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[lldb] Fix block address resolution for functions in multiple sections #137955

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merged 3 commits into from
May 7, 2025
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[lldb] Fix block address resolution for functions in multiple sections #137955

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[lldb] Fix block address resolution for functions in multiple sections
labath Apr 29, 2025
db6b2d1
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labath May 2, 2025
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labath May 5, 2025
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5 changes: 5 additions & 0 deletions lldb/include/lldb/Symbol/Block.h
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Original file line number Diff line number Diff line change
Expand Up @@ -354,7 +354,12 @@ class Block : public UserID, public SymbolContextScope {
// Member variables.
SymbolContextScope &m_parent_scope;
collection m_children;

/// Address ranges of this block. They are relative to the function entry
/// point so one must add/subtract GetFunction().GetAddress().GetFileAddress()
/// when converting from/to to the AddressRange representation.
RangeList m_ranges;

lldb::InlineFunctionInfoSP m_inlineInfoSP; ///< Inlined function information.
lldb::VariableListSP m_variable_list_sp; ///< The variable list for all local,
///static and parameter variables
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40 changes: 22 additions & 18 deletions lldb/source/Symbol/Block.cpp
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Expand Up @@ -283,39 +283,43 @@ uint32_t Block::GetRangeIndexContainingAddress(const Address &addr) {
return m_ranges.FindEntryIndexThatContains(file_addr - func_file_addr);
}

static AddressRange ToAddressRange(const Address &func_addr,
const Block::Range &block_range) {
assert(func_addr.GetModule());
return AddressRange(func_addr.GetFileAddress() + block_range.base,
block_range.size,
func_addr.GetModule()->GetSectionList());
}

bool Block::GetRangeAtIndex(uint32_t range_idx, AddressRange &range) {
if (range_idx >= m_ranges.GetSize())
return false;

Function &function = GetFunction();
const Range &vm_range = m_ranges.GetEntryRef(range_idx);
range.GetBaseAddress() = function.GetAddress();
range.GetBaseAddress().Slide(vm_range.GetRangeBase());
range.SetByteSize(vm_range.GetByteSize());
Address addr = GetFunction().GetAddress();
if (!addr.GetModule())
return false;

range = ToAddressRange(addr, m_ranges.GetEntryRef(range_idx));
return true;
}

AddressRanges Block::GetRanges() {
Address addr = GetFunction().GetAddress();
if (!addr.GetModule())
return {};

AddressRanges ranges;
Function &function = GetFunction();
for (size_t i = 0, e = m_ranges.GetSize(); i < e; ++i) {
ranges.emplace_back();
auto &range = ranges.back();
const Range &vm_range = m_ranges.GetEntryRef(i);
range.GetBaseAddress() = function.GetAddress();
range.GetBaseAddress().Slide(vm_range.GetRangeBase());
range.SetByteSize(vm_range.GetByteSize());
}
for (size_t i = 0, e = m_ranges.GetSize(); i < e; ++i)
ranges.push_back(ToAddressRange(addr, m_ranges.GetEntryRef(i)));
return ranges;
}

bool Block::GetStartAddress(Address &addr) {
if (m_ranges.IsEmpty())
Address func_addr = GetFunction().GetAddress();
if (!func_addr.GetModule() || m_ranges.IsEmpty())
return false;

Function &function = GetFunction();
addr = function.GetAddress();
addr.Slide(m_ranges.GetEntryRef(0).GetRangeBase());
addr = ToAddressRange(func_addr, m_ranges.GetEntryRef(0)).GetBaseAddress();
return true;
}

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110 changes: 110 additions & 0 deletions lldb/test/Shell/Commands/command-disassemble-sections.s
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@@ -0,0 +1,110 @@
## Test disassembling of functions which are spread over multiple sections (ELF
## segments are modelled as LLDB sections).


# REQUIRES: x86, lld

# RUN: split-file %s %t
# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux %t/file.s -o %t/file.o
# RUN: ld.lld %t/file.o -o %t/file.out -T %t/file.lds
# RUN: %lldb %t/file.out -o "disassemble --name func1" -o exit | FileCheck %s

# CHECK: (lldb) disassemble --name func1
# CHECK: file.out`func1:
# CHECK-NEXT: file.out[0x0] <+0>: int $0x2a
# CHECK: file.out`func1:
# CHECK-NEXT: file.out[0x1000] <+4096>: int $0x2f


#--- file.lds
## Linker script placing the parts of the section into different segments
## (typically one of these would be for the "hot" code).
PHDRS {
text1 PT_LOAD;
text2 PT_LOAD;
}
SECTIONS {
. = 0;
.text.part1 : { *(.text.part1) } :text1
.text.part2 : { *(.text.part2) } :text2
}

#--- file.s
## A very simple function consisting of two parts and DWARF describing the
## function.
.section .text.part1,"ax",@progbits
.p2align 12
func1:
int $42
.Lfunc1_end:

.section .text.part2,"ax",@progbits
.p2align 12
func1.__part.1:
int $47
.Lfunc1.__part.1_end:



.section .debug_abbrev,"",@progbits
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 1 # DW_CHILDREN_yes
.byte 37 # DW_AT_producer
.byte 8 # DW_FORM_string
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 17 # DW_AT_low_pc
.byte 1 # DW_FORM_addr
.byte 85 # DW_AT_ranges
.byte 23 # DW_FORM_sec_offset
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 2 # Abbreviation Code
.byte 46 # DW_TAG_subprogram
.byte 0 # DW_CHILDREN_no
.byte 85 # DW_AT_ranges
.byte 23 # DW_FORM_sec_offset
.byte 3 # DW_AT_name
.byte 8 # DW_FORM_string
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)

.section .debug_info,"",@progbits
.Lcu_begin0:
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
.Ldebug_info_start0:
.short 5 # DWARF version number
.byte 1 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.byte 1 # Abbrev DW_TAG_compile_unit
.asciz "Hand-written DWARF" # DW_AT_producer
.short 29 # DW_AT_language
.quad 0 # DW_AT_low_pc
.long .Ldebug_ranges0 # DW_AT_ranges
.byte 2 # Abbrev DW_TAG_subprogram
.long .Ldebug_ranges0 # DW_AT_ranges
.asciz "func1" # DW_AT_name
.byte 0 # End Of Children Mark
.Ldebug_info_end0:

.section .debug_rnglists,"",@progbits
.long .Ldebug_list_header_end0-.Ldebug_list_header_start0 # Length
.Ldebug_list_header_start0:
.short 5 # Version
.byte 8 # Address size
.byte 0 # Segment selector size
.long 1 # Offset entry count
.Lrnglists_table_base0:
.long .Ldebug_ranges0-.Lrnglists_table_base0
.Ldebug_ranges0:
.byte 6 # DW_RLE_start_end
.quad func1
.quad .Lfunc1_end
.byte 6 # DW_RLE_start_end
.quad func1.__part.1
.quad .Lfunc1.__part.1_end
.byte 0 # DW_RLE_end_of_list
.Ldebug_list_header_end0:
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