[DebugInfo] Add expression decoding for DW_OP_implicit_pointer

[jryans]

This allows llvm-dwarfdump to decode the DWARF 5 opcode DW_OP_implicit_pointer (0xa0). GCC makes use of this opcode in recent versions. LLVM contains some (unfinished) support as well. With existing usage in the ecosystem, adding decoding support here seems reasonable.

[llvmbot]

@llvm/pr-subscribers-debuginfo

Author: J. Ryan Stinnett (jryans)

Changes

This allows llvm-dwarfdump to decode the DWARF 5 opcode DW_OP_implicit_pointer (0xa0). GCC makes use of this opcode in recent versions. LLVM contains some (unfinished) support as well. With existing usage in the ecosystem, adding decoding support here seems reasonable.

---

Full diff: https://github.com/llvm/llvm-project/pull/102923.diff

3 Files Affected:

• (modified) llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp (+2-5)
• (modified) llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp (+2)
• (added) llvm/test/tools/llvm-dwarfdump/X86/DW_OP_implicit_pointer.yaml (+87)

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp index 00c2823cee0af9..6cb4c1ac01fbb0 100644 --- a/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp +++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp @@ -113,11 +113,8 @@ static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts, ArrayRef<uint8_t> Data, bool IsLittleEndian, unsigned AddressSize, DWARFUnit *U) { DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize); - // Note. We do not pass any format to DWARFExpression, even if the - // corresponding unit is known. For now, there is only one operation, - // DW_OP_call_ref, which depends on the format; it is rarely used, and - // is unexpected in location tables. - DWARFExpression(Extractor, AddressSize).print(OS, DumpOpts, U); + DWARFExpression(Extractor, AddressSize, U->getFormat()) + .print(OS, DumpOpts, U); } bool DWARFLocationTable::dumpLocationList( diff --git a/llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp b/llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp index b90addbfba04af..2ae5ff3efc8c5f 100644 --- a/llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp +++ b/llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp @@ -90,6 +90,8 @@ static std::vector<Desc> getOpDescriptions() { Descriptions[DW_OP_implicit_value] = Desc(Op::Dwarf4, Op::SizeLEB, Op::SizeBlock); Descriptions[DW_OP_stack_value] = Desc(Op::Dwarf4); + Descriptions[DW_OP_implicit_pointer] = + Desc(Op::Dwarf5, Op::SizeRefAddr, Op::SignedSizeLEB); Descriptions[DW_OP_addrx] = Desc(Op::Dwarf5, Op::SizeLEB); Descriptions[DW_OP_constx] = Desc(Op::Dwarf5, Op::SizeLEB); Descriptions[DW_OP_entry_value] = Desc(Op::Dwarf5, Op::SizeLEB); diff --git a/llvm/test/tools/llvm-dwarfdump/X86/DW_OP_implicit_pointer.yaml b/llvm/test/tools/llvm-dwarfdump/X86/DW_OP_implicit_pointer.yaml new file mode 100644 index 00000000000000..04c35da34658a9 --- /dev/null +++ b/llvm/test/tools/llvm-dwarfdump/X86/DW_OP_implicit_pointer.yaml @@ -0,0 +1,87 @@ +# Test that we can decode `DW_OP_implicit_pointer` (0xa0) +# RUN: yaml2obj %s | llvm-dwarfdump - | FileCheck %s + +# CHECK: DW_TAG_variable +# CHECK-NEXT: DW_AT_location (DW_OP_implicit_pointer 0x2a +0) + +--- !ELF +FileHeader: + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_DYN + Machine: EM_X86_64 +DWARF: + debug_abbrev: + - Table: + - Code: 0x00000001 + Tag: DW_TAG_compile_unit + Children: DW_CHILDREN_yes + Attributes: + - Attribute: DW_AT_language + Form: DW_FORM_data2 + - Attribute: DW_AT_low_pc + Form: DW_FORM_addr + - Attribute: DW_AT_high_pc + Form: DW_FORM_data4 + - Code: 0x00000002 + Tag: DW_TAG_subprogram + Children: DW_CHILDREN_yes + Attributes: + - Attribute: DW_AT_low_pc + Form: DW_FORM_addr + - Attribute: DW_AT_high_pc + Form: DW_FORM_data4 + - Attribute: DW_AT_frame_base + Form: DW_FORM_exprloc + - Code: 0x00000003 + Tag: DW_TAG_formal_parameter + Children: DW_CHILDREN_no + Attributes: + - Attribute: DW_AT_location + Form: DW_FORM_exprloc + - Code: 0x00000004 + Tag: DW_TAG_variable + Children: DW_CHILDREN_no + Attributes: + - Attribute: DW_AT_location + Form: DW_FORM_exprloc + debug_info: + - Length: 52 + Version: 5 + UnitType: DW_UT_compile + AbbrOffset: 0 + AddrSize: 8 + Entries: + - AbbrCode: 0x00000001 + Values: + - Value: 0x000000000000000C + - Value: 0x0000000100000F50 + - Value: 0x0000000000000034 + - AbbrCode: 0x00000002 + Values: + - Value: 0x0000000100000F50 + - Value: 0x0000000000000034 + - Value: 0x0000000000000001 + BlockData: + - 0x56 + - AbbrCode: 0x00000003 + Values: + - Value: 0x0000000000000002 + BlockData: + - 0x91 + - 0x78 + - AbbrCode: 0x00000004 + Values: + - Value: 0x0000000000000006 + BlockData: + - 0xa0 + - 0x2a + - 0x00 + - 0x00 + - 0x00 + - 0x00 + - AbbrCode: 0x00000000 + Values: + - AbbrCode: 0x00000000 + Values: +... 

[jryans]

Thanks for review! 😄 I believe all comments are addressed now.