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[dsymutil][DWARFLinker][NFC] Make interface of AddressMap more general.

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Current interface of AddressMap assumes that relocations exist.
That is correct for not-linked object file but is not correct
for linked executable. This patch changes interface in such way
that AddressMap could be used not only with not-linked object files:

hasValidRelocationAt()

replaced with:

hasLiveMemoryLocation()
hasLiveAddressRange()

Differential Revision: https://reviews.llvm.org/D87723
This commit is contained in:
Alexey Lapshin 2020-09-15 21:12:10 +03:00
parent e195dd75ce
commit 8c9a1f9e87
4 changed files with 78 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
include/llvm/DWARFLinker/DWARFLinker.h
View File

@ -64,14 +64,17 @@ public:
/// section. Reset current relocation pointer if neccessary.
virtual bool hasValidRelocs(bool ResetRelocsPtr = true) = 0;
/// Checks that there is a relocation against .debug_info
/// table between \p StartOffset and \p NextOffset.
///
/// This function must be called with offsets in strictly ascending
/// order because it never looks back at relocations it already 'went past'.
/// \returns true and sets Info.InDebugMap if it is the case.
virtual bool hasValidRelocationAt(uint64_t StartOffset, uint64_t EndOffset,
CompileUnit::DIEInfo &Info) = 0;
/// Checks that the specified DIE has a DW_AT_Location attribute
/// that references into a live code section. This function
/// must be called with DIE offsets in strictly ascending order.
virtual bool hasLiveMemoryLocation(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) = 0;
/// Checks that the specified DIE has a DW_AT_Low_pc attribute
/// that references into a live code section. This function
/// must be called with DIE offsets in strictly ascending order.
virtual bool hasLiveAddressRange(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) = 0;
/// Apply the valid relocations to the buffer \p Data, taking into
/// account that Data is at \p BaseOffset in the debug_info section.
@ -497,7 +500,6 @@ private:
/// Check if a variable describing DIE should be kept.
/// \returns updated TraversalFlags.
unsigned shouldKeepVariableDIE(AddressesMap &RelocMgr, const DWARFDie &DIE,
CompileUnit &Unit,
CompileUnit::DIEInfo &MyInfo, unsigned Flags);
unsigned shouldKeepSubprogramDIE(AddressesMap &RelocMgr, RangesTy &Ranges,

55
lib/DWARFLinker/DWARFLinker.cpp
View File

@ -421,32 +421,11 @@ void DWARFLinker::cleanupAuxiliarryData(LinkContext &Context) {
DIEAlloc.Reset();
}
/// Get the starting and ending (exclusive) offset for the
/// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
/// supposed to point to the position of the first attribute described
/// by \p Abbrev.
/// \return [StartOffset, EndOffset) as a pair.
static std::pair<uint64_t, uint64_t>
getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
uint64_t Offset, const DWARFUnit &Unit) {
DataExtractor Data = Unit.getDebugInfoExtractor();
for (unsigned I = 0; I < Idx; ++I)
DWARFFormValue::skipValue(Abbrev->getFormByIndex(I), Data, &Offset,
Unit.getFormParams());
uint64_t End = Offset;
DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End,
Unit.getFormParams());
return std::make_pair(Offset, End);
}
/// Check if a variable describing DIE should be kept.
/// \returns updated TraversalFlags.
unsigned DWARFLinker::shouldKeepVariableDIE(AddressesMap &RelocMgr,
const DWARFDie &DIE,
CompileUnit &Unit,
CompileUnit::DIEInfo &MyInfo,
unsigned Flags) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
@ -458,24 +437,12 @@ unsigned DWARFLinker::shouldKeepVariableDIE(AddressesMap &RelocMgr,
return Flags | TF_Keep;
}
Optional<uint32_t> LocationIdx =
Abbrev->findAttributeIndex(dwarf::DW_AT_location);
if (!LocationIdx)
return Flags;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
const DWARFUnit &OrigUnit = Unit.getOrigUnit();
uint64_t LocationOffset, LocationEndOffset;
std::tie(LocationOffset, LocationEndOffset) =
getAttributeOffsets(Abbrev, *LocationIdx, Offset, OrigUnit);
// See if there is a relocation to a valid debug map entry inside
// this variable's location. The order is important here. We want to
// always check if the variable has a valid relocation, so that the
// DIEInfo is filled. However, we don't want a static variable in a
// function to force us to keep the enclosing function.
if (!RelocMgr.hasValidRelocationAt(LocationOffset, LocationEndOffset,
MyInfo) ||
if (!RelocMgr.hasLiveMemoryLocation(DIE, MyInfo) ||
(Flags & TF_InFunctionScope))
return Flags;
@ -496,24 +463,14 @@ unsigned DWARFLinker::shouldKeepSubprogramDIE(
AddressesMap &RelocMgr, RangesTy &Ranges, const DWARFDie &DIE,
const DWARFFile &File, CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
unsigned Flags) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
Flags |= TF_InFunctionScope;
Optional<uint32_t> LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
if (!LowPcIdx)
auto LowPc = dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc));
if (!LowPc)
return Flags;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
DWARFUnit &OrigUnit = Unit.getOrigUnit();
uint64_t LowPcOffset, LowPcEndOffset;
std::tie(LowPcOffset, LowPcEndOffset) =
getAttributeOffsets(Abbrev, *LowPcIdx, Offset, OrigUnit);
auto LowPc = dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc));
assert(LowPc.hasValue() && "low_pc attribute is not an address.");
if (!LowPc ||
!RelocMgr.hasValidRelocationAt(LowPcOffset, LowPcEndOffset, MyInfo))
if (!RelocMgr.hasLiveAddressRange(DIE, MyInfo))
return Flags;
if (Options.Verbose) {
@ -527,6 +484,8 @@ unsigned DWARFLinker::shouldKeepSubprogramDIE(
if (DIE.getTag() == dwarf::DW_TAG_label) {
if (Unit.hasLabelAt(*LowPc))
return Flags;
DWARFUnit &OrigUnit = Unit.getOrigUnit();
// FIXME: dsymutil-classic compat. dsymutil-classic doesn't consider labels
// that don't fall into the CU's aranges. This is wrong IMO. Debug info
// generation bugs aside, this is really wrong in the case of labels, where
@ -563,7 +522,7 @@ unsigned DWARFLinker::shouldKeepDIE(AddressesMap &RelocMgr, RangesTy &Ranges,
switch (DIE.getTag()) {
case dwarf::DW_TAG_constant:
case dwarf::DW_TAG_variable:
return shouldKeepVariableDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
return shouldKeepVariableDIE(RelocMgr, DIE, MyInfo, Flags);
case dwarf::DW_TAG_subprogram:
case dwarf::DW_TAG_label:
return shouldKeepSubprogramDIE(RelocMgr, Ranges, DIE, File, Unit, MyInfo,

