class DwarfUnit

Defined at line 38 of file ../../src/developer/debug/zxdb/symbols/dwarf_unit.h

Represents a DWARF unit in the binary file. The primary purpose of this class is to allow

mocking the LLVM libraries. It corresponds to what we need from llvm::DWARFUnit and is consumed

primarily by ModuleSymbolsImpl which provides the high-level symbol interface.

This is a toplevel DWARF concept that contains all the different data types associated with the

compilation unit like line tables and abbreviation tables. The main thing it contains is the

Debug Information Entry (DIE) tree for the unit. This tree uses a root of DW_TAG_compilation_unit

and is represented in our system by the CompileUnit class.

These are similarly named so can be confusing, but this class is the higher-level construct.

Usually when something ion DWARF is "relative to the compilation unit" it means this class and

not the CompileUnit DIE.

Protected Members

WeakPtrFactory weak_factory_

Public Methods

DwarfBinary * GetBinary ()

Returns the binary this unit is a member of. May return null if the binary has been destroyed

out from under the reference-counted unit pointer.

llvm::DWARFUnit * GetLLVMUnit ()

Returns the LLVM unit for this object. Ideally this would be removed but it is necessary since

we expose a number of LLVM DIE helpers.

int GetDwarfVersion ()

Returns the DWARF specification version of this unit (e.g. "5").

llvm::DWARFDie GetUnitDie ()

Returns the DWARFDie corresponding to this unit.

LazySymbol FunctionForRelativeAddress (uint64_t relative_address)

Returns function covering the given absolute/relative address. This will the most specific

inlined subroutine if there are any. Returns an !is_valid() LazySymbol on failure.

uint64_t GetOffset ()

Returns the offset of the beginning of this unit within the symbol file. Returns 0 on failure.

The only failure case is that the symbols were unloaded.

std::string GetCompilationDir ()

The compilation directory is what the compiler decides to write. In normal usage this will be

an absolute directory on the current computer. In the Fuchsia in-tree build this will be

relative.

const LineTable & GetLineTable ()

The line table maps addresses to line numbers.

const llvm::DWARFDebugLine::LineTable * GetLLVMLineTable ()

Returns the internal LLVM line table. This will be null if there is no line table or there

is no LLVM object backing this unit.

TODO(brettw) this should be removed and all callers should use GetLineTable() so we don't have

to expose the internal LLVM line table pointer. This would allow us to mock the whole line

table for symbol tests.

The reason this function is here is that some older code uses the LLVM because making our

LineTable from LLVM's requires copying the table. This is nontrivial and we don't want to do

every time this is called. Therefore, we'd want to cache it on a DwarfUnit. But to be useful

the DwarfUnits must themselves be cached in the DwarfBinary whic does not happen yet.

uint64_t GetDieCount ()

Returns the number of DIEs in this unit.

llvm::DWARFDie GetLLVMDieAtIndex (uint64_t index)

Looks up a DIE in this unit by index or byte offset.

The byte offset is the absolute offset within the entire binary, but it must be a member of

this unit (LLVM does a binary search in the unit's DIE array for the DIE with the given

offset). See DwarfBinary::GetLLVMDieAtOffset() to query across units.

llvm::DWARFDie GetLLVMDieAtOffset (uint64_t offset)

uint64_t GetIndexForLLVMDie (const llvm::DWARFDie & die)

Back-computes the index for the given DIE in this unit. The DIE must be part of this unit or

the returned value will be incorrect (it just does a simple offset conversion).

fxl::WeakPtr<DwarfUnit> GetWeakPtr ()

Creates a weak pointer to this class. The units can get removed when modules or process are

unloaded so if you need to keep a pointer, either keep a weak ptr or an owning refptr.

Defined at line 42 of file ../../src/developer/debug/zxdb/symbols/dwarf_unit.h

Protected Methods

void DwarfUnit ()

Defined at line 105 of file ../../src/developer/debug/zxdb/symbols/dwarf_unit.h

void ~DwarfUnit ()

Defined at line 106 of file ../../src/developer/debug/zxdb/symbols/dwarf_unit.h

Friends

class RefCountedThreadSafe