arch("i386-unknown-linux");
+ FileSystem::Initialize();
+ auto module_sp = std::make_shared<YAMLModule>(arch);
+ lldb::ObjectFileSP objfile_sp =
+ std::make_shared<YAMLObjectFile>(module_sp, *sections_map);
+ module_sp->SetObjectFile(objfile_sp);
+ SymbolFileDWARF symfile_dwarf(objfile_sp, nullptr);
+
+ lldb::user_id_t uid = 0;
+ llvm::StringRef raw_debug_info = (*sections_map)["debug_info"]->getBuffer();
+ lldb_private::DataExtractor debug_info(
+ raw_debug_info.data(), raw_debug_info.size(), objfile_sp->GetByteOrder(),
+ objfile_sp->GetAddressByteSize());
+ lldb::offset_t offset_ptr = 0;
+ llvm::Expected<DWARFUnitSP> dwarf_unit = DWARFUnit::extract(
+ symfile_dwarf, uid,
+ *static_cast<lldb_private::DWARFDataExtractor *>(&debug_info),
+ DIERef::DebugInfo, &offset_ptr);
+ ASSERT_TRUE((bool)dwarf_unit);
+ // Constant is given as little-endian.
+ bool is_signed = true;
+ bool not_signed = false;
+
+ // Truncate to default unspecified (pointer-sized) type.
+ EXPECT_THAT_EXPECTED(Evaluate({DW_OP_const8u, 0x11, 0x22, 0x33, 0x44, 0x55,
+ 0x66, 0x77, 0x88, DW_OP_convert, 0x00},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(32, 0x44332211, not_signed)));
+ // Truncate to 32 bits.
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_const8u, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
+ DW_OP_convert, offs_uint32_t},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(32, 0x44332211, not_signed)));
+
+ // Leave as is.
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_const8u, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
+ DW_OP_convert, offs_uint64_t},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(64, 0x8877665544332211, not_signed)));
+
+ // Sign-extend to 64 bits.
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_const4s, 0xcc, 0xdd, 0xee, 0xff, //
+ DW_OP_convert, offs_sint64_t},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(64, 0xffffffffffeeddcc, is_signed)));
+
+ // Truncate to 8 bits.
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_const4s, 'A', 'B', 'C', 'D', 0xee, 0xff, //
+ DW_OP_convert, offs_uchar},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(8, 'A', not_signed)));
+
+ // Also truncate to 8 bits.
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_const4s, 'A', 'B', 'C', 'D', 0xee, 0xff, //
+ DW_OP_convert, offs_schar},
+ module_sp, dwarf_unit->get()),
+ llvm::HasValue(GetScalar(8, 'A', is_signed)));
+
+ //
+ // Errors.
+ //
+
+ // No Module.
+ EXPECT_THAT_ERROR(Evaluate({DW_OP_const1s, 'X', DW_OP_convert, 0x00}, nullptr,
+ dwarf_unit->get())
+ .takeError(),
+ llvm::Failed());
+
+ // No DIE.
+ EXPECT_THAT_ERROR(Evaluate({DW_OP_const1s, 'X', DW_OP_convert, 0x01},
+ module_sp, dwarf_unit->get())
+ .takeError(),
+ llvm::Failed());
+
+ // Unsupported.
+ EXPECT_THAT_ERROR(Evaluate({DW_OP_const1s, 'X', DW_OP_convert, 0x1d}, nullptr,
+ dwarf_unit->get())
+ .takeError(),
+ llvm::Failed());
+
+ FileSystem::Terminate();
+}
Index: lldb/source/Utility/Scalar.cpp
===================================================================
--- lldb/source/Utility/Scalar.cpp
+++ lldb/source/Utility/Scalar.cpp
@@ -416,6 +416,52 @@
Scalar::~Scalar() = default;
+Scalar::Type Scalar::GetBestType(size_t bit_size, bool sign) {
+ // Scalar types are always host types, hence the sizeof().
+ if (sign) {
+ if (bit_size <= sizeof(int)*8) return Scalar::e_sint;
+ if (bit_size <= sizeof(long)*8) return Scalar::e_slong;
+ if (bit_size <= sizeof(long long)*8) return Scalar::e_slonglong;
+ if (bit_size <= 128) return Scalar::e_sint128;
+ if (bit_size <= 256) return Scalar::e_sint256;
+ if (bit_size <= 512) return Scalar::e_sint512;
+ } else {
+ if (bit_size <= sizeof(unsigned int)*8) return Scalar::e_uint;
+ if (bit_size <= sizeof(unsigned long)*8) return Scalar::e_ulong;
+ if (bit_size <= sizeof(unsigned long long)*8) return Scalar::e_ulonglong;
+ if (bit_size <= 128) return Scalar::e_uint128;
+ if (bit_size <= 256) return Scalar::e_uint256;
+ if (bit_size <= 512) return Scalar::e_uint512;
+ }
+ return Scalar::e_void;
+};
+
+void Scalar::TruncOrExtendTo(Scalar::Type type, uint16_t bits) {
+ switch (type) {
+ default:
+ assert(false && "Promoting a Scalar to a specific number of bits is only "
+ "supported for integer types.");
+ break;
+ case e_sint:
+ case e_slong:
+ case e_slonglong:
+ case e_sint128:
+ case e_sint256:
+ case e_sint512:
+ m_integer = m_integer.sextOrTrunc(bits);
+ break;
+ case e_uint:
+ case e_ulong:
+ case e_ulonglong:
+ case e_uint128:
+ case e_uint256:
+ case e_uint512:
+ m_integer = m_integer.zextOrTrunc(bits);
+ break;
+ }
+ m_type = type;
+}
+
bool Scalar::Promote(Scalar::Type type) {
bool success = false;
switch (m_type) {
Index: lldb/source/Expression/DWARFExpression.cpp
===================================================================
--- lldb/source/Expression/DWARFExpression.cpp
+++ lldb/source/Expression/DWARFExpression.cpp
@@ -2559,6 +2559,83 @@
stack.back().SetValueType(Value::eValueTypeScalar);
break;
+ // OPCODE: DW_OP_convert
+ // OPERANDS: 1
+ // A ULEB128 that is either a DIE offset of a
+ // DW_TAG_base_type or 0 for the generic (pointer-sized) type.
