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[lldb] Fix block address resolution for functions in multiple sections (#137955)
Continuing the theme from #116777 and #124931, this patch ensures we compute the correct address when a functions is spread across multiple sections. Due to this, it's not sufficient to adjust the offset in the section+offset pair (Address::Slide). We must actually slide the file offset and then recompute the section using the result. I found this out due to a failure to disassemble some parts of the function, so I'm testing with that, although it's likely there are other things that were broken due to this.
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3 files changed

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‎lldb/include/lldb/Symbol/Block.h

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -354,7 +354,12 @@ class Block : public UserID, public SymbolContextScope {
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// Member variables.
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SymbolContextScope &m_parent_scope;
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collection m_children;
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/// Address ranges of this block. They are relative to the function entry
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/// point so one must add/subtract GetFunction().GetAddress().GetFileAddress()
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/// when converting from/to to the AddressRange representation.
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RangeList m_ranges;
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lldb::InlineFunctionInfoSP m_inlineInfoSP; ///< Inlined function information.
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lldb::VariableListSP m_variable_list_sp; ///< The variable list for all local,
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///static and parameter variables

‎lldb/source/Symbol/Block.cpp

Lines changed: 22 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -283,39 +283,43 @@ uint32_t Block::GetRangeIndexContainingAddress(const Address &addr) {
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return m_ranges.FindEntryIndexThatContains(file_addr - func_file_addr);
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}
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static AddressRange ToAddressRange(const Address &func_addr,
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const Block::Range &block_range) {
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assert(func_addr.GetModule());
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return AddressRange(func_addr.GetFileAddress() + block_range.base,
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block_range.size,
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func_addr.GetModule()->GetSectionList());
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}
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bool Block::GetRangeAtIndex(uint32_t range_idx, AddressRange &range) {
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if (range_idx >= m_ranges.GetSize())
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return false;
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290-
Function &function = GetFunction();
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const Range &vm_range = m_ranges.GetEntryRef(range_idx);
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range.GetBaseAddress() = function.GetAddress();
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range.GetBaseAddress().Slide(vm_range.GetRangeBase());
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range.SetByteSize(vm_range.GetByteSize());
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Address addr = GetFunction().GetAddress();
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if (!addr.GetModule())
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return false;
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range = ToAddressRange(addr, m_ranges.GetEntryRef(range_idx));
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return true;
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}
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AddressRanges Block::GetRanges() {
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Address addr = GetFunction().GetAddress();
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if (!addr.GetModule())
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return {};
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AddressRanges ranges;
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Function &function = GetFunction();
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for (size_t i = 0, e = m_ranges.GetSize(); i < e; ++i) {
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ranges.emplace_back();
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auto &range = ranges.back();
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const Range &vm_range = m_ranges.GetEntryRef(i);
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range.GetBaseAddress() = function.GetAddress();
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range.GetBaseAddress().Slide(vm_range.GetRangeBase());
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range.SetByteSize(vm_range.GetByteSize());
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}
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for (size_t i = 0, e = m_ranges.GetSize(); i < e; ++i)
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ranges.push_back(ToAddressRange(addr, m_ranges.GetEntryRef(i)));
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return ranges;
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}
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bool Block::GetStartAddress(Address &addr) {
313-
if (m_ranges.IsEmpty())
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Address func_addr = GetFunction().GetAddress();
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if (!func_addr.GetModule() || m_ranges.IsEmpty())
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return false;
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Function &function = GetFunction();
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addr = function.GetAddress();
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addr.Slide(m_ranges.GetEntryRef(0).GetRangeBase());
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addr = ToAddressRange(func_addr, m_ranges.GetEntryRef(0)).GetBaseAddress();
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return true;
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}
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‎lldb/test/Shell/Commands/command-disassemble-sections.s

