https://github.com/firmiana402 created https://github.com/llvm/llvm-project/pull/208478
This PR fixes a DW_OP_convert issue where LLDB derives the conversion width from DW_AT_byte_size * 8 before considering DW_AT_bit_size, #208203 For base types that carry both DW_AT_byte_size and DW_AT_bit_size, such as C _BitInt(31), DW_AT_bit_size describes the actual value width. LLDB should therefore prefer DW_AT_bit_size when it is present, and only fall back to DW_AT_byte_size otherwise. ## Tests Extended DWARFExpression.DW_OP_convert coverage with a base type that has both DW_AT_byte_size and DW_AT_bit_size, and verifies that the conversion uses the DW_AT_bit_size width. >From b1c7afeed41aa3ff91eaadd752a9d78b5c13d277 Mon Sep 17 00:00:00 2001 From: firmiana402 <[email protected]> Date: Thu, 9 Jul 2026 22:36:44 +0800 Subject: [PATCH] [lldb] Prefer DW_AT_bit_size for DW_OP_convert type width --- .../Plugins/SymbolFile/DWARF/DWARFUnit.cpp | 4 ++-- .../Expression/DWARFExpressionTest.cpp | 23 +++++++++++++++++++ 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp index 4b02124e987e8..974e0f6f875f5 100644 --- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp +++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp @@ -726,9 +726,9 @@ DWARFUnit::GetDIEBitSizeAndSign(uint64_t relative_die_offset) const { return llvm::createStringError("cannot resolve DW_OP_convert type DIE"); uint64_t encoding = die.GetAttributeValueAsUnsigned(DW_AT_encoding, DW_ATE_hi_user); - uint64_t bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8; + uint64_t bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0); if (!bit_size) - bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0); + bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8; if (!bit_size) return llvm::createStringError("unsupported type size"); bool sign; diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp index 75162ca0b5f3e..6609c9da51bb0 100644 --- a/lldb/unittests/Expression/DWARFExpressionTest.cpp +++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp @@ -445,6 +445,16 @@ TEST(DWARFExpression, DW_OP_convert) { Form: DW_FORM_data1 - Attribute: DW_AT_byte_size Form: DW_FORM_data1 + - Code: 0x00000003 + Tag: DW_TAG_base_type + Children: DW_CHILDREN_no + Attributes: + - Attribute: DW_AT_encoding + Form: DW_FORM_data1 + - Attribute: DW_AT_byte_size + Form: DW_FORM_data1 + - Attribute: DW_AT_bit_size + Form: DW_FORM_data1 debug_info: - Version: 4 AddrSize: 8 @@ -493,6 +503,12 @@ TEST(DWARFExpression, DW_OP_convert) { Values: - Value: 0x000000000000000b # DW_ATE_numeric_string - Value: 0x0000000000000001 + # 0x00000020: + - AbbrCode: 0x00000003 + Values: + - Value: 0x0000000000000005 # DW_ATE_signed + - Value: 0x0000000000000004 + - Value: 0x000000000000001f - AbbrCode: 0x00000000 )"; @@ -502,6 +518,7 @@ TEST(DWARFExpression, DW_OP_convert) { uint8_t offs_sint64_t = 0x00000014; uint8_t offs_uchar = 0x00000017; uint8_t offs_schar = 0x0000001a; + uint8_t offs_sint31_t = 0x00000020; DWARFExpressionTester t(yamldata, /*cu_index=*/1); ASSERT_TRUE((bool)t.GetDwarfUnit()); @@ -555,6 +572,12 @@ TEST(DWARFExpression, DW_OP_convert) { offs_schar, DW_OP_stack_value}), ExpectScalar(8, 'A', is_signed)); + // Prefer DW_AT_bit_size over DW_AT_byte_size when both are present. + EXPECT_THAT_EXPECTED( + t.Eval({DW_OP_const4u, 0x00, 0x00, 0x00, 0x40, DW_OP_convert, + offs_sint31_t, DW_OP_stack_value}), + ExpectScalar(31, 0x40000000, is_signed)); + // // Errors. // _______________________________________________ lldb-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