+ //
+ // DESCRIPTION: Pop the top stack element, convert it to a
+ // different type, and push the result.
+ case DW_OP_convert: {
+ if (stack.size() < 1) {
+ if (error_ptr)
+ error_ptr->SetErrorString(
+ "Expression stack needs at least 1 item for DW_OP_convert.");
+ return false;
+ }
+ const uint64_t die_offset = opcodes.GetULEB128(&offset);
+ Scalar::Type type = Scalar::e_void;
+ uint64_t bit_size;
+ if (die_offset == 0) {
+ // The generic type has the size of an address on the target
+ // machine and an unspecified signedness. Scalar has no
+ // "unspecified signedness", so we use unsigned types.
+ if (!module_sp) {
+ if (error_ptr)
+ error_ptr->SetErrorString("No module");
+ return false;
+ }
+ bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8;
+ if (!bit_size) {
+ if (error_ptr)
+ error_ptr->SetErrorString("unspecified architecture");
+ return false;
+ }
+ type = Scalar::GetBestType(bit_size, false);
+ } else {
+ // Retrieve the type DIE that the value is being converted to.
+ // FIXME: the constness has annoying ripple effects.
+ DWARFDIE die = const_cast<DWARFUnit *>(dwarf_cu)->GetDIE(die_offset);
+ if (!die) {
+ if (error_ptr)
+ error_ptr->SetErrorString("Cannot resolve DW_OP_convert type DIE");
+ return false;
+ }
+ uint64_t encoding =
+ die.GetAttributeValueAsUnsigned(DW_AT_encoding, DW_ATE_hi_user);
+ bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8;
+ if (!bit_size)
+ bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0);
+ if (!bit_size) {
+ if (error_ptr)
+ error_ptr->SetErrorString("Unsupported type size in DW_OP_convert");
+ return false;
+ }
+ switch (encoding) {
+ case DW_ATE_signed:
+ case DW_ATE_signed_char:
+ type = Scalar::GetBestType(bit_size, true);
+ break;
+ case DW_ATE_unsigned:
+ case DW_ATE_unsigned_char:
+ type = Scalar::GetBestType(bit_size, false);
+ break;
+ default:
+ if (error_ptr)
+ error_ptr->SetErrorString("Unsupported encoding in DW_OP_convert");
+ return false;
+ }
+ }
+ if (type == Scalar::e_void) {
+ if (error_ptr)
+ error_ptr->SetErrorString("Unsupported pointer size");
+ return false;
+ }
+ Scalar &top = stack.back().ResolveValue(exe_ctx);
+ top.TruncOrExtendTo(type, bit_size);
+ break;
+ }
+
// OPCODE: DW_OP_call_frame_cfa
// OPERANDS: None
// DESCRIPTION: Specifies a DWARF expression that pushes the value of
Index: lldb/source/Core/Section.cpp
===================================================================
--- lldb/source/Core/Section.cpp
+++ lldb/source/Core/Section.cpp
@@ -417,10 +417,6 @@
#pragma mark SectionList
-SectionList::SectionList() : m_sections() {}
-
-SectionList::~SectionList() {}
-
SectionList &SectionList::operator=(const SectionList &rhs) {
if (this != &rhs)
m_sections = rhs.m_sections;
Index: lldb/include/lldb/Utility/Scalar.h
===================================================================
--- lldb/include/lldb/Utility/Scalar.h
+++ lldb/include/lldb/Utility/Scalar.h
@@ -98,30 +98,14 @@
}
Scalar(llvm::APInt v) : m_type(), m_float(static_cast<float>(0)) {
m_integer = llvm::APInt(v);
- switch (m_integer.getBitWidth()) {
- case 8:
- case 16:
- case 32:
- m_type = e_sint;
- return;
- case 64:
- m_type = e_slonglong;
- return;
- case 128:
- m_type = e_sint128;
- return;
- case 256:
- m_type = e_sint256;
- return;
- case 512:
- m_type = e_sint512;
- return;
- }
- lldbassert(false && "unsupported bitwidth");
+ m_type = GetBestType(m_integer.getBitWidth(), true);
}
// Scalar(const RegisterValue& reg_value);
virtual ~Scalar();
+ /// Return the most efficient Scalar::Type for the requested size.
+ static Type GetBestType(size_t bit_size, bool sign);
+
bool SignExtend(uint32_t bit_pos);
bool ExtractBitfield(uint32_t bit_size, uint32_t bit_offset);
@@ -154,6 +138,9 @@
return (m_type >= e_sint) && (m_type <= e_long_double);
}
+ /// Convert integer to \p type, limited to \p bits size.
+ void TruncOrExtendTo(Scalar::Type type, uint16_t bits);
+
bool Promote(Scalar::Type type);
bool MakeSigned();
Index: lldb/include/lldb/Core/Section.h
===================================================================
--- lldb/include/lldb/Core/Section.h
+++ lldb/include/lldb/Core/Section.h
@@ -43,9 +43,8 @@
const_iterator begin() { return m_sections.begin(); }
const_iterator end() { return m_sections.end(); }
- SectionList();
-
- ~SectionList();
+ /// Create an empty list.
+ SectionList() = default;
SectionList &operator=(const SectionList &rhs);
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