54
tools/dsymutil/DwarfLinkerForBinary.cpp
View File

@ -649,6 +649,60 @@ bool DwarfLinkerForBinary::AddressManager::hasValidRelocationAt(
return true;
}
/// Get the starting and ending (exclusive) offset for the
/// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
/// supposed to point to the position of the first attribute described
/// by \p Abbrev.
/// \return [StartOffset, EndOffset) as a pair.
static std::pair<uint64_t, uint64_t>
getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
uint64_t Offset, const DWARFUnit &Unit) {
DataExtractor Data = Unit.getDebugInfoExtractor();
for (unsigned I = 0; I < Idx; ++I)
DWARFFormValue::skipValue(Abbrev->getFormByIndex(I), Data, &Offset,
Unit.getFormParams());
uint64_t End = Offset;
DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End,
Unit.getFormParams());
return std::make_pair(Offset, End);
}
bool DwarfLinkerForBinary::AddressManager::hasLiveMemoryLocation(
const DWARFDie &DIE, CompileUnit::DIEInfo &MyInfo) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
Optional<uint32_t> LocationIdx =
Abbrev->findAttributeIndex(dwarf::DW_AT_location);
if (!LocationIdx)
return false;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
uint64_t LocationOffset, LocationEndOffset;
std::tie(LocationOffset, LocationEndOffset) =
getAttributeOffsets(Abbrev, *LocationIdx, Offset, *DIE.getDwarfUnit());
return hasValidRelocationAt(LocationOffset, LocationEndOffset, MyInfo);
}
bool DwarfLinkerForBinary::AddressManager::hasLiveAddressRange(
const DWARFDie &DIE, CompileUnit::DIEInfo &MyInfo) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
Optional<uint32_t> LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
if (!LowPcIdx)
return false;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
uint64_t LowPcOffset, LowPcEndOffset;
std::tie(LowPcOffset, LowPcEndOffset) =
getAttributeOffsets(Abbrev, *LowPcIdx, Offset, *DIE.getDwarfUnit());
return hasValidRelocationAt(LowPcOffset, LowPcEndOffset, MyInfo);
}
/// Apply the valid relocations found by findValidRelocs() to
/// the buffer \p Data, taking into account that Data is at \p BaseOffset
/// in the debug_info section.

7
tools/dsymutil/DwarfLinkerForBinary.h
View File

@ -144,7 +144,12 @@ private:
/// @}
bool hasValidRelocationAt(uint64_t StartOffset, uint64_t EndOffset,
CompileUnit::DIEInfo &Info) override;
CompileUnit::DIEInfo &Info);
bool hasLiveMemoryLocation(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) override;
bool hasLiveAddressRange(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) override;
bool applyValidRelocs(MutableArrayRef<char> Data, uint64_t BaseOffset,
bool IsLittleEndian) override;