Lines changed: 110 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,110 @@
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## Test disassembling of functions which are spread over multiple sections (ELF
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## segments are modelled as LLDB sections).
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# REQUIRES: x86, lld
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# RUN: split-file %s %t
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# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux %t/file.s -o %t/file.o
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# RUN: ld.lld %t/file.o -o %t/file.out -T %t/file.lds
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# RUN: %lldb %t/file.out -o "disassemble --name func1" -o exit | FileCheck %s
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# CHECK: (lldb) disassemble --name func1
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# CHECK: file.out`func1:
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# CHECK-NEXT: file.out[0x0] <+0>: int $0x2a
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# CHECK: file.out`func1:
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# CHECK-NEXT: file.out[0x1000] <+4096>: int $0x2f
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#--- file.lds
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## Linker script placing the parts of the section into different segments
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## (typically one of these would be for the "hot" code).
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PHDRS {
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text1 PT_LOAD;
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text2 PT_LOAD;
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}
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SECTIONS {
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. = 0;
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.text.part1 : { *(.text.part1) } :text1
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.text.part2 : { *(.text.part2) } :text2
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}
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#--- file.s
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## A very simple function consisting of two parts and DWARF describing the
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## function.
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.section .text.part1,"ax",@progbits
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.p2align 12
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func1:
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int $42
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.Lfunc1_end:
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.section .text.part2,"ax",@progbits
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.p2align 12
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func1.__part.1:
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int $47
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.Lfunc1.__part.1_end:
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.section .debug_abbrev,"",@progbits
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.byte 1 # Abbreviation Code
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.byte 17 # DW_TAG_compile_unit
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.byte 1 # DW_CHILDREN_yes
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.byte 37 # DW_AT_producer
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.byte 8 # DW_FORM_string
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.byte 19 # DW_AT_language
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.byte 5 # DW_FORM_data2
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.byte 17 # DW_AT_low_pc
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.byte 1 # DW_FORM_addr
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.byte 85 # DW_AT_ranges
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.byte 23 # DW_FORM_sec_offset
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 2 # Abbreviation Code
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.byte 46 # DW_TAG_subprogram
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.byte 0 # DW_CHILDREN_no
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.byte 85 # DW_AT_ranges
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.byte 23 # DW_FORM_sec_offset
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.byte 3 # DW_AT_name
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.byte 8 # DW_FORM_string
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 0 # EOM(3)
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.section .debug_info,"",@progbits
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.Lcu_begin0:
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.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
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.Ldebug_info_start0:
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.short 5 # DWARF version number
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.byte 1 # DWARF Unit Type
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.byte 8 # Address Size (in bytes)
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.long .debug_abbrev # Offset Into Abbrev. Section
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.byte 1 # Abbrev DW_TAG_compile_unit
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.asciz "Hand-written DWARF" # DW_AT_producer
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.short 29 # DW_AT_language
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.quad 0 # DW_AT_low_pc
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.long .Ldebug_ranges0 # DW_AT_ranges
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.byte 2 # Abbrev DW_TAG_subprogram
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.long .Ldebug_ranges0 # DW_AT_ranges
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.asciz "func1" # DW_AT_name
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.byte 0 # End Of Children Mark
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.Ldebug_info_end0:
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.section .debug_rnglists,"",@progbits
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.long .Ldebug_list_header_end0-.Ldebug_list_header_start0 # Length
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.Ldebug_list_header_start0:
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.short 5 # Version
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.byte 8 # Address size
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.byte 0 # Segment selector size
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.long 1 # Offset entry count
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.Lrnglists_table_base0:
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.long .Ldebug_ranges0-.Lrnglists_table_base0
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.Ldebug_ranges0:
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.byte 6 # DW_RLE_start_end
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.quad func1
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.quad .Lfunc1_end
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.byte 6 # DW_RLE_start_end
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.quad func1.__part.1
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.quad .Lfunc1.__part.1_end
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.byte 0 # DW_RLE_end_of_list
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.Ldebug_list_header_end0:

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