Author: Felipe de Azevedo Piovezan Date: 2023-07-21T16:42:16-07:00 New Revision: f09f0a6b10765f0993255e52a62268472f586830
URL: https://github.com/llvm/llvm-project/commit/f09f0a6b10765f0993255e52a62268472f586830 DIFF: https://github.com/llvm/llvm-project/commit/f09f0a6b10765f0993255e52a62268472f586830.diff LOG: [lldb] Consider OP_addrx in DWARFExpression::Update_DW_OP_addr This rewrites DW_OP_addrx inside DWARFExpression as an DW_OP_addr so that we can update addresses that are originally located in the debug_addr section. The full discussion behind this can be found in https://discourse.llvm.org/t/dwarfexpression-and-dw-op-addrx/71627/12, but a summary follows. When SymbolFileDWARF::ParseVariableDIE creates DWARFExpressions for variables whose location is an OP_addr, it knows how to remap addresses appropriately in the DebugMap case. It then calls DWARFExpression::Update_DW_OP_addr, which updates the value associated with OP_addr. However, when we have an OP_addrx, the update function does nothing. This makes sense, as the DWARFExpression does not have a mutable view of the debug_addr section. In non-DebugMap flows this is not an issue, as the debug_addr contains the correct addresses of variables. In DebugMap flows, this is problematic because the work done by RelinkOSOAddress is lost. By updating the OP to OP_addr, we can also update the address as required, We also explored the alternative of relinking the debug_addr section when we are initializing OSOs (InitOSO). However, this creates an inconsistent story for users of DWARFExpression::GetLocation_DW_OP_addr. This function returns an address without telling callers whether that address came from an OP_addr or an OP_addrx. If we preemptively relink OP_addrx results without doing the same for OP_addr results, then callers can’t know whether the address they got was an executable address or an object file address. In other words, they can’t know whether they need to call LinkOSOFileAddress on those results or not. This patch addresses the majority of test failures when enabling DWARF 5 for MachO (over 200 test failures). Differential Revision: https://reviews.llvm.org/D155198 Added: Modified: lldb/source/Expression/DWARFExpression.cpp lldb/unittests/Expression/DWARFExpressionTest.cpp Removed: ################################################################################ diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp index b829a6f7c86477..93fcf0579be0b1 100644 --- a/lldb/source/Expression/DWARFExpression.cpp +++ b/lldb/source/Expression/DWARFExpression.cpp @@ -408,13 +408,33 @@ bool DWARFExpression::Update_DW_OP_addr(const DWARFUnit *dwarf_cu, // the heap data so "m_data" will now correctly manage the heap data. m_data.SetData(encoder.GetDataBuffer()); return true; - } else { - const offset_t op_arg_size = - GetOpcodeDataSize(m_data, offset, op, dwarf_cu); - if (op_arg_size == LLDB_INVALID_OFFSET) - break; - offset += op_arg_size; } + if (op == DW_OP_addrx) { + // Replace DW_OP_addrx with DW_OP_addr, since we can't modify the + // read-only debug_addr table. + // Subtract one to account for the opcode. + llvm::ArrayRef data_before_op = m_data.GetData().take_front(offset - 1); + + // Read the addrx index to determine how many bytes it needs. + const lldb::offset_t old_offset = offset; + m_data.GetULEB128(&offset); + if (old_offset == offset) + return false; + llvm::ArrayRef data_after_op = m_data.GetData().drop_front(offset); + + DataEncoder encoder(m_data.GetByteOrder(), m_data.GetAddressByteSize()); + encoder.AppendData(data_before_op); + encoder.AppendU8(DW_OP_addr); + encoder.AppendAddress(file_addr); + encoder.AppendData(data_after_op); + m_data.SetData(encoder.GetDataBuffer()); + return true; + } + const offset_t op_arg_size = + GetOpcodeDataSize(m_data, offset, op, dwarf_cu); + if (op_arg_size == LLDB_INVALID_OFFSET) + break; + offset += op_arg_size; } return false; } diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp index e35f35b369ea1e..b8b5b39422a4f6 100644 --- a/lldb/unittests/Expression/DWARFExpressionTest.cpp +++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp @@ -522,6 +522,11 @@ TEST_F(DWARFExpressionMockProcessTest, WASM_DW_OP_addr_index) { ASSERT_TRUE(evaluate(expr, status, result)) << status.ToError(); ASSERT_EQ(result.GetValueType(), Value::ValueType::LoadAddress); ASSERT_EQ(result.GetScalar().UInt(), 0x5678u); + + ASSERT_TRUE(expr.Update_DW_OP_addr(dwarf_cu, 0xdeadbeef)); + ASSERT_TRUE(evaluate(expr, status, result)) << status.ToError(); + ASSERT_EQ(result.GetValueType(), Value::ValueType::LoadAddress); + ASSERT_EQ(result.GetScalar().UInt(), 0xdeadbeefu); } class CustomSymbolFileDWARF : public SymbolFileDWARF { _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
